Atmospheric Aerosol Optical Properties and Climate Change in Arid and Semi-Arid Regions

Abstract

In recent years, there has been much attention to the study of atmospheric aerosols in Asia as aerosols generated in this region has significant direct and indirect effect on changing the Earth’s climate on a global scale. Aerosols are small particles in the air that originate from a number of different natural and human activities such as ocean spray, dust storms, fires and pollution from fossil fuel combustion. Aerosol particles may be solid or liquid and their sizes range from 0.01 microns to several tens of microns. Scientists have much to learn about how aerosols affect regional and global climate and the direct and indirect radiative forcing of aerosols are still not understood well. In the last decade, scientists from East Asian countries and the world’s science communities have organized and conducted many international and regional experiments and projects on aerosol optical properties and the measurement of radiation , for example: NASA AERONET (Aerosol Robotic Network), East Asian Regional Experiment 2005 (EAREX 2005) of the United Nations Environmental Program (UNEP), Atmospheric Brown Cloud (ABC) project, ABC Maldives Monsoon Experiment (APMEX), SKYNET (MEXT Sky Radiometer Network), ADEC (Japan-Sino Joint Aeolian Dust Experiment), ABC-EAREX (ABC East Asian Regional Experiment) and EASTAIRE (East Asian Study of Tropospheric Aerosols, International Regional Experiment). Figure 1 shows sites of above mentioned networks in East Asia. The AERONET provides quality-assured data for aerosol optical properties measured by the Sun/sky multi wavelength radiometer over the World. AERONET facility processes and archives these data according to a standardized procedure for the retrieval of aerosol properties. One of the AERONET site at Dalanzadgad of arid region of Mongolia has been operated continuously since 1999 (Tugjsuren N, 2010). Recently, studies on the aerosol monitoring over Eastern Asia using AERONET Sun-photometer acquired aerosol optical thickness and Angstrom exponent measurement have been conducted in the research on Aerosol properties in a Chinese semiarid region (Xia Xiango at al., 2004). Seasonal and monthly variations of columnar aerosol optical properties over east Asia determined from multi-year MODIS, LIDAR, and AERONET Sun/sky radiometer measurements, (Sang-woo Kim at al., 2006) The East Asian regional Experiment 2005 (FAREX 2005) project was organized and conducted from March to April 2005 by researches from east Asian countries and others. The regional experiment preceding to FAREX 2005 was the ABC Maldives Monsoon Experiment (ARMEX) conducted from 1 October to 15 November 2004 in the south Asian