The Urban Heat Island Effect in Malta and the Adequacy of Green Roofs in Its Mitigation Jonathan Scicluna James Madison University
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James Madison University JMU Scholarly Commons Masters Theses The Graduate School Spring 2016 The urban heat island effect in Malta and the adequacy of green roofs in its mitigation Jonathan Scicluna James Madison University Follow this and additional works at: https://commons.lib.jmu.edu/master201019 Part of the Environmental Health and Protection Commons, Environmental Studies Commons, Other Earth Sciences Commons, and the Sustainability Commons Recommended Citation Scicluna, Jonathan, "The urban heat island effect in Malta and the adequacy of green roofs in its mitigation" (2016). Masters Theses. 467. https://commons.lib.jmu.edu/master201019/467 This Thesis is brought to you for free and open access by the The Graduate School at JMU Scholarly Commons. It has been accepted for inclusion in Masters Theses by an authorized administrator of JMU Scholarly Commons. For more information, please contact [email protected]. THE URBAN HEAT ISLAND EFFECT IN MALTA AND THE ADEQUACY OF GREEN ROOFS IN ITS MITIGATION Jonathan Scicluna A dissertation submitted to the UNIVERSITY OF MALTA and JAMES MADISON UNIVERSITY In Partial Fulfilment of the Requirements for the degree of Master of Science in Sustainable Environmental Resources Management/ Master of Science in Integrated Science and Technology 2016 To my Family ii Acknowledgements I would like to express my gratitude to my supervisors Mr Antoine Gatt and Dr Wayne S. Teel as well as to Prof Louis F. Cassar. I would also like to thank the course coordinators Dr Elisabeth Conrad and Dr Maria Papadakis as well as the administrative staff at the Valletta Campus especially Mr Mario Cassar and Ms Mersia Mackay Zammit. My gratitude also goes to Dr Charles Galdies who suggested final improvements to this work and to Mr Joseph Schiavone who provided information about the meteorological stations in Malta. Finally, I wish to thank my family for their support especially my father who also accompanied me during my data collection, as well as my mother, who even though left this world before I could complete this work, has dedicated her life to our family and to making me a better person. iii “…but the temperature of the city is not to be considered as that of the climate; it partakes too much of an artificial warmth, induced by its structure, by a crowded population, and the consumption of great quantities of fuel in fires…” ‘The Climate of London’, Luke Howard, 1818 iv Table of Contents Dedication ..................................................................................................................................ii Acknowledgements................................................................................................................... iii List of Figures ............................................................................................................................ ix List of Tables ........................................................................................................................... xiii List of Acronyms and Abbreviations ........................................................................................xiv Abstract .................................................................................................................................... xv 1 Intrroduction 1.1 Background .................................................................................................................... 1 1.1.1 Preamble .................................................................................................................... 1 1.1.2 Malta .......................................................................................................................... 2 1.1.3 The Urban Heat Island ............................................................................................... 3 1.1.3.1 Classification of heat islands .......................................................................................... 5 1.1.3.2 Spatial considerations .................................................................................................... 6 1.1.3.3 UHI characteristics ......................................................................................................... 7 1.1.3.4 The importance of mitigating the UHI ........................................................................... 7 1.1.4 What are green roofs? ............................................................................................... 8 1.1.4.1 Green Roofs as a mitigating strategy ........................................................................... 11 1.1.4.2 Green roof studies in Malta ......................................................................................... 11 1.2 Rationale for the work ................................................................................................. 14 1.3 Research Question ....................................................................................................... 15 1.4 Structure of the dissertation ........................................................................................ 15 2 The Urban Heat Island 2.1 The Formation of UHIs ............................................................................................. 17 2.1.1 The inadvertent modification of the climate system ..................................................... 17 2.1.2 The source of heat .......................................................................................................... 19 2.1.3 The Surface Energy Balance (SEB) ................................................................................... 20 2.2 Urban Heat Island Analysis ...................................................................................... 38 2.2.1 UHI Strength.................................................................................................................... 38 2.2.2 Site Classification ............................................................................................................ 38 2.2.3 Collecting UHI data ......................................................................................................... 41 2.2.4 Fixed stations .................................................................................................................. 41 2.2.5 Mobile Traverses ............................................................................................................. 44 2.2.6 Remote sensing ............................................................................................................... 46 2.2.7Vertical sensing ................................................................................................................ 47 v 2.2.8 Energy balances .............................................................................................................. 48 2.2.9 Other methods: Weekday-Weekend differences ........................................................... 50 2.3 The Urban Heat Island Effect around the world ...................................................... 50 2.2.2 Equatorial wet climates .................................................................................................. 52 2.2.3 Tropical / Sub-tropical Climates ...................................................................................... 53 2.2.4 High latitude locations .................................................................................................... 56 2.2.5 The Mediterranean region .............................................................................................. 56 2.2.6 Similarities and differences of UHI in different climates ................................................ 57 3 The Case of Malta 3.1 Introduction ................................................................................................................. 59 3.2 Uncontrollable factors ................................................................................................. 60 3.2.1 Solar Radiation ......................................................................................................... 60 3.2.2 Seasonal climatic variation and anticyclonic activity ............................................... 61 3.2.3 Diurnal conditions .................................................................................................... 65 Diurnal insolation ..................................................................................................................... 65 Diurnal variation in atmospheric humidity .............................................................................. 68 Sea breezes .............................................................................................................................. 69 3.2.4 Wind ......................................................................................................................... 71 3.2.5 Cloud cover, fog and aerosols .................................................................................. 73 3.2.6 Other uncontrollable factors – Humidity and Marine influence ............................. 77 3.3 Controllable factors – Population related.................................................................... 79 3.3.1 Anthropogenic heat ................................................................................................. 79 3.3.1.1 Population density ....................................................................................................... 80 3.3.1.2 Per capita energy use 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