Abstract
The city of Melbourne in southeast Australia is planning to expand urban areas substantially by the year 2050 and this expansion has the potential to alter the Urban Heat Island (UHI), that is, higher temperatures in urban areas as compared to surrounding rural areas. Moreover, Melbourne has been experiencing more frequent heatwaves for last two decades, and the intensity and duration of heatwaves is expected to increase in the future, which could exacerbate the UHI. This study evaluates the potential impacts of future urban expansion on the urban meteorology in Melbourne city during four of the most severe heatwave events during the period 2000–2009. Urban expansion is implemented as high-density urban with a high urban fraction of 0.9 to investigate the maximum possible impact. Simulations are carried out using the Weather Research and Forecasting model coupled with the Single-Layer Urban Canopy Model with current land-use and future urban expansion scenarios. Urban expansion increases the near-surface (2-m) UHI (UHI2) by 0.75 to 2.80 °C and the skin-surface UHI (UHIsk) by 1.9 to 5.4 °C over the expanded urban areas during the night, with no changes in existing urban areas. No substantial changes in UHI2 and UHIsk occur during the day over both existing and expanded urban areas. This is largely driven by changes in the storage heat flux, with an increase in storage heat at night and a decrease during the day; that is, excess storage heat accumulated during the day is released at night, which causes a slower decrease of near-surface temperature and increase in the UHI. Urban expansion did not affect human thermal comfort (HTC) in existing urban areas and there were no marked differences in HTC between existing and expanded urban areas.
Original language | English |
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Pages (from-to) | 2586-2602 |
Number of pages | 17 |
Journal | Quarterly Journal of the Royal Meteorological Society |
Volume | 145 |
Issue number | 723 |
DOIs | |
Publication status | Published - 1 Jul 2019 |
Externally published | Yes |
Bibliographical note
Funding Information:information Australian Research Council Discovery Early Career Researcher Award, DE170100102Data support by the Bureau of Meteorology (BoM) Australia, ECMWF (ERA-Interim) data server (http://apps.ecmwf.int/datasets/data/interim-full-daily/levtype=ml/), and the Environment, Land, Water and Planning Department of the Victoria State Government (http://www.planmelbourne.vic.gov.au/maps) are gratefully acknowledged. The authors also acknowledge Stephanie Jacobs and Carlo Jamandre for providing urban categories data (Jackson et al.,) for the city of Melbourne. Jatin Kala is supported by an Australian Research Council Discovery Early Career Researcher Award (DE170100102).
Publisher Copyright:
© 2019 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society.
Copyright:
Copyright 2019 Elsevier B.V., All rights reserved.