We conducted climate two series of climate simulations – mesoscale and microscale. The climate simulations were intended to depict a typical summer day (24 hours) in Shanghai and thus demonstrate the variation in the urban microclimate over the course of the day.
The first series of simulations (mesoscale) covered the entire urban area of Shanghai (area 6.833 km2). The spatial resolution of the simulations was 1 km x 1 km within the urban area. The temporal resolution of the output data was 1 hour (although the actual simulation time step was significantly smaller). The urban geometry was considered in average only. The simulation period encompassed multiple days before, and including, the target 24-hour period, in order to be able to provide reliable initial conditions for the second simulation series. The simulations were conducted using the WRF (Weather Research and Forecasting) software.
The second series of simulations (miscroscale) covered two specific “focus areas” within the city centre. The horizontal extent of each of the two domains was approximately 2-3 km2. The spatial resolution of the simulation was 5 m x 5 m. This relatively high resolution means that the actual geometry of built-up structures was taken into account in the CFD (Computational Fluid Dynamics) simulations. The temporal resolution of the output data was 1 hour (although the actual simulation time step was significantly smaller). The initial conditions for these simulations were provided by the previously described mesoscale simulations of the whole Shanghai urban region. The simulations were conducted using the LES (Large Eddy Simulation) mode of the PALM-4U software.
For both scenarios, the following climatic conditions were estimated:
- Air temperature
- Air humidity
- Wind field characteristics
- Urban Heat Island (UHI) intensity
- Thermal comfort