The interaction between extreme precipitation and temperature events has significant implications for society, the economy, and the ecosystem. While numerous studies have explored changes in precipitation and temperature extremes in subtropical monsoon country, there is a dearth of knowledge regarding the coupling of these extremes, particularly the simultaneous occurrence of extreme events. To bridge this research gap, our study aims to investigate the modulation of coupling climatic extremes, their climate signals in subtropical monsoon country, and the underlying causes of changes. To accomplish this, we utilized monthly precipitation and temperature datasets from 20 sites across Bangladesh, along with two climate signal indices, covering the period from 1980 to 2017. We employed four indices, namely consecutive dry days (CDD), consecutive wet days (CWD), minimum daily temperature (TNn), and maximum daily temperature (TXx), to assess temperature and precipitation modulation patterns. Our findings indicate a positive trend in temperature indices, with warm days and nights exhibiting a more rapid increase compared to cool days and nights in Bangladesh. Analysis of precipitation indices reveals a mixed pattern of changes, with an increase in CWD and a decrease in CDD. However, when examining specific regions, we observe an increasing trend in monsoon CDD in the northwest and coastal districts, suggesting a shift towards drier conditions. Conversely, a declining trend in winter CDD in the southeast and northwest indicates a shift towards wetter conditions. Comparing coupled precipitation and temperature extremes between 1999 and 2017 and 1980–1998 reveals a broader impact of these extremes in recent decades. Detrended fluctuation analysis further suggests that the current trend in extremes is likely to persist in the future. Our study also establishes a relationship between the El Niño-Southern Oscillation (ENSO) and climate extremes in Bangladesh, albeit with modulations in cycles. Overall, a combination of elevated summer geopotential height, the absence of a visible anticyclonic center, reduced high cloud cover, and enhanced low cloud covers collectively contribute to increased frequency and intensity of warm extremes in subtropical country.

极端降水和温度事件之间的相互作用对社会、经济和生态系统具有重大影响。尽管大量研究探索了亚热带季风国家降水和极端温度的变化，但对这些极端事件的耦合，特别是极端事件同时发生的认识还很缺乏。为了弥补这一研究空白，我们的研究旨在调查耦合极端气候的调制、亚热带季风国家的气候信号以及变化的根本原因。为了实现这一目标，我们利用了孟加拉国 20 个地点的月降水量和温度数据集，以及涵盖 1980 年至 2017 年期间的两个气候信号指数。我们采用了四个指数，即连续干旱日数 (CDD)、连续潮湿日数 (CWD) ）、每日最低温度（TNn）和每日最高温度（TXx），以评估温度和降水调制模式。我们的研究结果表明，孟加拉国的温度指数呈积极趋势，与凉爽的白天和夜晚相比，温暖的白天和夜晚表现出更快的增长。降水指数分析揭示了混合的变化模式，CWD 增加，CDD 减少。然而，在研究特定地区时，我们观察到西北和沿海地区季风 CDD 呈增加趋势，表明气候条件正在向干燥转变。相反，东南部和西北部冬季 CDD 呈下降趋势，表明气候条件正在向更加湿润的方向转变。比较 1999 年至 2017 年和 1980 年至 1998 年的耦合降水和极端温度揭示了近几十年来这些极端事件的更广泛影响。去趋势波动分析进一步表明，当前的极端趋势在未来可能会持续下去。我们的研究还建立了厄尔尼诺南方涛动（ENSO）与孟加拉国极端气候之间的关系，尽管存在周期调节。总体而言，夏季位势高度升高、缺乏可见的反气旋中心、高云量减少和低云量增加，共同导致亚热带国家极端温暖事件的频率和强度增加。