滨海建成区过渡季热湿格局的尺度效应研究OACHSSCD

Under the background of global climate change and increasing heatwave risks,coastal cities experience more complex thermal-humidity patterns than inland cities due to the combined influence of the ocean and the built environment.Existing studies have primarily focused on summer or winter,and most have examined single meteorological variables.Consequently,there is a lack of systematic understanding of the coupled thermal-humidity characteristics of a coastal built-up area during the transitional season,the spatial attenuation patterns of the ocean's moderating effects,and the underlying response mechanisms at various scales.In this study,the gradient variations of temperature and humidity in a typical coastal built-up area near Dalian,along the coast-to-inland direction,in the spring transitional season,were investigated.The intensity and boundaries of the ocean's moderating effect were quantified,and the influencing mechanism of land surface factors on thermal-humidity patterns at different spatial scales was identified.The results provide references for climate adaptation planning in coastal cities.The study area was located in the region bounded by Qixian East Road and Xuezhi Road in Ganjingzi District,Dalian,and the areas on both sides of these roads.A typical urban transect perpendicular to the coastline was established,and mobile measurement experiments were conducted along the streets and alleys.Microclimate data,including air temperature,relative humidity,wind speed,black globe temperature,and solar radiation,were collected under two typical weather conditions:cloudy and sunny.Concurrently,variables such as NDVI,NDBI,building density(BD),building height(BH),and distance from the coastline(DIS)were extracted based on remote sensing imagery,building data,and geographic data.For data analysis,the relationships between temperature and humidity and meteorological factors were analyzed using Pearson correlation analysis.The relationship curves of temperature and humidity with distance to the coastline were established through polynomial fitting.The influence of the ocean was quantified by the oceanic conditioning index(OCI)and oceanic conditioning distance(OCD).Furthermore,multiple linear regression models were established at three scales of 500 m,1500 m,and 3000 m to compare the differences in the effects of land surface factors across these scales.The results indicated that during the transitional season,temperature and humidity in the coastal built-up area exhibited significant gradients in the landward direction.Specifically,temperature increased and humidity decreased with increasing distance from the sea.The maximum temperature difference reached 5.46℃,and the maximum humidity difference reached 20.37％,indicating that the ocean can significantly lower temperature and increase humidity.The 0～500 m zone exhibited the most dramatic changes in temperature and humidity,while the oceanic influence weakened significantly beyond 1500 m.Weather conditions had a significant impact on the moderating effects of the ocean.The cooling effect of the ocean was stronger under sunny conditions,with a temperature OCI of 5.6℃,higher than the 5.1℃ observed under cloudy conditions.The relative humidity OCI under sunny conditions was 20.1％,and the OCD was 2,280 m,indicating a nonlinear attenuation boundary in oceanic humidity regulation.Temperature and humidity generally exhibited a significant negative correlation.The relative humidity decreased by 2.75％under cloudy conditions and 2.85％under sunny conditions for every 1℃ increase in temperature,indicating that the temperature-humidity coupling response was more sensitive under clear conditions.Multiscale regression results showed that the effects of land surface factors exhibited significant scale differences.NDBI exhibited a warming effect at all scales and was an important driver of local warming.NDVI had a significant cooling effect at medium and large scales and exhibited a humidifying effect at small and medium scales.BH generally exhibited warming and dehumidification effects,while BD exhibited a characteristic shift from warming near the coast to cooling at medium and large scales.These findings indicate that thermal-humidity patterns in the coastal built-up area during the transitional season exhibit significant land-sea gradients,weather dependence,and scale heterogeneity.The moderating effect of the ocean was the strongest near the coast and decreased nonlinearly with increasing distance from the sea.As the influence of the ocean weakened,the role of land surface factors,such as vegetation and building morphology,gradually increased.On this basis,a hierarchical planning strategy of"humidity control near the coast,increased greening in the middle coastal zone,and corridor development in the outer coastal zone"is proposed to enhance the climate adaptation of coastal cities.