MESSR Radiometric Evaluation

Abstract

The accuracy of radiance measurements of the MOS-1 MESSR (instrument No. 1) was evaluated by comparing the MESSR data with simultaneously collected ground based measurement data as follows.
The upward radiances at the height of the MOS-1 were theoretically computed from the observed upward radiance at the ground surface using the atmospheric transemittance and the atmospheric path radiance. The transemittance and the path radiance were calculated from the data of the atmospheric turbidity, the vertical profiles of atmospheric temperature, the relative humidity etc. Those data were collected at the same time and place with the MESSR data. Multiple scattering theory was used for path radiance estimation, and the LOTWRAN6 code was used for the transemittance calculation.
Then the upward radiance computed as above were compared with those measured by the MESSR. As a result, it was shown that the measurement accuracies of MESSR in band 1, 2 and 3 were very close to the planned sensor accuracy. However, the radiance derived from band 4 data showed the gain of about 0.7 against the the radiance derived from the ground based measurements. This suggests the decline of the sensor response in band 4 has taken place since the launch of MOS-1.