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| Titel |
Estimation of evapotranspiration from MODIS TOA radiances in the Poyang Lake basin, China |
| VerfasserIn |
J. Peng, Y. Liu, X. Zhao, A. Loew |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 17, no. 4 ; Nr. 17, no. 4 (2013-04-15), S.1431-1444 |
| Datensatznummer |
250018848
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| Publikation (Nr.) |
 copernicus.org/hess-17-1431-2013.pdf |
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| Zusammenfassung |
| Routine and rapid estimation of ET (evapotranspiration) at regional scale is
of great significance for agricultural, hydrological and climatic studies. A
simplified single-source energy balance parameterization scheme, known as the
LST/NDVI (land surface temperature/normalized difference vegetation index) triangle method, has
been applied successfully to estimate regional clear sky ET in many studies.
Based on the triangle method, we proposed a new method in this study to
estimate daily ET directly using the TOA (top of atmosphere) radiances
without performing atmospheric correction and other complicated processes.
Firstly, the EF (evaporative fraction, defined as the ratio of latent heat
flux to surface available energy) was estimated by interpolation in the
LST/NDVI triangular-shaped scatter space, which was constructed using the
MODIS (Moderate Resolution Imaging Spectroradiometer) TOA radiances over a
heterogeneous area of the Poyang Lake basin in China. Then the net radiation
over the same study area was derived based entirely on MODIS TOA radiances as
well. Finally, daily ET maps were estimated from these EF maps and net
radiation maps by using a sinusoidal temporal interpolation model. The
estimated EF, net radiation and ET have been validated against field
observations collected for the period October 2007–July 2008. The results
indicate comparable accuracy to results of other current widely used
satellite-based methods. In addition, intercomparisons between the proposed
method-based estimates and MODIS products-based estimates were also carried
out over the validation site. The results suggest that the proposed method
could reach similar level of accuracy as the MODIS products-based triangle
method. Overall, the proposed algorithm requires fewer assumptions and can
avoid complex atmospheric corrections associated with the satellite derived
products. It should facilitate direct use of satellite data for determining
ET and relevant applications as well. Nonetheless, more validation work needs
to be carried out with more integration of satellite data and ground-based
measurements over various climatic regions and under different surface
conditions in the future. |
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