Urban atmospheric modelling experiments: The Urban Heat Island

Transcription

1 Urban atmospheric modelling experiments: The Urban Heat Island Dr Helen Macintyre 1, Dr Clare Heaviside 1,2,3, Dr Jonathon Taylor 4, Dr Phil Symonds 4, Dr Roberto Picetti 3, Dr Anna Mavrogianni 4, Prof Mike Davies 4, Dr Sotiris Vardoulakis 1,2,3 1. Public Health England, Air Pollution and Climate Change Group, Environmental Change Department, Centre for Radiation, Chemical & Environmental Hazards 2. University of Birmingham 3. London School of Hygiene and Tropical Medicine 4. University College London

2 European heatwaves August 2003 and July 2006 heatwave across Europe. Temperature records broken in most areas of the UK. 70,000 deaths across Europe in 2003 [Robine et al., 2007]. Heatwaves likely to become more frequent and severe in the future (IPCC AR5) Land surface temperature anomaly for 20 July 20 August 2003, compared with the average of the same period in 2000, 2001, 2002, (Image courtesy Reto Stöckli and Robert Simmon, Derived from MODIS Terra Data, Land surface temperature anomaly for July 2006 (c.f ). (Derived from MODIS Terra Data, 2 Urban atmospheric modelling experiments - Helen Macintyre - HPRU ECH Annual Meeting

3 West Midlands July 2006 West Midlands is the 2 nd most populous conurbation in the UK (~1 million), and contains 2 nd largest city in UK (Birmingham). West Midlands saw many more excess deaths during July 2006 (10% above average for recent years). July 2006 was the warmest calendar month since records began. Urbanisation across the West Midlands [ Maximum temperatures reached in July 2006 [Weather magazine, July (7)]. Excess deaths July 2006 in England and Wales. [Health Statistics Quarterly 32, Winter 2006, statistics.gov.uk] 3 Urban atmospheric modelling experiments - Helen Macintyre - HPRU ECH Annual Meeting

4 Urban Heat Island (UHI) 54% of the world s population live in urban areas; expected to rise to 66% by 2050 [UN (2014) World Urbanization Prospects]. In the UK this is 82% [Census 2011] Future population will be more exposed to urban environmental factors. Climate projections often don t account for the effect of the UHI. Causes of UHI Urban materials retain heat Buildings reduce heat radiated to the sky Lack of moisture and vegetation Temperatures up to +10ºC. Larger for low-wind, cloud free conditions, and usually more pronounced at night. Visible (top) and surface temperature (bottom) images of Atlanta, GA, 28 Sept (NASA images by Marit Jentoft-Nilsen, based on Landsat-7 data.) Effects of UHI: Health respiratory, stroke, heat exhaustion, death Increased energy consumption for cooling/ reduced in winter Increased greenhouse gases and air pollutant emissions 4 Urban atmospheric modelling experiments - Helen Macintyre - HPRU ECH Annual Meeting

5 Model Simulations WRF (Weather Research and Forecasting) model Regional weather simulation. Four nested domains (36km, 12km, 3km, 1km resolution). 2 metre air temperature modelled at 1km 2 resolution across the West Midlands. BEP (Building Energy Parameterization) Multilayer surface urban physics scheme 3 types of urban classes; specially adapted for Birmingham and the West Midlands Simulates the effects of the vertical distribution of heat, momentum and turbulent kinetic energy throughout the urban canopy layer. 5 Urban atmospheric modelling experiments - Helen Macintyre - HPRU ECH Annual Meeting

6 Simulating UHI Urban : Model is run using 3 detailed urban land surface categories to best capture the UHI effect using the BEP scheme. Rural : Model is run by replacing all urban categories with rural (grassland/pasture) categories. Industrial Commercial High-intensity residential Low-intensity residential Non-urban A comparison of temperature between the two simulations gives an indication of the UHI intensity 6 Urban atmospheric modelling experiments - Helen Macintyre - HPRU ECH Annual Meeting

7 UHI Intensity Difference in temperature between urban and rural land cover simulations. Averaged over July 2006 (all times of day), the whole region is 0.7 C warmer. Maximum UHI intensity, reaching +9.4 C (11pm, July 17 th ). 2m Temperature difference between urban and rural model simulations. Average differences in temperature across urban areas is +1.1 C for the whole time period. 7 Urban atmospheric modelling experiments - Helen Macintyre - HPRU ECH Annual Meeting

8 Spatial vulnerability Temperature Population Care homes Urban atmospheric modelling experiments - Helen Macintyre - HPRU ECH Annual Meeting

9 Health and care centres Care Homes Difference in 2m temperature at care homes and hospitals compared to the average 2m temperature across the whole domain (21.8 C). Day Night Hospitals 9 Urban atmospheric modelling experiments - Helen Macintyre - HPRU ECH Annual Meeting

10 Housing type Housing types not evenly distributed across cities. Some housing types may be more likely to overheat C Accommodation information at LSOA level from Census Housing types more likely to over heat (e.g. flats) are exposed to air temperature higher than average C Distribution of ambient temperatures for different housing types. Average temperature housing is exposed to is 22.4 C. Avg air temp across the region for this period is 21.8 C. 10 Urban atmospheric modelling experiments - Helen Macintyre - HPRU ECH Annual Meeting

11 Mitigation of the UHI effect Range of strategies which may reduce UHI intensity and bring multiple benefits, including addressing climate change. Benefits Lowering temperatures Reduced air pollution and GHG emissions Reduced energy demands Measures Increased vegetation Modifications to urban design 11 Urban atmospheric modelling experiments - Helen Macintyre - HPRU ECH Annual Meeting

