Retrieving land surface reflectances using the ATSR-2: A theoretical study
The measurement of absolute land reflectance from Earth‐orbiting satellites requires the separation of the signal due to the reflection of solar radiation by the surface from that due to scattering by the atmosphere. Thus for accurate but generally applicable quasi‐operational retrieval techniques i...
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| Published in: | Journal of Geophysical Research, Washington, DC Vol. 102; no. D14; pp. 17163 - 17171 |
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| Main Authors: | , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Blackwell Publishing Ltd
27-07-1997
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| Online Access: | Get full text |
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| Summary: | The measurement of absolute land reflectance from Earth‐orbiting satellites requires the separation of the signal due to the reflection of solar radiation by the surface from that due to scattering by the atmosphere. Thus for accurate but generally applicable quasi‐operational retrieval techniques it is necessary to derive atmospheric parameters, such as the aerosol type and loading, simultaneously with the surface reflectances. The assumption of large‐scale horizontal homogeneity across an image, or the presence of very low reflectance pixels within an image, is avoided, since these are not necessarily applicable in the general case. In this paper, results of simulated retrievals using the visible and near‐infrared channels of the ATSR‐2 satellite radiometer are presented on the basis of techniques which exploit the dual look and other features of the instrument. The pixel‐based retrieval scheme comprises a fast representation of atmospheric scattering and a simple surface reflectance approximation. The effect of the atmospheric approximation on the accuracy of retrieval of the surface reflectance and atmospheric optical depth is tested by using a full multiple‐scattering radiative transfer model with simpler surface model. The effect on retrieval accuracy of the surface model is tested using a full surface vegetation canopy reflectance model with inclusion of the hot‐spot effect, combined with a successive orders of scattering atmospheric radiative transfer model, taken to second order. The results indicate that the scheme could provide accurate retrieval of surface reflectances even where no extraneous information on the surface bidirectional reflectance or on the atmospheric optical thickness is available. The scheme is also applicable to the AATSR instrument to be launched on the ENVISAT (Environmental Satellite) and, more widely, to other satellite radiometers with multiple views of the Earth's surface. |
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| Bibliography: | istex:84B32CD7ABB5AD38945D912D4D99A9D08099A1A7 ark:/67375/WNG-B8PFFFQW-6 ArticleID:96JD02900 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
| ISSN: | 0148-0227 2156-2202 |
| DOI: | 10.1029/96JD02900 |