Abstract
Strong wind coinciding with rainfall is an important weather phenomenon in many science and engineering fields. This study investigates changes in hourly extreme driving rain wind pressure (DRWP)—a climatic variable used in building design in Canada—for future periods of specified global mean temperature change using an ensemble of a Canadian regional climate model (CanRCM4) driven by the Canadian Earth system model (CanESM2) under the Representative Concentration Pathway 8.5 scenario. Evaluation of the model shows that the CanRCM4 ensemble reproduces hourly extreme wind speeds and rainfall (> 1.8 mm/h) occurrence frequency and the associated design (5-year return level) DRWP across Canada well when compared with 130 meteorological stations. Significant increases in future design DRWP are projected over western, eastern, and northern Canada, with the areal extent and relative magnitude of the increases scaling approximately linearly with the amount of global warming. Increases in future rainfall occurrence frequency are driven by the combined effect of increases in precipitation amount and changes in precipitation type from solid to liquid due to increases in air temperature; these are identified as the main factors leading to increases in future design DRWP. Future risk ratios of the design DRWP are highly dependent on those of the rainfall occurrence, which shows large increases over the three regions, while they are partly affected by the increases in future extreme wind speeds over western and northeastern Canada. Increases in DRWP can be an emerging risk for existing buildings, particularly in western, eastern, and northern Canada, and a consideration for managing and designing buildings across Canada.
Highlights
Simultaneous occurrence of wind and rain is an important weather phenomenon in a number of areas, including atmospheric science (Hovind 1965; Johansson and Chen 2003), catchment hydrology (Blocken et al 2005), agriculture and forestry (Van Stan et al 2011), soil erosion (Foulds and Warburton 2007), energy infrastructure (Kikuchi et al 2003), and buildings (Blocken and Carmeliet 2004; Mirrahimi et al 2015)
Annual mean wind speed exhibits weaker spatial variability in comparison to rainfall, the CanRCM4 ensemble explains 52% of the spatial variability of observed annual mean wind speed. This result is comparable with the findings of Jeong and Sushama (2018b), who showed that the ERA-Interim reanalysis, an observationally constrained historical dataset, and Canadian Regional Climate Model version 5 (CRCM5) explain 53% and 58% of the spatial variability of observed station annual mean wind speeds, respectively, over Canada for 1981–2010 period
This study investigates projected changes to extreme driving rain wind pressure (DRWP) used in the design of buildings and their window systems over Canada for future periods with different levels of global mean temperature change (GMTC) using a 15 member initial condition ensemble of CanRCM4 driven by Canadian Earth system model 2 (CanESM2) under the RCP8.5 scenario
Summary
Simultaneous occurrence of wind and rain is an important weather phenomenon in a number of areas, including atmospheric science (Hovind 1965; Johansson and Chen 2003), catchment hydrology (Blocken et al 2005), agriculture and forestry (Van Stan et al 2011), soil erosion (Foulds and Warburton 2007), energy infrastructure (Kikuchi et al 2003), and buildings (Blocken and Carmeliet 2004; Mirrahimi et al 2015). Increases in future surface air temperature will lead to a change in precipitation type from snow to rain, which, in turn, will result in increases in rainfall occurrence frequency during the cold season over Canada (Harder et al 2015; Jeong and Sushama 2018a). The IPCC AR5 suggested increases in future precipitation amounts over Canada, again with larger increases in winter and in northern Canada (IPCC 2013). These changes in wind speed coinciding with rainfall pattern in a future warmer climate could result in substantial implications for extreme DRWPs as well as existing buildings that were designed based on the design DRWP estimated from historical observations
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