华东地区主要地形因子对极端小时降水峰型的影响研究

The influence of main topographic factors on peak types of extreme hourly precipitation in eastern China

在全球持续增温的背景下,极端降水事件频发,给人民的生产生活和社会的经济发展造成了严重威胁。本文利用华东315个气象台站2011—2018年的小时观测数据,按照降水日峰值特征将华东地区极端小时降水分为单峰型和多峰型,基于多尺度地理加权回归模型,探讨了两种峰型极端小时降水空间分布与地形因子的关系。研究表明两种峰型极端降水分别对应常规年份和厄尔尼诺年,地形起伏度在两类峰型的降水中都为最重要的地形因子,主导区域主要为浙江北部及浙闽山脉北部;其他地形因子在两类峰型的降水中作用存在显著差异。单峰型降水中,第二重要的地形因子为地形坡度,主导区域位于浙闽山脉东南侧;而在多峰型降水中,第二重要的地形因子为离海岸线距离,且主导区域位于沿海地区。对二者差异的机理分析发现,单峰型降水以午后对流为主,浙闽山脉东南侧地形坡度较大处的对流有效位能值较大,容易促发对流;而在多峰型降水中清晨降水以平流为主,水汽输送明显较单峰型降水大,因此,离海岸线距离对该类型降水有重要影响。

The increasing amount and intensity of extreme precipitation events due to global warming have had significant effects on the ecosystem,production,life,and society.This study uses precipitation data from 351 observation stations in Eastern China to explore the relationship between terrain factors and extreme hourly precipitation,which can be classified into single-peak and multi-peak precipitation based on diurnal variation characteristics,using the Multi-scale Geographically Weighted Regression model.The analysis of the spatial distribution of two peaks of extreme precipitation and topographic factors shows that the role of topographic factors in the two types of extreme rainfall is different.Topographic relief is the most important factor in the two types of peak-type precipitation,and the dominant areas are mainly the northern Zhejiang and the northern Zhejiang-Fujian Mountains.In single-peak precipitation,the topographic slope,besides topographic relief,is the most important factor,and the dominant area is in the southeast of the Zhejiang-Fujian Mountains.However,in multi-peak precipitation,the distance from the coastline has the greatest impact on extreme precipitation,and the dominant area is the coastal region.The mechanism analysis of the difference between these two types shows that convection dominates single-peak precipitation in the afternoon.The Convective Available Potential Energy(CAPE)value on the southeastern side of the Zhejiang-Fujian Mountains with a large topographic slope is higher,promoting convection.In multi-peak precipitation,advection dominates morning precipitation,and the water vapor transport is significantly larger than that of single-peak precipitation.Therefore,the distance from the coastline has a significant impact on this type of precipitation.Clarifying the relationship between terrain factors and extreme hourly precipitation under different diurnal variation characteristics can provide support for improving model simulation of extreme precipitation in regions with complex topography and disaster prevention and mitigation.