Document Type
Article
Publication Date
2005
Publication Title
IEEE Transactions on Geoscience and Remote Sensing
Publisher
Institute of Electrical and Electronics Engineers
Volume
43
Issue
12
First page number:
2822
Last page number:
2830
Abstract
Sand seas (ergs) of the Sahara are the most dynamic parts of the desert. Aeolian erosion, transportation, and deposition continue to reshape the surface of the ergs. The large-scale features (dunes) of these bedforms reflect the characteristics of the sand and the long-term wind. Radiometric emissions from the ergs have strong dependence on the surface geometry. We model the erg surface as composed of tilted rough facets. Each facet is characterized by a tilt distribution dependent upon the surface roughness of the facet. The radiometric temperature (T(b)) of ergs is then the weighted sum of the T(b) from all the facets. We use dual-polarization T(b) measurements at 19 and 37 GHz from the Special Sensor Microwave Imager aboard the Defense Meteorological Satellite Program and the Tropical Rainfall Measuring Mission Microwave Imager to analyze the radiometric response of erg surfaces and compare them to the model results. The azimuth angle (φ) modulation of T(b) is caused by the surface geometrical characteristics. It is found that longitudinal and transverse dune fields are differentiable based on their polarization difference (ΔT(b)) φ-modulation, which reflects type and orientation of dune facets. ΔT(b) measurements at 19 and 37 GHz provide consistent results. The magnitude of ΔT(b) at 37 GHz is lower than at 19 GHz due to higher attenuation. The analysis of ΔT(b) over dry sand provides a unique insight into radiometric emission over ergs.
Keywords
Azimuth angle modulation; Ergs; Microwave emission; Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI); Polarization difference; Radiometric temperature; Remote sensing; Sahara desert; Sand bedforms; Sand dunes; Sand radiometric emission; Special Sensor Microwave Imager (SSM/I); Surface geometry
Disciplines
Earth Sciences | Environmental Monitoring | Geographic Information Sciences
Language
English
Repository Citation
Stephen, H.,
Long, D. G.
(2005).
Modeling microwave emissions of erg surfaces in the Sahara Desert.
IEEE Transactions on Geoscience and Remote Sensing, 43(12),
2822-2830.
Institute of Electrical and Electronics Engineers.
http://dx.doi.org/10.1109/TGRS.2005.857899
Included in
Earth Sciences Commons, Environmental Monitoring Commons, Geographic Information Sciences Commons
Comments
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