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| Titel |
Mapping daily evapotranspiration and dryness index in the East African highlands using MODIS and SEVIRI data |
| VerfasserIn |
Z. Sun, M. Gebremichael, J. Ardö, H. A. R. Bruin |
| 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 ; 15, no. 1 ; Nr. 15, no. 1 (2011-01-18), S.163-170 |
| Datensatznummer |
250012593
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| Publikation (Nr.) |
 copernicus.org/hess-15-163-2011.pdf |
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| Zusammenfassung |
| Routine information on regional evapotranspiration (ET) and dryness index is
essential for agricultural water management, drought monitoring, and studies
of water cycle and climate. However, this information is not currently
available for the East Africa highlands. The main purpose of this study is
to develop (1) a new methodology that produces spatially gridded daily ET
estimates on a (near) real-time basis exclusively from satellite data, and
(2) a new dryness index that depends only on satellite data and weather
forecast data. The methodology that calculates daily actual ET involves
combining data from two sensors (MODIS and SEVIRI) onboard two kinds of
platforms (Terra – polar orbit satellite and MSG – geostationary orbit
satellite). The methodology is applied to the East African highlands, and
results are compared to eddy covariance measurements at one site. Results
show that the methodology produces ET estimates that accurately reproduce
the daily fluctuation in ET but tends to underestimate ET on the average. It
is concluded that the synergistic use of the polar-orbiting MODIS data and
the geostationary-orbiting SEVIRI data has potential to produce reliable
daily ET, but further research is needed to improve the accuracy of the
results. This study also proposes an operational new dryness index that can
be calculated from the satellite-based daily actual ET estimates and
daily reference ET estimates based on SEVIRI data and weather forecast air
temperature. Comparison of this index against ground measurements of daily actual ET at one site indicates that the new dryness index can be used for
drought monitoring. |
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