��ƷSM����ӰƬ

OP61 PDF (11 MB)

$10 + $5 shipping

Abstract

The glaciers of Mongolia have not been well studied; before now, the exact number of glaciers and their extent have not been known, and information about recent glacier fluctuations is sparse. The World Glacier Monitoring Service (WGMS) lists one Mongolian glacier; the Digital Chart of the World outlines only some glaciers in Mongolia; and the World Glacier Inventory (WGI) includes a few glaciers without providing information on when the data were collected. The international program Global Land Ice Measurements from Space (GLIMS) only recently added a so-called Regional Center for Mongolia to its list of regional observation centers, and the inventorying of all Mongolian glaciers has just been finalized. This contribution reviews and summarizes our knowledge about the glaciers, important current climatic conditions, and predicted future climate change in Mongolia. While it presents information from various published sources, it does not aim to evaluate the accuracy of this information or discuss potential disagreements within the scientific community.

OP60 PDF (2 MB)

OP60 Core Data Excel (0.3 MB) | OP60 Temp Data 1 of 2 Excel (21 MB) |  OP60 Temp Data 2 of 2 Excel (20 MB)

$13

Abstract

We present data from a field campaign focused on meltwater infiltration and horizontal water transport processes in firn of western Greenland. Data were collected during 2007-2009 along a 90 km transect extending from 2000 to 1300 m elevation. Fifteen intensive study sites were spaced 5-10 km along the transect. Near-surface heat flow was measured at each site with 33 channel thermistor strings extending to 10 m depth and logging year-round on a 30 minute time base. Firn stratigraphy and density were measured in 10-m-deep ice cores, with two or more cores at each study site for a total of 34 cores.

Analysis and interpretation of these data are made in other publications. Those analyses show that from 2000 to 1625 m elevation surface melt is minimal and meltwater infiltrates vertically to form thin ice layers. Between ≈1625 and 1475 m elevation strong surface melt infiltrates to fill about half of the available pore space of the upper 10 m. Infiltration shows a high degree of spatial variability in this elevation zone, with some water moving vertically and some water moving horizontally on top of decimeter- to meter-thick ice layers of irregular extent. In places, meltwater infiltrates to more than 10 m depth, and through multi-decade-old firn (i.e., well below the previous year's accumulation). Below ≈1475 m elevation, nearly all pore space is filled by infiltrated meltwater and excess water runs off. Both our thermal and density measurements indicate that the runoff limit is above the equilibrium line by on the order of 300 m in elevation and a distance of 30 km. Our results have implications for understanding the mass balance and surface elevation changes of the Greenland Ice Sheet.

OP59 PDF (1 MB)

$10.

Abstract

Radiocarbon Date List XI contains an annotated listing of 178 AMS radiocarbon dates on samples from marine (169 samples) and lake (9 samples) sediment cores. Marine sediment cores, from which the samples for dating were taken, were collected on the Greenland Shelf, Baffin Bay, and the Eastern Canadian Arctic Shelf. About 80% of the marine samples for dating were collected on the SW to N Icelandic shelf. The lake sediment cores were collected in northwestern Iceland. For dating of the marine samples, we submitted molluscs (117 samples), benthic and planktic foraminifera (45 samples), plant microfauna (3 samples), and one serpulid worm. For dating of the lake cores, we submitted wood (8 samples) and one peat sample. The Conventional Radiocarbon Ages range from 294 plus or minus 91¹⁴C yr BP to 34,600 plus or minus 640 ¹⁴C yr BP. The dates have been used to address a variety of research questions. The dates constrain the timing of high northern latitude late Quaternary environmental fluctuations, which include glacier extent, sea level history, isostatic rebound, sediment input, and ocean circulation. The dates also allowed assessment of the accuracy of commonly used reservoir correction. The samples were submitted by INSTAAR and affiliated researchers.

OP58 PDF (3 MB)

$10

Abstract

Glacier changes are having impacts on processes of global importance such as sea-level rise, hydrology of mountain-fed rivers, freshwater balance of oceans, and even the shape and rotation of the Earth. Here we discuss the effects of “small glaciers” — all perennial ice masses other than the Greenland and Antarctic ice sheets. We now estimate that the total area of these glaciers and ice caps to be about 785 ± 100 x 10³ km², somewhat larger than earlier estimates because of improved information on isolated glaciers and ice caps around the periphery of the large ice sheets. We estimate the total volume of this ice to be about 260 ± 65 x 10³ km³, equivalent to 0.65 ± 0.16 m of sea-level rise.

Glacier mass balance data (both annual and seasonal) can be used to infer current climatic change in precipitation and temperature, and the spatial distribution of these can assist in the analysis and modeling of climate change. This is especially important in high-mountain and high-latitude areas, where precipitation data are few and biased. Air temperature increase is the major forcing of glacier change. Glacier response to recent climate warming shows a steepening mass balance gradient with altitude due to increasing ice ablation below the equilibrium line altitude, and, to a lesser extent, increasing snow accumulation above that altitude. Observational results also show increasing glacier mass turnover and mass balance sensitivity to air temperature; these changes are not predicted by existing climate/glacier models. Sensitivity and turnover have also decreased in variability starting at the end of the 1980s.

Glacier wastage caused sea level to rise at a rate of 0.51 mm yr^–1 for the period 1961– 2003, but glaciers are now (1994–2003) causing sea level to rise 0.93 mm yr^–1. This freshwater addition to the oceans may be affecting ocean circulation and ocean ecosystems, and causing socio-economic impacts due to sea-level change. This contribution from glaciers is likely to continue to increase in the future. Acceleration of glacier wastage also affects other global processes, including spatial and temporal changes in Earth’s gravitational field, Earth oblateness and rotation rate, and regional uplift.

Global acceleration of glacier volume losses has affected the freshwater cycle at many scales, from global to local. The glacier contribution to the freshwater inflow to the Arctic Ocean has been increasing, and this increase will affect many aspects of the arctic climate system. Increasing summer runoff to large Asian rivers and high-elevation glacierized watersheds in both Americas is important for agriculture and human needs, but this release of water from ice storage may diminish in the future as the relatively small high-mountain glaciers begin to disappear.

OP57 PDF (0.3 MB)

$10

Abstract

As a result of both historic mining activity and natural biogeochemical processes, a large portion of the Snake River watershed in Summit County, Colorado has water quality that is impaired by acid rock drainage (ARD), resulting in low pH and elevated aqueous concentrations of metals, specifically Al, Cd, Cu, Mn, and Zn. This report presents chemical monitoring data collected during studies conducted from November 2001 through September 2002, a period of time which encompassed the most extreme drought that has been recorded in the region in the past 100 yr. This data set provides a description of several anthropogenic ARD sources. Further, it reveals that at most study sites, aqueous metal concentrations decreased during snowmelt in spring and were greatest in summer during the low stream flows associated with the severe drought conditions. This variability has direct implications for in-stream biota and for the design of future assessments of ecosystem potential.

OP56 PDF (4 MB)

$10

Abstract

Date List X contains an annotated listing of 213 radiocarbon dates determined on samples from marine and terrestrial environments. The marine samples were collected from the East Greenland, Iceland, Spitzbergen, and Norwegian margins, Baffin Bay, and Labrador Sea. The terrestrial samples were collected from Vestfirdir, Iceland and Baffin Island. The samples were submitted by INSTAAR and researchers affiliated with INSTAAR's Micropaleontology Laboratory under the direction of Dr.’s John T. Andrews and Anne E. Jennings. All of the dates from marine sediment cores were determined from either shells or foraminifera (both benthic and planktic). All dates were obtained by the Accelerator Mass Spectrometry (AMS) method. Regions of concentrated marine research include: Baffin Bay, Baffin Island, Labrador Sea, East Greenland fjords, shelf and slope, Denmark Strait, the southwestern and northwestern Iceland shelves, and Vestfirdir, Iceland. The non-marine radiocarbon dates are from peat, wood, plant microfossils, and mollusc. The radiocarbon dates have been used to address a variety of research objectives such as: 1. determining the timing of northern hemisphere high latitude environmental changes including glacier advance and retreat, and 2. assessing the accuracy of a fluctuating reservoir correction. Thus, most of the dates constrain the timing, rate, and interaction of late Quaternary paleoenvironmental fluctuations in sea level, glacier extent, sediment input, and changes in ocean circulation patterns. Where significant, stratigraphic and sample contexts are presented for each core to document the basis for interpretations.

OP55 PDF (2 MB)

Abstract

This is the most complete data set of parameters of glacier regime have ever been compiled and published before. Data presented in appendixes include annual mass balances and related variables of mountain and subpolar glaciers outside the two major ice sheets. All available sources of information, such as publications, archived data, personal communications have been collected and include time-series of about 280 glaciers. Only observational data have been used over the period since the beginning of measurements started in 1945/46 and until 1998. Data have been digitized and quality checked, and all errors found were eliminated. These all enhanced our knowledge on the modern glacier states, particularly:

1. The rate of annual melt-water production (ablation) by glaciers has been increasing, and comprised of about 1.7 m/yr in water equivalent for the period.
2. The annual accumulation (winter balance) rate has also been increasing with the average value of about 1.5 m/yr in water equivalent.
3. Annual volume change has been 90 km³/yr adding about 15-20% (0.25±0.11 mm/yr) to sea-level rise over the period.
4. The equilibrium-line altitude has risen by 200 m (square root error is about 100 m).
5. Accumulation area ratio decreased from about 60% in 1968 to 50% in 1998 (square root error is about 5%).
6. The mass balance sensitivity with respect to air temperature has changed at the end of 1980’s and reached – 700 mm per degree °C.

