Oceans and Local Soil Moisture Contribute to Extreme Heatwave over Eastern China in Summer 2022


In the summer of 2022, Eastern China experienced the most intense sustained regional heatwave since 1961, adversely affecting people's lives and social and economic development. An in-depth understanding of these extreme heatwaves is crucial for future disaster prevention and mitigation in these regions.
Recently, in a paper published in Environmental Research Letters, scientists from the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics at the Chinese Academy of Sciences, quantitatively assessed the relative contributions of three oceans, i.e., tropical Indian Ocean and Pacific and North Atlantic, the local soil moisture–temperature feedback, and global warming using linear regression method.
"The local soil moisture–temperature feedback is extremely important for the extreme heatwave in July and August 2022, accounting for approximately 42% and 66% of the temperature anomalies, respectively." Said Prof. LIU Yimin, corresponding author of the study. "Global warming also greatly facilitated extreme heatwaves, accounting for about 30%~40% of these events in summer 2022."
The team found that tropical Indo-Pacific SSTAs account for about 10% contribution in July. In August, they contributed to the development of strong western North Pacific anticyclones; however, their direct contribution to temperature anomalies was negligible. In addition, North Atlantic SSTAs contributed 10% and 9% of the total through mid-latitude steady Rossby waves in July and August, respectively.
"The monthly mean atmospheric circulation anomalies failed to explain the extreme heatwave in June 2022, with 10% combined contribution of three oceans and local soil moisture-temperature feedback." said JIANG Jilan, the first author of the study. "The propagation of recurrent synoptic Rossby wave packets in the same phase may dominate the occurrence of this heatwave."
"For persistent extreme heatwaves, the role of local soil moisture-temperature feedback cannot be ignored." Emphasized Prof. LIU. "Moreover, we should pay more attention to the month-to-month variation of climatic effects of tropical Indo-Pacific and North Atlantic SSTAs on Eastern China."
Citation: Jiang JL, Liu YM, Mao JY, Wu GX (2023). Extreme heatwave over Eastern China in summer 2022: the role of three oceans and local soil moisture feedback, Environmental research letters, 18, 044025. https://doi.org/10.1088/1748-9326/acc5fb.
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