A Physical Model for Television Frequency Interference (TFI) Correction of AMSR2 Data over Ocean near U. S. and Europe

Television (TV) radio frequency interference (TFI) signals are found in observations from the Advanced Microwave Scanning Radiometer 2 (AMSR2) over coastal regions near United States and Europe. When TV signals are reflected off the ocean surface and get into AMSR2 field-of-views, the AMSR2-measured radiance contains not only information of natural emission from Earth's surface but also the reflected TV signals. If not detected and corrected, TFI introduces errors into geophysical retrieval products. The occurrence and intensity of TFI are determined by the angle between the observation beam vector and the reflected TV signal vector (i.e., TFI glint angle) and the background TV signal intensity. In this study, a physical model is developed to quantitatively calculate the contribution of TFI signals to AMSR2 observations based on TFI glint angle and TV signal intensity. This physical model is then applied to AMSR2 K-band channels over North America and X-band channels over Europe. It is shown that the annual mean bias for TFI affected observations of 18.7 GHz channel at horizontal (vertical) polarization reduces from a value of more than 5K (2K) to about -0.5K (0.5) after TFI correction over the coastal ocean near North America. The annual mean bias for TFI affected observations of 10.65 GHz channel at horizontal (vertical) polarization reduces from a value of about 2.5 K to about -0.7K (0.5K) after TFI correction over the coastal ocean near Europe. False maxima in AMSR2 retrieved cloud liquid water path and dry anomalies in AMSR2 retrieved total precipitable water near the coastal regions are also eliminated after incorporating the TFI correction.