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CR prepress abstract   -  DOI: https://doi.org/10.3354/cr01584

Influence of cloud cover on the relationship between the sky view factor and nocturnal urban heat islands

Guixin Zhang, Guangxing Zhang, Chuxuan Zhou, Shanyou Zhu*

*Corresponding author:

ABSTRACT: Cloud amounts, their spatial distribution, and the sky view factor (SVF) have common effects on the nocturnal upwelling longwave radiation and result in different degrees of urban-rural radiation cooling, which are widely applied in studying the urban heat island phenomenon. Currently, most research studies discuss the influence of synoptic conditions and urban geometric morphology on urban heat islands respectively. This research attempted to discuss the influence of cloud cover on the relationship between the SVF and nocturnal urban heat islands by calculating the SVF considering the cloud amount and its distribution. This study selected the Adelaide central urban area of South Australia as the study area and used urban three-dimensional (3D) building data with a spatial resolution of 1 m and field measurement meteorological data, as well as ceilometer-observed cloud data. This study sequentially analyzed the influence of cloud amount on the instantaneous nocturnal urban heat island intensity (UHII), sky view factor, and SVF-UHII relationship. Then, the SVF-UHII feature space was constructed to explain the nocturnal urban heat island. The results reveal that there are high negative correlations between the total cloud amount and UHII, while the correlations changed with the site location. The cloud amount has an effect on the defined SVF. SVFs at all sites gradually increase with the cloud amount, and the SVF differences between various sites decrease with an increasing cloud amount. The SVF-UHII feature space can be preliminarily used to explain and simulate the UHII at some sites under different cloud cover conditions, and the mean relative error of the simulated UHII for the example data is 20%. Moreover, the uncertainties of the research and possible future work are also discussed.