Microwave brightness and moist-air correction (SWOT)

The SWOT Level 2 Radiometer Brightness Temperatures and Troposphere Interim Geophysical Data Record (IGDR) Version D dataset produced by the Surface Water and Ocean Topography (SWOT) mission provides atmospheric water vapor and liquid water content from the Advanced Microwave Radiometer (AMR), a Jason-class radiometer that measures sea surface brightness temperatures at three microwave frequencies (18.7, 23.8 and 34 GHz). Brightness temperatures are processed to estimate the wet troposphere content, atmospheric attenuation to backscatter, cloud liquid water, water vapor content, and wind speed coincident with each range measurement from the nadir altimeter and applied to correct for altimeter range delays caused by atmospheric effects. SWOT is a joint mission between NASA and CNES that launched on December 16, 2022. It aims to measure ocean surface topography with unprecedented resolution and accuracy, as well as map inland water bodies globally. The interim radiometer dataset consists of discrete measurements along two tracks located approximately 30-km to the left and right of the satellite nadir. The data were processed using the Medium-accuracy (preliminary) Orbit Ephemeris (MOE) with preliminary calibrations applied. They are distributed as one file per half-orbit in netCDF4 file format with a nominal latency of < 1.5 days.