Page 104 - 《高原气象》2025年第5期

高 原 气 象 44 卷
1222

The Ability of CMIP6 Models in Capturing the Relationship between

Summer Compound Heatwaves over The Sichuan-Chongqing
Region and Tibetan Plateau Atmospheric Heat Source

CHEN Huning， CHEN Zhang， GE Fei， JIN Zhengrui
（College of Atmospheric Sciences， Chengdu University of Information Technology / Sichuan Key Laboratory of
Plateau Atmosphere and Environment， Chengdu 610225， Sichuan， China）

Abstract： Compound heatwave events are heatwaves that occur simultaneously during the day and at night，
which not only threaten human health but also impede sustainable socio-economic and ecosystem development.
In recent years， the frequency of compound heatwave events in the Sichuan-Chongqing （SC） region has in‐
creased significantly， and 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 data， the relationship between the summer compound heat wave frequency （HWF） in SC and the
anomalous atmospheric heat source （AHS） over the Qinghai-Xizang （Tibetan） Plateau （QXP） is statistically an‐
alyzed in the present study. Then， this study evaluates the performance of 28 climate models from the Coupled
Model Intercomparison Project Phase 6 （CMIP6） in 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 SC， where the HWF variability shows a significant negative correlation with the sum‐
mer AHS over the southeastern QXP. When the AHS over the southeastern QXP is weaker in summer， an anoma‐
lous anticyclone is present over the eastern SC， leading to an anomalous downward motion. This anomalous
descent induces cloud cover and surface shortwave changes， leading 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. However， the
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. Fur‐
ther analysis shows that a good performance of the models usually depends on their ability to simulate the anoma‐
lous vertical motions and cloudiness in the SC regions， which can lead to air temperature variations. Therefore，
the 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.
Key words： compound heatwaves； Sichuan-Chongqing Region； Qinghai-Xizang （Tibetan） Plateau （QXP）；
atmospheric heat source； CMIP6