Coupling a single-layer urban canopy model with a simple atmospheric model: Impact on urban heat island simulation for an idealized case

We incorporated a single-layer urban canopy model into a simple two-dimensional atmospheric model in order to describe the fundamental impact of the urban canopy model on an idealized urban heat island simulation. We found that the heat island circulation developed less strongly than when using the atmospheric model with the standard slab urban model. Additionally, the coupling with urban canopy model (i) delays the phase of surface air temperature, (ii) reduces the diurnal range of the temperature, and (iii) produces a nocturnal heat island, which results from the difference in atmospheric stability between city and its surroundings. The features from the atmospheric model coupled with the canopy model agree well with those from observation, although the atmospheric model with the slab model does not. The simulated nocturnal heat island is caused by the larger heat storage of the canopy model which releases sensible heat after sunset.