Countermeasures Of A Heat Wave Based On Its Correlation With Urban Form

In recent years,many cities around the world have been hit by extreme heat waves and suffered heavy losses.The coastal city of Dalian in China has also been affected to a certain extent.Clever urban planning and architectural design to enhance the city’s ability to cope with hot weather has become an important aspect adaptive planning and the urban high-temperature mitigation strategy.To solve such problems,taking Dalian as an example from the perspective of urban planning and architecture,we use quantitative analysis methods such as correlation analysis and spatial regression models to explore how urban form parameters and the thermal environment under heat wave conditions relate to each other to provide an important basis for urban planning and design in response to heat wave.The main research contents are as follows:First of all,sort out the urban basic data to provide data support for quantitative analysis and response strategies.According to Landsat 8 remote sensing data,using ENVI to carry on the land surface temperature(LST)inversion.In the meanwhile,this essay obtains the surface land use parameters(NDVI,Normalized Difference Vegetation Index;MNDWI,Modified Normalized Difference Water Index;NDBI,Normalized Difference Building Index).Moreover,this essay calculates the heat island intensity and grade according to the land-use situation of the study area.Its use GIS spatial analysis technology based on Python to calculate the urban form parameters,including sky view factor(SVF),building density(BD),floor area ratio(FAR),average height(AH),and urban roughness length(URL).Through the spatial distribution of LST and heat island intensity,it is found that the surface temperature increases from the coastline and mountains to the city center,and a large area of the high-temperature area appears in the Ganjingzi area.Secondly,using urban form parameters,land use parameters and LST as variables,with the help of SPSS and GeoDa,the Pearson correlation coefficient is calculated,and the spatial regression model is established to explore the quantitative relationship between urban climate factors and surface temperature.In the Pearson correlation coefficient,the correlation between vegetation coverage and LST is the largest,showing a negative correlation,which is-0.595.Apart from the land cover types,the correlation between building density and LST is the largest,with a positive correlation,which is 0.360.The correlation between SVF and LST is the smallest.GeoDa is used to calculate the global Moran index of LST,and the result is 0.8,which proves that there is obvious spatial autocorrelation.Considering that the urban climate is not affected by a single parameter,the applicability of the spatial regression model in urban thermal environment research is further studied.There are two groups of experiments,and each group is set with 12 models,each group of models is composed of different parameter combinations,one is spatial regression model,the other is a traditional regression model.In the multiple spatial regression model,BD,FAR,AH is significant while SVF and URL are not significant,and the relationship between FAR,SVF,and LST are also various in different combinations.By comparing the coefficients of each parameter in the two experimental models,it is found that the traditional regression model can enlarge or reduce the influence of a certain factor on LST,such as MNDWI.Furthermore,the maximum LL(Log likelihood),AIC(Akaike information criterion),and BIC(Bayesian information criterion)parameters in the two groups of experiments also prove that the spatial regression model is more suitable for the study of urban climate factors.Finally,based on the above research results,a strategy for heat wave is proposed for study from the perspective of urban planning,architectural design,and urban management.From the perspective of urban planning,the city "cold island" and "heat island" are divided according to the intensity of the heat island.By analyzing the relationship between the distance from the coastline(DFC)of the study area and the LST,it is found that the sea breeze has the best cooling effect on the city within approximately 5800 m of the coastline;this is the main reason for the formation of "cold islands." Combining with the geographical location of the "cold island," it is proposed to protect the "cold island" through reasonable land use and at the same time use the "cold island" to establish a ventilation corridor to direct the cooler air toward the "hot island" to maximize the cooling effect of the sea breeze.For the "heat island," in addition to the construction of ventilation corridors,countermeasures are proposed involving the underlying material,urban shading measures,and isolation.In order to improve the cooling efficiency of wind corridors and sea breezes,it is recommended that a spatial lag model be constructed to control the planning indicators of plots on the coast and the areas where the wind corridors are located.From the perspective of architectural design,suggestions are made regarding materials and shapes of the buildings.In order to ensure the implementation of the first two and compensate for areas in which they cannot be implemented,from the point of view of urban management it is proposed that high temperature early warning systems be improved.Using policies,regulations,and other forms management to establish a linked multi-sectoral system,the whole of society can participate in the high-temperature response system.To sum up,the research uses relevant knowledge of geospatial analysis,mathematical statistics,urban planning,and urban climate to provide a research idea for a thermal environment.It will also provide the basis and methodology for mitigating heat wave conditions in coastal cities in cold mid-latitudes and an important reference for urban planners and architects to create livable cities.