Global and regional trends of aerosol optical depth over land and ocean  using SeaWiFS measurements from 1997 to 2010

Abstract. This study evaluates a new spectral aerosol optical depth (AOD) dataset derived from Sea-viewing Wide Field-of-view Sensor (SeaWiFS) measurements over land. First, the data are validated against Aerosol Robotic Network (AERONET) direct-sun AOD measurements and found to compare well on a global basis. If only data with the highest quality flag are used, the correlation is 0.86 and 72 % of matchups fall within an expected absolute uncertainty of 0.05 + 20 % (for the wavelength of 550 nm). The quality is similar at other wavelengths and stable over the 13-yr (1997-2010) mission length. Performance tends to be better over vegetated, low-lying terrain with typical AOD of 0.3 or less, such as found over much of North America and Eurasia. Performance tends to be poorer for low-AOD conditions near backscattering geometries, where SeaWiFS overestimates AOD, or optically-thick cases of absorbing aerosol, where SeaWiFS tends to underestimate AOD. Second, the SeaWiFS data are compared with midvisible AOD derived from the Moderate Resolution Imaging Spectrometer (MODIS) and Multiangle Imaging Spectroradiometer (MISR). All instruments show similar spatial and seasonal distributions of AOD, although there are regional and seasonal offsets between them. At locations where AERONET data are available, these offsets are largely consistent with the known validation characteristics of each dataset. With the results of this study in mind, the SeaWiFS over-land AOD record is suitable for quantitative scientific use.

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“…A trend analysis of the SeaWiFS data, in conjunction with AERONET and other satellite datasets, has been performed by Hsu et al (2012).…”

Section: Regional Comparisonsmentioning

confidence: 99%

Global and regional evaluation of over-land spectral aerosol optical depth retrievals from SeaWiFS

et al. 2012

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“…Fine particles with aerodynamic diameters of 2.5 µm and less (PM 2.5 ) are the most effective factor for visibility impairment and fugitive dust) and regional emissions under the influence of different meteorological conditions, especially in spring and winter (Hou et al, 2011;Long et al, 2014). In recent years, haze events in Shanghai have been widely concerned and intensely studied (Hsu et al, 2012;Cheng et al, 2013;Lin et al, 2014). Cheng et al (2013) summarized that visual range in the Yangtze River Delta endured a reduction from 13.2 to 10.5 km from 1980 to 2000.…”

Section: Introductionmentioning

confidence: 99%

“…Cheng et al (2013) summarized that visual range in the Yangtze River Delta endured a reduction from 13.2 to 10.5 km from 1980 to 2000. Hsu et al (2012) analyzed the global and regional trends of aerosol optical depth over land and ocean based on remote sensing products from 1997 to 2010. Fu et al (2008) showed that the hourly PM 2.5 and PM 10 concentrations of the heavy haze days in Shanghai could reach as high as 466 and 744 µg m -3 on 19 January 2007, respectively.…”

Section: Introductionmentioning

confidence: 99%

A Heavy Haze Episode in Shanghai in December of 2013: Characteristics, Origins and Implications

Yan

Fan

et al. 2015

Aerosol Air Qual. Res.

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As the largest Chinese city by population and the largest city proper by population in the world, Shanghai has frequently suffered the heavy haze in recent years. In this study, the observational data (PM 2.5 , PM 10 , O 3 , NO 2 , CO and SO 2 ) at the ten urban monitoring stations in Shanghai from November 25 to December 9, 2013, were used to analyze the haze pollution. The source contributions of PM 2.5 in Shanghai were identified by trajectory clustering and hybrid receptor models (potential source contribution function (PSCF) and concentration weighted trajectory (CWT)). The results showed that for the whole study period, the ranges of pollutant concentrations are 2. . It was found that PM 2.5 contributed more than 80% of PM 10 for the whole period except the relatively clean period in which only 45% of PM 10 is PM 2.5 . The model analyses show that clean air masses reaching at Shanghai were from the far away regions like Mongolia and Inner Mongolia with the high mean wind speed (fast air masses). On the other hand, the heavy haze air masses were mainly from the nearby industrialized and urbanized provinces with industrial cities. It was found that the formation of the extremely heavy haze from December 5 to 7 in Shanghai was mainly because of the air pollution transported from the nearby provinces (i.e., Anhui, Jiangsu, Zhejiang) and central part provinces (such as Shandong, Hebei) of eastern China. The correlation analyses among PM 2.5 and other pollutants show that the PM 2.5 formation in Shanghai is affected by the sources similar to those of CO such as combustion, industry, mobile and oxidation of hydrocarbons. Finally, the controlling strategies are discussed on the basis of this result.

