D28: Internal seiche mixing study - Hydromod

Integrated Water Resource Management for Important Deep European Lakes and their Catchment Areas
EUROLAKES
Depth [m]
D28: Internal seiche mixing study
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Days since 2002/05/01
FP5_Contract No.: EVK1-CT1999-00004
Version: 1.2
Date: 24.08.2004
File: D28.doc
Water Temperature in Loch Lomond near Ross Point
Page 86 of 92
Figure 60 : Temperature profiles from 3 rd May to 9 th June 2002 in the mid basin position (Post,
2002)
The recordings from all three locations show considerable short-term fluctuations and at
certain times sudden vertical homogeneity in the thermal conditions. Interpretation of
these (horizontally seen) point measurements is not as straightforward as it might seem
because Loch Lomond has a very irregular shape. This means that a generalisation of
these profiles as “basin characteristic” is not possible. Investigations with 3D models
(described in other reports of EUROLAKES) did show strong wind-driven currents with
pronounced upwelling/downwelling processes near steep lake shores and the possible
occurrence of longer period internal standing waves in the fjord-like section of the lake.
Generally, however, it can be stated that long internal waves in the south basin are very
intermittent and associated mixing processes will be much smaller than the turbulent
mixing associated with the wind stress at the surface. Therefore in this report analysis
of data is confined to the mid and north basin locations where stratification is strong in
the upper 40 metres of the water column. Measurements are scheduled to proceed until
spring 2003 but we are concentrating here on the summer situation.
12.7
12.2
11.7
11.2
10.7
10.2
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9.2
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8.2
7.7
7.2
6.7