Spatial Distribution Assessment Of High Temperature And Heat Wave Risk In The Yangtze River Delta Region

Extreme high temperature events occur frequently around the world,and they are characterized by high frequency,high intensity,and wide range.The frequency of extreme high temperature wea-ther in June,July,and August has repeatedly reached new highs,and some areas are even affe-cted by high temperature disasters every year.Extremely high temperature weather has brought serious harm to human health and social and economic development.High temperature weather has attar-cted more and more attention from domestic and foreign research scholars.This paper selects 27 cities in the Yangtze River Delta region as the study area,and uses the monitoring data of 42 national reference weather stations in the study area from 1951 to2018 to obtain the daily high temperature data of each site in June,July,and August.High temperature inte-nsity is used as an indicator of the risk factor of high temperature heat waves,and the Gumbel recur-ence cycle principle is used to calculate the occurrence of once in five years,once in ten years,once in 20 years,once in 30 years,and once in 50 years.According to the influence of the high tempera-ture threshold on the number and intensity of high temperature days under different recurrence peri-ods,a spatial distribution map of the n-year risk factor index is made with a 1km×1km grid as the basic evaluation unit.Social data such as population density,population structure,gross domestic product(GDP),vehicle ownership,and underlying factors are collectively used as vulnerability factor indicators.The number of air conditioners,the convenience of transportation,the level of medical care,and public financial budget expenditures are used as the index of high temperature prevention capabilities.Using the method of combining the AHP analytic hierarchy process and the expert scoring method,calculate the index weights of different factors,and use the addition and subtraction method to establish the high temperature heat wave risk index model of the risk factor,the vulnerability factor and the high temperature prevention ability factor,and finally obtain n The spatial distribution map of the annual high temperature heat wave risk index.conclusion as below:(1)The mountainous area of southern Anhui is affected by the foehn effect of the mountain,and the area has more high temperature days.Jinhua,Zhejiang is located in the Jinqu Basin,surrou-nded by mountains,resulting in rapid temperature rise during the day and slow heat dissipation at night,so the monitored weather site temperature Compared with meteorological stations in plain areas,the temperature is higher,and the risk of high temperature exposure is also greater.Due to the influence of the summer monsoon in the coastal areas,there are fewer high-temperature weather,and the high-temperature risk is less than that of the inland areas.Overall,the distribution charact-eristics of high-temperature heat wave risk in areas with large undulating terrain and low high-temperature heat wave risk in coastal areas are formed.(2)The higher risk of high temperature and heat wave is mainly concentrated in the city center of each city,that is,the higher the risk of high temperature in areas with more concentrated populat-ion.The main reason is that social life and production are concentrated in areas with high populatio-n density.The greater the high temperature risk vulnerability,the higher the high temperature risk.(3)The spatial distribution characteristics of the high temperature heat wave risk index for diff-erent recurrence periods are roughly similar,but with the increase of the value of n,the high temper-ature threshold of each meteorological station also increases,the number of high temperature days reaching the threshold continues to decrease,and the risk factor decreases.As a result,the statistical characteristic value of the high temperature risk index R decreases,indicating that the recurrence period is inversely proportional to the statistical characteristic value of the high temperature risk index,that is,the larger the value of n,the smaller the characteristic value and the high-risk area is also decreasing.(4)The overall and urban high temperature risk index analysis and ranking of the six represent-tative cities in the Yangtze River Delta.Under the same high temperature recurrence cycle,the over-all high temperature risk index of the city from high to low is:Hangzhou>Ningbo>Hefei>Nanjing> Suzhou>Shanghai,while the urban high temperature risk index is from high to low: Hefei?Hang-zhou>Shanghai >Ningbo>Nanjing>Suzhou.In the high temperature heat wave risk index of these two regions,Shanghai's ranking has changed the most.The main reason is that Shanghai's permanent population has reached24,237,800,and the social life and production of the vast maj-ority of people are concentrated in the vicinity of the old city.Its high temperature is fragile.Bec-ause of its high nature,the high temperature risk index in the urban area is higher than that of Shanghai as a whole.