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| Titel |
Evaporation in a Mediterranean environment by energy budget and Penman methods, Lake Baratz, Sardinia, Italy |
| VerfasserIn |
F. Giadrossich, M. Niedda, D. Cohen, M. Pirastru |
| 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 ; 19, no. 5 ; Nr. 19, no. 5 (2015-05-22), S.2451-2468 |
| Datensatznummer |
250120720
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| Publikation (Nr.) |
 copernicus.org/hess-19-2451-2015.pdf |
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| Zusammenfassung |
| In Mediterranean environments, evaporation is a key component of lake water
budgets. This applies to Lake Baratz in Sardinia, Italy, a closed lake that
almost dried up in 2008 after a succession of years with low seasonal
rainfall. We used the energy budget method and Penman's equation to estimate
evaporation over Lake Baratz. We measured, using a raft station, water
temperature at the surface, at 1, 2, 4, 6 m depth and at the bottom of the lake, as well as air
temperature, relative humidity, wind speed, and net radiation over a period
of 3 years. We also compared Penman's equation and the energy budget
method in two other climatic zones using published data. Our results indicate
that mean yearly evaporation over Lake Baratz was 950 mm. On an annual
scale, evaporation estimated by Penman's method omitting heat storage as is
usually done was 18% higher than by the energy budget method that included
heat storage, with monthly differences ranging between −38 and +60%.
Including the heat storage term in Penman's equation changed the monthly
values but did not change the yearly value significantly. Solar radiation and
heat storage were found to be the most important energy fluxes to and from
the lake and had the greatest effect on evaporation rates for the energy
budget method. The bias between the two methods has a seasonal cycle due to
the storage and release of energy from the lake. Energy advected to and from
the lake by precipitation, surface water and ground water had minor effect
on evaporation rates. Lake Baratz, like other lakes in a Mediterranean
environment, is particularly sensitive to the summer hot and dry climate. In
contrast, we found that rates of evaporation estimated from Penman and the
energy budget methods over tropical African lakes were nearly constant over
the entire year and the difference between the two methods smaller.
Difference between the two methods for North American lakes is also smaller
probably owing to the ice-cover season and to lower radiation and lower
temperatures during summer. |
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