Cite this paper:
REN Yongzheng, DONG Qing, HE Mingxia. Preliminary validation of SMOS sea surface salinity measurements in the South China Sea[J]. Journal of Oceanology and Limnology, 2015, 33(1): 262-271

Preliminary validation of SMOS sea surface salinity measurements in the South China Sea

REN Yongzheng1, DONG Qing1, HE Mingxia2
1 Key Laboratory of Digital Earth Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100094, China;
2 Ocean Remote Sensing Institute, Ocean University of China, Qingdao 266002, China
Abstract:
The SMOS (soil moisture and ocean salinity) mission undertaken by the European Space Agency (ESA) has provided sea surface salinity (SSS) measurements at global scale since 2009. Validation of SSS values retrieved from SMOS data has been done globally and regionally. However, the accuracy of SSS measurements by SMOS in the China seas has not been examined in detail. In this study, we compared retrieved SSS values from SMOS data with in situ measurements from a South China Sea (SCS) expedition during autumn 2011. The comparison shows that the retrieved SSS values using ascending pass data have much better agreement with in situ measurements than the result derived from descending pass data. Accuracy in terms of bias and root mean square error (RMS) of the SSS retrieved using three different sea surface roughness models is very consistent, regardless of ascending or descending orbits. When ascending and descending measurements are combined for comparison, the retrieved SSS using a semi-empirical model shows the best agreement with in situ measurements, with bias -0.33 practical salinity units and RMS 0.74. We also investigated the impact of environmental conditions of sea surface wind and sea surface temperature on accuracy of the retrieved SSS. The SCS is a semi-closed basin where radio frequencies transmitted from the mainland strongly interfere with SMOS measurements. Therefore, accuracy of retrieved SSS shows a relationship with distance between the validation sites and land.
Key words:    sea surface salinity (SSS)|soil moisture and ocean salinity (SMOS)|sea surface roughness model|South China Sea (SCS)   
Received: 2013-12-17   Revised: 2014-03-19
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Articles by REN Yongzheng
Articles by DONG Qing
Articles by HE Mingxia
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