The Ability of CMIP6 Models in Capturing the Relationship between Summer Compound Heatwaves over The Sichuan-Chongqing Region and Tibetan Plateau Atmospheric Heat Source

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  • College of Atmospheric SciencesChengdu University of Information Technology / Sichuan Key Laboratory of Plateau Atmosphere and EnvironmentChengdu 610225SichuanChina

Online published: 2025-04-11

Abstract

Compound heatwave events are heatwaves that occur simultaneously during the day and at nightwhich not only threaten human health but also impede sustainable socio-economic and ecosystem development. In recent yearsthe frequency of compound heatwave events in the Sichuan-ChongqingSCregion has in‐ creased significantlyand an advanced understanding of the plausible factors of compound heatwave variations over the SC region is of great importance for a better understanding of their impacts. Based on observational and reanalysis datathe relationship between the summer compound heat wave frequencyHWFin SC and the anomalous atmospheric heat sourceAHSover the Qinghai-XizangTibetanPlateauQXPis statistically analyzed in the present study. Thenthis study evaluates the performance of 28 climate models from the Coupled Model Intercomparison Project Phase 6CMIP6in simulating the relationship between the SC HWF and the QXP AHS of 1985-2014 and explores the key factors causing the differences in the simulation capability among the models. The results show that both the climate mean and the standard deviation of the HWF have relatively large values in the eastern SCwhere the HWF variability shows a significant negative correlation with the summer AHS over the southeastern QXP. When the AHS over the southeastern QXP is weaker in summeran anomalous anticyclone is present over the eastern SCleading to an anomalous downward motion. This anomalous descent induces cloud cover and surface shortwave changesleading to the formation of heatwave events over the eastern SC. Most CMIP6 models can essentially simulate the spatial distribution characteristics of the observed climate states of the summer HWF in the SC region and the summer AHS in the QXP. Howeverthe models perform better in simulating the standard deviation of the AHS over the QXP than in simulating the HWF in the SC regions. There are significant differences in the simulated relationship between the SC HWF and the QXP AHS between different models. This is mainly due to the different abilities of the models to simulate the anomalous vertical motions over the SC regions corresponding to the anomalous summer AHS over the QXP. Further analysis shows that a good performance of the models usually depends on their ability to simulate the anomalous vertical motions and cloudiness in the SC regionswhich can lead to air temperature variations. Thereforethe simulated vertical motion and cloudiness anomalies in the eastern SC in response to the QXP AHS anomalies are the key circulation factors affecting the model’s performance in simulating the HWF-AHS relationship.

Cite this article

CHEN Huning, CHEN Zhang, GE Fei, JIN Zhengrui . The Ability of CMIP6 Models in Capturing the Relationship between Summer Compound Heatwaves over The Sichuan-Chongqing Region and Tibetan Plateau Atmospheric Heat Source[J]. Plateau Meteorology, 0 : 1 . DOI: 10.7522/j.issn.1000-0534.2025.00019

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