The TanSat Team is pleased to announce the availability of ACGS Version 2 Level 1B data. Many improvements are listed below:

 

 1. Bias correction of spectral calibration

The biases in three bands are corrected based on the analysis result of solar Fraunhofer lines observed by TanSat solar calibration.

 

2. The new background coefficients are applied to the calculation of background signals from October 27, 2017.

 

3. The datasets of land cover are added to the new version.

 

4. Updates of water-land indicator

  The values in the new version range from 0-100 with units of percentage.

 

5. Updates of polarization angles

The polarization angle is updated to the included angle between the accepted polarization axis of the instrument and the instrument reference plane for polarization, defined as the plane formed by the LOS and the ray from the sounding location to the local zenith

 

6. Changes of radiance units

The ACGS radiance units are changed from W/m2/sr/nm to Ph/S/m2/sr/um in order to adapt the solar input irradiance units. It should be noted that the signal to noise coefficients is suited for the old units W/m2/sr/nm because these coefficients is derived from the lab noise testing which used the old units.

 

7. The radiance in version 2 is calibrated to the half of the raw radiance in version 1.

 

8. The file names are updated to include the version number, the whole satellite name and instruments name.