 |
| Titel |
Estimating spatially distributed monthly evapotranspiration rates by linear transformations of MODIS daytime land surface temperature data |
| VerfasserIn |
J. Szilagyi, J. Jozsa |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1027-5606
|
| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 13, no. 5 ; Nr. 13, no. 5 (2009-05-20), S.629-637 |
| Datensatznummer |
250011862
|
| Publikation (Nr.) |
 copernicus.org/hess-13-629-2009.pdf |
|
|
|
|
|
| Zusammenfassung |
| Under simplifying conditions catchment-scale vapor
pressure at the drying land surface can be calculated as a function of its
watershed-representative temperature (<Ts>) by the wet-surface
equation (WSE, similar to the wet-bulb equation in meteorology for
calculating the dry-bulb thermometer vapor pressure) of the Complementary
Relationship of evaporation. The corresponding watershed ET rate,
<ET>, is obtained from the Bowen ratio with the help of air temperature,
humidity and percent possible sunshine data. The resulting
(<Ts>,<ET>) pair together with the wet-environment surface
temperature (<Tws>) and ET rate (ETw), obtained by the
Priestley-Taylor equation, define a linear transformation on a monthly basis
by which spatially distributed ET rates can be estimated as a sole function
of MODIS daytime land surface temperature, Ts, values within the
watershed. The linear transformation preserves the mean which is highly
desirable. <Tws>, in the lack of significant open water surfaces
within the study watershed (Elkhorn, Nebraska), was obtained as the mean of
the smallest MODIS Ts values each month. The resulting period-averaged
(2000–2007) catchment-scale ET rate of 624 mm/yr is very close to the
water-balance derived ET rate of about 617 mm/yr. The latter is a somewhat
uncertain value due to the effects of (a) observed groundwater depletion of
about 1m over the study period caused by extensive irrigation, and; (b) the
uncertain rate of net regional groundwater supply toward the watershed. The
spatially distributed ET rates correspond well with soil/aquifer properties
and the resulting land use type (i.e. rangeland versus center-pivot
irrigated crops). |
| |
|
| Teil von |
|
|
|
|
|
|
|
|