Abstract
Abstract. Long-term measurements of aerosol optical depths (AODs) at 440 nm and Ångström exponents (AE) between 440 and 870 nm made for CARSNET were compiled into a climatology of aerosol optical properties for China. Quality-assured monthly mean AODs are presented for 50 sites representing remote, rural, and urban areas. AODs were 0.14, 0.34, 0.42, 0.54, and 0.74 at remote stations, rural/desert regions, the Loess Plateau, central and eastern China, and urban sites, respectively, and the corresponding AE values were 0.97, 0.55, 0.82, 1.19, and 1.05. AODs increased from north to south, with low values (< 0.20) over the Tibetan Plateau and northwestern China and high AODs (> 0.60) in central and eastern China where industrial emissions and anthropogenic activities were likely sources. AODs were 0.20–0.40 in semi-arid and arid regions and some background areas in northern and northeastern China. AEs were > 1.20 over the southern reaches of the Yangtze River and at clean sites in northeastern China. In the northwestern deserts and industrial parts of northeast China, AEs were lower (< 0.80) compared with central and eastern regions. Dust events in spring, hygroscopic particle growth during summer, and biomass burning contribute the high AODs, especially in northern and eastern China. The AODs show decreasing trends from 2006 to 2009 but increased ~ 0.03 per year from 2009 to 2013.
Highlights
Aerosol particles are important for global and regional climate because particulate matter (PM) can scatter or absorb solar radiation, depending on the particles’ composition, size, etc. (Charlson et al, 1992) and cause either large-scale cooling or warming (Hansen et al, 1997)
The primary objective of this paper is to present a climatology of aerosol optical properties developed from CARSNET measurements made from 2002 to 2013
The aerosol optical depths (AODs) increased from north to south (Fig. 2a)
Summary
Aerosol particles are important for global and regional climate because particulate matter (PM) can scatter or absorb solar radiation, depending on the particles’ composition, size, etc. (Charlson et al, 1992) and cause either large-scale cooling or warming (Hansen et al, 1997). China is the most populated and largest developing country in the world, and it has become one of the largest global sources for aerosol particles and their precursors due to the copious industrial emissions and frequent dust events (Huebert et al, 2003; Seinfeld et al, 2004; Li et al, 2007) These aerosol particles affect the local atmospheric environment and are transported to the East Asia and Pacific regions and beyond (Streets et al, 2001; Eck et al, 2005) where the transported materials can cause significant effects on regional weather and climate and human health (Che et al, 2005; Liang and Xia, 2005; Xia, 2010; Chen et al, 2011)
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