Variability of solar radiation under cloud‐free skies in China: The role of aerosols

Abstract

Analysis of long‐term surface global and diffuse solar radiation, aerosol single scattering albedo (SSA), and relative humidity (RH) data reveals that much of China experienced significant decreases in global solar radiation (GSR) and increases in diffuse solar radiation under cloud‐free skies between the 1960s and 1980s. With RH and aerosol SSA being rather constant during that time period, we suggest that the increasing aerosol loading from emission of pollutants is responsible for the observed reduced GSR and increased diffuse radiation in cloud‐free skies. Although pollutant emissions continue to increase after the 1980s, the increment of aerosol SSA since 1980s can partly explain the transition of GSR from a decreasing trend to no apparent trend around that time. Preliminary analysis is also provided on the potential role of RH in affecting the global and diffuse solar radiation reaching the earth surface.

Impact of land use/land cover change on changes in surface solar radiation in eastern China since the reform and opening up

“…In China, a decadal transition in SSR from dimming to brightening or at least a leveling off after approximately 1990 has also been reported (e.g., Liu et al 2004;Che et al 2005;Qian et al 2007Qian et al , 2011aShi et al 2008;Tang et al 2011). Changes in clouds cannot explain the dimming because more cloud-free sky has been observed (Qian et al 2006).…”

“…The transition can be seen more distinctly when the radiative effects of cloud cover variability is removed (Allen et al 2013). Several studies have suggested that the increasing emissions of anthropogenic aerosols have resulted in less solar radiation reaching the ground (Che et al 2005;Qian et al 2006Qian et al , 2007Shi et al 2008;Wild 2009a). Moreover, researchers have suggested that changes in fuel utilization (Streets et al 2008) and, thus, in anthropogenic aerosol composition and associated single-scattering albedo (Qian et al 2007) may be responsible for the observed transition in SSR (Wild 2009a).…”

“…Several studies have suggested that the increasing emissions of anthropogenic aerosols have resulted in less solar radiation reaching the ground (Che et al 2005;Qian et al 2006Qian et al , 2007Shi et al 2008;Wild 2009a). Moreover, researchers have suggested that changes in fuel utilization (Streets et al 2008) and, thus, in anthropogenic aerosol composition and associated single-scattering albedo (Qian et al 2007) may be responsible for the observed transition in SSR (Wild 2009a). Global interests have been paid to the transition in China, particularly the leveling off period when the USA, Europe, and Japan have reported brightening trends, whereas China has experienced neither apparent brightening nor dimming (Wild 2012;Allen et al 2013).…”

Urbanization effect on trends in sunshine duration in China

“…However, using TOMS AOD at 500 nm along with MODIS AOD at 550 nm (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008), Guo et al (2011) observed a continuous upward trend in average AOD over eight typical regions across China without any transition in 1990. A significant increment of aerosol single-scattering albedo was reported in China between the early 1980s and 1998, which could result in less absorption and thus more radiation reaching the Earth's surface (Qian et al, 2007). The difference in the trends between PM concentrations and satellite AOD might be explained by the emission control policies in China, which target primary aerosols (mainly related to PM) but are less strict for secondary aerosol precursors (e.g., NO x , NMVOC, and NH 3 , mainly related to AOD; Lin et al, 2010).…”

Analysis of extinction properties as a function of relative humidity using a <i>κ</i>-EC-Mie model in Nanjing

“…Visibility throughout the world has generally decreased in recent decades, especially in Asia. In China, horizontal visibility has significantly decreased since 1980 (Che et al, 2007;Qian and Giorgi, 2000;Qian et al, 2007;Streets et al, 2008;Fu et al, 2013;Yang et al, 2016;Liu et al, 2016). For example, in Guangzhou, one of the largest cities in the Pearl River Delta (PRD), low visibility occurs on 150 days per year (Deng et al, 2008).…”