The cold air outbreaks in the northern parts of India exert significant impacts on human health, energy, agriculture and transportation. In this study, we investigate the synoptic dynamics of cold waves and their linkages to large scale circulations for the winter period from 1982 to2020. Cold waves are classified into normal and intense (NCWs and ICWs) based on intensity and we examine the underlying mechanisms of formation and their atmospheric drivers. Notably, the spatial extent of the ICWs is almost double than that of normal ones thereby having the potential to affect a wider population. The NCWs are often influenced by western disturbances, leading to the inflow of cold air from Siberia (a region of shallow high). In contrast, ICWs are mostly linked to the presence of an omega block over the Ural-Siberian region. The downstream portion of the Ural block favours the inflow of cold northerlies into north India, leading to cold air advection and extreme cold wave conditions. The influence of Arctic warming for ICWs is further confirmed through a prominent Quasi-Resonant Amplification (QRA) fingerprint. Furthermore, La Niña condition seems to play a crucial role in triggering ICWs over north India. During La Niña, the prominent low level cyclonic anomaly helps in advecting the cold air from the higher latitudes into the country. The frequency as well as the duration of cold wave events are also found to be higher in La Niña years compared to El Niño and neutral years. The trend analysis of cold wave events over north India reveals a significant decrease in the frequency, duration and intensity during the analysis period due to a combination of various factors such as rising winter minimum temperatures (due to global warming), decreasing number of synoptic winter weather systems and Arctic amplification.

印度北部地区爆发的冷空气对人类健康、能源、农业和交通产生了重大影响。在这项研究中，我们研究了 1982 年至 2020 年冬季寒潮的天气动态及其与大尺度环流的联系。根据强度，寒潮分为正常和强烈（NCW 和 ICW），我们研究了形成的潜在机制及其大气驱动因素。值得注意的是，ICW 的空间范围几乎是正常空间范围的两倍，因此有可能影响更广泛的人群。NCW经常受到西部扰动的影响，导致冷空气从西伯利亚（浅高地区）流入。相比之下，ICW 主要与乌拉尔-西伯利亚地区上空欧米茄区块的存在有关。乌拉尔地块的下游部分有利于冷北风流入印度北部，导致冷空气平流和极端寒潮条件。通过显着的准谐振放大（QRA）指纹进一步证实了北极变暖对ICW的影响。此外，拉尼娜现象似乎在触发印度北部的ICW方面发挥了至关重要的作用。拉尼娜现象期间，突出的低层气旋异常有助于将冷空气从高纬度地区平流进入该国。与厄尔尼诺年和中性年相比，拉尼娜年寒潮事件的频率和持续时间也更高。印度北部寒潮事件的趋势分析表明，由于多种因素的综合作用，例如冬季最低气温上升（由于全球变暖）、天气冬季数量减少，分析期间的频率、持续时间和强度显着下降天气系统和北极放大。