The existing trend in glacier volume change shows that wastage of glaciers will accelerate in continental regions, North America South America, Central Asia. Subpolar glaciers, outside the two major ice sheets, will contribute more to sea-level rise.

OP54 PDF (0.7 MB)

$10

Abstract

This Date List contains an annotated listing of 385 radiocarbon dates determined on samples from the marine environments of Antarctic, Arctic Ocean, northern North Atlantic, Icelandic Lakes, and Colorado. Samples were submitted by people affiliated with INSTAAR’s Micropaleontology Lab under the direction of Drs. John T. Andrews and Anne E. Jennings. Nearly all of the dates are from marine cores on acid-insoluble organic material, shells, and foraminifera. All of the dates were obtained by the Accelerator Mass Spectrometry (AMS) method. Regions of concentrated research include: the Ross Sea, the Weddell Sea, the Beaufort Sea, Hudson Strait, Baffin Bay, the Labrador Shelf and Sea, East Greenland fjords and shelf, the Denmark Strait, Iceland Plateau, the southwestern and northwestern Iceland Shelves. The three non-marine radiocarbon dates are from lake sediments in Iceland and on a gastropod from an outcrop in Colorado. The radiocarbon dates have been used to address a variety of research questions including timing of the environmental changes including glacier advance and retreat, the appropriateness of commonly adopted marine reservoir corrections, and testing the validity of acid- insoluble organic dates for Antarctica. Thus, most of the dates constrain the timing, rate, and interaction of late Quaternary paleoenvironmental fluctuations in sea level, glacier extent, sediment input, and changes in ocean circulation patterns. Stratigraphic and sample contexts are presented for each core to document the basis for interpretations.

OP53 PDF (8 MB)

OP 53 Data Tables Excel (0.2 MB)

$5

Abstract

The issues of development of alpine areas and the possible influences of climate change in the Rocky Mountain region have both increased the focus of understanding processes controlling the water quality of mountain streams. This report presents 10 years of water quality and stream flow data from two headwater basins in Summit County, Colorado. The upper reach of the Snake River is acidic and metal-enriched from the natural and anthropogenic weathering of pyrite in the watershed, whereas the water quality of Deer Creek is pristine with a circumneutral pH. The Snake River and Deer Creek watersheds have been sites of extensive research for the past 15 years, and the data in this report have been used in these interpretative studies. The data sets are one of the longest water quality records for streams in the upper Colorado Rivers basin and provide a description of how water quality has varied with differences between years in snowpack and other climatic parameters.

OP52 PDF (7 MB)

$5

Abstract

[From the Preface] This volume contains the proceedings from two workshops that describe progress toward a Circumpolar Arctic Vegetation Map (CAVM). The bulk of the volume is devoted to the Second International CAVM Workshop in Arendal, Norway, 19-24 May 1996. This workshop was attended by representatives from all of the circumpolar nations. Twenty-seven papers described the progress that had been made since the first workshop in St. Petersburg, Russia, in 1994, and the abstracts of those papers are presented here. The second part of this volume contains the results of a North American CAVM workshop held in Anchorage, Alaska, 14-16 January 1997. This workshop was attended by participants from Greenland, Canada, and the US. A summary of the proceedings, and a paper describing a prototype map for northern Alaska are presented. The purpose of these proceedings is to keep the arctic-science and vegetation-science communities appraised of progress and to provide documentation to the membership of the CAVM working group.

OP51 PDF (2 MB)

Corrected Table 32 PDF (1 MB)

$5

Abstract

The McMurdo Dry Valleys, located in South Victoria Land, are the largest of the polar desert oases found along the coast of Antarctica. Glacial meltwater streams are an important aquatic habitat in the McMurdo Dry Valleys.

This report presents results on the abundance and species distribution of algal mats at 16 stream sites in Taylor Valley.

Results indicate that species of filamentous cyanobacteria are the most abundant algae in the dry valley streams. Algal mats were classified on the basis of on apparent color into four mat types. "Black-colored algae" were found in the wetted zone adjacent to the streambed and were primarily composed of Nostoc. "Green-colored algae" were found attached to the surface/undersurface of rocks in the main stream channel and were mainly composed of Prasiola. "Orange-colored" and "red-colored algae" occurred in the streambed regions with the greatest flow and had a greater diversity of species. The abundance of algal mats is controlled by sediment transport and the characteristics of the streambed. Algal mats were more abundant in streams where the streambed is composed of a stone pavement. In streams with abundant algal mats, the nutrient concentrations are lower than in streams with sparse algal mats.

OP50 PDF (14 MB)

Abstract

This Date List contains an annotated listing of 420 radiocarbon dates determined on samples from the Eastern Canadian Arctic, Labrador, Northern Quebec, East Greenland, Iceland, and Antarctica. Nearly two-thirds of the dates are on materials recovered from marine cores from northern Hudson Bay, Hudson Strait, the southern and eastern Baffin Island Shelves, the Labrador Shelf and Sea, Baffin Bay, the East Greenland Fjords, Shelf and Slope, the southwestern and northwestern Iceland Shelves, the Ross Sea Shelf, and offshore the Northern Antarctic Peninsula. Much of the remainder of the dates are on materials obtained from terrestrial geologic and archeological sites near Ungava Bay, on northern Ungava Peninsula, and on southern Baffin Island, including the shores of Meta Incognita Peninsula and Frobisher Bay. One-tenth of the dates are on materials obtained from lake cores taken from northern Labrador, northeast Quebec, and southern Baffin Island. The dates have been used to address a variety of research questions. Their stratigraphic and sample contexts are presented here to document the basis for interpretations. Most of the dates constrain the timing, rate, and interaction of late Quaternary paleoenvironmental fluctuations in sea level, glacier extent, sediment input, and ocean circulation. Others bear on investigations into the limitations and applications of geochronologic methods, or on the pace and timing of cultural evolution in high latitudes. Nearly all of the dates (85%) were obtained by the Accelerator Mass Spectrometry (AMS) method. The majority of the dates (61%) were produced by the National Science Foundation – University of Arizona AMS Facility. The prevalent use of AMS dating reflects the ability to analyze small samples to obtain high-resolution chronologies of environmental change.

OP49 PDF (6 MB)

$5

Abstract

Sorted nets, sorted stripes, earth hummocks, and frost boils were studied from 1961 until 1969 on Niwot Ridge and in the Boulder City Watershed, Colorado Front Range. The study produced maps, profile descriptions, and fabric data for representative patterns, measurements of modern activity, and observations on age and paleoenvironmental significance. Field evidence and laboratory studies suggest that most of the patterns formed rapidly, by upward mass displacement of plugs of fine earth in response to density imbalances in the thawing soil; some of the patterns then continued to evolve slowly due to circulatory overturn driven by vertical frost heaving in their centers.

The occurrence of large-scale sorted nets and stripes on well-drained knolls and ridgecrests at altitudes as low as 3245 m implies that icy permafrost existed at least 100 m below modern timberline during the late Pleistocene. Sorted nets have developed at even lower altitudes during the past century, but only in microenvironments where autumn saturation does not require the presence of a frozen substratum. Moisture-induced changes in frost intensity during the Holocene caused areas of patterned-ground activity to contract and expand; the general trend in the Front Range during the past 25 yr has been toward revegetation of frost-patterned ground

OP48 PDF (7 MB)

$5

Abstract

This Date List contains an annotated listing of 217 radiocarbon dates obtained on samples from the Canadian Arctic and East Greenland shelf. The dated material was recovered from marine cores from the Baffin Island and East Greenland shelves, collected from lake cores, and terrestrial exposures in western Hudson Strait, southeastern Baffin Island, and northern Baffin Island. The dates are used to address a variety of research questions. Some dates concern the timing and rate of paleoenvironmental changes such as sea-level, glacial, and sedimentological fluctuations; others bear on investigations into the applications and limitations of geochronological methods. Most of the dates (93%) were produced by the Accelerator Mass Spectrometer (AMS) at the University of Arizona. The prevalent use of AMS dating reflects the enhanced potential for obtaining a high-resolution chronostratigraphy using this technology, especially in arctic lake and marine environments where dateable materials are frequently scarce.

OP47 PDF (3 MB)

$5

Abstract

Svalbard Radiocarbon Date List I is the first compilation of radiocarbon dates from the Svalbard Archipelago. Reported are 135 radiocarbon dates on whalebone, driftwood, peat, shell, and foraminifera collected mostly from raised marine and glacial deposits. A number of the whalebones have both collagen and apatite radiocarbon ages. A majority of the dated material is either <13 ka or >30 ka. These dates provide a firm chronologic basis to understand the timing of relative sea level and glacial events during the Weichselian on Svalbard.

