Aerosol optical depth over land: Comparing AERONET, AVHRR and MODIS

Hauser, Adrian; Oesch, David; Foppa, Nando

doi:10.1029/2005gl023579

Cited by 34 publications

(21 citation statements)

References 20 publications

(29 reference statements)

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“…However, it may also occur that subpixel clouds are tagged as aerosol, which would erroneously raise the retrieved aerosol AOD. Further studies report MODIS AOD overestimates such as Ichoku et al [2005], Abdou et al [2005], and Hauser et al [2005].…”

Section: Resultsmentioning

confidence: 90%

“…MODIS satellite data exist on a daily, near‐real‐time operational basis, starting in the year 2000 for TERRA satellite and 2002 for the MODIS instrument aboard AQUA. Existing studies that have evaluated and intercompared these data mostly rely on older MODIS collection 4 (C4) data, investigate only 1–2 years or only one site, or focus on other continents [e.g., Chu et al , 2003; Hauser et al , 2005; Tripathi et al , 2005; Kovacs , 2006; Li et al , 2007; Misra et al , 2008; de Almeida Castanho et al , 2008].…”

Section: Introductionmentioning

confidence: 99%

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Regional representativity of AERONET observation sites during the biomass burning season in South America determined by correlation studies with MODIS Aerosol Optical Depth

et al. 2009

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[1] This paper presents an analysis of ground-based Aerosol Optical Depth (AOD) observations by the Aerosol Robotic Network (AERONET) in South America from 2001 to 2007 in comparison with the satellite AOD product of Moderate Resolution Imaging Spectroradiometer (MODIS), aboard TERRA and AQUA satellites. Data of 12 observation sites were used with primary interest in AERONET sites located in or downwind of areas with high biomass burning activity and with measurements available for the full time range. Fires cause the predominant carbonaceous aerosol emission signal during the dry season in South America and are therefore a special focus of this study. Interannual and seasonal behavior of the observed AOD at different sites were investigated, showing clear differences between purely fire and urban influenced sites. An intercomparison of AERONET and MODIS AOD annual correlations revealed that neither an interannual long-term trend may be observed nor that correlations differ significantly owing to different overpass times of TERRA and AQUA. Individual anisotropic representativity areas for each AERONET site were derived by correlating daily AOD of each site for all years with available individual MODIS AOD pixels gridded to 1°Â 1°. Results showed that for many sites a good AOD correlation (R 2 > 0.5) persists for large, often strongly anisotropic, areas. The climatological areas of common regional aerosol regimes often extend over several hundreds of kilometers, sometimes far across national boundaries. As a practical application, these strongly inhomogeneous and anisotropic areas of influence are being implemented in the tropospheric aerosol data assimilation system of the Coupled Chemistry-Aerosol-Tracer Transport Model coupled to the Brazilian Regional Atmospheric Modeling System (CCATT-BRAMS) at the Brazilian National Institute for Space Research (INPE). This new information promises an improved exploitation of local site sampling and, thus, chemical weather forecast.

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Section: Resultsmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Regional representativity of AERONET observation sites during the biomass burning season in South America determined by correlation studies with MODIS Aerosol Optical Depth

et al. 2009

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“…Many ground-based remote sensing aerosol networks have been established around the world. For example, the Aerosol Robotic Network (AERONET) can provide continuous cloud-screened observations of spectral AOD values around the world [6,7]. In China, AOD values are routinely measured at about 50 sites within the China Aerosol Remote Sensing Network (CARSNET) [8][9][10].…”

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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“…Knapp and Stowe (2002) derived τ a from the reduced resolution (110 × 110 km 2 ) Pathfinder-Atmosphere (PATMOS) data set using also bright surface targets. Hauser et al (2005a) applied a similar technique to derive τ a at full resolution (1.1 × 1.1 km 2 ) for Central Europe using NOAA-16 AVHRR and they further qualitatively compared monthly and seasonal means from this product with MODIS collection 004 data (Hauser et al, 2005b). A full resolution τ a climatology from AVHRR covering land surfaces is still missing.…”

Section: Introductionmentioning

confidence: 99%

Validation of a modified AVHRR aerosol optical depth retrieval algorithm over Central Europe

et al. 2010

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Abstract. The Advanced Very High Resolution Radiometer (AVHRR) carried on board the National Oceanic and Atmospheric Administration (NOAA) and the Meteorological Operational Satellite (MetOp) polar orbiting satellites is the only instrument offering more than 25 years of satellite data to analyse aerosols on a daily basis. The present study assessed a modified AVHRR aerosol optical depth τ a retrieval over land for Europe. The algorithm might also be applied to other parts of the world with similar surface characteristics like Europe, only the aerosol properties would have to be adapted to a new region. The initial approach used a relationship between Sun photometer measurements from the Aerosol Robotic Network (AERONET) and the satellite data to post-process the retrieved τ a . Herein a quasistand-alone procedure, which is more suitable for the pre-AERONET era, is presented. In addition, the estimation of surface reflectance, the aerosol model, and other processing steps have been adapted. The method's cross-platform applicability was tested by validating τ a from NOAA-17 and NOAA-18 AVHRR at 15 AERONET sites in Central Europe (40.5 • N-50 • N, 0 • E-17 • E) from August 2005 to December 2007. Furthermore, the accuracy of the AVHRR retrieval was related to products from two newer instruments, the Medium Resolution Imaging Spectrometer (MERIS) on board the Environmental Satellite (ENVISAT) and the Moderate Resolution Imaging Spectroradiometer (MODIS) on board Aqua/Terra. Considering the linear correlation coefficient R, the AVHRR results were similar to those of MERIS with even lower root mean square error RMSE. Not surprisingly, MODIS, with its high spectral coverage, gave the Correspondence to: M. Riffler (riffler@giub.unibe.ch) highest R and lowest RMSE. Regarding monthly averaged τ a , the results were ambiguous. Focusing on small-scale structures, R was reduced for all sensors, whereas the RMSE solely for MERIS substantially increased. Regarding larger areas like Central Europe, the error statistics were similar to the individual match-ups. This was mainly explained with sampling issues. With the successful validation of AVHRR we are now able to concentrate on our large data archive dating back to 1985. This is a unique opportunity for both climate and air pollution studies over land surfaces.

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Aerosol optical depth over land: Comparing AERONET, AVHRR and MODIS

Cited by 34 publications

References 20 publications

Regional representativity of AERONET observation sites during the biomass burning season in South America determined by correlation studies with MODIS Aerosol Optical Depth

Regional representativity of AERONET observation sites during the biomass burning season in South America determined by correlation studies with MODIS Aerosol Optical Depth

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

Validation of a modified AVHRR aerosol optical depth retrieval algorithm over Central Europe

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