海洋物理学

A new scheme for retrieving ocean surface salinity from simulated multi-angular SMOS brightness temperature

  • 王振占 ,
  • 殷晓斌
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  • Center for Space Science and Applied Research, CAS, Beijing 100190, China

收稿日期: 2008-12-13

  修回日期: 2009-03-02

  网络出版日期: 2009-10-10

A new scheme for retrieving ocean surface salinity from simulated multi-angular SMOS brightness temperature

  • WANG Zhen-zhan ,
  • YIN Xiao-bin
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  • Center for Space Science and Applied Research, CAS, Beijing 100190, China

Received date: 2008-12-13

  Revised date: 2009-03-02

  Online published: 2009-10-10

摘要

The European Space Agency will launch the first salinity satellite for remotely sensing the global soil moisture and ocean salinity (SMOS) at a sun-synchronous orbit in 2009. One of the payloads on the satellite is a synthetic aperture microwave radiometer (MIRAS), which is an innovative instrument designed as a two-dimensional (2D) interferometer for acquiring brightness temperature (TB) at L-band (1.4 GHz). MIRAS allows measuring TB at a series of incidences for full polarizations. As the satellite travels, a given location within the 2D field of view is observed from different incidence angles. The authors develop a new scheme to retrieve the sea-surface salinity (SSS) from SMOS’s TB at multi-incidence angles in a pixel, utilizing the properties of emissivity changing with incidence angles. All measurements of a given Stokes parameter in a pixel are first fitted to incidence angles in three order polynomial, and then the smoothed data are used for retrieving the SSS. The procedure will remove the random noise in TB greatly. Furthermore, the new method shows that the error in retrieved SSS is very sensitive to the system biases in the calibrated TB of the sensor, but the error in the retrieval is also a system bias, which can be corrected by post-launch validation. Therefore, this method may also serve as a means to evaluate the calibration precision in TB.

本文引用格式

王振占 , 殷晓斌 . A new scheme for retrieving ocean surface salinity from simulated multi-angular SMOS brightness temperature[J]. 热带海洋学报, 2009 , 28(5) : 11 -17 . DOI: 10.11978/j.issn.1009-5470.2009.05.011

Abstract

The European Space Agency will launch the first salinity satellite for remotely sensing the global soil moisture and ocean salinity (SMOS) at a sun-synchronous orbit in 2009. One of the payloads on the satellite is a synthetic aperture microwave radiometer (MIRAS), which is an innovative instrument designed as a two-dimensional (2D) interferometer for acquiring brightness temperature (TB) at L-band (1.4 GHz). MIRAS allows measuring TB at a series of incidences for full polarizations. As the satellite travels, a given location within the 2D field of view is observed from different incidence angles. The authors develop a new scheme to retrieve the sea-surface salinity (SSS) from SMOS’s TB at multi-incidence angles in a pixel, utilizing the properties of emissivity changing with incidence angles. All measurements of a given Stokes parameter in a pixel are first fitted to incidence angles in three order polynomial, and then the smoothed data are used for retrieving the SSS. The procedure will remove the random noise in TB greatly. Furthermore, the new method shows that the error in retrieved SSS is very sensitive to the system biases in the calibrated TB of the sensor, but the error in the retrieval is also a system bias, which can be corrected by post-launch validation. Therefore, this method may also serve as a means to evaluate the calibration precision in TB.

参考文献

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