ABSTRACT: We investigated the time evolution of heat waves and warm nights over the 7 agro-climatic zones of Tamil Nadu, India, during the period 1951-2016, including the spatiotemporal patterns of concurrent hot day and hot night (CHDHN) episodes and the concurrent warm spells in daytime temperature and drought (CWD) episodes. The research relied upon gridded temperature and rainfall observations from the India Meteorological Department. We used the Heat-Wave Magnitude Index daily to study the warm spells in daytime and nighttime temperature, while the analysis of droughts was based on the Standardized Precipitation Evapotranspiration Index. We observed a considerable increase in the count, intensity and duration of heat waves and warm night episodes across Tamil Nadu between the periods 1951-1983 and 1984-2016. Particularly, the number of heat wave events almost doubled in the second half of the study period. We observed a west-east gradient in the severity of heat waves. The intensity and duration of warm night events increased up to 3-fold in the second half of the study period, especially over central Tamil Nadu. The study recorded a multi-fold increase in the number and frequency of CHDHN episodes and the number of CWD episodes during 1984-2016 compared to the base period 1951-1983. More importantly, the incidence of compound events that coexisted with anomalous phases of sea surface temperatures registered a statistically significant spike in many locations. These changes in temperature-induced extremes pose an exceptional public health threat that can increase morbidity and mortality, disproportionately affecting vulnerable sections of Tamil Nadu’s populace engaged in outdoor work.

中文翻译：

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印度泰米尔纳德邦极端温度事件的近期模式

摘要：我们调查了 1951 年至 2016 年期间印度泰米尔纳德邦 7 个农业气候带的热浪和暖夜的时间演变，包括同时发生的热昼热夜 (CHDHN) 事件的时空模式和白天温度和干旱 (CWD) 事件中的并发暖期。该研究依赖于印度气象部门的网格温度和降雨量观测。我们每天使用热浪强度指数来研究白天和夜间温度的暖期，而干旱的分析则基于标准化降水蒸散指数。我们观察到，在 1951 年至 1983 年和 1984 年至 2016 年期间，泰米尔纳德邦的热浪和暖夜事件的数量、强度和持续时间都显着增加。特别，在研究期间的后半段，热浪事件的数量几乎翻了一番。我们观察到热浪严重程度呈东西向梯度。在研究期间的后半段，暖夜事件的强度和持续时间增加了 3 倍，尤其是在泰米尔纳德邦中部。该研究记录了 1984-2016 年 CHDHN 发作次数和频率以及 CWD 发作次数与 1951-1983 年基期相比成倍增加。更重要的是，与海面温度异常阶段共存的复合事件的发生率在许多地方都出现了统计上显着的峰值。这些由温度引起的极端事件的变化构成了特殊的公共卫生威胁，可能会增加发病率和死亡率，