关键词: 地表热场, 地表温度, 不透水地表盖度, 京津唐

Abstract:

The changes in the characteristics of urban land surface thermal field caused by urban development have significant impacts on regional climate and ecological environment. Urban land surface thermal field reflects the relationship between urban expansion and environmental temperature. Understanding the formation causes and coupling association of urban land surface thermal field and urban development has important academic research significance. Conducting long-term surface monitoring and measurement in Beijing-Tianjin-Tangshan region, studying the characteristics of the land surface thermal field and its variation by the perspective of regionalization. Land surface temperature (LST) and impervious surface percentage (ISP) in the main urban area of Beijing-Tianjin-Tangshan in 1995, 2005, and 2015 were obtained by Landsat remote sensing images. The methods of ten fold cross validation and record value verification were used to evaluate results of ISP and LST. Based on the hot spot aggregation method, study area was zoned for low, medium, and high LST zones. In the same way, study area was zoned to natural land surface, low, and high ISP zones based on threshold segmentation method. And the land surface thermal field in the main urban area of Beijing-Tianjin-Tangshan was divided into nine types according to the regionalization information about LST and ISP. Then the development law, the inter-annual change situation, and the regional contribution of different types of land surface thermal field were analyzed and discussed based on the method of mathematical statistics, standard deviation ellipse, and contribution index. The study find that the LST has a significant correlation with the ISP in main urban area of Beijing-Tianjin-Tangshan, the multiple correlation coefficients are 0.88, 0.92, and 0.94 from 1995 to 2015, this also reflects that the relationship between the two land surface attributes is gradually strengthening. The LST would rise with the increase of ISP. This growth phenomenon performs fast in 1995 and is slow in 2005 and 2015 relative. The mean value of ISP is 49.72%, 53.87%, and 57.17% in three periods, and high LST zone area also maintains 1.5 time growth rates over time. The development focal axis of land surface thermal field remains in the northwest-southeast direction and accumulates along the axis over time. The centroid of land surface thermal field in the main urban area of Beijing-Tianjin-Tangshan is concentrated in the central part of each city. The inter-annual change rate of land surface thermal field increases from 12.00% to 13.71%, the type of land surface thermal field continues to change to the form of “high LST and high ISP”. Besides, the land surface thermal field shows the change characteristics of “step down” in LST and “large at both ends and small in the middle” in ISP. The land surface thermal field of the main urban area of Beijing-Tianjin-Tangshan continues to expand in space. The spatial distribution of the land surface thermal field in Beijing’s main urban area gradually spreads from the south to the entire area. Tianjin’s land surface thermal field spreads rapidly from the central area to the port. Tangshan’s spatial distribution of land surface thermal field is more significant in the north. Different main urban areas have different contributions to the overall area: Beijing's contribution is concentrated in areas of high-grade land surface thermal fields. Tianjin's contribution to various types of land surface thermal field is balanced. And Tangshan's contribution is inclined to shift to higher grade land surface thermal fields. The study is applicable to assessing spatial and temporal changes in the thermal field in the Beijing-Tianjin-Tangshan region, and promoting the coordinated development of construction planning and ecological environment in the urban community area.

Key words: land surface thermal field, land surface temperature, impervious surface percentage, Beijing-Tianjin-Tangshan