OP46 PDF (6 MB)

$5

Abstract

Date List III from Labrador and Northern Ungava includes 8 new radiocarbon dates, whereas Date List VI for Baffin Island adds another 116 radiocarbon assays to the earlier compilations. In Date List VI the dates are listed from south to north in each of six geographic areas. This list includes 66 accelerator mass spectrometry (AMS) dates on small milligram samples of shell, foraminifera, and organics; many of the AMS dates are from a suite of marine piston cores collected within the fiords and on the shelf of Baffin Island. The bulk of the samples, 72/122, are on marine shells but 31 dates are reported on the acid-insoluble fine-grained organic matter fraction (ATOM) of cores. Seven samples are on hand-picked foraminifera. Two indexes are provided for the combined date lists, ordered by laboratory identification number or by reported radiocarbon age.

Two indexes are provided to 470 radiocarbon dates from previous date lists from Baffin Island. These indexes are ordered by laboratory identification number and by the reported radiocarbon date.
For interested parties this compilation (Date Lists III and VI) can be purchased as an ASCII file for PC computers.

OP45 PDF (3 MB)

$5

Abstract

The seeds and other propagules of 75 species of alpine plants were collected from the tundra zone of Niwot Ridge, Colorado Front Range. We present here a photographic atlas of these seeds, and a key to their identification.

OP43 PDF (8 MB)

$5

Abstract

This bibliography comprises 993 references to the literature on the alpine and subalpine areas of the Front Range, Colorado. This bibliography is interdisciplinary and covers 25 scientific disciplines from Archaeology to Taxonomy. It will serve as an introduction to the rich literature about the science of the high mountain regions west of the University of Colorado at Boulder. As an historical document, emphasis has been placed on the heritage of research associated with the Mountain Research Station and the Institute of Arctic and Alpine Research. Additional literature from Rocky Mountain National Park south to Longs Peak has been included. References are listed by author and indexed by key word and author. The key word system was developed as part of the Long-Term Ecological Research program of the National Science Foundation.

OP42 PDF (6 MB)

$5

Abstract

Nine hundred and one references are listed by year and then by author, followed by an index to all authors. Research reported has been carried out during the past 17 years by members and associates of the Institute of Arctic and Alpine Research (INSTAAR), University of Colorado. Field areas reported on cover arctic and alpine areas worldwide, concentrating on Alaska, Arctic Canada, and the Colorado Rocky Mountains, and related paleoenvironments.

OP41 Vol. I PDF (30 MB)

OP41 Vol II. PDF (18 MB)

$10

Abstract

Approximately thirteen hundred annotated references to the literature on Holocene paleoclimates, with emphasis on high latitude and high altitude areas, are presented as the result of a project sponsored by the U.S. Department of Energy, Carbon Dioxide Research Division. Covering the past twenty years of research results published worldwide, materials are included from the physical, biological, and earth sciences wherever environmental phenomena sensitive to climatic changes have resulted in proxy records. The references have been divided into fifteen subject categories, based on the primary method of climatic reconstruction. The references are indexed by author, subject category, keywords, time period within the Holocene epoch, geographic area, title, and dating methods; maps are included for reference. The bibliography is preceded by an introduction that details selection and formatting procedures. [Keywords: Agriculture, Archaeology, Climatology, Dendroclimatology, Geology, Geomorphology, Glacial geology, Glaciology, History, Oceanography, Paleobotany, Paleozoology, Palynology, Pedology, Stratigraphy]

OP40 PDF (4 MB)

$5

Abstract

The two combined radiocarbon date lists for Baffin Island and Labrador include 100 samples: 81 are from Baffin Island; 16 from Labrador and three miscellaneous dates, two of which are from the Ottawa Islands, N.W.T. (Hudson Bay) and the third on marine carbon from the state of Maine. Most dates come from marine shells but significant numbers are also reported from peats, lake sediments, and marine sediments. The sites of the dated samples come from 17 1:250,000 NTS Map Sheets, although the largest concentrations of dates are from the Frobisher and Grinnell Glacier maps sheets of southern Baffin Island. Organic carbon dates from marine cores in nearshore troughs off the eastern coast of Baffin Island give basal dates of between 16,000 and 26,000 yr BP.

OP39 PDF (16 MB)

Abstract

Textural parameters, mass physical properties, mineralogy, x-radiography, and chemistry were used to identify and delineate lithofacies in the sediments of Kane Basin. Q-mode factor analysis was used to group the sediments into compositionally similar factors. This resulted in three factors which account for 91.7% of the variance. Detailed studies of the parameters making up the factors as well as an examination of sediment fabric allowed placement of the sediments into the following lithofacies:

Recent
Factor I {Sediments dominated by ice rafting
{Sediments dominated by water transport

Relict
Factor II {Ellesmere Island till (till 1)
Factor III {Greenland till (till 2)

The sediments dominated by water transport occur near the Inglefield Land coast, and extend to the northwest. Sediments dominated by ice rafting are most abundant in the vicinity of the Humboldt Glacier. They are also present in the south central part of the Basin, northwest of Inglefield Land. The Ellesmere Island till (till 1) is found in the western Basin while the Greenland till (till 2) is located in the northeastern Basin along the topographic high, southwest of Washington Land, Greenland.
Examination of the areal and temporal (down core) distribution of the lithofacies indicates that the tills were deposited concomitantly. They differ primarily in terms of mineralogy and gravel composition. These differences reflect different source areas. Much of the Ellesmere Island till (till 1) originated from the materials making up the Tertiary outliers found in northeastern Ellesmere Island. The Greenland till (till 2) was derived from Paleozoic carbonate rocks of Washington Land, and the crystalline basement beneath the Humboldt Glacier.
The deposition of the tills was followed by a period when ice rafting was dominant. This was succeeded by an increase in the deposition of water-transported materials emanating primarily from Inglefield Land. Both ice rafting and water transport are going on at the present time.

OP38 PDF (8 MB)

$6

Abstract

No abstract. Published in Spanish. The English version of this paper was published as Occasional Paper 27.

OP37 PDF (17 MB)

Abstract

[From the Preface] This report reviews the understanding of the alpine ecosystems as a first step in the University of Colorado, Long-Term Ecological Research project (CULTER), which is monitoring and studying the alpine ecosystem as exemplified on Niwot Ridge and in the Green Lakes Valley above the Mountain Research Station.

[From the Contents] “Introduction: The University of Colorado Long-Term Ecological Program,” “Physical and Geological Nature of the Indian Peaks, Colorado Front Range,” “Water and Sediment Flows in the Green Lakes Valley, Colorado Front Range,” “Air Quality and Surface Energy Budget,” “Review of the Late Quaternary History of Vegetation and Climate in the Mountains of Colorado,” “Spatial and Temporal Variation of the Vegetation and Its Productivity on Niwot Ridge, Colorado,” “The Effects of Augmented Winter Snow Cover on the Canopy Structure of Alpine Vegetation,” “Success of Transplanted Alpine Plants on Niwot Ridge, Colorado,” “Plant Population Biology above Timberline: Biotic Selective Pressures and Plant Reproductive Success,” “Ecological and Evolutionary Studies of Forest Trees in Colorado,” “Air Pollution and the Ecology of Plants,” “Small Mammal Herbivores of the Colorado Alpine Tundra,” “Invertebrate Communities and Dynamics of Alpine Flowages,” “The Status of Unexploited Fish Populations in the Green Lakes Valley, an Alpine Watershed, Colorado Front Range,” “A Review of Some Aspects of Bacteriological Decomposition of Plant Litter in the Colorado Alpine.”

OP36 PDF (3 MB)

$5

Abstract

[From the Preface] This is the first Occasional Paper devoted to listing radiocarbon dates of the Labrador-Ungava peninsula. Five radiocarbon date lists have already been published for Baffin Island to make a total of six lists now covering the eastern Canadian Arctic. The samples reported were collected by INSTAAR members, students, and associates over four field seasons. Radiocarbon date lists conveniently bring together information which would otherwise be dispersed throughout the literature.

Site descriptions and locations are presented for 92 radiocarbon dated samples from the Labrador-Ungava peninsula, Canada. The samples are primarily lake and peat sediments, reflecting a bias for pollen-rich sediments; their dates range between 0 and 19,000 BP. Two dates on a single shell collection are significantly older. (>34,000 and >42,000 BP). The dates are presented by geographic location using the 1:250,000 Canadian NTS map series as well as in chronological order

This list will be of interest and importance to all students of the Quaternary of Labrador and northern Quebec, especially palynologists, biogeographers, and glacial geologists.

OP35 PDF (8 MB)

$5

Abstract

A color vegetation map at the scale of 1:12,000 of the area surrounding the Rocky Flats, Rockwell International Plant near Boulder, Colorado, provides a permanent record of baseline data which can be used to monitor changes in both vegetation and environment and thus to contribute to future land management and land-use policies. Sixteen mapping units based on species composition were identified, and characterized by two 10-m² vegetation stands each. These were grouped into prairie, pasture, and valley side on the basis of their species composition. Both the mapping units and these major groups were later confirmed by agglomerative clustering analysis of the 32 vegetation stands on the basis of species composition. A modified Bray and Curtis ordination was used to determine the environmental factor complexes controlling the distribution of vegetation at Rocky Flats. So that a great number of zero similarities between stands would not occur, a growth-form data matrix was used as ordination input; this proved to be a satisfactory alternative to input of species data to ordination programs. It was determined during ordination trials that the above-mentioned ordination technique was more efficient and successful in interpreting the vegetation at Rocky Flats than principal components analysis when growth-form data input was used. Three environmental factor complexes correlated significantly with the ordination axes: percentage of nonvegetated area (X axis), moisture regime (Y axis), and grazing regime (Z axis). This correlation agreed well with the observations made during field work and during map analysis. The growth forms were shown to have a significant relationship with the controlling environmental factors. Recommendations are made for future policies of environmental management and predictions of the response to environmental change of the present vegetation at the Rocky Flats site.

