Sand Dune Ridge Alignment Effects on Surface BRF over the Libya-4 CEOS Calibration Site
The Libya-4 desert area, located in the Great Sand Sea, is one of the most important bright desert CEOS pseudo-invariant calibration sites by its size and radiometric stability. This site is intensively used for radiometer drift monitoring, sensor intercalibration and as an absolute calibration refe...
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| Format: | Article |
| Language: | English |
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MDPI AG
2015-02-01
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| Series: | Sensors |
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| Online Access: | http://www.mdpi.com/1424-8220/15/2/3453 |
| _version_ | 1811297867771412480 |
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| author | Yves M. Govaerts |
| author_facet | Yves M. Govaerts |
| author_sort | Yves M. Govaerts |
| collection | DOAJ |
| description | The Libya-4 desert area, located in the Great Sand Sea, is one of the most important bright desert CEOS pseudo-invariant calibration sites by its size and radiometric stability. This site is intensively used for radiometer drift monitoring, sensor intercalibration and as an absolute calibration reference based on simulated radiances traceable to the SI standard. The Libya-4 morphology is composed of oriented sand dunes shaped by dominant winds. The effects of sand dune spatial organization on the surface bidirectional reflectance factor is analyzed in this paper using Raytran, a 3D radiative transfer model. The topography is characterized with the 30 m resolution ASTER digital elevation model. Four different regions-of-interest sizes, ranging from 10 km up to 100 km, are analyzed. Results show that sand dunes generate more backscattering than forward scattering at the surface. The mean surface reflectance averaged over different viewing and illumination angles is pretty much independent of the size of the selected area, though the standard deviation differs. Sun azimuth position has an effect on the surface reflectance field, which is more pronounced for high Sun zenith angles. Such 3D azimuthal effects should be taken into account to decrease the simulated radiance uncertainty over Libya-4 below 3% for wavelengths larger than 600 nm. |
| first_indexed | 2024-04-13T06:11:27Z |
| format | Article |
| id | doaj.art-275365b5b5bc4239bc62cfce3f446052 |
| institution | Directory Open Access Journal |
| issn | 1424-8220 |
| language | English |
| last_indexed | 2024-04-13T06:11:27Z |
| publishDate | 2015-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj.art-275365b5b5bc4239bc62cfce3f4460522022-12-22T02:59:01ZengMDPI AGSensors1424-82202015-02-011523453347010.3390/s150203453s150203453Sand Dune Ridge Alignment Effects on Surface BRF over the Libya-4 CEOS Calibration SiteYves M. Govaerts0Rayference, 1030 Brussels, BelgiumThe Libya-4 desert area, located in the Great Sand Sea, is one of the most important bright desert CEOS pseudo-invariant calibration sites by its size and radiometric stability. This site is intensively used for radiometer drift monitoring, sensor intercalibration and as an absolute calibration reference based on simulated radiances traceable to the SI standard. The Libya-4 morphology is composed of oriented sand dunes shaped by dominant winds. The effects of sand dune spatial organization on the surface bidirectional reflectance factor is analyzed in this paper using Raytran, a 3D radiative transfer model. The topography is characterized with the 30 m resolution ASTER digital elevation model. Four different regions-of-interest sizes, ranging from 10 km up to 100 km, are analyzed. Results show that sand dunes generate more backscattering than forward scattering at the surface. The mean surface reflectance averaged over different viewing and illumination angles is pretty much independent of the size of the selected area, though the standard deviation differs. Sun azimuth position has an effect on the surface reflectance field, which is more pronounced for high Sun zenith angles. Such 3D azimuthal effects should be taken into account to decrease the simulated radiance uncertainty over Libya-4 below 3% for wavelengths larger than 600 nm.http://www.mdpi.com/1424-8220/15/2/3453calibrationradiometryremote sensing |
| spellingShingle | Yves M. Govaerts Sand Dune Ridge Alignment Effects on Surface BRF over the Libya-4 CEOS Calibration Site Sensors calibration radiometry remote sensing |
| title | Sand Dune Ridge Alignment Effects on Surface BRF over the Libya-4 CEOS Calibration Site |
| title_full | Sand Dune Ridge Alignment Effects on Surface BRF over the Libya-4 CEOS Calibration Site |
| title_fullStr | Sand Dune Ridge Alignment Effects on Surface BRF over the Libya-4 CEOS Calibration Site |
| title_full_unstemmed | Sand Dune Ridge Alignment Effects on Surface BRF over the Libya-4 CEOS Calibration Site |
| title_short | Sand Dune Ridge Alignment Effects on Surface BRF over the Libya-4 CEOS Calibration Site |
| title_sort | sand dune ridge alignment effects on surface brf over the libya 4 ceos calibration site |
| topic | calibration radiometry remote sensing |
| url | http://www.mdpi.com/1424-8220/15/2/3453 |
| work_keys_str_mv | AT yvesmgovaerts sandduneridgealignmenteffectsonsurfacebrfoverthelibya4ceoscalibrationsite |