We examine wet events (WEs) defined from an hourly rainfall dataset based on 64 gauged observations across India (1969–2016). More than 90% of the WEs (accounting for nearly 60% of total rainfall) are found to last less than or equal to 5 h. WEs are then clustered into six canonical local-scale storm profiles (CanWE). The most frequent canonical type (CanWE#1 and #2) are associated with very short and nominal rainfall. The remaining canonical WEs can be grouped into two broad families: (i) CanWE#3 and #5 with short (usually less than or equal to 3–4 h), but very intense rainfall strongly phase-locked onto the diurnal cycle (initiation peaks in mid-afternoon) and probably related to isolated thunderstorms or small mesoscale convective clusters (MCS), and (ii) CanWE#4 and #6 with longer and lighter rainfall in mean (but not necessarily for their maximum) and more independent of the diurnal cycle, thus probably related to larger MCSs or tropical lows. The spatial extent of the total rainfall received during each CanWE, as shown by IMERG gridded rainfall, is indeed smaller for CanWE#3 and #5 than for CanWE#4 and especially #6. Most of the annual maximum 1 hour rainfalls occur during CanWE#5. Long-term trend analysis of the June–September canonical WEs across boreal monsoonal India reveals an increase in the relative frequency of the convective storm types CanWE#3 and #5 in recent years, as expected from global warming and thermodynamic considerations.

This article is part of a discussion meeting issue ‘Intensification of short-duration rainfall extremes and implications for flash flood risks’.

我们研究了基于每小时降雨数据集的湿事件（WEs），该数据基于印度（1969-2016年）的64个观测值而得出。发现超过90％的WE持续时间少于或等于5小时（约占总降雨量的60％）。然后，将WE聚类为六个规范的局部尺度风暴剖面（CanWE）。最常见的规范类型（CanWE＃1和＃2）与非常短的名义降雨相关。其余的经典WE可以分为两个大类：（i）CanWE＃3和＃5的时间短（通常小于或等于3-4 h），但是非常强烈的降雨强烈地锁定在昼夜周期上（初始午后达到峰值），可能与孤立的雷暴或小型中尺度对流星团（MCS）有关，（ii）CanWE＃4和＃6的平均降雨时间更长且更轻（但不一定达到最大值），并且与昼夜周期更不相关，因此可能与更大的MCS或热带低气压有关。如IMERG网格式降雨所示，每个CanWE期间接收到的总降雨量的空间范围确实比CanWE＃4，尤其是＃6的CanWE＃3和＃5小。每年最多1小时的大部分降雨量发生在CanWE＃5中。根据全球变暖和热力学考虑，对北季风印度地区6月至9月典型西风的长期趋势分析表明，对流风暴类型CanWE＃3和＃5的相对频率近年来有所增加。如IMERG网格式降雨所示，每个CanWE期间接收到的总降雨量的空间范围确实比CanWE＃4，尤其是＃6的CanWE＃3和＃5小。每年最多1小时的大部分降雨量发生在CanWE＃5中。根据全球变暖和热力学考虑，对北季风印度地区6月至9月典型西风的长期趋势分析表明，对流风暴类型CanWE＃3和＃5的相对频率近年来有所增加。如IMERG网格式降雨所示，每个CanWE期间接收到的总降雨量的空间范围确实比CanWE＃4，尤其是＃6的CanWE＃3和＃5小。每年最多1小时的大部分降雨量发生在CanWE＃5中。根据全球变暖和热力学考虑，对北季风印度地区6月至9月典型西风的长期趋势分析显示，近年来对流风暴类型CanWE＃3和＃5的相对频率增加。

本文是讨论会议问题“短期降雨极端事件的加剧及其对山洪灾害风险的影响”的一部分。