Polarization effect in NOAA-20 reflective solar bands and its mitigation in Earth view imagery and radiometry (Conference Presentation)

Abstract

The NOAA-20 Visible Infrared Imager Radiometer Suite (VIIRS) was launched on November 18, 2017 and started to collect Earth view visible/reflective imagery on December 13, 2017. VIIRS is a whiskbroom radiometer that provides ±56.28° scans of the Earth view. It has 22 bands, among which 14 are reflective solar bands (RSBs) covering a spectral range from 0.410 to 2.250 μm. The NOAA-20 VIIRS RSBs are much more sensitive to the polarization of incident light than the SNPP VIIRS RSBs. For VIIRS, it is specified that the polarization factor should be smaller than 3% for 410 and 862 nm bands and 2.5% for other RSBs for the scan angle within ±45°. Prelaunch polarization sensitivity tests demonstrated that most of NOAA-20 VIIRS RSBs are out of the polarization sensitivity specification, especially bands M1 and M4, and the polarization are strongly scan angle, detector as well as wavelength dependent. In this paper, it will be shown that the polarization effect induces strong stripping in sensor data records (SDR) Earth view (EV) imagery due to polarization sensitivity differences among the detectors of same band and the stripping are strongly scan angle and band dependent. In this analysis, the polarization effect correction is applied to SDR products to mitigate the impact of the polarization effect. It is demonstrated that the correction can successfully remove the polarization effect in the NOAA-20 VIIRS RSB SDR products and restore the quality of the EV imagery as well as accuracy of EV radiometry for the RSBs.