Abstract
Abstract. Anthropogenic dusts are those produced by human activities on disturbed soils, which are mainly cropland, pastureland, and urbanized regions, and are a subset of the total dust load which includes natural sources from desert regions. Our knowledge of anthropogenic dusts is still very limited due to a lack of data. To understand the contribution of anthropogenic dust to the total global dust load, it is important to identify it apart from total dust. In this study, a new technique for distinguishing anthropogenic dust from natural dust is proposed by using Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) dust and planetary boundary layer (PBL) height retrievals along with a land use data set. Using this technique, the global distribution of dust is analyzed and the relative contribution of anthropogenic and natural dust sources to regional and global emissions are estimated. Results reveal that local anthropogenic dust aerosol due to human activity, such as agriculture, industrial activity, transportation, and overgrazing, accounts for about 25 % of the global continental dust load. Of these anthropogenic dust aerosols, more than 53 % come from semi-arid and semi-wet regions. Annual mean anthropogenic dust column burden (DCB) values range from 0.42 g m−2, with a maximum in India, to 0.12 g m−2, with a minimum in North America. A better understanding of anthropogenic dust emission will enable us to focus on human activities in these critical regions and with such knowledge we will be more able to improve global dust models and to explore the effects of anthropogenic emission on radiative forcing, climate change, and air quality in the future.
Highlights
Dust accounts for some of the highest mass loadings in the atmosphere and plays an important role in modulating radiative forcing and climate via a number of complex processes (Huang et al, 2006a, b, 2014; Su et al, 2008)
We determine and use planetary boundary layer (PBL) height to exclude long-distance transport of dust aerosol from dust sources above the anthropogenic surface described above, so it is important to accurately determine PBL height to separate out the anthropogenic dust
These major dust sources are located in the broad “dust belt” that stretches from the western coast of North Africa to China, covering the Sahara and Sahel regions, the Arabian Peninsula, northern India, the Tarim Basin and the Gobi Desert
Summary
Dust accounts for some of the highest mass loadings in the atmosphere and plays an important role in modulating radiative forcing and climate via a number of complex processes (Huang et al, 2006a, b, 2014; Su et al, 2008). The atmospheric dust load that originates from soils disturbed by human activities such as land use practices, which can be interpreted as “anthropogenic” dust (Tegen and Fung, 1995), can increase dust loading, which, in turn, affects the radiative forcing. Sokolik and Toon (1996) made the rough assumption that the dust production rate is linearly proportional to the dust source area and estimated the amount of anthropogenic mineral aerosols through assessment of the land area converted to desert by human activities. MODIS products do not include vertical distribution information and cannot readily exclude natural dust aerosols from deserts or marine sea salt aerosols that are transported over anthropogenic sources. We develop a new technique for detection of anthropogenic dust emissions that uses CALIPSO lidar measurements and analyzes their global distribution.
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