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Ocean Surface Salinity Features as Observed by SMOS and Aquarius
[17-Apr-2013] Liu, W.T. and Xie, X.
Presented at the 2013 SMOS-Aquarius Science Workshop
One year of coincident observations of ocean surface salinity by Argo, SMOS, and Aquarius are compared in their identifications of the temporal and spatial characteristics of major ocean features. In the Circumpolar Current, neither SMOS nor Argo shows any seasonal variation of surface salinity, but Aquarius shows a summer peak and a winter low. All three data sets agree well under the intertropical Convergence Zone (ITCZ) in central Pacific, with broad high in spring and low in autumn. All three data reveal two peaks under the ITCZ in the eastern Pacific, but SMOS has higher magnitudes. Aquarius data capture the outflows of major rivers - Amazon, Ganges, Congo, and the Yangtze - but SMOS and Argo are limited by coverage and spatial resolution. At the northern end of Bay of Bengal, near the mouth of the Ganges River, SMOS data are mostly missing and too noisy to identify the summer high and the autumn low as Aquarius and Argo data. Argo data show much reduced range compared with Aquarius. In West Africa, all data sets show same annual cycle caused by outflow of the Congo, but Argo shows less range. An area of intense salinity deficit is revealed by both SMOS and Aquarius, north of the Amazon estuary, but not seen in Argo data. In this area, the salinity is higher in January to June, but drops sharply at the end of June. Only Aquarius data are available in the East China Sea to examine the outflow of the Yangtze River, with higher salinity (less discharge) in autumn. We did not acquire sufficient Argo data in the Gulf of Mexico to characterize the outflow of the Mississippi, and SMOS salinity is lower than Aquarius data in this area. We have also examined the complementarity between Aquarius and SMOS data in the characterization the major oceanographic processes.

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