OP34 PDF (7 MB)

$5

Abstract

Baffin Island and nearby regions of the eastern Canadian Arctic have been the focus of many recent and ongoing paleoclimatic and glaciological studies. The region is very suitable for these studies because of the sensitivity of regional ice and snow conditions to small changes in summer temperature (which average a few degrees above freezing). Baffin Island’s location beneath one of the major features of the general atmospheric circulation, a trough in the upper westerlies, raises the possibility that regional climate variations may be closely linked to changes in the global-scale climate and circulation. The existence of such a link would greatly enhance the importance of Baffin Island paleoclimatic and glaciological studies.

In this study, thirty summers (1946–76) of surface temperature and pressure, and upper air data for the Baffin region, the Arctic, and the extratropical northern hemisphere, are analyzed to establish the nature and significance of the regional-global summer climate and circulation links.

The variability of Baffin area summer temperatures is shown to be statistically significant on time scales greater than two years and to be closely correlated with the variability of the Arctic zonal average summer temperature. The most significant climatological event at Baffin Island during the thirty summers of record is the cooling of the early 1960’s; this event is given special emphasis in this study.

From an analysis of daily surface synoptic pressure patterns, subjective surface cyclone tracks, and 500 mb positive vorticity flux, it is found that colder summers at Baffin Island are associated with an increase of cyclone activity over Baffin Bay and an intensification of the Arctic front storm track across northern Canada. Colder summers are also associated with eastward displacements of the upper (500 mb and 700 mb) Baffin trough, which in turn are associated with stronger upper westerly winds at the latitude of the trough and over most of the northern hemisphere. Stronger westerly winds are shown to be related to greater meridional temperature gradients associated with general hemispheric coolings.

Because of the regional-global scale correlations found in this study, Baffin Island appears to be a significant indicator of larger-scale summer climate conditions and of the nature of the general circulation over time scales from 2 to 10 years. These correlations do not weaken within these time scales, and may very well extend to the time scales of interest to paleoclimatologists and glaciologists.

OP33 PDF (13 MB)

$5

Abstract

Over four hundred and sixty references, the majority of which include abstracts from secondary sources, are presented. Covering the broad subject area of the Quaternary environment of Baffin Island, Canada, they are arranged according to thirteen more specific subject categories. An author index follows the bibliography. Two figures and some introductory remarks give the user a reference framework.

OP32 PDF (6 MB)

$5

Abstract

[From the Preface] Increasing use of mountainous areas of the western United States for recreation and mining places great stress on all parts of the montane environment. One aspect of this environment which has received relatively little attention in the past has been the quality of mountain air — once assumed to be pristine but now, in many places, in danger from the wood-burning fires of ski resort condominiums and dust from the machines of the strip miner.

This study provides a contribution to the field of air quality maintenance in complex terrain with emphasis on the single valley case. Such sites are where vacation resorts are often located. A review of basic approaches to estimating atmospheric dispersal and subsequently air quality in complex terrain shows the box model to be useful in many cases. Its applicability would be extended if the upper limit of the 'box' could be found without making actual observations. Thus attempts are made to determine the location of the lid in the absence of on-site data. Long term National Weather Service Rawinsonde data give interesting results but none that can be used operationally. Little success is met in seeking spatial relations in short term inversion data. The most profitable approach seems to be in the use of a theoretical model of inversion rise dynamics. A box model of atmospheric dispersion is utilized in a) a standard form, b) with modeled mixing heights and c) with a tilted inversion lid. The latter does not significantly improve the performance of the basic model. However, there is evidence to suggest the flexibility of using modeled mixing height data with the box model. An interesting lag effect is noted for the model. Finally, some practical aspects with regard to air pollution potential and the land use manager are discussed.

Abstract

A climatological study of the North Pacific Oscillation (NPO) between 1906 and 1978, and a related analysis of the eigenvectors of northern hemisphere sea level pressure (SLP) and 500 mb height departures for the winters 1946–47 through 1976–77, are performed. Two types of eigenvector analysis are carried out: the first is for mean winter pressure and height anomalies for the 31 winters and the second is for daily pressure and height departures during each individual winter. Eigenvector patterns based on daily data are compared between winters and also with the seasonal mean anomaly eigenvector patterns. Eigenvector patterns based upon unnormalized data appear to show real spatial variability in atmospheric anomaly fields whereas eigenvectors from normalized data are less useful. The associations between the time coefficients of the pressure and height eigenvector patterns, and their relationship to the climatological fields associated with the NPO and the Greenland-Europe winter temperature “seesaw,” or North Atlantic Oscillation (NAO), are elaborated.

The NPO results from longitudinal variations in the mean position of the Aleutian Low and is associated with regional variations in climatic parameters, particularly over North America. The NAO is due to variations in the intensity of the Icelandic Low and is associated with hemispheric variations in climatic parameters. Both oscillations, and their eigenvector pattern equivalents, are climatic features characterized by interannual variability. The NAO is associated with hemispheric trends in temperature, which vary with the relative frequency of the two modes of the oscillation. In contrast neither mode of the NPO has predominated over the other since 1906. The two oscillations represent separate patterns of teleconnection in pressure and winds.

Other results show that large, significant variations in air temperature and precipitation occur between modes of the NPO. Variations in the Bering Sea ice edge averaged about 275 km between occurrences of the two oscillation modes during recent winters, but there was little significant difference in sea surface temperatures in the North Pacific Ocean.

The patterns of January mean pressure variability during the modes of the NPO are shown to resemble the second eigenvector of SLP anomalies determined in an independent study employing January data. Both the eigenvector and pressure variability patterns change spatially when data for winters (DJF) are used, suggesting that the climatic fields associated with this oscillation vary during the course of the winter. This oscillation is compared with the climatic fields found for the NAO, which resembles the first eigenvector when either January or wintertime data are used. The NAO shows little change during winter months.

The time coefficients of the first eigenvector pattern of 500 mb height anomalies are highly correlated to the coefficients of both the first and second SLP eigenvectors. The thermal anomalies in the atmosphere suggested by the first 500 mb eigenvector pattern also resemble those which are associated with the NAO and NPO. The analysis of daily-data eigenvectors for individual winters shows between-year differences. Winters when daily-data eigenvector patterns resemble the mean winter anomaly field are usually those when one or both of the oscillations occur and particularly modes with persistent blocking. Most eigenvector patterns based on daily data resemble weather noise, but the percent of the total variance they explain increases when the data are filtered using five-day or eleven-day running means. The patterns change little when the data are smoothed.

OP30 PDF (10 MB)

$5

Abstract

[From the Preface] Many researchers over the years have been interested in the relationships between atmospheric circulation patterns and local weather and climate. Numerous classifications of pressure pattern or airflow types have been formulated and catalogs of their daily occurrence prepared. Until recently, investigators had to use subjectively determined classification categories and the labor involved in preparing catalogs of synoptic types spanning several decades was considerable. Now several “objective” techniques exist which permit long series of such circulation statistics to be prepared rapidly. This study utilizes one of these techniques to classify circulation patterns over Alaska and adjacent ocean areas. The climatic characteristics of the circulation types are documented for stations on the Beaufort Sea coast of Alaska and the results are analyzed in terms of their meteorological reality, as well as statistically.

The study is part of a broader program relating to the effects of both the seasonal climatic regime and synoptic weather events on shorefast ice conditions along the Beaufort Sea coast. The specific climatic information will be of interest to many environmental scientists working on Alaskan problems, while the procedures employed by R. E. Moritz provide a proven systematic approach for application of synoptic-climatological methods in other regions.

OP29 PDF (4 MB)

$5

Abstract

Site descriptions and locations are presented for 79 radiocarbon dated samples from Baffin Island, NWT, Canada that have not been reported in previous date lists (Andrews and Drapier, 1967; Andrews and Miller, 1972; Andrews, 1975; Andrews, 1976). The samples were collected from eastern and central Baffin Island between latitudes 62 and 72°N and longitudes 61 and 76°W. The largest percentages of dates are from sites on northern Cumberland Peninsula, Cumberland Sound, and Frobisher Bay. The dates are nearly evenly divided between marine shells and plant remains, plus three dates on whale bone. Most of the shell dates fall between 8000 and 11,000 BP with an additional group between 44,000 and 51,000 BP, reflecting the predominance of marine deposits in these time ranges. The list includes multiple dates on successive leaches of a single shell collection, interlaboratory checks and organic/inorganic carbon comparisons. Dates on plant remains are more varied and range between 0 and 10,000 BP with an additional group between 38,000 and 50,000 BP.

The dates are presented by geographic location using the 1:250,000 Canadian NTS map series. Individual samples are located both by latitude and longitude as well as the 10 × 10 km UTMG grid system. In all cases, locations are based on the most recent issue of the 1:250,000 map series. Grid locations are given by a pair of three digit figures, the first referring to 10² m eastings, the latter to 10² m northings. A separate listing of dates in chronological order is also provided.