12 2m temperature ( C) Initial analysis of cool roofs When all roofs are made into cool roofs (now 70% reflecting compared with 20%), average 2m temperature difference across the whole region is C, which is approximately 20% of the magnitude of UHI (0.7 C). Station at city centre shows average daytime temperatures are -0.9 C m Temperature difference ( C) when applying cool roofs over all urban areas (albedo 0.7 compared with 0.2) th 17 th 18 th 19 th 20 th 21 st 22 nd 23 rd 24 th 25 th 26 th 27 th 28 th Birmingham centre (urban) 2m temperature with standard and cool roofs. Average -0.5 C, maximum -2.2 C. 12 Urban atmospheric modelling experiments - Helen Macintyre - HPRU ECH Annual Meeting

13 WRF-Chem Attended the WRF-Chem workshop on urban air pollution at Wageningen University (The Netherlands). Protocol drafted for coupling the meteorological model to a composition model. Many options for chemical mechanism, emissions, boundary conditions, and computational expansion required. Examples courtesy of NCAS: 13 Urban atmospheric modelling experiments - Helen Macintyre - HPRU ECH Annual Meeting

14 Presentations Clare Heaviside, Xiaoming Cai, Sotiris Vardoulakis. The health impacts of the Urban Heat Island during a heatwave: a modelling case study for the UK. July 2015, Climate Change and Health Workshop, InVS, Paris, France. Clare Heaviside, Xiaoming Cai, Anna Mavrogianni, Jonathon Taylor, Mike Davies, Sotiris Vardoulakis. Heatrelated health impacts associated with the urban heat island and climate change in the West Midlands, UK. July 2015, International Conference on Urban Climate, Toulouse, France. Helen Macintyre, Clare Heaviside, Sotiris Vardoulakis, Cool roofs and the Urban Heat Island, Fourth jointlyrun NCAR-NCAS workshop for European-based users of the WRF Model, 18 September 2015, Chester, UK. Clare Heaviside, Xiao-Ming Cai, Sotiris Vardoulakis, High resolution modelling of the UHI for Health Impact Assessment, Urban Heat Island Workshop, 7 October 2015, LSHTM, UK. Helen Macintyre, Clare Heaviside, Sotiris Vardoulakis, The sensitivity of the UHI to urban parameters: Cool roofs, Urban Heat Island Workshop, 7 October 2015, LSHTM, UK. Helen Macintyre, Clare, Heaviside, Sotiris Vardoulakis, Modelling the health impacts of the Urban Heat Island, and the potential benefits of mitigation techniques in a UK city, International Conference on Urban Risks, 30 June 2 July 2016, Lisbon, Portugal. Attending author: Helen Macintyre. Jonathon Taylor, Roberto Picetti, Phil Symonds, Clare Heaviside, Helen Macintyre, Paul Wilkinson, Mike Davies, Anna Mavrogianni, Estimating changes in heat-related mortality following built environment adaptations in the West Midlands, UK, PHE Annual Conference, September 2016, Warwick, UK. Attending author: Helen Macintyre. Helen Macintyre, Clare Heaviside, Sotiris Vardoulakis, Modelling the health impacts of the Urban Heat Island, and the potential benefits of mitigation interventions across the West Midlands, PHE Annual Conference, September 2016, Warwick, UK. Attending author: Helen Macintyre. 14 Urban atmospheric modelling experiments - Helen Macintyre - HPRU ECH Annual Meeting

15 Published works Heaviside, C., Cai, X.-M., & Vardoulakis, S. (2015). The effects of horizontal advection on the urban heat island in Birmingham and the West Midlands, United Kingdom during a heatwave. Quarterly Journal of the Royal Meteorological Society, 141, , doi: /qj.245 Heaviside, C., Vardoulakis, S., & Cai, X. (2016). Attribution of mortality to the Urban Heat Island during heatwaves in the West Midlands, UK. Environmental Health, 15 Suppl 1:27, doi: /s Macintyre, H. L., Heaviside, C., & Vardoulakis, S. (2016). Modelling the health impacts of the Urban Heat Island, and the potential benefits of mitigation interventions in a UK city. Conference proceedings, International Conference on Urban Risks, Lisbon Macintyre, H. L., Heaviside, C., & Vardoulakis, S. (2016). Urban Heat Islands Workshop Report, NIHR Health Protection Research Unit (HPRU) in Environmental Change and Health, Theme 2 - Healthy Sustainable Cities. Workshop held 7th October 2015 in London, UK. Public Health England. Salmond, J. A., Tadaki, M., Vardoulakis, S., Arbuthnott, K., Coutts, A., Demuzere, M., et al. (2016). Health and climate related ecosystem services provided by street trees in the urban environment. Environmental Health, 15(1), , doi: /s Symonds, P., Taylor, J., Chalabi, Z., Mavrogianni, A., Davies, M., Hamilton, I., et al. (2016). Development of an England-wide indoor overheating and air pollution model using artificial neural networks. Journal of Building Performance Simulation, 1-14, doi: / Bassett, R., Cai, X., Chapman, L., Heaviside, C., Thornes, J. E., Muller, C. L., et al. (2016). Observations of urban heat island advection from a high-density monitoring network. Quarterly Journal of the Royal Meteorological Society, 142(699), , doi: /qj Urban atmospheric modelling experiments - Helen Macintyre - HPRU ECH Annual Meeting

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