==================2017-12-29====================================

How is interpolated the brightness temperature in browse product ?

As SMOS is not a scanning system, the different points are not necessarily obtained at 42.5°. In order to have an almost fixed angle data are interpolated to 42.5 degrees. This angle is obtained by linear interpolation of all TB acquired at an angle between 37.5° and 47.5°. Note that the L1C browse corresponds to measured SMOS data while in the level 2 it is modelled brightness temperature at 42.5° that correspond to the results of the retrievals

from SMOS Blog

============================2018-3-3===============================

1)
BT_X: data is from dataset "BT_Value_Real" filtered by  (i.e. using only pixels acquired at)  XX antenna polarisation
BT_Y: data is from dataset BT_Value_Real" filtered by YY antenna polarisation
BT_H and BT_V are BT measurements at ground polarisations HH resp. VV. These and their errors at ground are calculated according to Camps et al. (2005, Eqs. 13, 14; IEEE Geoscience and Remote Sensing Letters, 1545) where the rotation of the electric fields incident in the antenna plane is given by the difference of the Faraday and geometric rotations.

2)
The BT data in the browse products is interpolated at an incidence angle of 42.5º from the MIRAS data in the ESA ground-segment processor, the data in the science product is not interpolated; all incidence angles are present.For display, the SMOS-Box interpolates the BT values on-the-fly to the 42.5 deg incidence angle, using only values with incidence angles between 37.5 and 52.5 degrees and the appropriate polarisation. So there might be small differences in the BT data between the science and the browse data display.
The browse products do not contain rotation angle data, you can not derive V and H polarisation from these products. Please also check the ESA documentation: https://earth.esa.int/documents/10174/1854583/SMOS_L1_Aux_Data_Product_Specification

=======================2018-03-24==================================

问：SNAP 展示的亮温是哪个角度的亮温？

答：For the browse view all bands in the science product represent measured values interpolated for an incidence angle of 42.5 degrees by means of a linear regression of all measurements at the same polarisation considering incidence angles from 37.5 to 47.5 degrees.

Take into account, however, that TB_H is not directly obtained from the SMOS product. It is computed by SNAP as a virtual band from the TB_X, TEC and geometric information values available in the product.