The Soil Moisture Active Passive (SMAP) "Uncorrected Brightness Temperature 9 km" layer displays brightness temperatures (TBs) uncorrected for the presence of water in Kelvin (K) for the horizontal (H) polarization of the aft scan from the SMAP radiometer. To enhance the grid resolution, Backus-Gilbert optimal interpolation techniques are used to extract maximum information from SMAP antenna temperatures and convert them to brightness temperatures, which are posted to the 9 km EASE-Grid 2.0 in a global cylindrical projection. At the L-band frequency used by SMAP, the TB of the land surface is proportional to its emissivity multiplied by its physical temperature.

The SMAP spacecraft carries two instruments, a radar (active) and a radiometer (passive), that together make global measurements of land surface soil moisture and freeze/thaw state. It is useful for monitoring and predicting natural hazards such as floods and droughts, understanding the linkages between Earth’s water, energy and carbon cycles, and reducing uncertainties in predicting weather and climate.

References: SMAP Enhanced L1C Radiometer Half-Orbit 9 km EASE-Grid Brightness Temperatures

Data field: cell_tb_h_aft