The impact of urban changes from 1989 to 2015 on urban rainstorms is assessed for the rapidly expanding Indian city of Hyderabad. A typical event that occurred during 12–14 June 2015 is simulated, and the possible association between altered urban-sprawl and shifts in the rainfall timing and patterns are analyzed. The simulation results revealed that the consideration of urban footprint changes was necessary to correctly simulate the heavy rainfall in the high-resolution Weather Research and Forecasting (WRF) model. With the urban expansion and associated anthropogenic heating (AH), the rainfall was more distributed, and its occurrence delayed by ~1–2 h. The results suggest that urbanization can affect rainfall both in terms of the timing as well as the location with respect to the urbanized area. The urban downwind region received an increased rainfall, and this spatial shift was more pronounced with increasing urbanization - from being over the urban area to over rural-urban boundary downwind of the city. The analysis of hydrometeors indicated that rain and cloud quantity decreased with an increasing AH in the urban area. Study results highlight the possibility that the change in the rainfall timing is another climatological signature of urban modification of rainfall.

对于迅速扩张的印度海得拉巴市，评估了1989年至2015年城市变化对城市暴雨的影响。模拟了2015年6月12日至14日发生的典型事件，分析了城市植被变化与降雨时间和格局变化之间的可能关联。仿真结果表明，在高分辨率天气研究与预测（WRF）模型中，必须正确考虑城市足迹的变化，才能正确地模拟强降雨。随着城市的扩张和相关的人为加热（AH），降雨更加分散，并且发生时间延迟了约1-2小时。结果表明，城市化可能会影响降雨的时间安排以及相对于城市化地区的位置。城市顺风地区的降雨增加，并且随着城市化程度的提高，这种空间变化更加明显-从城市上方到城市的城乡边界上方。对水汽的分析表明，市区的雨量和云量随着AH的增加而减少。研究结果突显出降雨时间的变化是城市降雨改变的另一个气候特征。