Multi-method Mapping of Intra-urban Microclimate Variability in a Desert City

Cities are characterized by high heterogeneity of built form, land use and land cover, all of which contribute to diverse microclimate effects. As urban planners and city authorities seek to address the effects of unprecedented global-scale environmental degradation and the potential consequences of climate change on as local a scale as possible, it is becoming increasingly important to map in detail the spatial and temporal variability of indicators accounting for pivotal human-environmental interactions. This includes an accurate and spatially explicit description of the urban microclimate. Taking the city of Beer Sheva in the Negev Desert of Israel as a case study, we quantify the spatial and temporal pattern of urban-rural and intra-urban temperature variability by means of satellite observation, vehicular traverse measurement, and simulation using an urbanized energy balance model - the Canyon Air Temperature (CAT) model. In contrast to the abundance of research in temperate climate zones, understanding the urban microclimate in dryland areas fills a crucial gap in the global debate on urban climate change adaptation, particularly given that arid/semi-arid regions take up 41.3% of the global land and are home to more than one third of the world's population. This study presents a novel and computationally efficient approach to derive urban geometric parameters, e.g. canyon aspect ratio and street orientation, based solely on building footprints data. As these parameters are also commonly required as input to a variety of modelling schemes, our approach constitutes a useful supplement to a broad range of academic communities. Meanwhile, investigating the urban microclimate from seemingly divergent perspectives (skin vs. screen levels, surface radiometric temperature vs. near-surface air temperature) serves as a complementary paradigm to deliver a complete picture of urban microclimate, which is scarcely promised by single-method based analyses. Results from the three methods are contrasted and implications for their use in decision-making towards a climate-resilient urban planning are discussed.