Interdecadal Changes in the Interannual Variability of the East Asian Winter Temperature since 1880

Le résumé fourni par la source

Abstract This study investigates the characteristics and underlying mechanisms of the interannual variability changes in the winter East Asian–averaged surface air temperature (EASAT) since 1880. The results reveal that the EASAT interannual variability experiences interdecadal enhancement during 1934–63 (P2) but suppression during 1890–1933 (P1) and 1964–2001 (P3). This fluctuation is driven by the interannual variability changes in the western part of the East Asian trough (WEAT), primarily through modulating downward surface shortwave radiation of clouds. The WEAT variability changes are closely related to the variations of the background zonal wind and meridional temperature gradient around midlatitude East Asia, which are stronger during P2 but weaker during P1 and P3. As a result, the amplified transient eddy feedback forcing and the enhanced available potential energy extraction cause stronger variability in the WEAT and the EASAT during P2 compared to P1 and P3. Moreover, the Atlantic multidecadal oscillation (AMO) phase shifts excite a zonal Rossby wave train across the Eurasian continent, inducing the anomalous meridional dipole circulations over East Asia and explaining the interdecadal variations of the background zonal wind and meridional temperature gradient. The positive AMO phases amplify the EASAT variability and vice versa. Significance Statement Amplified temperature variability increases the risk of cold and warm extremes, causing significant socioeconomic impacts. This article investigates changes in the interannual variability of the East Asian winter temperature. Based on long-term observational and reanalysis datasets, our results display strong variability during 1934–63 but weak levels during 1890–1933 and 1964–2001. Those changes are driven by the Atlantic multidecadal oscillation (AMO), which affects the intensity of the transient eddy feedback to the mean flow and the strength of baroclinic energy conversion over midlatitude East Asia. As such, precise forecasting of the AMO helps predict the temperature variability over East Asia and manage the risk of temperature extremes.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.