Breeze effects at a large artificial lake: summer case study
<p>Natural lakes and big artificial reservoirs can affect the weather regime of surrounding areas but, usually, consideration of all aspects of this impact and their quantification is a difficult task. The Alqueva reservoir, the largest artificial lake in western Europe, located on the sout...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-10-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://www.hydrol-earth-syst-sci.net/22/5191/2018/hess-22-5191-2018.pdf |
| Summary: | <p>Natural lakes and big artificial reservoirs can affect the weather regime of
surrounding areas but, usually, consideration of all aspects of this impact
and their quantification is a difficult task. The Alqueva reservoir, the largest
artificial lake in western Europe, located on the south-east of Portugal, was
filled in 2004. It is a large natural laboratory that allows the study of
changes in surface and in landscape and how they affect the weather in the
region. This paper is focused on a 3-day case study, 22–24 July 2014, during
which an intensive observation campaign was carried out. In order to quantify
the breeze effects induced by the Alqueva reservoir, two simulations with the
mesoscale atmospheric model Meso-NH coupled to the FLake freshwater lake model
has been performed. The difference between the two simulations lies in the
presence or absence of the reservoir on the model surface. Comparing the two
simulation datasets, with and without the reservoir, net results of the lake
impact were obtained. Magnitude of the impact on air temperature, relative
humidity, and other atmospheric variables are shown. The clear effect of a lake
breeze (5–7 m s<sup>−1</sup>) can be observed during daytime on distances up to
6 km away from the shores and up to 300 m above the surface. The lake breeze
system starts to form at 09:00 UTC and dissipates at 18:00–19:00 UTC with
the arrival of a larger-scale Atlantic breeze. The descending branch of the
lake breeze circulation brings dry air from higher atmospheric layers
(2–2.5 km) and redistributes it over the lake. It is also shown that
despite its significant intensity the effect is limited to a couple of
kilometres away from the lake borders.</p> |
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| ISSN: | 1027-5606 1607-7938 |