Long-term autonomous vicarious calibration of VIS-NIR channels of MODIS

摘要

In this Letter, we present the automated observation radiometric calibration (AORC) approach for vicarious calibration to determine the surface reflectance for any arbitrary test site in the absence of ground personnel. It has successfully operated at Dunhuang test site for 4 months, with a suite of instruments including an automated test-site radiometer, a precision solar radiometer, and a visible and short-wave infrared hyper-spectral irradiance meter. The predicted top-of-atmosphere (TOA) radiance are in good agreement with those obtained from the on-board calibration system of Terra Moderate Resolution Imaging Spectrometer (MODIS), the average percent difference less than 3.10% in nine bands except 5.14% in band 5. It enable us to improve the calibration frequency, currently once a year in situ, to 1~2 times every month and maintain radiometric accuracy on par with manned field campaigns which making it possible to establish long-term trends in sensor performance.