Salinity Effects on L-band Microwave Remote Sensing of Soil Moisture

Global satellite missions for measuring soil moisture will assume that soil salinity is unimportant for soil moisture retrieval, but many parts of the world have large areas of highly saline soil. Approximately 7% of the earth’s continental surface area is salt-affected [1], so failing to account for potential salinity-effects could compromise soil moisture satellite missions. Significant work has gone into correcting for effects on the signal due to vegetation, surface roughness and soil properties (e.g., [2], [3]). However, the effects of salinity have not been thoroughly tested. Existing models ([4]) and lab experiments ([5], [6]) suggest salinity may significantly reduce L-band microwave brightness temperature (Tb). While past field studies have either been inconclusive ([5], [7]) or found salinity effects were small ([8]), none were conducted in highly saline areas, where salinity-effects would be most pronounced. This study aims to test the sensitivity of L-band Tb to salinity in a highly saline area. The results of this study will have important implications for determining the error budget of L-band soil moisture missions.