Microwave remote sensing has been used for decades to monitor the oceans, atmosphere, cryosphere and biosphere from space. The need to monitor the water cycle is as critical as ever. Since 2010, SMOS then Aquarius and SMAP satellite missions provide new L-Band radiometric measurements that have enabled a broad range of applications. L-Band radiometry derived parameters, such as Sea Surface Salinity and Soil Moisture have become essential tools for monitoring, understanding and constraining the terrestrial and marine components of the water cycle. New projects and research aim at ensuring enhanced and continuous monitoring of these parameters, reducing their uncertainties and improving their spatial resolution.

This session focuses on recent developments and efforts aimed at improving water cycle related variables taking advantage of low frequency microwave radiometry. This encompasses 1/ radiative transfer model components, based on new theoretical approaches, original analysis of present satellite data or laboratory measurements and 2/ development of new instrumental concepts operating at L-Band, possibly combined with the more established observations at 6 GHz and above, as well as at expanding the frequency domain even lower into the P-band.