Detection and Correction of AMSR-E Radio-Frequency Interference |
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| Authors: | Ying Wu Fuzhong Weng |
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| Institution: | Center of Data Assimilation for Research and Application, Nanjing University of Information Science & Technology, Nanjing 210044, China
School of Remote Sensing, Nanjing University of Information Science & Technology, Nanjing 210044, China;NOAA/NESDIS/Center for Satellite Application and Research, Camp Springs, MD 20746, USA |
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| Abstract: | Radio-frequency interference (RFI) affects greatly the quality of the data and retrieval products from space-borne microwave
radiometry. Analysis of the Advanced Microwave Scanning Radiometer on the Earth Observing System (AMSR-E) Aqua satellite observations
reveals very strong and widespread RFI contaminations on the C- and X-band data. Fortunately, the strong and moderate RFI
signals can be easily identified using an index on observed brightness temperature spectrum. It is the weak RFI that is difficult
to be separated from the nature surface emission. In this study, a new algorithm is proposed for RFI detection and correction.
The simulated brightness temperature is used as a background signal (B) and a departure of the observation from the background (O-B) is utilized for detection of RFI. It is found that the O-B departure can result from either a natural event (e.g., precipitation or flooding) or an RFI signal. A separation between
the nature event and RFI is further realized based on the scattering index (SI). A positive SI index and low brightness temperatures
at high frequencies indicate precipitation. In the RFI correction, a relationship between AMSR-E measurements at 10.65 GHz
and those at 18.7 or 6.925 GHz is first developed using the AMSR-E training data sets under RFI-free conditions. Contamination
of AMSR-E measurements at 10.65 GHz is then predicted from the RFI-free measurements at 18.7 or 6.925 GHz using this relationship.
It is shown that AMSR-E measurements with the RFI-correction algorithm have better agreement with simulations in a variety
of surface conditions. |
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| Keywords: | radio-frequency interference (RFI) RFI index RFI detection |
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