An ongoing research project aims to identify and explain teleconnections and future changes in the East Asian Winter Monsoon under Arctic Amplification. The project is led by Dr. Wen Zhou of City University of Hong Kong.
Since 1990, a significant winter cooling trend has occurred in the midlatitudes, including western Siberia, where cold air activity in East Asia originates. Simultaneously, a pronounced warming trend has been observed over the polar region accompanying the reduction of Arctic sea ice, which is known as the Arctic amplification. Arctic amplification has thus occurred alongside cold midlatitude winters in recent years, in contrast to cold winters in earlier periods. After the severe and prolonged snowstorms in South China in January 2008, several extreme cold spells hit different parts of the Northern Hemisphere in the seven winters between 2008/09 and 2015/16.
"Because the intensity and duration of these cold spells were exceptional in the past few decades, more research should be devoted to understanding the underlying physical mechanisms of cold extremes under a changing climate in order to better predict their occurrence in the future." Zhou explains the motif of the project.
"One area of our particular concern is the effect that climate change and the substantial reduction in Arctic sea ice might have on the winter monsoon circulation over East Asia." Zhou says. "How the East Asian winter monsoon will respond to a warmer planet is not totally clear. One possibility is that anomalous blocking events (frequency, location, intensity, duration) due to Arctic amplification and sea-ice loss may enhance extreme cold spells, but the mechanisms potentially involved in such changes are still under discussion."
Therefore, Zhou and her colleagues set out to understand and quantify the relationship between the East Asian winter monsoon (EAWM) and blocking in observations and general circulation models, to identify physical and dynamical processes of large-scale teleconnections of the EAWM with blocking based on reanalysis data, and to project the impact of Arctic amplification on the future characteristics of the EAWM based on CMIP5 models. This work was fully supported by the Research Grants Council of Hong Kong, China [grant number 11305715].
In a project report published in Atmospheric and Oceanic Science Letters, Zhou hopes that, "This integral study would be beneficial for policymakers in evaluating the risk of cold extremes in East Asia, and will be of great importance for the socioeconomic development of this densely populated region."