Predicting the Timing of the Final Disappearance of all Ice on Large Inland Water Bodies in the Angara River Watershed Using Teleconnection Indices
E. N. Sutyrina
The description of developed method of predicting the dates of the final disappearance of all ice on large inland water bodies in the Angara River watershed using teleconnection indices are presented in this paper. Ice forecasts for huge inland water bodies are of great practical value for navigation since ice prevents shipping. The main objective of this study has been to develop a regional technique of long-term ice forecasts of the dates of the final disappearance of all ice on Lake Hovsgol, water areas of South, Central and North basins of Lake Baikal, Bratsk and Ust'-Ilimsk reservoirs, using teleconnection indices AO (Arctic Oscillation) and NAO (North Atlantic Oscillation).
As a part of this work the features of the final ice disappearance on Lake Hovsgol, South, Central and North basins of Lake Baikal, Bratsk and Ust'-Ilimsk reservoirs have been previously determined, including estimating of the timing of occurring of phenomena in the target water bodies, their average and extreme dates and ranges.
It has been found that the inter-annual variation of the timing of the final disappearance of all ice on these water bodies are in antiphase with the inter-annual fluctuations of the values of teleconnection indices AO and NAO, this circumstance favors to the use of values of these indices as predictors of regional forecasting relation.
Also as a result of the research, the regional relationships for ice forecasts have been determined based on the analysis of values of teleconnection indices AO and NAO, averaged over different time intervals, and data array of the timing of the final disappearance of all ice on water area under investigation. These predictive relationships permit to anticipate the nature of ice phenomena with an average lead time of 14 up to 32 days.
As a result of evaluation of the accuracy of the proposed predictive dependencies it has been found that the category of quality of methods of forecasting of the timing of complete disappearance of all ice on South, Central and North Basins of the Lake Baikal has been identified as a good, the category of quality of methods of forecasting of final disappearance of all ice on the Bratsk and Ust'-Ilimsk reservoirs and Lake Hovsgol has been determined as satisfactory.
Lake Baikal, Lake Hovsgol, Bratsk reservoir, Ust'-Ilimsk reservoir, ice forecasts, AO, NAO
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