 |
| Titel |
Modelling hourly rates of evaporation from small lakes |
| VerfasserIn |
R. J. Granger, N. Hedstrom |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1027-5606
|
| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 15, no. 1 ; Nr. 15, no. 1 (2011-01-21), S.267-277 |
| Datensatznummer |
250012601
|
| Publikation (Nr.) |
 copernicus.org/hess-15-267-2011.pdf |
|
|
|
|
|
| Zusammenfassung |
The paper presents the results of a field study of open water evaporation
carried out on three small lakes in Western and Northern Canada. In this
case small lakes are defined as those for which the temperature above the
water surface is governed by the upwind land surface conditions; that is, a
continuous boundary layer exists over the lake, and large-scale atmospheric
effects such as entrainment do not come into play. Lake evaporation was
measured directly using eddy covariance equipment; profiles of wind speed,
air temperature and humidity were also obtained over the water surfaces.
Observations were made as well over the upwind land surface.
The major factors controlling open water evaporation were examined. The
study showed that for time periods shorter than daily, the open water
evaporation bears no relationship to the net radiation; the wind speed is
the most significant factor governing the evaporation rates, followed by the
land-water temperature contrast and the land-water vapour pressure contrast.
The effect of the stability on the wind field was demonstrated;
relationships were developed relating the land-water wind speed contrast to
the land-water temperature contrast. The open water period can be separated
into two distinct evaporative regimes: the warming period in the Spring,
when the land is warmer than the water, the turbulent fluxes over water are
suppressed; and the cooling period, when the water is warmer than the land,
the turbulent fluxes over water are enhanced.
Relationships were developed between the hourly rates of lake evaporation
and the following significant variables and parameters (wind speed,
land-lake temperature and humidity contrasts, and the downwind distance from
shore). The result is a relatively simple versatile model for estimating the
hourly lake evaporation rates. The model was tested using two independent
data sets. Results show that the modelled evaporation follows the observed
values very well; the model follows the diurnal trends and responds
to changes in environmental conditions. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|