Urban-Rural Surface Temperature Deviation and Intra-Urban Variations Contained by an Urban Growth Boundary
Urban-Rural Surface Temperature Deviation and Intra-Urban Variations Contained by an Urban Growth Boundary
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DOI：
10.3390/rs11222683
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发表时间：
2019-11
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影响因子：
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通讯作者：
K. Moffett;Yasuyo K. Makido;V. Shandas
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作者：
K. Moffett;Yasuyo K. Makido;V. Shandas
城市热岛（UHI）概念描述了至少在温带/潮湿地区，城市温度相对于农村温度升高的热量捕获。在旱地，城市灌溉反而会产生城市冷岛（UCI）效应。然而，UHI/UCI的特征在选择具有代表性的城市/农村末端成员时存在不确定性，UHI和UCI之间存在人为的两分法，以及在嵌套尺度上缺乏其他热变化模式的一致术语。我们以波特兰（美国俄勒冈州）周围历史上执行良好的城市增长边界（UGB）为例：探索从中分辨率成像光谱辐射计（MODIS）地表温度数据中得出的地表温度UHI （SUHI）的代表性，测试典型的“温暖”或“凉爽”土地覆盖（lc）的常见假设，并命名其他常见的城市热特征。我们发现，UGB既包含热量，也包含蔓延，在城市/农村边界上产生了明显的地表温度差异。对比范围很大，取决于所选择的端元，从正（SUHI）到负（sui）值。我们提出了一个新的，包容性的“城市热偏差”（UTD）术语，以涵盖可能的uhi - 0 - uci条件的范围。我们还在更精细的尺度上区分了“微热极值”（mte）和微热异常（mta）。微热极值是指与LC或周围环境的热预期或趋势相反的离散区域，但与LC或周围环境的热预期或趋势相反。这种区别很重要，因为mte表明需要对当地热景观进行调节，而mta可能提出解决方案。
The urban heat island (UHI) concept describes heat trapping that elevates urban temperatures relative to rural temperatures, at least in temperate/humid regions. In drylands, urban irrigation can instead produce an urban cool island (UCI) effect. However, the UHI/UCI characterization suffers from uncertainty in choosing representative urban/rural endmembers, an artificial dichotomy between UHIs and UCIs, and lack of consistent terminology for other patterns of thermal variation at nested scales. We use the case of a historically well-enforced urban growth boundary (UGB) around Portland (Oregon, USA): to explore the representativeness of the surface temperature UHI (SUHI) as derived from Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature data, to test common assumptions of characteristically “warm” or “cool” land covers (LCs), and to name other common urban thermal features of interest. We find that the UGB contains heat as well as sprawl, inducing a sharp surface temperature contrast across the urban/rural boundary. The contrast ranges widely depending on the end-members chosen, across a spectrum from positive (SUHI) to negative (SUCI) values. We propose a new, inclusive “urban thermal deviation” (UTD) term to span the spectrum of possible UHI-zero-UCI conditions. We also distinguish at finer scales “microthermal extremes” (MTEs), discrete areas tending in the same thermal direction as their LC or surroundings but to extreme (hot or cold) values, and microthermal anomalies (MTAs), that run counter to thermal expectations or tendencies for their LC or surroundings. The distinction is important because MTEs suggest a need for moderation in the local thermal landscape, whereas MTAs may suggest solutions.