Small , Eric E. 1 ; Larson , Kristine M. 2 1 Geological Sciences, ¾«Æ·SMÔÚÏßӰƬ 2 Aerospace Engineering Sciences, ¾«Æ·SMÔÚÏßӰƬ Data from NSF's EarthScope Plate Boundary Observatory (PBO), and similar GPS networks worldwide, can be used to monitor the terrestrial water cycle. GPS satellites transmit L-band microwave signals,...