Status of Aquarius Salinity Retrievals and Applications
[26-Nov-2014] Le Vine, D., Dinnat, E., Lagerloef, G., de Matthaeis, P., Kao, H.Y., Meissner, T., and Wentz, F.
Presented at the 2014 Ocean Salinity Science and Salinity Remote Sensing Workshop
This paper will give the status of the Aquarius instrument and salinity retrieval, mention some new applications of the data and summarize the current research issues being addressed to improve the retrieved salinity. Aquarius was launched on June 10, 2011 to monitor the global salinity field in the open ocean. This radiometer/scatterometer (i.e. passive/active) instrument is part of the Aquarius/SAC-D observatory. The instrument has been operating continuously since being turned on in August and the initial map of sea surface salinity was released one month later (September, 2011). The quality of the salinity retrieval has improved continuously since then and is approaching the goal of 0.2 psu accuracy (RMS globally each month). The maps produced by Aquarius show dynamic features of the salinity field such as the freshening in the Bay of Bengal due to increased run off during the Indian monsoon; and now after three years of operations, data is available to give a first look at the inter-annual changes in the global salinity field. An improved salinity product, Version 3.0, has just been released to the public (June, 2014) and includes significant refinements in the retrieval algorithm such as reduced ascending/descending differences and improved calibration (see: http://podaacftp.jpl.nasa.gov). Mapping the salinity field in the open ocean is a challenging remote sensing task, and to accomplish this Aquarius has a number of unique features. These include an active instrument (scatterometer) to help correct for surface roughness, a polarimetric channel in the radiometer to help correct for Faraday rotation and rapid sampling to help mitigate radio frequency interference (RFI). These features have been carefully tailored to work together to improve the salinity product. They are also the source of novel applications such as the potential for retrieving sea ice thickness and identifying the effects of topography on the radiometric signal over land. Monthly maps of the salinity field and other products from Aquarius (e.g. RFI maps and soil moisture and salinity at high latitudes) are available at the Aquarius website
. Work continues to improve the salinity product including research to refine the geophysical corrections and to extend the calibration to the warm (land) and cold (sky) temperature ranges and to become less dependent on a reference ocean scene.