Aquarius Radio Frequency Interference (RFI) Ancillary Dataset V1.0

Aquarius ancillary Radio Frequency Interference (RFI) product used in ADPS mission processing contains monthly-averaged Radio Frequency Interference (RFI) data for ascending/descending passes as detected by the Aquarius radiometers and scatterometer. The data is available for ascending (northward) and descending (southward) passes of the satellite only and ascending/descending passes combined.

The values stored in this product are the percentage of radiometer and scatterometer measurements identified as corrupted by interference by the RFI detection algorithms [1,2] within each data point, averaged over one month. An additional RFI flag [3] is used to identify locations where the measured brightness temperature over land exceeds the expected limits of surface emissivity. This flag is not used to remove samples from further processing, but, in generating the radiometer RFI data, 100% RFI is assigned to points where this flag is raised.

This product can be used to reproduce the RFI maps available on the Aquarius website at University of Maine (https://aquarius.umaine.edu/cgi/gal_radiometer.htm for the radiometer, and https://aquarius.umaine.edu/cgi/gal_scatterometer.htm for the scatterometer), by plotting the variables Rad_RFI_percent_AscDes_AllBeams and Scat_RFI_percent_AscDes_AllBeams on the latitude/longitude grid. Additionally, the user can generate maps by using only a particular beam or only ascending passes, for example. All combinations of beams and ascending/descending passes are possible.

This product contains information about RFI, but it is also relevant for the retrieved Sea Surface Salinity (SSS). Over the ocean, the RFI percentage in this product corresponds to the amount of raw measurements discarded due to RFI contamination before SSS retrieval. Therefore, maps of the RFI percentage can give the user an indication of where RFI is more likely to have affected the quality of SSS retrievals, for a particular month, or for a series of months.