Validation of the GRAPE single view aerosol retrieval for ATSR-2 and insights into the long term global AOD trend over the ocean

Thomas, G. E.; Poulsen, C.; Siddans, Richard; Sayer, A. M.; Carboni, Elisa; Marsh, S.; Dean, S. M.; Grainger, R. G.; Lawrence, B. N.

doi:10.5194/acp-10-4849-2010

Cited by 39 publications

(33 citation statements)

References 38 publications

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“…The use of temporal averaging of AERONET data and spatial averaging of level 2 satellite products when comparing the two is common practice (Ichoku et al, 2002;Thomas et al, 2010). It is an attempt to reduce the sampling differences between the two measurement systems -on the basis that the spatial averaging of a view of 10 km 2 satellite pixels and the temporal averaging of an hour's worth of AERONET data represent values taken over air masses of similar sizesand to increase the number of matches between satellite and AERONET.…”

Section: G E Thomas Et Al: Aerosol Radiative Effect From Globaerosmentioning

confidence: 99%

Regional and monthly and clear-sky aerosol direct radiative effect (and forcing) derived from the GlobAEROSOL-AATSR satellite aerosol product

et al. 2013

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Abstract. Using the GlobAEROSOL-AATSR dataset, estimates of the instantaneous, clear-sky, direct aerosol radiative effect and radiative forcing have been produced for the year 2006. Aerosol Robotic Network sun-photometer measurements have been used to characterise the random and systematic error in the GlobAEROSOL product for 22 regions covering the globe. Representative aerosol properties for each region were derived from the results of a wide range of literature sources and, along with the de-biased GlobAEROSOL AODs, were used to drive an offline version of the Met Office unified model radiation scheme. In addition to the mean AOD, best-estimate run of the radiation scheme, a range of additional calculations were done to propagate uncertainty estimates in the AOD, optical properties, surface albedo and errors due to the temporal and spatial averaging of the AOD fields. This analysis produced monthly, regional estimates of the clear-sky aerosol radiative effect and its uncertainty, which were combined to produce annual, global mean values of (−6.7 ± 3.9) W m −2 at the top of atmosphere (TOA) and (−12 ± 6) W m −2 at the surface. These results were then used to give estimates of regional, clear-sky aerosol direct radiative forcing, using modelled pre-industrial AOD fields for the year 1750 calculated for the AEROCOM PRE experiment. However, as it was not possible to quantify the uncertainty in the pre-industrial aerosol loading, these figures can only be taken as indicative and their uncertainties as lower bounds on the likely errors. Although the uncertainty on aerosol radiative effect presented here is considerably larger than most previous estimates, the explicit inclusion of the major sources of error in the calculations suggest that they are closer to the true constraint on this figure from similar methodologies, and point to the need for more, improved estimates of both global aerosol loading and aerosol optical properties.

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Section: G E Thomas Et Al: Aerosol Radiative Effect From Globaerosmentioning

confidence: 99%

Regional and monthly and clear-sky aerosol direct radiative effect (and forcing) derived from the GlobAEROSOL-AATSR satellite aerosol product

et al. 2013

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“…In the surface reflectance model, the Bidirectional Reflectance Distribution Function (BRDF) is used to describe the angular variation of the surface reflectance and the effects and variations of white caps, under light and sun glint are considered. More detail descriptions of the algorithm and forward model are given by Thomas et al (2009aThomas et al ( ,b, 2010; Sayer et al (2010).…”

Section: Datamentioning

confidence: 99%

Relationship between wind speed and aerosol optical depth over remote ocean

2010

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Abstract. The effect of wind speed on aerosol optical depth (AOD) at 0.55 µm over remote ocean regions is investigated. Remote ocean regions are defined by the combination of AOD from satellite observation and wind direction from ECMWF. According to our definition, many ocean regions cannot be taken as remote ocean regions due to long-range transportation of aerosol from continents. Highly correlated linear relationships are found in remote ocean regions with a wind speed range of 0-20 ms −1 . The enhancement of AOD at high wind speed is explained as the increase of sea salt aerosol production.

