Comparison of the Retrieval of Sea Surface Salinity Using Different Instrument Configurations of MICAP

Lanjie Zhang,Zhenzhan Wang,Xiaobin Yin

doi:10.3390/rs10040550

Abstract

The Microwave Imager Combined Active/Passive (MICAP) has been designed to simultaneously retrieve sea surface salinity (SSS), sea surface temperature (SST) and wind speed (WS), and its performance has also been preliminarily analyzed. To determine the influence of the first guess values uncertainties on the retrieved parameters of MICAP, the retrieval accuracies of SSS, SST, and WS are estimated at various noise levels. The results suggest that the errors on the retrieved SSS have not increased dues poorly known initial values of SST and WS, since the MICAP can simultaneously acquire SST information and correct ocean surface roughness. The main objective of this paper is to obtain the simplified instrument configuration of MICAP without loss of the SSS, SST, and WS retrieval accuracies. Comparisons are conducted between three different instrument configurations in retrieval mode, based on the simulation measurements of MICAP. The retrieval results tend to prove that, without the 23.8 GHz channel, the errors on the retrieved SSS, SST, and WS for MICAP could also satisfy the accuracy requirements well globally during only one satellite pass. By contrast, without the 1.26 GHz scatterometer, there are relatively large increases in the SSS, SST, and WS errors at middle/low latitudes.

Highlights

At a given pressure, the salinity and temperature determine the density of sea water so that the salinity plays an important role in the formation and circulation of water masses [1,2]
The root mean square (RMS) errors are smaller at 3 m/s than those obtained at 7 m/s
In contrast to the Soil Moisture and Ocean Salinity (SMOS) and Aquarius, Microwave Imager Combined Active/Passive (MICAP) uses \ multi-frequency (1.4 GHz, 6.9 GHz, 18.7 GHz and 23.8 GHz) radiometers combined with the 1.26 GHz scatterometer to measure sea surface salinity (SSS), sea surface temperature (SST), and wind speed (WS)

Summary

Introduction

The salinity and temperature determine the density of sea water so that the salinity plays an important role in the formation and circulation of water masses [1,2]. Knowledge of the distribution of SSS is key to understanding how the water cycle affects the ocean circulation and the climate variability [6]. For the past ten years, with the successful launch of the Soil Moisture and Ocean Salinity (SMOS) mission, the Aquarius/SAC-D mission and the Soil Moisture Active-Passive (SMAP) mission, satellite SSS has become a reality. These three missions can systematically map SSS over all areas of the open ocean except near land and ice boundaries [8], and offer complementary information to existing in situ measurements [8,10]

Objectives

Results

Conclusion