Journal article
A sea surface reflectance model for (A)ATSR, and application to aerosol retrievals
- Abstract:
- A model of the sea surface bidirectional reflectance distribution function (BRDF) is presented for the visible and near-IR channels (over the spectral range 550 nm to 1.6 μm) of the dual-viewing Along-Track Scanning Radiometers (ATSRs). The intended application is as part of the Oxford-RAL Aerosols and Clouds (ORAC) retrieval scheme. The model accounts for contributions to the observed reflectance from whitecaps, sunglint and underlight. Uncertainties in the parametrisations used in the BRDF model are propagated through into the forward model and retrieved state. The new BRDF model offers improved coverage over previous methods, as retrievals are possible into the sun-glint region, through the ATSR dual-viewing system. The new model has been applied in the ORAC aerosol retrieval algorithm to process Advanced ATSR (AATSR) data from September 2004 over the south-eastern Pacific. The assumed error budget is show to be generally appropriate, meaning the retrieved states are consistent with the measurements and a priori assumptions. The resulting field of aerosol optical depth (AOD) is compared with colocated MODIS-Terra observations, AERONET observations at Tahiti, and cruises over the oceanic region. MODIS and AATSR show similar spatial distributions of AOD, although MODIS reports values which are larger and more variable. It is suggested that assumptions in the MODIS aerosol retrieval algorithm may lead to a positive bias in MODIS AOD of order 0.01 at 550 nm over ocean regions where the wind speed is high.
- Publication status:
- Published
- Peer review status:
- Reviewed (other)
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(Preview, Version of record, pdf, 3.8MB, Terms of use)
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- Publisher copy:
- 10.5194/amtd-3-1023-2010
- Publisher:
- Copernicus Publications
- Journal:
- Atmospheric Measurement Techniques Discussions More from this journal
- Volume:
- 3
- Issue:
- 2
- Pages:
- 1023-1098
- Publication date:
- 2010-03-01
- Edition:
- Publisher's version
- DOI:
- EISSN:
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1867-8610
- Language:
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English
- Keywords:
- Subjects:
- UUID:
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uuid:451788f3-2d9e-4408-86d0-a3711493cf6b
- Local pid:
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ora:4006
- Deposit date:
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2010-07-07
Terms of use
- Copyright holder:
- A M Sayer, G E Thomas & R G Grainger
- Copyright date:
- 2010
- Notes:
- Citation: Sayer, A. M., Thomas, G. E. & Grainger, R. G. (2010). 'A sea surface reflectance model for (A)ATSR, and application to aerosol retrievals', Atmospheric Measurement Techniques Discussion, 3(2), 1023-1098. [Available at http://www.atmos-meas-tech-discuss.net/3/1023/2010/]. © Authors 2010. This article is distributed under the terms of the Creative Commons Attribution 3.0 Licence (http://creativecommons.org/licenses/by/3.0/). This permits the copying, distribution, transmission and adaption of the work, provided the original authors are credited. For any reuse or distribution, you must make clear to others the license terms of this work. These conditions may be waived if you get permission from the copyright holder. N.B. A revised version of this paper is also available in ORA.
- Licence:
- CC Attribution (CC BY)
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