 |
| Titel |
Reference crop evapotranspiration derived from geo-stationary satellite imagery: a case study for the Fogera flood plain, NW-Ethiopia and the Jordan Valley, Jordan |
| VerfasserIn |
H. A. R. Bruin, I. F. Trigo, M. A. Jitan, N. Temesgen Enku, C. Tol, A. S. M. Gieske |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1027-5606
|
| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 14, no. 11 ; Nr. 14, no. 11 (2010-11-10), S.2219-2228 |
| Datensatznummer |
250012479
|
| Publikation (Nr.) |
 copernicus.org/hess-14-2219-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
First results are shown of a project aiming to estimate daily values of
reference crop evapotranspiration ET0 from geo-stationary satellite
imagery. In particular, for Woreta, a site in the Ethiopian highland at an
elevation of about 1800 m, we tested a radiation-temperature based
approximate formula proposed by Makkink (MAK), adopting ET0 evaluated
with the version of the Penman-Monteith equation described in the FAO
Irrigation and Drainage paper 56 as the most accurate estimate. More
precisely we used the latter with measured daily solar radiation as input
(denoted by PMFAO-Rs). Our data set for Woreta concerns a period where the
surface was fully covered with short green non-stressed vegetation. Our
project was carried out in the context of the Satellite Application Facility
on Land Surface Analysis (LANDSAF) facility. Among others, the scope of
LANDSAF is to increase benefit from the EUMETSAT Satellite Meteosat Second
Generation (MSG). In this study we applied daily values of downward solar
radiation at the surface obtained from the Spinning Enhanced Visible and
Infrared Imager (SEVIRI) radiometer. In addition, air temperature at 2 m was
obtained from 3-hourly forecasts provided by the European Centre for
Medium-Range Weather Forecasts (ECMWF).
Both MAK and PMFAO-Rs contain the psychrometric "constant", which is
proportional to air pressure, which, in turn, decreases with elevation. In
order to test elevation effects we tested MAK and its LANDSAF input data for
2 sites in the Jordan Valley located about 250 m b.s.l.
Except for a small underestimation of air temperature at the Ethiopian site
at 1800 m, the first results of our LANDSAF-ET0 project are promising.
If our approach to derive ET0 proves successfully, then the LANDSAF will
be able to initiate nearly real time free distribution of ET0 for the
full MSG disk. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|