Asian dust weather categorization with satellite and surface observations

Abstract

This study categorizes various dust weather types by means of satellite remote sensing over central Asia. Airborne dust particles can be identified by satellite remote sensing because of the different optical properties exhibited by coarse and fine particles (i.e. varying particle sizes). If a correlation can be established between the retrieved aerosol optical properties and surface visibility, the intensity of dust weather can be more effectively and consistently discerned using satellite rather than surface observations. In this article, datasets consisting of collocated products from Moderate Resolution Imaging Spectroradiometer Aqua and surface measurements are analysed. The results indicate an exponential relationship between the surface visibility and the satellite-retrieved aerosol optical depth, which is subsequently used to categorize the dust weather. The satellite-derived spatial frequency distributions in the dust weather types are consistent with China's weather station reports during 2003, indicating that dust weather classification using satellite data is highly feasible. Although the period during the springtime from 2004 to 2007 may be not sufficient for statistical significance, our results reveal an increasing tendency in both intensity and frequency of dust weather over central Asia during this time period.

Acknowledgements

We thank Dr. Douglas Westphal for providing the visibility data, and the MODIS team from the Goddard Space Flight Center for the MODIS data set. We also thank Dr. Myeong-Jae Jeong for data processing assistance and C. Liang for reviewing the English in this article. This research was supported by the National Science Council (NSC) and the Environmental Protection Administration of Taiwan under grants NSC 96-2752-M-008-005-PAE, 96-2745-M-008-003, 97-2752-M-008-012-PAE, 97-2745-M-008-012 and 97-EPA-M-008-001.