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“…The Advanced Along Track Scanning Radiometer (AATSR) aboard Envisat can also provide AOD products with high nadir spatial resolution (1 km × 1 km) [14][15][16][17]. Meanwhile, the Seaviewing Wide Field-of-view Sensor (SEAWIFS) aboard GeoEye's OrbView-2 can provide AOD data over the globally ocean with a spatial resolution of 9 km × 9 km [18][19][20]. Long-term daily and monthly AOD records can also be obtained from the Advanced Very High Resolution Radiometer (AVHRR) aboard on TIROS-N and NOAA series with nadir spatial resolution of 1.1 km × 1.1 km [21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Characteristic and Driving Factors of Aerosol Optical Depth over Mainland China during 1980–2017

et al. 2018

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Abstract:Since the reform and opening up of China, the increasing aerosol emissions have posted great challenges to the country's climate change and human health. The aerosol optical depth (AOD) is one of the main physical indicators quantifying the atmospheric turbidity and air pollution. In this study, 38-years (1980-2017) of spatial and temporal variations of AOD in China were analyzed using AOD records derived from MODIS atmosphere products and the MERRA-2 dataset. The results showed that the annual mean AOD values throughout China have gone through an increasing, but fluctuating, trend, especially in 1982 and in 1992 due to two volcano eruptions; the AOD values experienced a dramatically increasing period during 2000-2007 with the rapid economic development and "population explosions" in China/after 2008, the AOD values gradually decreased from 0.297 (2008) to 0.257 (2017). The AOD values in China were generally higher in spring than that in other seasons. The Sichuan Basin has always been an area with high AOD values owing to the strong human activity and the basin topography (hindering aerosol diffusions in the air). In contrast, the Qinghai Tibet Plateau has always been an area with low AOD values due to low aerosol emissions and clear sky conditions there. The trend analysis of AOD values during 1980-2017 in China indicated that the significant increasing trend was mainly observed in Southeastern China. By contrast, the AOD values in the northernmost of China showed a significant decreasing trend. Then, the contributions (AODP) of the AOD for black carbon aerosol (BCAOD), dust aerosol (DUAOD), organic carbon aerosol (OCAOD), sea salt aerosol (SSAOD), and SO 4 aerosol (SO 4 AOD) to the total AOD values were calculated. The results showed that DUAOD (25.43%) and SO 4 AOD (49.51%) were found to be the main driving factors for the spatial and temporal variations of AOD values. Finally, the effects of anthropogenic aerosol emissions, socioeconomic factors, and land-use and land coverage changes on AOD were analyzed. The GDP, population density, and passenger traffic volume were found to be the main socioeconomic drivers for AOD distributions. Relatively larger AOD values were mainly found in urban land and land covered by water, while lower AOD values were found in grassland and permanent glacier areas.

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Global and regional trends of aerosol optical depth over land and ocean using SeaWiFS measurements from 1997 to 2010

Cited by 84 publications

References 33 publications

Global and regional evaluation of over-land spectral aerosol optical depth retrievals from SeaWiFS

Global and regional evaluation of over-land spectral aerosol optical depth retrievals from SeaWiFS

A Heavy Haze Episode in Shanghai in December of 2013: Characteristics, Origins and Implications

Characteristic and Driving Factors of Aerosol Optical Depth over Mainland China during 1980–2017

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