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Extratropical cyclones (or low-pressure systems) traveling along the Kuroshio in East Asia most frequently occur in spring, bringing heavy rain and snowfall in the region. Researchers at the University of Tsukuba unveiled the mechanism underlying the peak observed in the activity of "Kuroshio cyclones" during spring using four-dimensional atmospheric data spanning several decades. Their findings revealed that air over Eurasia warmed from winter to spring intensified the low-level jet stream around the East China Sea, increasing the occurrence probability of low-pressure systems during spring.

Tsukuba, Japan—Extratropical cyclones traveling along the Kuroshio in East Asia, called "Kuroshio cyclones," bring heavy rain and snowfall in populated and industrial areas in East Asian countries. They considerably affect societies and economic sectors, including agriculture, transportation, logistics, and renewable-energy-based power generation sectors. Although extratropical cyclones in East Asia are known to occur frequently in spring, the reason behind this seasonality is not yet clarified.

The research group previously developed a method for objectively identifying mobile high- and low-pressure systems from global atmospheric data to elucidate the mechanism underlying the seasonality of extratropical cyclones and recent changes in high- and low-pressure systems in the North Pacific. In the current study, the researchers employed the method to four-dimensional atmospheric data spanning several decades. Results indicated that the activity of the "Kuroshio cyclones" peaks in spring because the low-level jet stream around the East China Sea is intensified by air over Eurasia in the west of Japan warmed from winter to spring, facilitating the formation of low-pressure systems.

A better elucidation of the mechanism underlying the seasonality of extratropical cyclone activity in East Asia can improve our understanding of the changes in the climate system around the region under the global warming scenario and improve the accuracy of seasonal forecasts in East Asian countries.

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This study is supported in part by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) through the Arctic Challenge for Sustainability II (ArCS-II; JPMXD1420318865) and the Advanced Studies of Climate Change Projection (SENTAN; JPMXD0722680395, by the Japan Science and Technology Agency through COI-NEXT JPMJPF2013, by the Japanese Ministry of Environment through Environmental Restoration and Conservation Agency Fund JPMEERF20242001, and by the Japan Society for the Promotion of Science (JSPS) through Grants-in-Aid for Scientific 681 Research 19H05702 (on Innovative Areas 6102), 20H01970, 21H01164, 22H01292, and 22K14097. RP acknowledges support from NOAA Climate Variability and Predictability Program NA22OAR4310617.

Original Paper

Title of original paper:

Mechanisms for an Early Spring Peak of Extratropical Cyclone Activity in East Asia

Journal:

Journal of Climate

DOI:

10.1175/JCLI-D-24-0203.1

Correspondence

Associate Professor OKAJIMA Satoru
Institute of Life and Environmental Sciences, University of Tsukuba

Professor NAKAMURA Hisashi
Research Center for Advanced Science and Technology, The University of Tokyo

Associate Professor KUWANO-YOSHIDA Akira
Disaster Prevention Research Institute, Kyoto University

Related Link

Institute of Life and Environmental Sciences