OP28 PDF (8 MB)

$5

Abstract

A prominent feature of inter-annual variability in middle and high latitudes is the so-called “Greenland Seesaw,” the well-known tendency for winter temperatures to be low over northern Europe when they are high over Greenland (GA), and vice versa (GB). Well-defined mean pressure anomalies over the North Pacific, America, North Atlantic, and Europe are associated with these temperature patterns. In this study tropical teleconnections associated with the seesaw are discussed. It has been found that the strength of mean sea-level westerlies in the central North Atlantic Ocean during seesaw winters is highly correlated with that of the northeast and southeast trades in the Atlantic, with the trades being stronger (weaker) during GB (GA) winters. Similar associations exist with the trade winds in the North Pacific. There is a statistically significant correlation between the strength of the northeast and southeast trades in the Atlantic during the seesaw winters, but not in other winters. The position of the subtropical jet at 300 mb in the Northern Hemisphere appears to move north (south) in the GB (GA) winters with the exception of a shift in the opposite sense over Africa. A southward (northward) shift in the position of the ITCZ in Africa, as defined by the belt of heaviest precipitation, is seen during the winters when Greenland temperatures are well below (above) those in northern Europe.

Relative sea levels taken across the Gulf Stream indicate that geostrophic velocity of the current decreases (increases) in the GB (GA) winters. Significantly lower (higher) sea surface temperatures exist across the tropical North Atlantic, North Pacific, and Indian Oceans during GB (GA) winters. Atmospheric-related patterns appear strongly only during seesaw winters, although small magnitude pressure anomaly patterns of the type seen during seesaw winters are present in autumns preceding those seesaw winters. Trade wind anomalies seem to persist through all seasons prior to and following seesaw winters south of 20°N, with the northern fringes of the trade wind belt reacting mainly during seesaw winters. In contrast, ocean-related features associated with the seesaw occur at all latitudes in summers and autumns preceding, and springs following, seesaw winters.

OP27 PDF (8 MB)

$5

Abstract

[From the Introduction] The monograph that follows is a discussion of the high-altitude, mountainous environment in southern Peru. Geology, climate, soils, and natural and domesticated biota will be considered. Initially our description will be of the central Andes as a region and of the complex gradients of climate and vegetation, which cross this area northwest to southeast and northeast to southwest. These gradients then provide the environmental context for more detailed treatment of a limited geographic area surrounding the town of Nuñoa (Melgar Province, Department of Puno), an example of the highland region, or altiplano.

Since a full discussion of our topic is clearly impossible, we have attempted to partition the information we can present. Emphasis in the text will be on the complex set of interacting factors that combine to form an environment multiply heterogeneous in time, space, and pattern. The preponderance of descriptive data will be found in figures and graphs. We have also attempted to balance the presentation of normative data, which provide a general picture of an environment, with data representing environmental variability. The relative extremes of environmental variables are often critical in the study of adaptation. Where environmental factors are treated as stressors we will be concerned with their frequency, intensity, duration, and regularity, and with the effect of these parameters on the variety of adaptive responses available to plants and animals. This review of highland environment and general biotic adaptation to the highland zone sets the context for the detailed treatment of human adaptation.

OP26 PDF (14 MB)

$5

Abstract

The fast-ice regime in the vicinity of Broughton Island, N.W.T., Canada, is described based on field studies during 1971–75, analysis of satellite imagery, and synoptic climatological analyses. The period studied exhibited strong contrasts with no ice breakup in 1972; the average date is 31 July ± 10 days, coinciding with about 180 thawing degree days (°C) at Broughton Island (581 m). Southwesterly flow situations with strong sensible heat advection accelerate melt, whereas northeasterly airflow retards it. The report includes an objective catalog of daily MSL pressure patterns for 1946–74, description of a simple melt model, microclimatological measurements on the fast ice, and analysis of climatic trends related to ice conditions.

OP25 PDF (20 MB)

$5

Abstract

[From the Preface] This is the second avalanche atlas produced by the Institute of Arctic and Alpine Research (INSTAAR) for the main transportation arteries of a San Juan Mountain county. In a sense, it is a natural extension of the first, compiled by Miller, Armstrong, and Armstrong (1976), for San Juan County. Together, the two atlases represent a major component of INSTAAR’s research, now in its sixth year, that deals with snow and avalanche studies in the San Juan Mountains. This atlas constitutes the work of the INSTAAR Snow and Avalanche Project, based at Silverton under the leadership of Richard L. Armstrong. It is complemented by a natural hazard research project supported by a grant from the National Aeronautical and Space Administration (NASA) Office of University Affairs.

Snow avalanches present a major obstacle to effective land-use planning in the San Juan Mountains in particular, and in the entire mountain area of the Western United States and Canada in general. Despite several generations of studies in Switzerland, and in adjacent alpine countries, many serious problems remain unsolved. It is perhaps not so remarkable that the mechanical properties of snow are so far from being fully understood when it is realized that the physical properties of the medium itself change constantly in time and space. In view of this problem, it seemed logical for INSTAAR to adopt a multi-facetted strategy which includes: studies of the properties of snow; attempts to develop a numerical forecast model to improve the prediction of avalanche occurrence; systematic collection of data on current and past avalanche events; studies of alternative methods to explosives for artificial avalanche release; and graphic portrayal of avalanche path characteristics in map and atlas forms.

OP24 PDF (19 MB)

$5

Abstract

An examination of historical data relating to avalanche activity in Ouray County, Colorado, was undertaken for the period 1877–1976. Ouray County was a booming gold and silver producing area, reaching its peak in population, mineral production, and, correspondingly, avalanche deaths and destruction to property during the period 1880 to World War I.

Data were obtained from newspapers of the period and by interviews with long-time residents. Avalanche sites were plotted on USGS 1:24,000 scale maps and tabulations of avalanche frequency were developed, chronologically and by geographic location. A total of sixty-two avalanche deaths were recorded during the survey period. Of these, 50 percent occurred while the victims were in fixed positions, either in or near a building. The remaining 50 percent of deaths occurred while the victims were traveling. Thirty-three properties were struck by avalanches. Twenty-six geographic locations were plotted where deaths or burial from avalanches resulted. Case studies of the Barstow and Camp Bird mines are presented and detailed histories of these mines and their avalanche problems are given. A case study of U.S. Highway 550, from Ouray to Red Mountain Pass, is also presented, with detailed histories of two active avalanche paths affecting the highway, the Mother Cline and East Riverside.

The avalanche hazard is traced from the early mining days to the present. During the historical period, the hazard was widespread and not concentrated in any particular area, primarily because the mining operations were scattered throughout the county with diverse traffic routes. This represents a significant difference from the present-day pattern of avalanche hazard, which is mainly concentrated along Highways 550 and 361 and the Camp Bird Mine.

OP23 PDF (4 MB)

$5

Abstract

[From the Introduction] This handbook is a brief description of the background to and procedures for the use of annual growth layers (annual rings) of woody plants for dating snow avalanche events. Trees are most often used as subjects for study but there are some possibilities for using shrubs to date events over short intervals. The methodology of ring-dating is based on the growth behavior of woody plants in cold and temperate climates with marked differences between summer and winter temperature regimes. The winter conditions cause the plants to slow or stop their growth so that there is a discernible difference between the cell size and structure at the end of a growing season compared with that at the beginning of a new growing season. The numbers of rings in cross-sections of selected stems can provide a means of dating and reconstructing events of the past such as glacier fluctuations (Lawrence 1950, Sigafoos and Hendricks 1961), timberline changes (La Marche and Mooney 1972), lake level fluctuations (Cameron 1957, Lawrence 1972), landslides (Heath 1959, 1960), floods (Grant 1965, 1966), fires (Spurr 1954), and other natural and man-made changes. For the purposes of this handbook, the methodology will be referred to as tree-ring analysis, rather than dendrochronology. The latter term has come to be applied, more narrowly, to the somewhat more specialized methodology of use, for dating, cross-dating (to extend chronologies) and climatic analysis of sequences of wide and narrow growth layers in sensitive species in arid or cold climates (Glock 1937, Fritts 1966, 1969, Ferguson 1970, Suess 1970, La Marche and Fritts 1971, Fritts and Blasing 1974). Nevertheless, both methodologies make much the same use of knowledge of the characteristics of tree growth and wood structures. In certain rare circumstances, mentioned later, dendrochronological techniques might be applied to the dating of snow avalanches. Techniques most useful in tree ring analysis are described by Lawrence (1950), Potter (1969), and Stokes and Smiley (1968).

This handbook is couched in simple terms which can be understood by non-biologists; references are given to fuller accounts of aspects of the subject and a glossary of terms is included at the end. The book is specifically relevant to the forests and mountains of Colorado, but it could be adapted for use in other areas.

OP22 PDF (8 MB)

$5

Abstract

In this study the physical processes producing the major centers of synoptic activity in the eastern Canadian Arctic are examined. We choose the total vertical velocity at 85 centibars as an indicator of the intensity of the synoptic activity. A diagnostic three-dimensional atmospheric model from which the total vertical velocity from six physical processes may be computed is designed and validated. These processes are: the differential advection of vorticity, the thickness advection, the release of latent heat, the effects of the surface enthalpy flux, and the influence of friction and orography at the surface. By partitionment of this diagnostic model (the omega equation) into the component vertical velocities the magnitude and relative importance of each process may be determined.

