Assessment of Snow-Cover Mapping Accuracy in a Variety of Vegetation-Cover Densities in Central Alaska
Section snippets
Introduction and background
During April 1995, a field and aircraft experiment was conducted in the boreal forest of central Alaska in support of the Earth Observing System (EOS) Moderate Resolution Imaging Spectroradiometer (MODIS) snow-cover mapping project. MODIS is scheduled for launch on the EOS AM-1 polar-orbiting platform in 1999. The MODIS Airborne Simulator (MAS), a 50-channel spectroradiometer, was flown onboard a NASA ER-2 aircraft. Field measurements were also acquired. An objective of the mission was to
Results and discussion
Vegetation-cover density map derived from MAS-derived reflectances. Vegetation-cover density was estimated from integrated reflectance (Ri) values in the 13 April 1995 MAS scene acquired over central Alaska (Fig. 3 top) in the following manner. The integrated reflectance is the reflectance integrated over a portion of the electromagnetic spectrum (Hall et al., 1989). The highest Ri values correspond to snow-covered bare areas or areas covered with very low vegetation, snow-covered ice, or
Conclusions
At least in central Alaska, the technique of using the wintertime reflectances as a surrogate measure of vegetation density Robinson and Kukla 1985, Foster et al. 1994 appears to be valid. In this article, we compared a vegetation-density map derived from integrated reflectances (from Channels 1–9 of MAS data), with an independently produced vegetation type and density map (derived from TM and ancillary data). The TM-derived map is assumed to be an accurate depiction of the actual vegetation
Acknowledgements
The authors would like to thank Janet Chien/GSC, Laurel, Maryland, for her expertise in image processing, and Ken Brown of NASA/Goddard Space Flight Center, for discussions about the MODIS Airborne Simulator.
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