A climatology of aerosol optical depth over China from recent 10 years of MODIS remote sensing data

Abstract

Using the recent 10-year (March 2000 to February 2010) MODIS data of aerosol optical depth (AOD), the distributions of annual and seasonal mean AOD over China are presented, and the trends and seasonal variations in AOD over 10 regions in China are analysed. The spatial pattern of annual mean AOD is characterized generally with two low centres and two high centres over China. Two low AOD centres are located in the areas with a high vegetation cover and a sparse population in (1) the high-latitude region in Northeast China with AOD of about 0.2 and (2) the high-altitude region in Southwest China with AOD from 0.1 to 0.2. These two low AOD centres are connected by a low AOD zone (0.2-0.3) in a northeast-southwest direction across China. Demarcated by this low AOD zone, two high centres with AOD of about 0.8 are situated in (1) the most densely populated and industrialized regions in China with high anthropogenic aerosols from North China Plain, Yangtze River areas covering Sichuan Basin, Central China and Yangtze River Delta to South China with Pearl River Delta region and (2) Tarim Basin in Northwest China with high natural aerosols dominated with desert dust. The spatial AOD patterns over China keep seasonally unchanged, but the strengths of the AOD-centres vary from season to season. The wintertime AOD is lowest in China. The monthly AOD variations from March to September in Southern China correspond with high AOD before, after the rain periods and low AOD during the rain periods of Asian summer monsoon. Asian summer monsoons also make a notable impact on the seasonal cycle of aerosols in China. The AOD in Northern China changes monthly with a single peak between April and June and a low in the winter months. The positive trends in AOD occur mostly in the aerosol source regions with higher annual mean AOD (>0.25), while the negative trends are found in the regions with lower annual mean AOD (<0.25) over China.

Two decades of satellite observations of AOD over mainland China using ATSR-2, AATSR and MODIS/Terra: data set evaluation and large-scale patterns

“…It is noted that the BTH, PRD and YRD regions host three major urban clusters that constitute huge spatial sources of anthropogenic aerosols . This brief discussion clearly illustrates the seasonal variation of the AOD, as well as the regional differences in the seasonal variation as earlier shown by, e.g., Song et al (2009), Luo et al (2014 and Li et al (2017).…”

“…Earlier studies on the aerosol climatology and trends over China were made using ground-based remote sensing, i.e., sun photometers in CARSNET , hand-held sun photometers in the Chinese Sun Hazemeter Network (CSHNET; Y. and solar radiation measurements (e.g., X. , or satellite data, in partic-ular MODIS (e.g., Li et al, 2003;Song et al, 2009;Luo et al, 2014;Tan et al, 2015;H. Xu et al, 2015;Ma et al, 2016; but also using multiple satellite data (Lin et al, 2010;Guo et al, 2011Guo et al, , 2016bDong et al, 2017;Zhao et al, 2017;Zhang et al, 2017).…”

Impact of atmospheric circulations on aerosol distributions in autumn over eastern China: observational evidence

“…3. Luo et al (2014) considered the value of AOD > 0.5 as the big value in China. However, in our data for more than half of eastern China, the frequency of AOD > 0.5 is larger than 50 % (Fig.…”

“…Wu et al (2013) pointed out that MODIS data were usually valid throughout China and revealed the characteristics of aerosol transport and different extinction features in East Asia. Luo et al (2014) verified the good quality of MODIS AOD over land in China and used 10-year data to construct the climatology of AOD over China. Based on the previous validations, MODIS AOD data are considered to have good quality over China region and can capture the features of aerosol distribution.…”

Evaluation of the MODIS C6 Aerosol Optical Depth Products over Chongqing, China

“…Two MODIS onboard Terra and Aqua measure the earth system in multiple bands since 1999 and 2002, respectively. The Visible Infrared Imaging Radiometer Suite (VIIRS) that is onboard the National Polar-orbiting Partnership (Suomi-NPP) with similar device climatology [35,44]. These products have great potentials to serve air quality monitoring and research.…”