数据说明
Sea Surface Salinity (SSS) from SMOS
上传时间：2019-05-22 14:07:21 浏览次数：作者与来源：admin
Sea surface salinity (SSS) is the water salinity close to the ocean's surface. The exact meaning of surface varies according to the measurement method used, generally, it is about 3 millimeters below the sea surface. Psu (Practical salinity units) is the unit of SSS, it represents the amount of salt dissolved in every kilogram (roughly one liter by volume) of seawater.
Unit: psu
Resolution: 0.25 degree, monthly
Duration: Jan 2010 - present
Source: Soil Moisture and Ocean Salinity (SMOS), European Space Agency
Version: V2.0
Processing: Original monthly mean products are shown
These products have been generated from the last version of SMOS-OS Level 2 products provided by ESA (v6.22). SSS value are calculated by blending algorithms based on sea surface emission model as documented in the SMOS algorithm theoretical baseline document.
The SMOS 2D interferometric concept allows the instrument to perform measurements over two-dimensional sNon-Algal Particle (NAP)shots so that a grid point over the ocean is seen by numerous independent sNon-Algal Particle (NAP)shots under various incidence and azimuth angles. The retrieval of SSS is based on a maximum likelihood Bayesian approach. The SMOS measured brightness temperatures Tbimeas at different incident angles θi are compared to Tb modeled brightness temperatures to get the SSS. These measured data need to be fitted into a direct model find the best solution of the parameters (i.e. SSS).
Tbbmod=f(θ,SSS,SST,Prough)
Where Prough is a vector that includes the parameters used in each model to describe the sea roughness.
The implies minimization of the following constrains cost function:
x2=∑i=0 Nm-1[Tbimeas- Tbimod]2/σTbi2+∑j=0 Nm-1[Pj-Pjpriori]/σPj2
Being Pj ,the j parameters that influence the Tb: SSS, SST, WS, and depending on the cases, also significant wave height Hs, wind direction φ, inverse wave-age Ω, and TEC parameter in case of not using first stokes, etc. is the incidence angle of measurements from nadir. In case of cardioid retrieval, the Pj parameters are Acard and the surface temperature.
Pjpriori is a value of parameter Pj known a priori to the measurement with an uncertainty σPj2. The uncertainty σPj2 of each parameter, could change depending on the area of observation.
σTbi2 is the uncertainty of the measurement used for each incidence angle
Known issues
Land Sea Contamination has been mitigated by means of the empirical salinity debiasing method proposed in [Olmedo et al., 2016].
Reference
Olmedo, E., Martínez, J., Umbert, M., Hoareau, N., Portabella, M., Ballabrera, J., Turiel, A. Improving time and space resolution of SMOS salinity maps using multifractal fusion. Remote Sensing of Environment, 2016,180:246-263.
DOI: 10.1016/j.rse.2016.02.038
All the contents of this page are quoted from Barcelona Expert Centre, European Space Agency. All project documentation and related publications can be found at website: https://earth.esa.int/web/guest/missions/esa-operational-eo-missions/smos/content/-/asset_publisher/t5Py/content/how-to-obtain-data-7329 andhttp://bec.icm.csic.es/ocean-datasets/
Unit: psu
Resolution: 0.25 degree, monthly
Duration: Jan 2010 - present
Source: Soil Moisture and Ocean Salinity (SMOS), European Space Agency
Version: V2.0
Processing: Original monthly mean products are shown
These products have been generated from the last version of SMOS-OS Level 2 products provided by ESA (v6.22). SSS value are calculated by blending algorithms based on sea surface emission model as documented in the SMOS algorithm theoretical baseline document.
The SMOS 2D interferometric concept allows the instrument to perform measurements over two-dimensional sNon-Algal Particle (NAP)shots so that a grid point over the ocean is seen by numerous independent sNon-Algal Particle (NAP)shots under various incidence and azimuth angles. The retrieval of SSS is based on a maximum likelihood Bayesian approach. The SMOS measured brightness temperatures Tbimeas at different incident angles θi are compared to Tb modeled brightness temperatures to get the SSS. These measured data need to be fitted into a direct model find the best solution of the parameters (i.e. SSS).
Tbbmod=f(θ,SSS,SST,Prough)
Where Prough is a vector that includes the parameters used in each model to describe the sea roughness.
The implies minimization of the following constrains cost function:
x2=∑i=0 Nm-1[Tbimeas- Tbimod]2/σTbi2+∑j=0 Nm-1[Pj-Pjpriori]/σPj2
Being Pj ,the j parameters that influence the Tb: SSS, SST, WS, and depending on the cases, also significant wave height Hs, wind direction φ, inverse wave-age Ω, and TEC parameter in case of not using first stokes, etc. is the incidence angle of measurements from nadir. In case of cardioid retrieval, the Pj parameters are Acard and the surface temperature.
Pjpriori is a value of parameter Pj known a priori to the measurement with an uncertainty σPj2. The uncertainty σPj2 of each parameter, could change depending on the area of observation.
σTbi2 is the uncertainty of the measurement used for each incidence angle
Known issues
Land Sea Contamination has been mitigated by means of the empirical salinity debiasing method proposed in [Olmedo et al., 2016].
Reference
Olmedo, E., Martínez, J., Umbert, M., Hoareau, N., Portabella, M., Ballabrera, J., Turiel, A. Improving time and space resolution of SMOS salinity maps using multifractal fusion. Remote Sensing of Environment, 2016,180:246-263.
DOI: 10.1016/j.rse.2016.02.038
All the contents of this page are quoted from Barcelona Expert Centre, European Space Agency. All project documentation and related publications can be found at website: https://earth.esa.int/web/guest/missions/esa-operational-eo-missions/smos/content/-/asset_publisher/t5Py/content/how-to-obtain-data-7329 andhttp://bec.icm.csic.es/ocean-datasets/