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“…However, although AVHRR could provide continues and long-term observations because it have been mounted on various platforms (i.e. TIROS-N, NOAA-6∼19, and MetOp-A), the absence of on-board calibration devices as well as the orbital drift could make a serious bias in trend analysis (Thomas et al, 2010). Zhang and Reid (2010) explained both regional and global aerosol trends above oceans using MODIS andMISR aerosol products (2000-2009), which included both level 2 and level 3 (data assimilation) data sets.…”

Section: Introductionmentioning

confidence: 99%

“…negative trend for MISR and positive for MODIS). Thomas et al (2010) investigated the long-term global AOT trend using ATSR-2 instrument covering time period 1995-2001. They derived a positive trend over the ocean rather than the negative one, consistently found with respect to the AVHRR analyses.…”

Section: Introductionmentioning

confidence: 99%

“…Several algorithms using, for example, Advanced Very High Resolution Radiometer (AVHRR), Total Ozone Mapping Spectrometer (TOMS)/Ozone Monitoring Instrument (OMI), Along Track Scanning Radiometer (ATSR), Multi-angle Imaging SpectroRadiometer (MISR), Moderate Resolution Imaging Spectroradiometer (MODIS), and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) on polar-orbiting satellites (Remer et al, 2005;Kaufman et al, 1997;Higurashi and Nakajima, 1999;Mishchenko et al, 1999;Higurashi et al, 2000;Stowe et al, 1999;Heidinger et al, 2004;Torres et al, 2002;Veefkind et al, 1998;Grey et al, 2006;Thomas et al, 2009;Di Girolamo and Wilson, 2003;Martonchik et al, 2004;Diner et al, 2006;Martins et al, 2002;Robbinson et al, 2003;Wang and Shi, 2005) have been developed to retrieve the global Aerosol Optical Thickness (AOT). Up to now AVHRR, TOMS/OMI, ATSR, MISR, and MODIS have been used in the analysis of global and regional aerosol trends, because they have continuous and long-term observation histories.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of linear long-term trend of aerosol optical thickness derived from SeaWiFS using BAER over Europe and South China

et al. 2011

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Abstract. The main purposes of the present paper are not only to investigate linear long-term trends of Aerosol Optical Thickness (AOT) at 443 and 555 nm over regions in Europe and South China, but also to show the uncertainty caused by cloud disturbance in the trend analysis of cloudfree aerosol. These research areas are the densely urbanised and often highly polluted regions. The study uses the Bremen AErosol Retrieval (BAER) and Sea-viewing Wide Field-ofview Sensor (SeaWiFS) data for AOT retrievals in the specified regions from October 1997 to May 2008. In order to validate the individually retrieved AOTs and the corresponding trends, AErosol RObotic NETwork (AERONET) level 2.0 data have been used. The retrieved AOTs were in good agreement with those of AERONET (0.79 ≤ R ≤ 0.88, 0.08 ≤ RMSD ≤ 0.13). The contamination of the aerosol retrievals and/or AERONET observations by thin clouds can significantly degrade the AOT and lead to statistically nonrepresentative monthly-means, especially during cloudy seasons. Therefore an inter-correction method has been developed and applied. The "corrected" trends for both BAER SeaWiFS and AERONET AOT were similar and showed in average a relative difference of ∼25.19 %. In general terms, negative trends (decrease of aerosol loading) were mainly observed over European regions, with magnitudes up to −0.00453 and −0.00484 yr −1 at 443 and 555 nm, respectively. In contrast, the trend in Pearl River Delta was positive, most likely attributed to rapid urbanization and industrialization. The magnitudes of AOT increased by +0.00761 and +0.00625 yr −1 respectively at 443 and 555 nm.

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Validation of the GRAPE single view aerosol retrieval for ATSR-2 and insights into the long term global AOD trend over the ocean

Cited by 39 publications

References 38 publications

Regional and monthly and clear-sky aerosol direct radiative effect (and forcing) derived from the GlobAEROSOL-AATSR satellite aerosol product

Regional and monthly and clear-sky aerosol direct radiative effect (and forcing) derived from the GlobAEROSOL-AATSR satellite aerosol product

Relationship between wind speed and aerosol optical depth over remote ocean

Analysis of linear long-term trend of aerosol optical thickness derived from SeaWiFS using BAER over Europe and South China

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