<p>The unprecedented heat event over the middle-lower Yangtze River Basin (YRB) in August 2022 had disastrous socioeconomic impacts. Based on the general mechanism of multi-year surface air temperature (SAT) variation in August, this study focuses on the key local atmospheric processes responsible for the record-breaking event in 2022. We firstly propose that through hydrostatic adjustment, the local atmospheric perturbation thickness (APT) between 1000 and 500 hPa is the most crucial factor dynamically influencing the SAT over the YRB in August. Net diabatic heating from the surface affects the SAT thermodynamically at the same time. Analysis of the geopotential thickness tendency reveals that vertical motion (<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="382_2025_7760_Article_IEq1.gif" Format="GIF" Height="10" Rendition="HTML" Resolution="72" Type="Linedraw" Width="14" /> </InlineMediaObject> <EquationSource Format="TEX">$\omega$</EquationSource> <EquationSource Format="MATHML"><math> <mi>ω</mi> </math></EquationSource> </InlineEquation>) and diabatic heating (Q) within the air column significantly affect the thickness of the air column in August, highlighting the pivotal role of the interaction among local APT,<InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="382_2025_7760_Article_IEq1.gif" Format="GIF" Height="10" Rendition="HTML" Resolution="72" Type="Linedraw" Width="14" /> </InlineMediaObject> <EquationSource Format="TEX">$\omega$</EquationSource> <EquationSource Format="MATHML"><math> <mi>ω</mi> </math></EquationSource> </InlineEquation>, and Q. The specific performance is that the downward motion and enhanced Q within the air column lead to increased local APT. Meanwhile, the increased APT and downward motion amplified the Q above the surface by reducing cloud cover. Therefore, thermodynamic processes are initiated by dynamic processes and exert a reciprocal influence on them. The results exhibit that this heat event was driven by both the hydrostatic adjustment of dynamic processes and diabatic heating of thermodynamic processes, with the dynamic processes playing a dominant role. Moreover, the APT and <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="382_2025_7760_Article_IEq1.gif" Format="GIF" Height="10" Rendition="HTML" Resolution="72" Type="Linedraw" Width="14" /> </InlineMediaObject> <EquationSource Format="TEX">$\omega$</EquationSource> <EquationSource Format="MATHML"><math> <mi>ω</mi> </math></EquationSource> </InlineEquation> serve as crucial bridges through which upper-level atmospheric circulation affects the SAT. Additionally, despite these large-scale interannual processes, synoptic regional foehn effect should be taken into consideration.</p>

Key local atmospheric processes of the heat extreme over the middle-lower Yangtze River basin in August 2022

期刊论文
发表日期：

2025年6月23日

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Yue Sun,
Jianping Li,
Yang Zhao,
Hongyuan Zhao,
Hao Wang,
Mian Zhu,
Ning Wang

摘要

The unprecedented heat event over the middle-lower Yangtze River Basin (YRB) in August 2022 had disastrous socioeconomic impacts. Based on the general mechanism of multi-year surface air temperature (SAT) variation in August, this study focuses on the key local atmospheric processes responsible for the record-breaking event in 2022. We firstly propose that through hydrostatic adjustment, the local atmospheric perturbation thickness (APT) between 1000 and 500 hPa is the most crucial factor dynamically influencing the SAT over the YRB in August. Net diabatic heating from the surface affects the SAT thermodynamically at the same time. Analysis of the geopotential thickness tendency reveals that vertical motion ( $\omega$ $ω$ ) and diabatic heating (Q) within the air column significantly affect the thickness of the air column in August, highlighting the pivotal role of the interaction among local APT, $\omega$ $ω$ , and Q. The specific performance is that the downward motion and enhanced Q within the air column lead to increased local APT. Meanwhile, the increased APT and downward motion amplified the Q above the surface by reducing cloud cover. Therefore, thermodynamic processes are initiated by dynamic processes and exert a reciprocal influence on them. The results exhibit that this heat event was driven by both the hydrostatic adjustment of dynamic processes and diabatic heating of thermodynamic processes, with the dynamic processes playing a dominant role. Moreover, the APT and $\omega$ $ω$ serve as crucial bridges through which upper-level atmospheric circulation affects the SAT. Additionally, despite these large-scale interannual processes, synoptic regional foehn effect should be taken into consideration.