Cooling Effect And Influencing Factors Of Main Parks In Qinhuangdao City Urban Area

With the acceleration of urbanization,the urban heat island effect is becoming more and more serious,especially in summer.Urban park green space can effectively regulate urban heat island effect,improve local microclimate and play an important role in maintaining urban ecological balance.It is of great practical significance to discuss the influence of park green space form and green space pattern on urban heat island effect,and to clarify how urban parks can reduce urban heat island phenomenon to a greater extent and improve the adaptability and sustainability of urban park green space to climate environment,which is of great practical significance to guide the planning and design of urban parks and realize the maximization of ecological benefits of urban park green space.In this study,Google Earth image and Landsat-8OLI/TIRS remote sensing image were used as data sources,and 41 main parks in Qinhuangdao city were taken as research objects.Through the software platforms of ENVI5.3,Arc GIS10.8,Fragstats4.2,Guidos3.0 and SPSS26,the cooling effect of the main parks in Qinhuangdao city,as well as the morphological characteristics,landscape pattern,morphological spatial pattern and parks were discussed.The main results are as follows:(1)The cooling effects in the buffer zones of the parks in the study area were obviously different.The overall average temperature of the parks was 29.95℃,and the overall cooling distance of the parks was between 120 m and 480 m.The cooling distance of Qinhuangdao Forest Wetland Park and Lianfengshan Park was the farthest,both of which were 480 m.The maximum cooling intensity of Tanghe Park was7.97℃,and the maximum cooling efficiency of Xinyuan was 69.66.Tanghe Park,Tashan Park,and Tangshan Park were the highest.(2)For the whole park with water,no water and waterfront,the proportion of green space was negatively correlated with the average temperature in the park,and the park area,park perimeter,area perimeter ratio and green space area were positively correlated with the cooling area.In terms of park scale,large parks had a stronger influence on the cooling effect,while small parks had a stronger correlation with different types of land use.As far as the park area was concerned,the park and cooling effect in Haigang District and Beidaihe District were more influential.Through the fitting function of the overall park and park cooling effect index,it can be seen that the park area was about 40hm~2,the park perimeter was about 1.6km,and the area-perimeter ratio was about 6.5,and the temperature drop in the park tend to be gentle.(3)In terms of horizontal landscape pattern,LPI and LSI,which were impervious to water surface,had the greatest influence on cooling effect,while the aggregation degree of green space and water area had the greatest influence on cooling effect,among which water area had the greatest influence on cooling efficiency,cooling intensity and cooling gradient,and green space has the greatest influence on average temperature and cooling distance in the park.According to the regression analysis,when the impervious surface LSI was greater than 10,the cooling efficiency was decreasd obviously,and when the impervious surface shape index was greater than 20,the cooling area was increased obviously.From the horizontal landscape pattern,LPI and LSI had the greatest influence on the cooling effect,followed by fragmentation and patch richness.According to the regression analysis,the maximum patch area was about 20%,which is more conducive to the park cooling,and the park shape index was about 5,which was more conducive to the park cooling.(4)The greater the proportion of core area in green space,the stronger the cooling effect,the smaller the proportion of edge area,the stronger the cooling effect,and the smaller the proportion of branches.According to the function trend of regression analysis,the cooling effect was obviously enhanced when the core area accounts for more than 80%of the green space,and it was obviously enhanced when the edge area accounts for less than 10%of the green space.(5)The correlation between the vegetation coverage in the park green space and the cooling effect index was better than that in the park,and the vegetation coverage in the park green space had a very significant correlation with the average temperature(-0.741),cooling distance(0.509),cooling intensity(0.445)and cooling area(0.446)in the park.Regression analysis shows that the cooling effect was obviously enhanced when the vegetation coverage was greater than 0.7.(6)The building density and population density in the 600m buffer zone around the park had obvious negative effects on the cooling effect of the park green space,and the correlation between the building density and the average temperature in the park is the strongest,which is 0.624;The vegetation coverage in the surrounding600m buffer zone had a positive effect on the cooling effect of park green space,and the correlation between vegetation coverage and the average temperature in the park is the strongest,which was-0.737.It can be seen that the surrounding environment,especially the distribution of surrounding vegetation and buildings,had a significant impact on the temperature in the park.