The significance of each physical mechanism is examined at 48 hour intervals throughout the history of a mid-latitude depression system which enters the region as a developing cyclone on July 13, 1973 and leaves on July 22 as a stagnant vortex. The relationships between the large scale flow (the advected properties) and the local influences at various stages of development and decay are of interest. Also discussed is the effect of this synoptic system on the local thermal regime. An important ice melt event occurred during this interval along the eastern Baffin Island coast.

For the winter and summer seasons of 1973 the major synoptic systems in the area are identified by pattern (eigenvector) classification of the 85 centibar total vertical velocity field. For each synoptic feature the average physical processes responsible for the vertical circulation are determined by empirical comparison of patterns in each component field with the pattern of the synoptic feature, and by comparison of magnitudes of the total and component vertical velocities at the center of the feature throughout time. The physical linkages proposed by considerations of these two independent tests are verified by subjective analysis of individual cases. Seasonal trends of these mechanistic linkages are also discussed.

OP21 PDF (26 MB)
Note that original scan was 82 MB and included scans of alternate blank pages.

Abstract

Eighty-five new radiocarbon dates are described and located for the coast of east Baffin Island between latitudes 66° and 72°N. The dates are clustered in Cumberland Peninsula and in the area between Cape Henry Kater, Clyde Fiord, and Scott Inlet. The greatest number of samples are on buried soils and/or peats. The majority of these date from the Neoglacial, although a number have ¹⁴C ages of between 8,000 to 11,000 BP and one is slightly older than 50,000 BP (probably a minimum age). Marine shells constitute the second major class of sample material. A significant number of these samples date between 35,000 and 48,000 BP with another subset dating between 8,000 and 10,000 BP. Samples are located by (1) 1:250,000 NTS Map Sheet, (2) latitude and longitude, and (3) UTMG reference system. This last method is based on identification within 10 × 10 km grid squares marked on the Canadian 1:250,000 map sheets. The grid location is given by a six-digit reference accurate to ±100 m. This is an easier method for locating sites than latitude and longitude coordinates.

OP20 PDF (3 MB)

$5

Abstract

Sixty-two landslides have been identified in a 68-square-mile area west of Aspen, Colorado, and mapped, primarily from air photographs. Their distribution is a clustered one which reflects the spatial control of landslide location.

Landslides are found on every major lithologic unit in the area and landslide characteristics do not differ significantly between lithologies. They are, however, located preferentially on east-facing slopes of north­trending valleys and on north-facing slopes of east-trending valleys. Nearly all landslides also involve a component vector of bedrock dip in the direction of slope. No landslides have starting zone slope angles of less than 16°.

Age determinations, based on vegetation and stratigraphy, suggest an age range of pre–Bull Lake to presently active, with most of the landslides considered to have occurred soon after 11,000 BP in association with conditions of the immediate postglacial time. A few slides have been initiated in the past 100 years.

The most critical parameters involved in landslide initiation are water and slope angle. Dry slopes and those at an angle of less than 12° are not expected to slide. Inactive old landslides and slopes of morainal deposits or Mancos Shale are exceptionally susceptible to movement. The margin of stability over the entire area is considered to be slim and caution is advised in land use, especially where a changed water use is involved

OP19 PDF (23 MB)

$15

Abstract

This final report covers research conducted by the San Juan Avalanche Project, Institute of Arctic and Alpine Research (INSTAAR), University of Colorado for the period August 1971 to June 1975. The research was supported by Contract No. 14-06-D-7155 with the Division of Atmospheric Water Resources Management, U.S. Bureau of Reclamation, Department of the Interior, and has had as its purpose the study of the nature and causes of snow avalanches within the vicinity of Red Mountain Pass, Molas Pass, and Coal Bank Pass in the San Juan Mountains of southwestern Colorado. The ultimate objective of the project was to develop a methodology to accurately forecast avalanche occurrences through study of the complex relationship which exists among terrain, climate, snow stratigraphy, and avalanche formation. When the project was initiated, only a limited amount of climatological data was available for the study area. Recognizing that an avalanche prediction model relies heavily upon data gathered from highly accurate, reliable instruments installed on carefully selected sites, a network of fixed instrumentation was utilized to measure meteorological parameters, determine physical properties within the snowpack, and detect avalanche events.

The primary snow study site located at Red Mountain Pass (3400 m) included instrumentation to measure air temperature, temperatures within the snowpack, wind speed and direction, precipitation rate and amount, snow settlement rate, and net all-wave radiation at the snow surface. In addition an isotopic profiling snow gauge provided snow density and water equivalent values throughout the snowpack at 1.0 cm intervals. Seismic and infrasonic instrumentation for avalanche event detection was investigated during the first two winters, but neither of these systems proved feasible.

Detailed investigations into the physical properties of the snow within the study area were prompted by the fact that the San Juan Mountains exhi bit climatic extremes not found in more northerly latitudes where most practical and scientific knowledge of snow avalanche formation has been accumulated. The combination of high altitude, low latitude and predominately continental climate produces a specific radiation snow climate. Generally, this condition is the result of two factors. First, the extreme nocturnal radiational cooling occurring on all exposures produces snowpack temperature gradients of a magnitude sufficient to cause significant recrystallization or temperature-gradient metamorphism. The second factor is the substantial amount of solar energy available to slopes with a southerly exposure. This daytime condition causes melt at the snow surface and subsequent freeze-thaw crusts. These two situations continue to influence the snowcover throughout the winter. The resulting stratigraphy is highly complex and often unstable.

During the second winter many snow pits were dug to collect data on snow stratigraphy. These snow pits were of three types. One type was located at standard, level snow study sites, while a second was located on test slopes or avalanche release zones. Special emphasis was given to the third type associated with the actual avalanche fracture lines. The first two types are acquired as a series at fixed sites to determine changes in snow structure with time. During the third and fourth winters, these received the major emphasis with particular attention directed towards the temperature gradient process. Snow temperatures were measured throughout the depth of the snowcover on a daily basis at sites at three different elevations. Periodic snowpits at these sites demonstrated the relationship between the magnitude of the temperature-gradient and the type and extent of subsequent metamorphism.

As a part of the daily operational procedure during the 1972-73, 1973-74, and 1974-75 winters this project produced an “in-house” stability evaluation and avalanche occurrence forecast for the research area. Such forecasts were made for each 24 hour period and at more frequent intervals during storms. Each avalanche occurrence forecast was evaluated the following day in terms of actual conditions and events subsequent to the initial forecast. During the third winter the avalanche forecast procedure was further refined to give forecasts for specific groups of paths, as well as general area forecasts. Methods employed by the field observers to evaluate numerous meteorological and snowcover parameters in order to produce an avalanche forecast were isolated and described. Forecasting accuracies of 81 percent for the general area and 73 percent for specific path groups were achieved. On the completion of the third winter’s data collection, work began on the development of a statistical model for the purpose of avalanche prediction.

Following the fourth winter’s research, the statistical forecast model was further refined. During this final winter an unusually high level of avalanche activity prevailed, allowing twice the annual average number of avalanche events to be included in the statistical analysis. The stepwise discriminant function program allowed stratification of avalanche and non-avalanche days in terms of antecedent conditions described by ten variables over five, three, and two-day periods prior to each avalanche or non-avalanche day. Analysis suggests that the two-day time step is most efficient, thus reducing the amount of computation, with no loss in forecasting precision. A clear difference is found between dry snow and wet snow avalanche conditions. The dry snow avalanche days are most clearly identified by reference to precipitation totals during the few hours prior to avalanche release and by air temperature over varying time periods according to the magnitude of event being considered. The wet snow avalanche days are best related to the mean and maximum two hour air temperatures in the 12 to 24 hour period prior to the avalanche event. While rapid temporary warming may often preceed cycles of small wet loose avalanches, a more prolonged period of warming is required for larger wet avalanche cycles to occur. A measure of the relative distance of a discriminant score from the discriminant index allows a more precise forecast than a simple “yes” or “no.” This refinement enables the forecast to be stated in probability terms, an approach not previously attempted in numerical avalanche forecasting.

Evidence suggests that avalanche release within sub-freezing snow layers is primarily dependent on precipitation to trigger unstable layers deep within the snowcover. Delayed-action events are extremely rare. While avalanche frequency and magnitude are influenced by precipitation rates and amounts, they are thus determined primarily by the snow structure which exists within the release zone at the time precipitation-loading occurs. Avalanche magnitude is further affected by mechanical strength of all snow layers in mid-track, for this determines the penetration depth of sliding snow and the ultimate volume of the moving avalanche.

In conclusion, the claim is made that the Silverton Avalanche Research Project has been able to produce for the first time an approach to an operational real-time statistical forecast model. This model which, for major avalanche cycles during the dry and wet snow seasons, has an accuracy of 88% and 82% respectively, is also the first to be applied to groups of starting zones and individual paths, and to predict magnitude of avalanche occurrence.

OP18 PDF (31 MB)

$5

Abstract

An examination of historical data relating to avalanche activity in San Juan County was undertaken for the period 1875–1975. San Juan County was a booming gold- and silver-producing area, reaching its peak in population, mineral production, and, correspondingly, avalanche deaths and destruction to property during the period 1880 through World War I.

