TOMSK, April 12. /TASS/. Weather and climatic anomalies in Siberia are related to the fact that Rossby atmospheric waves, which "manage" the weather, have changed due to warming in the Arctic, scientists from Tomsk, Irkutsk and Novosibirsk found. In the coming years, Siberia will face droughts and heavy rains, fires and floods, the press service of the Tomsk Scientific Center (the Russian Academy of Sciences' Siberian Branch) said.
"The Rossby wave spread in southern Siberia has changed significantly since the mid-1990s under the influence of warming in the Arctic. The waves' amplitude increases, and blockages occur more often, leading to quasi-stationary, "frozen" conditions of atmospheric flow with repetitive modes. A particularly interesting pattern is that the blockage in Siberia leads to unusual weather phenomena in the region's south - heavy precipitation in summer and cold weather in winter. At the same time, the opposite phenomena are observed in the north: it is hot and dry in summer, which increases chances of forest fires, and paradoxically warm weather in winter," the press service said.
The atmospheric Rossby waves emerge because of the Earth rotation due to the shift of vortex flows under the Coriolis effect influence at different geographical latitudes, scientists say. Stretching for thousands of kilometers, they act as "choreographers" of the weather, directing the movement of storms and changing weather conditions. "Imagine an air flow high in the sky, some 5,000 - 8,000 meters, where the wind speed may reach 200 kilometers per hour. This fast high-altitude river manages our weather systems," the press service quoted as saying Olga Antokhina, the project's one of the authors, a senior researcher at the Zuev Institute of Atmospheric Optics (the Russian Academy of Sciences' Siberian Branch).
As they move, the waves bend and intensify, creating areas of high and low pressure. When the waves increase significantly, they can slow down or stop, and it is at that point that the "magic of atmospheric blocking" starts. At first, an intensifying wave creates a high-pressure ridge, and subsequently, when collapsing, it develops an extensive stable anticyclone. It is the cyclone that becomes an obstacle for weather systems, as it forces them to bypass the blocked area or to stay in one place.
Thus, we can observe long periods of sunny weather and warmth in one region, while long rains or cold weather may be nearby. This, for example, caused extreme cold in 2012, and catastrophic forest fires in Siberia in 2019.
"Having analyzed these trends, we may expect that in the coming years we will face new weather anomalies, leading to droughts and heavy rains, fires and floods. In order to control these effects of climate change, we need to develop more accurate forecasting methods and a deep understanding of the atmospheric phenomena dynamics," the press service said in a release. The research has been supported by a grant from the Russian Science Foundation.