A comprehensive framework model for the trend, period and evaluation of the precipitation enhancement effect: TPEM

In this study, a framework model (TPEM) for evaluating the temporal and spatial variation of urban precipitation is established. TPEM includes seven calculation methods at the same time. Taking the annual precipitation and flood season precipitation data of 8 meteorological stations in Zhengzhou, China from 1960 to 2020 as an example, the trend and period of rain island effect in Zhengzhou are analyzed from the annual and flood season rainfall scale, and the distance method is introduced to quantitatively evaluate the rain island effect. The results show that the rain island effect in the central urban area of Zhengzhou has an sudden increase trend in 1997 and 2004 respectively, and the increasing trend of rain island effect on the scale of annual and flood season rainfall lasts for 4 and 10 years respectively; At the same time, it has fluctuation periods of 8-10a, 16-18a, 3-5a, 17-20a, 5-7a, and 2-3a respectively. The rain island effect in Zhengzhou is concentrated in the flood season. The research can provide a scientific basis for cities to deal with the rain island effect in the future.