Data were obtained from newspapers of the period and by interviews. Avalanche sites were plotted on USGS 1:24,000 scale maps and tabulations of avalanche frequency were developed, chronologically and by geographic location. A total of 95 avalanche deaths were recorded during the survey period. Of these, 69 percent occurred while the victims were in fixed positions, either in or near a building. The remaining 31 percent of deaths occurred while the victims were traveling in the mountains. One hundred properties were damaged by avalanches; of these, 89 were hit between one and three times and 11 were hit four or more times. The location suffering the most damage was the Iowa­Tiger Mill in Arastra Gulch, 2.7 miles due east of Silverton. During a period of 23 years, it was hit on eight occasions, being almost totally destroyed twice. Fifteen geographic locations were plotted where deaths and/or burial from avalanches resulted.

The major avalanche disasters occurred during heavy storm periods, March 1884 and March 1906. During the storm of March 1906, 12 men were killed in the Shenandoah Mine boarding house above Cunningham Gulch, 4.4 miles southeast of Silverton, and six deaths were recorded elsewhere during the storm period. However, avalanche deaths and destruction also occurred during periods of light or no snowfall. After the storm of February 1891, when only 6 inches of new snow fell, one avalanche death was reported and three men were caught but escaped injury.

The avalanche hazard during this historical period was widespread and not concentrated in any particular area primarily because the mining operations were scattered throughout the county with diverse traffic routes. This represents a significant difference from the present-day pattern of avalanche hazard which is concentrated along highways 550 and 110 and within the town of Silverton.

OP17 PDF (10 MB)
Reduced file size but optimized quality.
Original scan is ~50 MB and similar quality as the reduced verion.
 (warning: may take awhile to load).

Abstract

[From the Introduction] The San Juan Avalanche Atlas was developed for the San Juan Planning Commission and the San Juan County Commissioners. It is intended to aid those in need of information concerning avalanche hazards related to land use planning.

The idea of an avalanche atlas is not a new one; the Swiss were interested in compiling a register of avalanches in the 1800’s. In North America, the first avalanche atlas was produced by the U.S. Forest Service for use by the Colorado Department of Highways in 1964 and is still being used for avalanche control, highway design, and highway maintenance. Similar atlases were developed in Washington State. The Washington State Department of Highways avalanche atlases are more detailed than the original Colorado atlas and include all avalanche paths affecting the highways.

The San Juan Avalanche Atlas attempts to take the next step in the evolution of the avalanche atlas in North America by providing more detailed information on the summary sheet than has been attempted in the past. Detailed technical data are supplied for each path and may be helpful to those interested in designing defensive structures for buildings, highways, etc. The information is not intended for critical engineering purposes, but rather as a guide for subsequent data gathering where necessary.

The atlas is a catalog of avalanche activity which has been observed from the late 1870’s through 1975 along highways 550 and 110 in San Juan County, Colorado. However, all known avalanche paths visible from these highways are not included; only paths for which data are readily available are cataloged.

OP16 PDF (6 MB)

Abstract

[From the Preface] Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, Occasional Paper No. 16 has been published four years out of sequence due to a number of unavoidable difficulties. It was originally intended as a sequel to No. 15, “Palynological and Paleoclimatic Study of the Late Quaternary Displacements of the Boreal Forest-tundra Ecotone in Keewatin and Mackenzie, N.W.T., Canada,” by Professor Harvey Nichols, since the computerization of data processing and pollen diagram construction that is described in No. 16 was an outgrowth of palynological research that formed the basis of its predecessor. It is, nevertheless, still intended for use as a sequel. Technical problems initially delayed publication; yet as the basic research program progressed, the computer applications continued to evolve. In fact, improvements in the computer programs have been effected by the senior author as recently as December 1978. In addition, a variety of different data sets have exercised most aspects of the computer programs, sometimes uncovering errors or deficiencies in the original treatment. Thus an opportunity has arisen, if somewhat circumstantially, to correct the original programs, develop them further, and to make the end product produced here much more valuable to the potential user. It is also anticipated and hoped that further evolution will occur, both within INSTAAR and through the critical applications of this work by other groups.

This Occasional Paper, though highly specialized, is yet another product of INSTAAR’s interdisciplinary research team concentrating upon applied and purely scientific aspects of environmental research in arctic and alpine regions. Since the linking theme of climatic change runs through the major part of INSTAAR endeavor, palynology and its derivatives are close to its core. It is also hoped that the present work will be applicable to all other environmental studies that apply palynology as a critical tool.

Margaret Eccles has been in association with INSTAAR as computer programmer since 1971. She has made valuable consultative contributions to many different areas of INSTAAR research and must be credited with the major burden of bringing this work to fruition. Margaret Hickey was a member of the INSTAAR research staff from 1970 to 1976, during which time she organized the daily routine of the Palynological Laboratory and provided invaluable input into the original developments of computerized pollen diagram construction and data processing. All of this, however, arose out of the early research of Harvey Nichols, senior INSTAAR palynologist, which resulted in reconstructions of the position of the arctic treeline in Keewatin and Mackenzie, N.W.T., Canada, over the last 10,000 years and which formed the basis of Occasional Paper No. 15.

OP15 PDF (30 MB)
Reduced file size. Original scan 114 MB.

$5

Abstract

[From the Preface] The aim of this study was to discover the Holocene displacements of the Canadian boreal forest-tundra ecotone resulting from climatic changes. Previous work (Nichols, 1967a, 1967b) had used palynology and peat stratigraphy to extend the initial findings of ecotonal shifts reported by Bryson, Irving, and Larsen (1965). These two studies involved vegetation boundary shifts caused by mean Arctic Front displacement in summer. They related to events along approximately 100°W between 62°N and 65°N, but appeared to have wider applicability (Nichols, 1967b, 1972, 1974). This project extended the earlier studies along the ecotone to test the validity of the schematic models of ecotonal displacement and paleotemperature reconstructions (Nichols, 1967b).

The ecotonal shifts and the associated alterations in paleowind directions were also believed to transport varying amounts of boreal forest pollen into the tundra and two short tundra pollen profiles were analyzed using a modification of routine methods to learn whether exotic pollen influx in the tundra could identify tree line movements.

Six ecotonal pollen diagrams are presented here (in addition to two from the High Arctic) and added to published evidence, they exhibit a cohesive response to climatic changes along the entire length of the ecotone so far examined by me, approximately 1400 km.

OP14 PDF (9 MB)

$5

Abstract

Methods and guidelines are developed to determine the optimal use of ski slopes and their social carrying capacity. Emphasis is placed on the effects of crowding on users’ attitudes and behavior.

The three ski areas operated by the Aspen Skiing Corporation in Aspen, Colorado, served as the study area. From the findings of a standardized interview, users’ characteristics, motivations, satisfactions, and their evaluations of use were obtained. By placing a varied number of skiers on specific slopes, users’ behavior has been observed under all types of density situations.

Results indicate that skiers’ evaluations of use vary according to certain user characteristics, location, time, and weather and snow conditions. If the individual is under the age of thirty, has a high technical skiing ability, participates in other winter sports, or had parents that skied at any time, he feels congestion more acutely than skiers not in this group. Skiers sense more congestion on more difficult terrain and during the last two hours of the skiing day. Skiers are also aware that there is significantly lower use on Saturdays, during the first hour of the skiing day, and under some adverse snow and weather conditions.

Results also indicate that skiers feel that use on the ski slopes is within an optimal range except at Aspen Mountain during mid-February where users sense a crowded situation. However, in the near future, skiers may feel congestion at more places and for greater lengths of time, since analysis of present user characteristics and actual use trends confirm prospects for continued growth of the skiing population. In addition; the analysis of users’ behavior confirms the hypothesis that skiers avoid skiing crowded slopes.

The study concludes with recommendations for maintaining the optimum level of carrying capacity characteristic of Aspen. Incorporated into the recommendations are the conflicting constraints of community attitudes and policies on growth, U.S. Forest Service policy, and the ski slope operators’ views on growth and on restriction of use. The present method of restricting use by monetary means is reviewed in accordance with the historical view of use on public lands. Finally, specific research recommendations on recreational carrying capacity are suggested.

OP13 PDF (9 MB)

$5

Abstract

This report covers research conducted by the San Juan Avalanche Project, Institute of Arctic and Alpine Research, University of Colorado for the period August 1973 to August 1974. The research is supported by a contract with the Bureau of Reclamation, U.S. Department of Interior, and has as its purpose the study of the nature and causes of snow avalanches in the San Juan Mountains of southwestern Colorado, and specifically within the area of Red•Mountain Pass, Molas Divide, and Coal Bank Hill. The ultimate objective of the project is to develop a methodology to evaluate and predict avalanche hazard within the study area in order to be able to accurately forecast avalanche occurrences. The project has undertaken the study of the problem of avalanche initiation by analysis of the complex relationship which exists among terrain, climate, and snow stratigraphy. When the project was initiated, only a limited amount of climatological data was available for the study area. It was recognized that an avalanche prediction model relies heavily upon data gathered from highly accurate, reliable instruments installed on carefully selected sites. Therefore, a network of fixed instrumentation is utilized to measure meteorological parameters, determine certain physical properties within the snowpack, and detect avalanche events. Data regarding certain meteorological and snowpack parameters, as well as that related to the accurate accounting of avalanche events, including the numerous descriptive parameters which catagorize each event are dependent on highly skilled and well trained field observers.

