Hourly air temperature projection in future urban area by coupling climate change and urban heat island effect

Abstract

Global climate change and urban heat island (UHI) effect are changing the urban microclimate and ecosystem of building and outdoor environment. In this study, CMIP5 family, which was found to have the most consistent projection with the current worldwide observation till now, was chosen to evaluate climate change’s impact on urban climate. This research uses Principal Component Analysis and Gaussian Mixture Model based building type clustering method to obtain urban morphological data and input parameters of the UHI model, and the validated UHI model is then coupled to the projections from various global climate models (GCMs).It is found that future urban microclimate prediction after considering the UHI effect can significantly improve the prediction accuracy of air temperature when downscaling future weather data from various selected GCMs, indicating the UHI shall be considered in predicting future weather data in urban tissue. After using the best-fit climate change prediction model MRI-CGCM3 to couple with the UHI model, the projections of the heating degree days (HDD) and cooling degree days (CDD) of Shenzhen from 2020 to 2099 has shown that comparing with the typical meteorological year, the average HDD in Shenzhen will be reduced by 57.5% in 2020–2099 under the RCP8.5 scenario, and the CDD will increase by 25.1%, which will exert considerable impacts on building energy use in urban tissue.