Each file represents gridded data for a single sensor channel and polarization, derived from either ascending or descending orbits for one day, thereby allowing discrimination of diurnal changes in earth surface processes.
Grids represent spatially interpolated data.
The interpolation techniques maximize the radiometric integrity of original brightness temperature values, maintain high spatial and temporal precision, and involve no averaging of original swath data. SMMR coverage began October 1978 and continued through July 1987. Grid resolution is 25 km for all channels. I coverage began August 1987 and continues through the present. Processing is ongoing with current data available within three to six months of sensor data acquisition.