Assessing Current & Future Exposure to Urban Climate Impacts
Work Package Leader: Dr Paul J Alexander
Duration: 9 months (August 2016- April 2017)
Detailed numerical modelling of the Dublin Bay (coastal inundation) and Greater Dublin area (temperature and precipitation) will be undertaken to assess spatial and temporal (current and potential future) variations in levels of exposure to coastal inundation and changes in temperature and precipitation. The models will be developed using existing datasets (provided through WP2) and new data (developed through WP3) and will be validated against recent and observed meteorological and environmental data.
3.1 Assessing Current and Projected Future Levels of Exposure to Coastal Inundation
The key element of this task is the development of a validated numerical model that will enable both current and future inundation levels to be determined for a number of possible scenarios. It is proposed to use the DHI developed MIKE21 software as it incorporates all the core features required for this purpose. The model domain will be generated using the most recent topographic and bathymetric data available and the resolution will be increased in areas known to be high risk. The input forcing conditions will include tidal variation, wave and wind conditions, river discharge and storm surge. Once validated against existing recorded events the model will then be forced with a range of possible climate future scenarios established through global climate modelling experiments (e.g. IPCC AR5) to establish potential future levels of inundation (including inundation attributed to SLR and/or storm surge).
3.2 Assessing Current and Projected Future Levels of Exposure to Temperature Changes (T2M)
In order to assess projected changes in the T2M (average, maximum and minimum) and the Urban Heat Island (UHI) effect, existing GCM simulations will be employed and down‐scaled for the Greater Dublin Area. This task will first involve an assessment of climate projections from the Climate Model Inter‐comparison Project Phase 5 (CMIP5) to identify a range of models that are fit‐for‐purpose and encompass the range of Representative Concentration Pathways (RCP), i.e. RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5. Relevant variables (e.g. temperature, wind speed and humidity) will then be extracted and downscaled for the area under investigation using an appropriate climate model i.e. a model that employs a surface module capable of representing the urban surface. For example, the Surface Urban Energy and Water Balance Scheme (SUEWS) is a land surface scheme for urban areas designed for scales of hundreds of meters to kilometers.
Once validated against urban meteorological measurements, the model will then be employed to assess possible future changes in temperatures for the Greater Dublin Area and across the range of RCPs.
3.3 Assessing Current and Projected Future Levels of Exposure to Precipitation Changes
The simulation of precipitation is a major challenge with a cascade of errors increasing as higher spatial and temporal resolutions are sought. As a result, as part of the proposed research, a subset of results considered to be robust for Ireland e.g. those reported by Nolan et al. (2014), and covering the range of RCPs will be employed in assessing future changes in precipitation (average and maximum) for the Greater Dublin Area.