Radio Frequency Interference and the SMAP Radiometer: Risk Assessment and Reduction

Achieving the soil moisture retrieval goals set for the SMAP mission [1]-[2] requires avoiding any significant degradations of SMAP’s L-band radiometer observations. Radio Frequency Interference (RFI) is an important risk factor, even given the “protected” status of the 1400-1427 MHz band within which the radiometer operates. RFI forecasts based on known radar sources were used in initial planning studies [3], but such studies neglect any other potential source of interference. Although L-band RFI effects have been observed in numerous previous groundand air-based campaigns [3]-[5], the majority of the observed RFI information available was anecdotal and insufficient for performing a risk assessment over large spatial scales. Recent airborne campaigns in support of SMOS [6] and SMAP [7]-[10] however have provided more detailed RFI characterizations for RFI risk assessment. Information on the RFI levels observed by SMOS is also of great interest, and will be incorporated as it becomes available.