A new scheme for retrieving ocean surface salinity from simulated multi-angular SMOS brightness temperature
- 出版年：2009
- 作者：WANG Zhen-zhan， YIN Xiao-bin
- 单位1：Center for Space Science and Applied Research，CAS，Beijing 100190，China
- 语种：英文
- 作者关键词：SMOS；salinity retrieval；multi-incidence angle
- 起始页：11
- 总页数：7
- 刊名：热带海洋学报
- 是否内版：否
- 刊频：双月刊
- 创刊时间：1982
- 主管单位：中国科学院
- 主办单位：中国科学院南海海洋研究所
- 主编：张偲
- 地址：广州市新港西路164号
- 邮编：510301
- 电子信箱：jto@scsio.ac.cn
- 网址：http：//jto@scsio.ac.cn；http：//www.jto.ac.cn
- 卷：28
- 期：5
- 期刊索取号：P226.06 842
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 mnovative 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 etrieving 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.
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 etrieving 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.