Analysis of Radio Frequency Interference in Metop ASCAT Backscatter Measurements

The advanced scatterometer (ASCAT) is a radar system carried on board the ESA/EUMETSAT METOP series of satellites. It is designed for the purpose of retrieving wind field over oceans. It also provides information on surface soil moisture content and sea ice. Although ASCAT uses a linear frequency mo...

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Bibliographic Details
Published inIEEE journal of selected topics in applied earth observations and remote sensing Vol. 10; no. 5; pp. 2360 - 2371
Main Authors Ticconi, Francesca, Anderson, Craig, Figa-Saldana, Julia, Wilson, John Julian William, Bauch, Helmut
Format Journal Article
LanguageEnglish
Published IEEE 01.05.2017
Subjects
Advanced scatterometer (ASCAT)
Backscatter
C-band scatterometer
Noise measurement
Radar measurements
radio frequency interference (RFI)
Radiofrequency interference
Receivers
Sea measurements
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Summary:The advanced scatterometer (ASCAT) is a radar system carried on board the ESA/EUMETSAT METOP series of satellites. It is designed for the purpose of retrieving wind field over oceans. It also provides information on surface soil moisture content and sea ice. Although ASCAT uses a linear frequency modulated pulse with a center frequency of 5.255 GHz (C-band), it is subject to radio frequency interference (RFI). This paper analyses seven years of ASCAT data and shows an increase of the number of noise outliers and an increase of the noise background level over specific land areas. This suggests that the outliers are not a natural occurrence, but are due to RFI from ground-based equipments. As regards the observed increase of the noise background level, it is not straightforward to associate possible RFI sources which could have caused it. However, since the ASCAT has a dynamic range of about 30 dB, the worse measured increase of 1 dB in the noise floor has almost no impact on performance, in particular, on soil moisture retrieval. In addition, the effect of the noise outliers on the estimate of the ASCAT receiver filter shape function used in the processing is also examined and is found to introduce errors of up to 0.4 dB. However, the occurrence of the noise outliers is generally very low, typically two out of 60 000 noise measurements per day, so the impact on the operational use of ASCAT data for wind vector retrieval is limited.
ISSN:1939-1404
DOI:10.1109/JSTARS.2016.2640561