Assessment of cooling effect of sea breeze under future climate based on analysis of heat balance mechanism of urban space

Abstract

In this study, a scheme was developed to quantitatively assess the effectiveness of measures against hot outdoor environments under future climate conditions. In this scheme, each component of heat balance (i.e. advection, turbulent diffusion, anthropogenic heat release) were analyzed based on mesoscale simulations. By comparing the current and future values of the component of the heat balance corresponding to the measure being targeted, it is possible to clarify how the effectiveness of the measure changes. To illustrate the application of the scheme, it was applied to a coastal city (Sendai, Japan) and the advection component was analyzed to assess the effectiveness of introducing a sea breeze into a coastal city as a measure against hot outdoor environments under future climate conditions. Mesoscale simulations were conducted using WRF (Weather Research and Forecasting model) and pseudo global warming method was adopted to create boundary conditions. The increase in air temperature and humidity from the 2000s to the 2050s was more significant in the coastal area than in the inland areas, resulting in increased incoming sensible and latent heat fluxes generated by advection. It was quantitatively demonstrated that while it is currently effective to introduce the sea breeze as a measure against the hot outdoor environment in coastal cities, the effectiveness will not be as significant in the future.