Context Understanding how landscape components affect the urban heat islands is crucial for urban ecological planning and sustainable development. Objective The purpose of this study was to quantify the spatial pattern of land surface temperatures (LSTs) and associated heat fluxes in relation to land-cover types in Beijing, China, using portable infrared thermometers, thermal infrared imagers, and the moderate resolution imaging spectroradiometer. Methods The spatial differences and the relationships between LSTs and the hierarchical landscape structure were analyzed with in situ observations of surface radiation and heat fluxes. Results Large LST differences were found among various land-use/land-cover types, urban structures, and building materials. Within the urban area, the mean LST of urban impervious surfaces was about 6-12°C higher than that of the urban green space.LSTs of built-up areas were on average 3-6°C higher than LSTs of rural areas. The observations for surface radiation and heat fluxes indicated that the differences were caused by different fractions of sensible heat or latent heat flux in net radiation. LSTs decreased with increasing elevation and normalized difference vegetation index. Conclusions Variations in building materials and urban structure significantly influenced the spatial pattern of LSTs in urban areas. By contrast, elevation and vegetation cover are the major determinants of the LST pattern in rural areas. To alleviate urban heat island intensity, urban planners and policy makers should pay special attention to the selection of appropriate building materials, the reasonable arrangement of urban structures, and the rational design of landscape components.Keywords Urban heat island Á Land surface temperature Á Urban landscape Á Land-use/land-cover Á MODIS Á Portable infrared thermometer
The evacuation of large municipal areas in an efficient manner during emergencies and disasters is one of the critical tasks of emergency management agencies. This paper presents a corridor-based emergency evacuation system and an example application of the system for the Washington, D.C., metropolitan area. The proposed system features flexibility by accounting for various critical issues associated with both planning and real-time operations, including the integration of data from multiple sources, network decomposition, network-level traffic routing, contraflow design, staged evacuation, optimal signal timing, and the incorporation of pedestrian and bus operations. Under a hypothetical emergency scenario for Union Station in Washington, D.C., the proposed system demonstrated its effectiveness at producing evacuation routing strategies, identifying potential bottlenecks, and evaluating the performance of evacuation operations.
Black carbon (BC) has attracted much attention over the last several decades as it has known impacts on human health and climate. BC in the atmosphere can absorb solar radiation, thus it has positive radiative forcing (
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