Ground-based aerosol climatology of China: aerosol optical depths from the China Aerosol Remote Sensing Network (CARSNET) 2002–2013

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.

SAHARA: A Simplified AtmospHeric Correction AlgoRithm for Chinese gAofen Data: 1. Aerosol Algorithm

“…According to the two 10 km retrievals, we can see that the AODs for the upper part of the image (Shandong Peninsula) are much smaller compared to the lower part (Jiangsu Province). The main reason for this is that there are more industries in Jiangsu province while the main aerosol source because the straw combustion season (starting from late August) over Shandong has not yet started [51]. We can clearly see a large difference near the cloud edge (lower part of the image), indicating potential cloud contamination for GF4 aerosol retrieval.…”

Optimized Broadband Extinction Method for Retrieving 500 nm AOD with Long-Term Direct Solar Radiation: Model Test and Application

“…The smallest AOD of 0.51 occurred in 2009, and the largest AODs of 0.63 were noted in 1993 and 1996. Because the AOD value decreased with the increase in monitoring channels, the OBEM retrieval datasets were lower than those of Che et al(2015) and higher than those of Xu et al(2015). As is shown in Fig.…”

“…Two peaks existed in 2003 and 2006, among which the AOD in 2006 was relatively high, with a value of approximately 0.60. Che et al (2015) analyzed the 440 nm AOD variation of the Beijing site belonging to CARSNET for the duration of 2002-2013 and also noted that the AOD decreased year by year. Fig.…”

Improving Spatial Coverage for Aqua MODIS AOD using NDVI-Based Multi-Temporal Regression Analysis

“…Aerosol optical depth (AOD), which characterizes the integral of aerosol extinction coefficients in the vertical atmospheric column, has been widely acknowledged as a key parameter in atmospheric research, such as atmospheric corrections in remote sensing [4]. Although the Aerosol Robotic Network (AERONET) can measure relatively accurate AOD values and provides regional analysis [5][6][7], the sparse distribution of AERONET sites hardly characterizes AOD spatial variation [8]. Satellite-derived AOD fills this vacancy with spatially continuous observations, providing better spatial and temporal coverage for regional assessments on a large scale [9].…”