Study On The Comprehensive Impact Of Weather Type And Local Climate Zone On Daily Temperature Range And High Temperature Heat Wave In The Yangtze River Delt

The warming phenomenon caused by urbanization has brought increasing health and economic risks to residents,while urban excessive warming is complex and uncertain under the joint regulation of weather circulation and local elements.Based on a variety of meteorological station data,satellite data and reanalysis data with high spatial and temporal resolution,this paper systematically investigates the influence of large-scale weather circulation and local geographic environment and meteorological elements on the diurnal temperature range and heat waves of the Yangtze River Delta urban agglomeration and its regulation mechanism from regional large circulation scale and local scale by using objective weather classification,random forest machine learning model and other methods.The main conclusion are as follows:1)The diurnal temperature range and heat waves of the Yangtze River Delta urban agglomeration are affected by uneven urbanization showing spatial urban-rural differences,and the diurnal temperature range and heat waves will be enhanced in the year controlled by the anomalous Northwest Pacific subtropical high,where the heat waves will amplify the diurnal temperature range.2)The large-scale atmospheric circulation background and local meteorological factors influence the diurnal temperature range and the frequency of heat waves by regulating the upward or downward trend of maximum and minimum temperatures in different amplitude.There are significant differences in diurnal temperature range and heat waves under different weather circulation types,and these differences are characterized by the combined regulation of weather conditions such as humidity,cloud cover and vertical airflow motion under different weather patterns.3)The spatial variation of diurnal temperature range and heat waves are regulated by the differences of geophysical environment,building density and ventilation conditions in different local climate zones.The low wind speed and poor ventilation in dense urban areas are conductive to increasing the diurnal temperature range and frequency of heat wave events,while the stronger diurnal temperature range and more heat wave events in urban open areas are mainly affected by the horizontal advective transport of urban heat under medium wind speeds.In this paper,the regulation mechanism of diurnal temperature range and heat waves are revealed through the multi-scale study of regional large-scale weather circulation pattern and local climate zones,which can provide scientific reference for further understanding,assessment and mitigation of urban heat risk.