Analysis of the impact of high temperature heat wave on the characteristics of urban heat island change in Dalian City
Heat wave(HW)events frequently exacerbate the negative impacts of urban heat island(UHI),it is of great significance to investigate the differences in UHI variations during different growing seasons in the HW period for residents to cope with urban heat stress.Based on Landsat 8 data from the early,middle and late stages of the growing seasons of the 2018 and 2019 in the main city of Dalian,the differences in urban heat island(UHI)variations between heat wave and non-heat wave(NHW)periods are compared and analyzed in this study.By incorporating the normalized difference vegetation index(NDVI)and normalized difference built-up index(NDBI),the relationship between land surface cover types and urban heat island effects is further quantitatively explored.The results show that ① Compared to the non-heat wave years,the heat wave years all showed a significant warming trend throughout the growing season,and the standard deviation of LST decreased by 0.3 ℃ in the middle of the growing season,indicating that the LST dispersion decreased and the LST variation stabilized in 2019.(2)The effect of HW on UHI generally shows a more obvious promoting effect.Temporally,the heat island intensity in the middle of the growing season corresponding to HW is significantly stronger than NHW,and the area share of stronger heat island and weak heat island increases from 12.8％and 17.7％in non-heat wave years to 27.3％and 21.2％in heat wave years.Spatially,the heat island intensity is strongest in the central city,showing a trend of spreading from the central city to the surrounding area.(3)UHI is significantly correlated with NDVI and NDBI during the growing season for HW and NHW(P＜0.05).UHI is negatively correlated with NDVI,it is also positively correlated with NDBI.In the early and late growing season,UHI is mainly influenced by both NDVI and NDBI together,while in the middle of the growing season in 2018,UHI is influenced not only by NDVI and NDBI,but also by high temperature heat waves.The findings of this study can provide effective scientific support and theoretical basis for urban residents to mitigate urban heat stress.
NETL
NSTL
万方数据
维普
