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1. Urban-Rural Surface Temperature Deviation and Intra-Urban Variations Contained by an Urban Growth Boundary

   https://doi.org/10.3390/rs11222683  

   Moffett, Kevan B. ; Makido, Yasuyo ; Shandas, Vivek ( November 2019 , Remote Sensing)

   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 themore »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.« less
2. Impact of the Economic Structure of Cities on Urban Scaling Factors: Implications for Urban Material and Energy Flows in China: Impact of the Economic Structure of Cities on Urban Scaling Factors

   https://doi.org/10.1111/jiec.12563  

   Ramaswami, Anu ; Jiang, Daqian ; Tong, Kangkang ; Zhao, Jerry ( March 2017 , Journal of Industrial Ecology)
3. Impact of urban canopy models and external parameters on the modelled urban energy balance in a tropical city: Urban Canopy Models and External Parameters Sensitivity

   https://doi.org/10.1002/qj.3028  

   Demuzere, M. ; Harshan, S. ; Järvi, L. ; Roth, M. ; Grimmond, C. S. ; Masson, V. ; Oleson, K. W. ; Velasco, E. ; Wouters, H. ( April 2017 , Quarterly Journal of the Royal Meteorological Society)
4. Structure and evolution of flash flood producing storms in a small urban watershed: FLASH FLOODING STORMS IN URBAN WATERSHED

   https://doi.org/10.1002/2015JD024478  

   Yang, Long ; Smith, James ; Baeck, Mary Lynn ; Smith, Brianne ; Tian, Fuqiang ; Niyogi, Dev ( April 2016 , Journal of Geophysical Research: Atmospheres)
5. Revisiting the Relation Between Momentum and Scalar Roughness Lengths of Urban SurfacesRevisiting the Relation Between the Momentum and Scalar Roughness Lengths of Urban Surfaces

   https://doi.org/10.1002/qj.3839  

   Li, Qi ; Bou‐Zeid, Elie ; Grimmond, Sue ; Zilitinkevich, Sergej ; Katul, Gabriel ( June 2020 , Quarterly journal of the Royal Meteorological Society)

   Large Eddy Simulations (LES) of neutral flow over regular arrays of cuboids are conducted to explore connections between momentum (z 0m ) and scalar (z 0s ) roughness lengths in urban environments, and how they are influenced by surface geometry. As LES resolves the obstacles but not the micro‐scale boundary layers attached to them, the aforementioned roughness lengths are analyzed at two distinct spatial scales. At the micro‐scale (roughness of individual facets, e.g. roofs), it is assumed that both momentum and scalar transfer are governed by accepted arguments for smooth walls that form the basis for the LES wall model. At the macro‐scale, the roughness lengths are representative of the aggregate effects of momentum and scalar transfer over the resolved roughness elements of the whole surface, and hence they are directly computed from the LES. The results indicate that morphologically‐based parameterizations for macro‐scale z 0m are adequate overall. The relation between the momentum and scalar macro‐roughness values, as conventionally represented by log(z 0m /z 0s ) and assumed to scale with urn:x-wiley:00359009:media:qj3839:qj3839-math-0001 (where Re * is a roughness Reynolds number), is then interpreted using surface renewal theory (SRT). SRT predicts n = 1/4 when only Kolmogorov‐scale eddies dominate the scalarmore »exchange, whereas n = 1/2 is predicted when large eddies limit the renewal dynamics. The latter is found to better capture the LES results. However, both scaling relations indicate that z 0s decreases when z 0m increases for typical urban geometries and scales. This is opposite to how their relation is usually modeled for urban canopies (i.e. z 0s /z 0m is a fixed value smaller than unity).« less