| As the typical disasters of urbanization,urban heat islands and high temperature heat waves which seriously affect the life and health of urban residents.It is of great significance to explore its fine-scale spatial and temporal variation characteristics for cities and urban residents to deal with the harm caused by heat hazard.Domestic FY-2F land surface temperature products play a positive role in the refined research of urban thermal environment due to their high temporal resolution characteristics,but the products usually have certain data missing problems,it is very necessary to fill in the missing value of the products or reconstruct the land surface temperature so as to obtain the data products that can satisfy the study of the diurnal variation characteristics of the urban thermal environment.At the same time,urban residents as the main carriers of urban operations,the spatial and temporal changes of the urban thermal environment will inevitably have a certain impact on it,and there are still few studies on the dynamics of urban residents under the influence of this thermal environment.How to reveal the degree of dynamic exposure of urban residents to urban heat islands and high temperature heat waves is of particular importance for cities and urban residents to deal with the risk of thermal environment.Based on the above background,this study took Shenzhen from July 26,2018 to August 1,2018 as a time period,first combined with the mode of diurnal variation over land surface temperature(INA08)and ordinary Kriging interpolation to reconstruct FY-2F land surface temperature and air temperature data,the characteristics of hourly change of land surface temperature and high temperature heat waves with time are obtained;then based on the reconstructed FY-2F land surface temperature data products,combined with MCD12Q1 land surface coverage type data,the characteristics of the hourly urban heat islands in Shenzhen were analyzed,at the same time,using correlation analysis and comparative analysis to explore the relationship between urban heat islands and high temperature heat waves;finally,based on the population-weighted model and geographic weighted regression model with mobile phone data,statistical population,and urban points of interest data,the characteristics of hourly dynamic population exposure under the influence of urban heat islands and high temperature heat waves were studied.The main conclusions are as follows:(1)The FY-2F land surface temperature reconstructed based on the mode of diurnal variation over land surface temperature(INA08)and ordinary Kriging interpolation recon-struction,the results of reconstruction have high accuracy.The mean absolute error(MAE)of the reconstruction results of over 90%is between 0 and 1.00,and about 92%of the root mean square error(RMSE)is between 0 and 1.00.In addition,the accuracy of the hourly temperature results based on ordinary Kriging interpolation is relatively high,with the mean absolute error(MAE)fluctuating between 0 and 0.50,and the root mean square error(RMSE)below 0.70.(2)The overall urban heat islands in Shenzhen shows a trend from aggregated state to discrete state and then to aggregated change,and the distribution zone mainly shows"centralized and strong in the middle,higher in the west than east",and the average area proportion of urban heat islands is basically the same at night(64.56%)and in daytime(64.80%),the area ratio of extremely weak urban heat islands at night(36.70%)is stronger than that of daytime(35.11%),the area ratio of weak urban heat islands in daytime(27.65%)is higher than that at night(26.58%),and the area ratio of strong urban heat islands at night(1.27%)is lower than that in daytime(1.97%),and the characteristics of extremely strong urban heat islands are weak.In terms of the occurrence of high temperature heat waves or not,the peak value of area ratio of urban heat islands appeared in 17:00?18:00 in the day and the lowest value appeared in 04:00?06:00 in the morning during the high temperature heat waves period,while the hourly urban heat islands showed no obvious"peak value"or"valley value".(3)The zone of high temperature(greater than 308.15 K)and the potential high temper-ature zone(307.15?308.15K)in Shenzhen showed that the western part was higher than the eastern zone and the southern region was lower than the northern region,and its potential of high temperature and high temperature is given priority to with 12:00 noon began to rise rapidly,reaching a peak between 13:00 and 17:00 in the afternoon,and then starts to fall back to non-potential high temperature levels(below 307.15K)at 18:00.(4)The influence of high temperature heat waves on urban heat islands generally presents a relatively obvious synergistic promoting effect,and the enhancement is higher at night than at daytime;However,the intensity of different urban heat islands not only showed obvious synergistic effect,but also showed a certain degree of inhibition,and this effect was generally characterized by"day and night difference".(5)The hourly population spatial distribution tends to be relatively stable,with the overall regional trend higher than 6521 people/km~2,which is characterized by the zonal distribution from the west of Longgang district to the middle of Longhua and Guangming districts via Baoan district,Nanshan district and Luohu district,taking Huaqiang north street in Futian district as the origin.Affected by the heat waves,the average of daily,night and daytime population exposure ratio to urban heat islands is about 69%in Shenzhen,and the average of hourly population exposure ratio to urban heat islands is between 60.62%and 79.18%.During the non-heat waves period,the average of daily,night and daytime population exposure ratio to urban heat islands was about 73.53%,and the average of hourly exposure ratio fluctuated between 58.61%and 79.31%,and the high exposure was mainly concentrated in urban built-up areas.During this high temperature heat waves,the daily population exposure to potential high temperature and high temperature are mainly concentrated in Guangming district,Baoan district and Longgang district in the north.The persistent and large-area coverage of high population exposure(greater than or equal to 6521 people/Km~2.h)is mainly concentrated on July 29 and July 30 for 2 days,especially from July 30 at 13:00 to 17:00,the percentage of population exposure is higher than 95%,and the percentage of population exposure from 14:00 to 16:00 is higher than 99%and the concentration distribution in nine administrative regions in addition to Yantian district.(6)People in Longgang district,Baoan district,Nanshan district,Luohu district and other areas of Shenzhen are exposed to high heat hazard,and the elderly people suffering from chronic diseases have a high risk of heat hazard and stress;Similar points of interest at different times and different points of interest at the same time have obvious characteristics of spatio-temporal driving mechanism differences and selection preferences in the mobile interaction behavior of people to reduce heat wave exposure,which objectively reflects that the layout of urban infrastructure has a great impact on residents'adaptability to cope with urban disasters. |
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