How are the enhanced SMAP radiometer products generated and what are the benefits of using these products?
There is considerable overlap of the SMAP radiometer footprints, or Instantaneous Fields of View (IFOVs), which are defined by the contours where the sensitivity of the antenna has fallen by 3db from its maximum. The IFOVs are spaced about 11 km apart in the along scan direction with scan lines spaced about 28 km apart near the sub-satellite track. Thus, by interpolating the values from the nearest 6 IFOVs to each 9 km EASE-Grid 2.0 cell location a product with enhanced detail is possible. This is evident when comparing the 36 km gridded (standard) products with the 9 km gridded (enhanced) products in regions of sharp gradients, such as coastlines.
For more information on the Backus-Gilbert optimal interpolation, see the SMAP Level-1 Radiometer Enhancement Algorithm Theoretical Basis Document.
The enhanced SMAP radiometer product suite includes:
- SMAP Enhanced L1C Radiometer Half-Orbit 9 km EASE-Grid Brightness Temperatures
- SMAP Enhanced L2 Radiometer Half-Orbit 9 km EASE-Grid Soil Moisture
- SMAP Enhanced L3 Radiometer Global Daily 9 km EASE-Grid Soil Moisture
- SMAP Enhanced L3 Radiometer Northern Hemisphere Daily 9 km EASE-Grid Freeze/Thaw State