Ganguli Poulomi
Agricultural and Food Engineering Department, Indian Institute of Technology Kharagpur, Kharagpur, India.
Clim Dyn. 2023;60(3-4):1061-1078. doi: 10.1007/s00382-022-06324-y. Epub 2022 Jun 20.
Compound warm-dry spells over land, which is expected to occur more frequently and expected to cover a much larger spatial extent in a warming climate, result from the simultaneous or successive occurrence of extreme heatwaves, low precipitation, and synoptic conditions, e.g., low surface wind speeds. While changing patterns of weather and climate extremes cannot be ameliorated, effective mitigation requires an understanding of the multivariate nature of interacting drivers that influence the occurrence frequency and predictability of these extremes. However, risk assessments are often focused on univariate statistics, incorporating either extreme temperature or low precipitation; or at the most bivariate statistics considering concurrence of temperature versus precipitation, without accounting for synoptic conditions influencing their joint dependency. Based on station-based daily meteorological records from 23 urban and peri-urban locations of India, covering the 1970-2018 period, this study identifies four distinct regions that show temporal clustering of the timing of heatwaves. Further, combining joint probability distributions of interacting drivers, this analysis explored compound warm-dry potentials that result from the co-occurrence of warmer temperature, scarcer precipitation, and synoptic wind patterns. The results reveal 50-year severe heat stress solely based on the temperature at each location tends to be more frequent and is expected to become 5 to 17-year compound warm-dry events considering interdependence between attributes. Notably, considering dependence among drivers, a median 6-fold amplification (ranging from 3 to 10-fold) in compound warm-dry spell frequency is apparent relative to the expected annual number of a local (univariate) 50-year severe heatwave episode, indicating warming-induced desiccation is already underway over most of the urbanized areas of the country.
The online version contains supplementary material available at 10.1007/s00382-022-06324-y.
陆地上的复合型暖干事件预计在气候变暖的情况下会更频繁地发生，且范围会大幅扩大，它是由极端热浪、低降水量以及天气形势（如低地表风速）同时或相继出现导致的。虽然天气和气候极端事件的变化模式无法改善，但有效的缓解措施需要了解影响这些极端事件发生频率和可预测性的相互作用驱动因素的多变量性质。然而，风险评估往往侧重于单变量统计，纳入极端温度或低降水量；或者最多考虑温度与降水量同时出现的双变量统计，而没有考虑影响它们共同依存关系的天气形势。基于印度23个城市和城郊地区1970 - 2018年的逐日气象记录，本研究确定了四个不同区域，这些区域显示出热浪发生时间的时间聚类。此外，结合相互作用驱动因素的联合概率分布，该分析探讨了由温度升高、降水稀缺和天气风型共同出现所导致的复合型暖干可能性。结果显示，仅基于每个地点的温度，50年一遇的严重热应激往往更频繁，考虑到各属性之间的相互依存关系，预计将变为5至17年一遇的复合型暖干事件。值得注意的是，考虑到驱动因素之间的依存关系，复合型暖干事件的频率相对于当地（单变量）50年一遇严重热浪事件的预期年数有明显的中位数6倍放大（范围为3至10倍），这表明该国大部分城市化地区已经开始出现变暖导致的干燥化。
在线版本包含可在10.1007/s00382-022-06324-y获取的补充材料。
