Abstract:The Urban Heat Island (UHI) is one of the most well documented phenomena in urban climatology. Although a range of measurements and modelling techniques can be used to assess the UHI, the paucity of traditional meteorological observations in urban areas has been an ongoing limitation for studies. The availability of remote sensing data has therefore helped fill a scientific need by providing high resolution temperature data of our cities. However, satellite-mounted sensors measure land surface temperatures (LST) and not canopy air temperatures with the latter being the key parameter in UHI investigations. Fortunately, such data is becoming increasingly available via urban meteorological networks, which now provide an opportunity to quantify and compare surface and canopy UHI on an unprecedented scale. For the first time, this study uses high resolution air temperature data from the Birmingham Urban Climate Laboratory urban meteorological network and MODIS LST to quantify and identify the spatial pattern of the daytime and night-time UHI in Birmingham, UK (a city with an approximate population of 1 million). This analysis is performed under a range of atmospheric stability classes and investigates the relationship between surface and canopy UHI in the city. A significant finding of this work is that it demonstrates, using observations, that the distribution of the surface UHI appears to be clearly linked to landuse, whereas for canopy UHI, advective processes appear to play an increasingly important role. Strong relationships were found between air temperatures and LST during both the day and night at a neighbourhood scale, but even with the use of higher resolution urban meteorological datasets, relationships at the city scale are still limited.

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ABSTRACT:Energy consumption and outdoor ambient temperatures are inherently related. Low temperatures increase consumption via space heating, whereas high temperatures result in increased demand for refrigeration and air conditioning. A common approach used for investigating this relationship in detail is via the calculation of heating and cooling degree days. Starting with a critical review of studies in the scientific literature that have used this technique, this study highlights a range of limitations with the methodology, particularly with respect to standardization, which potentially hinder the utility of the technique in climate change risk assessments. Using an analysis of electricity consumption in Birmingham, UK, as an example, this study calls for a standardization of the approach via the use of a universal base temperature calculated using average outdoor air temperatures. Adoption of this measure will not only enable meaningful comparisons to be made across regions, but will also permit a more robust means to account for acclimatization in longer term analyses such as that required by climate change risk assessments. This is demonstrated in this study by coupling the existing degree days methodology with a temporal analogue.

Urban heat and residential electricity consumption: a preliminary study. AbstractThe Urban Heat Island (UHI) is a well-documented phenomenon occurring in cities across the world resulting in city centres often being several degrees warmer than their surroundings.This local elevation in temperatures could potentially impact upon local energy consumption, with residents in the warmer central section of the city using more energy to cool their homes in summer and less energy to warm them in winter. This study uses a combination of Geographical Information System techniques and Remote Sensing data (MODIS LST and NDVI), as a preliminary investigation, to assess the spatial relationship between UHI, urban greenspace, household income and electricity consumption in Birmingham, UK. It provides simple and repeatable steps, based on freely available datasets, for urban planners, industry, human and physical geographers, and non-specialists to reproduce the analyses. The results show that, the present impact of the UHI is limited and instead highlights the dominance of household income over local climate in explaining consumption patterns across Birmingham.