ICESat-2 Observed Salton Sea Surface Water Levels during 2018-2020

Abstract:

The Salton Sea, in southern California, has been termed an ecologically stressed region, with concerns that long-term evaporation will shrink water volume to an such an extent that increases in airborne particulates across the Imperial and Coachella Valleys will form considerable health hazards. Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) mission mean surface heights, based on photon returns (from the ATL03 photon science product, rel004), and based on a more robust estimate of water surface heights (from the ATL13 Inland Water science product, rel004) help to monitor water level changes across the Salton Sea. The time span investigated is still somewhat short, about 21 months, spanning October, 2018 through July, 2020, but trends and seasonal variations are clearly detectable. Six ground tracks provide a total of 27 distinct satellite passes, including off-nadir-pointing passes. Where possible, each of the six beams were independently processed to yield estimates of mean surface orthometric surface height. These surface heights were placed into time order, providing an ICESat-2-based series of the height variations of the Salton Sea Surface. The time series was compared to a time series obtained from a USGS water level monitoring gauge located southeast of Salton City. Each time series demonstrates a clear seasonal variation of Salton Sea height. The time series were additionally investigated to ascertain correlation with daily precipitation; (1) as locally measured at the Cochran Regional Airport near Thermal; and (2) as modeled by ECMWF ERA5 estimates of precipitation. ICESat-2 LIDAR profile geometries over the Salton Sea were compared to ECMWF ERA5 models of wind field components in order to investigate correlations with fetch characteristics.