Analysis of Record-High Temperature over Southeast Coastal China in Winter 2018/19: The Combined Effect of Mid- to High-Latitude Circulation Systems and SST Forcing over the North Atlantic and Tropical Western Pacific

Abstract

In winter 2018/2019, southeast coastal China experienced extreme warm temperatures due to a weak East Asian winter monsoon. Based on observations from 10 meteorological stations and reanalysis data, the large-scale circulation patterns associated with this extreme warm winter and the possible driving mechanism of its related sea surface temperature (SST) anomalies are investigated in this study. During this winter, many places in this region reached their highest winter mean temperature record and had more extreme warm days and fewer extreme cold days compared to climatology. According to the circulation patterns during winter 2018/2019, several large-scale circulation conditions associated mainly with the weak East Asian winter monsoon are identified: the eastward shift of the Siberian high and a shallower East Asian trough, which is related to the low blocking frequency over the Aleutian region, are both unfavorable for cold air intrusion southward. Meanwhile, strong low-level southerly wind anomalies over southeast China are related mainly to the 2018/2019 El Niño event. Furthermore, the possible role of SST anomalies over the North Atlantic and tropical western Pacific is examined by using an atmospheric general circulation model, suggesting that both the “tripole pattern” of North Atlantic SST and tropical western Pacific SST anomalies in winter 2018/2019 played a role in influencing the East Asian trough. The combined effect of all these factors seems responsible for this extreme warm winter over southeast coastal China.

Understanding human influence on climate change in China

“…These studies consistently show that anthropogenic forcings have substantially increased the probability of high-temperature events in China. While different factors including atmospheric circulation [ 88 ], sea surface temperature [ 89 ] and the effect of urbanization [ 90 ] have been considered, anthropogenic forcings appear to have played the dominant role in the increase in the magnitude and frequency of high-temperature events.…”

Possible mechanisms for persistent anomalous rainfall over the middle and lower reaches of Yangtze River in winter 2018/2019

“…Compared with the atmospheric responses to the tropical oceans, the predictability of the Rossby wave train propagating along the Asian jet stream is relatively low at monthly to seasonal time scales, which further limits the seasonal predictability of the East Asian climate (Kosaka et al ., 2012). The energy source of the wave train might be related to the atmospheric internal dynamic processes, such as kinetic energy conversion from synoptic disturbances, while some other research emphasizes the influence of equatorial Atlantic warming (Hu et al ., 2018; Chowdary et al ., 2019; Huang et al, 2020; Jian et al ., 2020; Li et al ., 2020; Liu et al, 2020). The mechanism behind the formation and persistence of Rossby waves in the upper troposphere over Eurasia and its connection with climate extremes of East Asia needs for further investigation.…”

Interdecadal Variation in Available Potential Energy of Stationary Eddies in the Midlatitude Northern Hemisphere in Response to the North Pacific Gyre Oscillation

“…In this study, we utilize the simplified atmospheric general circulation model SPEEDY provided by the International Centre for Theoretical Physics, which reasonably simulates global climatological features compared to observations and has inexpensive computation requirements (Kucharski et al., 2006, 2013; Molteni, 2003). Thus, this model is widely used in studying atmospheric response to anomalous SST (Cheung et al., 2021; Gore et al., 2020; Jian et al., 2020, 2021, Leung et al., 2020, 2022; Sun et al., 2017). The model is initially run with the climatological mean SST for 160 years.…”