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| Titel |
Comparison of MODIS-derived land surface temperatures with ground surface and air temperature measurements in continuous permafrost terrain |
| VerfasserIn |
S. Hachem, C. R. Duguay, M. Allard |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 6, no. 1 ; Nr. 6, no. 1 (2012-01-13), S.51-69 |
| Datensatznummer |
250003374
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| Publikation (Nr.) |
 copernicus.org/tc-6-51-2012.pdf |
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| Zusammenfassung |
| Obtaining high resolution records of surface temperature from satellite
sensors is important in the Arctic because meteorological stations are
scarce and widely scattered in those vast and remote regions. Surface
temperature is the primary climatic factor that governs the existence,
spatial distribution and thermal regime of permafrost which is a major
component of the terrestrial cryosphere. Land Surface (skin) Temperatures
(LST) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS)
sensor aboard the Terra and Aqua satellite platforms provide spatial
estimates of near-surface temperature values. In this study, LST values from
MODIS are compared to ground-based near-surface air (Tair) and ground
surface temperature (GST) measurements obtained from 2000 to 2008 at
herbaceous and shrub tundra sites located in the continuous permafrost zone
of Northern Québec, Nunavik, Canada, and of the North Slope of Alaska,
USA. LSTs (temperatures at the surface materials-atmosphere interface) are
found to be better correlated with Tair (1–3 m above the ground) than
with available GST (3–5 cm below the ground surface). As Tair is most
often used by the permafrost community, this study focused on this
parameter. LSTs are in stronger agreement with Tair during the snow
cover season than in the snow free season. Combining Aqua and Terra LST-Day
and LST-Nigh acquisitions into a mean daily value provides a large number of
LST observations and a better overall agreement with Tair. Comparison
between mean daily LSTs and mean daily Tair, for all sites and all
seasons pooled together yields a very high correlation (R = 0.97; mean
difference (MD) = 1.8 °C; and standard deviation of MD (SD) = 4.0 °C).
The large SD can be explained by the influence of surface heterogeneity
within the MODIS 1 km2 grid cells, the presence of undetected clouds
and the inherent difference between LST and Tair. Retrieved over
several years, MODIS LSTs offer a great potential for monitoring surface
temperature changes in high-latitude tundra regions and are a promising
source of input data for integration into spatially-distributed permafrost
models. |
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