Evaluating calibration consistency of Terra and Aqua MODIS LWIR PV bands using Dome C

Abstract

Over the years, data from Terra and Aqua MODIS (The Moderate Resolution Imaging Spectroradiometer) has provided invaluable information about Earth's atmosphere, land and oceans. Both MODIS sensors have exceeded their designed lifetime of 6 years and are still in operation. Therefore, it is important to understand the on- orbit performance of both sensors. The thermal emissive bands (TEB) on MODIS are comprised of 16 spectral bands with wavelengths from 3.7 to 14.4 μm. The TEB are calibrated on orbit on a scan-by-scan basis using a blackbody calibration source. Since the mission beginning, a steady increase in electronic crosstalk has been observed in Terra MODIS bands 27-30. The MODIS Characterization Support Team (MCST) at NASA/GSFC has recently derived a set of correction factors that correct these bands for the entire mission. These corrections are being applied in Terra Collection 6.1. In this study, the effectiveness of this crosstalk correction is assessed. First, the observed brightness temperatures over Dome C for Terra with and without the crosstalk correction are compared. Then, the calibration consistency and stability between the TEB of Terra, with the crosstalk correction, and Aqua MODIS are also assessed. Finally, the relative bias between the two MODIS instruments is evaluated using the near-surface temperature measurements from an Automatic Weather Station (AWS).