The primary snow study site is located at Red Mountain Pass (3400 m)and includes instrumentation providing such basic information as air temperature, temperatures within the snowpack, wind speed and direction, precipitation rate and amount, snow settlement rate, and net all-wave radiation at the snow surface. In addition, an isotopic profiling snow gauge provides snow density and water equivalent values throughout the snowpack at 1.0 cm intervals. Trip wires have been installed in the paths of frequently occurring avalanches in order to acquire accurate event times.

The initial objective of establishing a research procedure capable of adequately observing and recording the various phenomena associated with avalanche initiation was accomplished during the first winter’s research. The next step was to attempt to determine the relative contribution of each factor and to isolate those processes which contribute most directly to avalanche formation. During the next two winters’ research, considerable emphasis was given to the study of snow stratigraphy.

Detailed investigations into the physical properties of the snow within the study area were prompted by the fact that the San Juan Mountains exhibit climatic extremes not found in more northerly latitudes where most practical and scientific knowledge of snow avalanche formation has been accumulated. The combination of high altitude, low latitude, and predominately continental climate produces a specific radiation snow climate.

Generally, this condition is the result of two factors. First, the extreme nocturnal radiational cooling occurring on all exposures produces snowpack temperature gradients of a magnitude .sufficient to cause significant recrystallization or temperature-gradient metamorphism. The second factor is the substantial amount of solar energy available to south- and west-facing slopes. This daytime condition causes melt just below the surface and subsequent freeze-thaw crusts. These two situations continue to influence the snowcover throughout the winter and the resulting stratigraphy is highly complex.

Therefore, during the second winter’s research considerable emphasis was directed towards a better understanding of the snow stratigraphy within the study area through the acquisition of abundant snow pit data. These snow pits are of three types. One type is located at standard level snow study sites, a second type is located on a test slope or avalanche release zone, and the third is associated with the actual fracture line of an avalanche. During the third winter, this emphasis was sustained with particular attention directed towards the tempera ture-gradient process. Snow temperatures were measured throughout the depth of the snowcover on a daily basis at sites at three different elevations. Periodic snow pits at these sites provided data showing the relationship between the magnitude of the temperature gradient and type of subsequent metamorphism determining crystal morphology.

As part of the daily operational procedure, this project produces an “in-house” stability evaluation and avalanche hazard forecast for the study area. Such forecasts are made for each 24 hour period and at more frequent intervals during storms. Each avalanche occurrence forecast is evaluated the following day in terms of actual conditions and events subsequent to the initial forecast. During the third winter the avalanche forecast procedure was further refined and the trend towards forecasts for specific groups of paths, as well as a general area forecast continued. Methods employed by the field observers to evaluate numerous meteorological and snowcover parameters in order to produce an avalanche forecast were isolated and described. On the completion of the third winter’s data collection, work began on the development of a statistical model for the purpose of avalanche prediction.

Finally, the overall objective of the San Juan Avalanche Project continues to be to identify and analyse those processes which contribute most directly to the initiation of avalanches within the study area, to establish empirical relationships among these processes, and to expose these relationships to a detailed statistical analysis.

OP12 PDF (5 MB)

Abstract

Using data contained in published literature and the Radiocarbon Data Bank of the Institute of Arctic and Alpine Research, an isochrone map is constructed which describes the pattern of deglaciation of the northeastern sector of the Laurentide Ice Sheet from the time of the late Wisconsin maximum (8000 yr to 8500r B.P.) to the present. The change in area and volume of the Northern Baffin Island Ice Cap from 7000 yr B.P. to the present is calculated using the isochrone map and two models relating ice area to volume. The volume measurements are then used to determine the contribution of the ice cap to world sea level rise since 7000 yr B.P.

Based on 325 shoreline locations, radiocarbon dated between 250 yr and 8750 yr B.P., eight isobase maps of the study area are produced depicting the amounts of uplift accomplished since 8000 yr B.P. and 1000 yr intervals thereafter. The pattern of isobases on the 8000 yr B.P. surface shows good agreement with the outline of the late Wisconsin terminal position. The 7000 yr B.P. and younger surfaces show the land recovering around five semi-independent uplift centers over the Queen Elizabeth Islands, Southampton Island, southeastern Keewatin, western Quebec, and northern Baffin Island. These uplift centers correspond to late-glacial centers of retreat.

The change in geometry of the uplift surface over northern Baffin Island is analyzed in detail and is found to be a function of the rate of decay of the Northern Baffin Island Ice Cap. Graphs derived from manipulations of the isochrone and isobase maps describe this functional relationship.

Finally the duration and amount of residual rebound at the regional center of uplift over Southampton Island is predicted on the basis of the measured displacement of isobases between 8000 yr and 1000 yr B.P. It is suggested that rebound in that area will be complete within the next 4000 yr resulting in a further 48 m or less of uplift.

OP11 PDF (22 MB)
Reduced file size. Original scan 112 MB.

Abstract

[From the Introduction] The data presented in this volume were obtained as part of a continuing study of the synoptic energy budget climatology of Eastern Baffin Island and Davis Strait. The principal concern of this program is to produce accurate estimates of energy exchange at snow, ice, and water surfaces in response to weather events on a synoptic scale and in the context of interannual and longer term climatic variations. The main features of the program have been described elsewhere (cf. Barry et a1., 1974, and Jacobs et al., 1974).

Accurate estimates of the radiation balance are obviously essential to energy budget calculations. While the Canadian radiation measurements network provides coverage over much of the Canadian Arctic (Latimer and Truhlar, 1967), no regular observations are made on Baffin Bay and Davis Strait. Therefore, in order to obtain adequate coverage for purposes of the research program described, the Institute of Arctic and Alpine Research (INSTAAR) began a program of radiation measurements in the summer of 1971 at Broughton Island, just off the eastern Baffin Island Coast. The object was to obtain continuous records of global solar radiation and net radiation over a representative surface to be related to special studies on the sea ice, glacier, and tundra surfaces in the area. Data on these two parameters for the summers 1971 through 1973 form the main part of this report. During the latter year, observations continued through December and included measurements of the downward atmospheric flux component and of the direct solar flux component for purposes of calculating transmissivity and turbidity factors, and these are reported here as well.

These data along with some explanation of the measurements program are summarized here. The results of further analysis and interpretation will be published elsewhere.

Radiation measurements were included in a program of glacio-climatic studies by INSTAAR in 1970 on the Boas Glacier (67°35′N, 65°16′W), some 50 km west of Broughton Island (Jacobs et al., 1972; Andrews and Barry, 1972).

OP10 PDF (14 MB)

Abstract

no abstract 

OP09 PDF (32 MB)
Reduced file size. Original scan 167 MB.

Abstract

[From the Preface] Climatological investigations by the Institute of Arctic and Alpine Research (INSTAAR) in eastern Baffin Island began in 1970. Since 1971 the program has focused particularly on ice conditions in western Davis Strait–Baffin Bay in relation to weather and climate but, in addition, a variety of other related climatic studies have been carried out. These investigations complement the specific field measurements of energy budgets in relation to fast-ice breakup processes. This report is one of a planned series which presents preliminary results of some of these projects and documents data, and information on field activities.

OP08 PDF (12 MB)

$5

Abstract

[From the Table of Contents] This report begins by summarizing the county’s mineral resources, soils, water resources, air pollution, wildlife, and natural hazards. The report follows with detailed  descriptions of the bedrock geology, surficial deposits, vegetation, climate, mineral resources, soils, water resources, air pollution, wildlife, natural hazards, and land use and tenure.

OP07 PDF (13 MB)

Abstract

No abstract

OP06 PDF (10 MB)

$10

Abstract

This guide to the Colorado mosses is patterned after the excellent series of little books produced by Prof. Helmut Gams of Innsbruck, Austria, entitled "Kleine Kryptogamenflora von Mitteleuropa." They are field guides to the mosses, lichens, ferns, fungi and algae of Central Europe, and their author is one of the keenest field men in Europe. As a compromise to the field requirement, they contain only keys and ecological notes. For more detailed descriptions and illustrations they assume the availability of more comprehensive literature. They also expect a certain amount of background on the part of the user.

I intend to enlarge this guide to include an instructional introduction, a glossary of terms, and illustrations of the species, but the present version is offered for testing and criticism in the meantime. Although this distillation represents more than twenty-five years of sporadic research, the work is now only well begun. The stones are laid, but the building has not assumed its final shape. We think we know what grows here, but there will be additions as soon as active field work by many students begins. We have some notions of habitats, but they are primitive notions and need refinement. Every observer comes to the field with a different pair of eyes and a different core of experience, and there have been too few of us up to now. I shall be satisfied if this guide will serve to bring bryology within the competence of students and ecological researchers, and serve as a guide to visiting bryologists from abroad, until such time as a more sophisticated work is made possible.

All of the species listed in the Guide are documented by herbarium specimens in the herbarium (cup) of the University of Colorado Museum. We welcome comments and criticisms, and are always interested in adding to the collections through contributions from collectors.

OP05 PDF (5 MB)

Abstract

No abstract

OP04 PDF (10 MB)

Abstract

No abstract

OP03 PDF (9 MB)

Abstract

No abstract

OP02 PDF (9 MB)

Abstract

[From the Introduction] The purpose of the research discussed in this report was to attempt an integrated analysis of the past and present climates of the northern Cumberland Peninsula region with specific attention focused on the links between glacier distribution and fluctuations and the climate. The final objective of the research is to attempt to model the paleoclimate of the region during the late Quaternary.

OP01 PDF (5 MB)

Abstract

No abstract.