Salinity Retrieval and Radio Frequency Interference (RFI)
[27-Aug-2018] Soldo, Y., de Matthaeis, P., and Le Vine D.M.
Presented at the 2018 Ocean Salinity Science Team and Salinity Continuity Processing Meeting
Although RFI at L-band is much less a problem for remote sensing over the ocean (compared to overland), it is a significant issue for remote sensing of salinity. In fact, retrievals of salinity require finer radiometric accuracy than retrievals of soil moisture. Mitigating RFI was the reason Aquarius employed fast sampling (i.e. at 10 ms intervals). Some ocean areas such as the one along the East coast of China are strongly impacted by RFI. The sources are believed to be on land, but because the radiometric sensitivity required for remote sensing of SSS is so restrictive, distant RFI received via antenna sidelobes can still have non-negligible impact on the retrievals. In fact, even after RFI filtering several regions are not used during Aquarius calibration because of evidence of contamination by residual RFI.
Research at GSFC to address RFI at L-band that began with Aquarius is continuing with SMAP. The precedent of producing monthly global maps of RFI percentage of occurrence is being continued with SMAP. These maps will appear on the SMAP salinity website. In addition, research is underway to improve RFI detection and mitigation for SMAP salinity. This includes improved detection, localization of sources, and (to address perhaps the biggest problem) understanding of missed-detection. The work includes comparison of RFI detection by SMOS, Aquarius and SMAP.
This talk will present examples of the SMAP RFI maps and research being done on RFI detection and mitigation in support of the SMAP salinity project.