Atmospheric correction of PROBA/CHRIS data in an urban environment

Abstract

The Compact High Resolution Imaging Spectrometer (CHRIS) is an imaging spectrometer onboard the European Space Agency (ESA) Project for On-Board Autonomy (PROBA) satellite. However, it has been shown that CHRIS presents some miscalibration trends over the spectral region covered. This paper reports a practical procedure for the atmospheric correction of CHRIS images based on field recalibration in an urban environment. In the first stage, the spectra of surface targets are measured and used to simulate the spectral radiance at the top of the atmosphere (TOA) for each channel and to determine the recalibration coefficients of the CHRIS images. In the second stage, two methods for atmospheric correction are examined: the radiative transfer model (RTM) and the improved dark-object subtraction (IDOS) method. For comparison purposes, the empirical line method (ELM) is also evaluated. The accuracy assessment shows that the RTM with the Moderate Resolution Transmittance (MODTRAN) code provides the most accurate atmospheric correction for the multiangular CHRIS images when using the proposed procedure.

Acknowledgements

This work was partially supported by a Natural Sciences and Engineering Research Council of Canada (NSERC) grant to Dr J. Wang and by the opening funding of the State Key Laboratory for Remote Sensing Science, Beijing Normal University and Institute of Remote Sensing Applications of Chinese Academy of Sciences. J. Zhou thanks the China Scholarship Council for financial support. The PROBA/CHRIS dataset used in this research was provided by the European Space Agency. The water vapour and aerosol optical depth data was provided by AERONET and observed by the Institute of Atmospheric Physics, Chinese Academy of Sciences. The assistance of Prof. Yunhao Chen, Dr Jinbao Jiang and Bin Xi with fieldwork in Beijing is acknowledged. We thank the anonymous referees for their constructive criticism and comments.