Characterization of K-band radio frequency interference from AMSR-E, WindSat and SSM/I

An algorithm to detect radio-frequency interference in microwave radiometer brightness temperatures is developed and applied to K-band observations from AMSR-E, WindSat and SSM/I. This algorithm uses the monthly peak difference between co-polar brightness temperatures at 22 and 19 GHz to find RFI. Data from July 2005, July 2008, and January 2008 are shown. Less K-band RFI is seen in SSM/I data than in WindSat or AMSR-E data, likely due to differences in K-band center frequency and spatial resolution. A significant source of RFI is present in the 2008 and 2009 AMSR-E and WindSat data that was not present in 2005. This is likely due to transmissions from the DirecTV 10 satellite, which was launched in July of 2007. This RFI source is seen in reflection off of the Earth´s surface. This reflection is strongest over ocean, but is also seen over snow where the diffuse component of the reflection creates a relatively wide swath of RFI.