TASK FORCE “WATER TEMPERATURE IN LAKES OF THE NORTH” Canada, 2009

1. TASK FORCE “WATER TEMPERATURE IN LAKES OF THE NORTH” Canada, 2009

2. Impotance ot the task. Freezing dimictic lakes are located in Euro-Asian and North-American continents, and their overall number is over 600 000.The water temperature and characteristics of ice cover lakes are very sensitive to climate change and it are major parameters determining the unfolding of many hydrophysical and chemical-biological processes in the lakes.

3. Objectivities • to investigate the water temperature variations and estimate possible effects of climate variability and climate change.  

4. Participation of member countries. • Finland: Dr. J.Korhonen - Finnish Environment Institute • Dr. A-R.Elo - Helsinki University • Russia: prof. N.Filatov-NWPI, • Dr.T.Efremova-NWPI, • Dr. N.Palshin-NWPI. • Ms.L.Nazarova • Sweden: prof. L.Bengtsson- Lund Univ. • Dr. S. Cintia Bertacchi Uvo

5. During the last two years: • created the database for high latitude lakes (large, medium and small size) situated in North West of Russia & Finland; • determined the effects of climatic parameters (including atmospheric indexes) on water temperatures, water level and ice characteristics;. • applied statistical models for the description of the thermal regime of lakes; • quantified the effect of climate and main features of the lakes (morptometry, depth)  on their water temperature annual cycle and the vertical thermal structure; • estimated the possible changes of annual cycle of the lake’s surface temperature and their vertical thermal structure for different scenarios of regional climate changes.

6. Joint Russian-Finnish team (Efremova T., Korhonen J., Palshin N.) developed data analysis and modeling annual course of vertical thermal structure of deep lakes and published paper in Russian journal of Water Resources (translated to English).

7. Table 1 Characteristics of the studied lakes

8. Figure 1 Map of study area Russia and Finland

9. Sample of data base

10. Figure 2 Relationship between stratification of lakes and their area and max depth. 1-3 are hypo-, meta- and epithermal lakes, respectively. Some results

11. Dr. Aja-Ritta Elo (Finland, Helsinki University): • employed one of the longest time series characterizing the thermal regimes inherent in the Finnish lakes. • aimed at establishing the regularities in interannual and seasonal variability of the lake thermal regime driven by climate changes and morphology-specific features is highly relevant. The important aim of this study is to improve our understanding of feedback interactions involving hydrological features of the lakes and climate changes as well as the lake morphology by means of the representative hydrological and meteorological data together with one-dimensional mathematical modeling.

12. Lakes in Finland with long-term study data (Aja-Ritta Elo)

13. Cooperation with partner from Lund University (Sweden) • devoted to analysis of climatic parameters, atmospheric circulations (including NAO index) with water temperatures, water level and ice characteristics of Lakes Ladoga and Onego. • Data base for lakes of Sweden did’t created.

14. Fig.4. NAO index and near surface layer air temperature fluctuations over Lake Ladoga. In full line air temperature values are shown, in dotted line - NAO

15. Publications. • Efremova T.V., Korhonen J., Palshin N.I. EMPIRICAL MODELLING ANNUAL COURSE OF VERTICAL THERMAL STRUCTURE OF DEEP LAKES. J. Water Resourses Efremova T, Palshin N. Effect of climate and morphometry on thermal regime of lakes . Proceedings of 16 NRB Symposium. Petrozavodsk 2007. • Efremova T, Palshin N.Dependence of lake ice cover and lake temperature on geography and lake bathymetry. 2-th Large Lakes Symposium. Sweden. 2009. • Rukhovets L.&N.Filatov (Ed.)Ladoga and Onego - Great European Lakes:Observations and Modeling. Springer-Praxis. 2009.

16. The completion of the task force • During the year to prepare joint report and article to Journal of Hydrology Research.

17. Thanks for your attention!