摘要
Compound heatwaves with both daytime and nighttime hot extremes(hereafter compound heatwaves)have been occurring frequently worldwide,threatening human health and ecosystems.Land-air coupling(LAC)has been identified as a key factor in amplifying the intensity and frequency of purely daytime heatwaves,but it remains unclear whether it affects the frequency and structure of compound heatwaves.Here,using CMIP6 models,we reveal that LAC will cause an increase in concurrent daytime-nighttime hot extremes and independent hot days,with a decrease in independent hot nights during a compound heatwave event in most areas of the globe during 1995–2099.This change in the structure of compound heatwaves is particularly pronounced in the long-term future(2080–2099)under the high-emission scenario.With the uncontrolled greenhouse-gases emissions,enhanced LAC appears to intensify the daytime surface sensible heat flux and nighttime surface upwelling longwave radiation,thereby raising near-surface temperatures.With more non-hot days/nights,independent hot days and nights converted into concurrent daytime-nighttime hot extremes,short-term compound heatwaves will be merged into longer ones,exacerbating their risks.The intensity of concurrent daytime-nighttime hot extremes due to LAC during a compound heatwave in the long-term future maybe 39,101,42,and 7 times higher than in the historical period in hotspots such as central North America,northern South America,the Mediterranean coast,and northern Australia,respectively.In contrast,under other scenarios,the limited influence of LAC may cause a higher frequency of short-term compound heatwaves,which in turn would increase the frequency of compound heatwaves.Our results provide a scientific foundation for the policy decisions related to compound heatwaves under the non-emission-reduction scenarios.
基金
supported by the National Natural Science Foundation of China(Grant Nos.42288101,42175053)
the National Key Research and Development Program of China(Grant No.2022YFF0801703)
the Science and Technology Commission of Shanghai Municipality(Grant No.24YF2738900)
the Undergraduate Research Grant Program of Fudan University(Grant No.22033)。
