Crosstalk effect and its mitigation in thermal emissive bands of remote sensors

摘要

It has been found that there is severe electronic noise in the Terra Moderate Resolution Imaging Spectroradiometer (MODIS) bands 27-30 which corresponds to wavelengths ranging between 6.7 μm to 9.73 μm. The cause for the issue has been identified to be crosstalk, which is significantly amplified since 2010 due to severe degradation in the electronic circuitry. The crosstalk effect causes unexpected discontinuity/change in the calibration coefficients and induces strong striping artifacts in the earth view (EV) images. Also it is noticed, that there are large long-term drifts in the EV brightness temperature (BT) in these bands. An algorithm using a linear approximation derived from on-orbit lunar observations has been developed to correct the crosstalk effect for them. It was demonstrated that the crosstalk correction can remarkably minimize the discontinuity/change in the calibration coefficients, substantially reduce the striping in the EV images, and significantly remove the long-term drift in the EV BT in all these bands. In this paper, we present the recent progresses in the crosstalk effect analysis and its mitigation. In addition, we will show that besides these four bands, the TEBs in other satellite remote sensors also have significant crosstalk contaminations. Further, it will be demonstrated that the crosstalk correction algorithm we developed can be successfully applied to all the contaminated TEBs to significantly reduce the crosstalk effects and substantially improve both the image quality and the radiometric accuracy of Level-1B (L1B) products for the bands.