GPS Precipitable Water Observations of Atmospheric River Events

Precipitable water (PW) measurements from GPS travel-time delays have been used to study the onshore structure of landfalling atmospheric rivers. Previous studies of atmospheric rivers have used SSM/I PW images of the atmospheric rivers over the ocean, but these images are not available over land and they're also limited by satellite overpass timing. In our study we use archived delay data from hundreds of GPS receivers that have been put in place for studies of plate motions and geophysical processes. Most of these sites do not have co-located meteorological sensors, so the necessary meteorological information has been inferred from North American Regional Reanalysis (NARR) geopotential heights and temperatures. This technique allows atmospheric rivers to be studied with high geographic and temporal resolution.