Simulating Australian Urban Climate in a Mesoscale Atmospheric Numerical Model

Abstract

We develop an urban canopy scheme coupled to a mesoscale atmospheric numerical model and evaluate the simulated climate of an Australian city. The urban canopy scheme is based on the Town Energy Budget approach, but is modified to efficiently represent the predominately suburban component of Australian cities in regional climate simulations. Energy conservation is improved by adding a simple model of air-conditioning to prevent the urban parametrization acting as an energy sink during the Australian summer. In-canyon vegetation for suburban areas is represented by a big-leaf model, but with a largely reduced set of prognostic variables compared to previous approaches. Although we have used a recirculation/venting based parametrization of in-canyon turbulent heat fluxes that employs two canyon wall energy budgets, we avoid using a fixed canyon orientation by averaging the canyon fluxes after integrating over 180 • of possible canyon orientations. The urban canopy scheme is evaluated by simulating the climate for Melbourne, Australia after coupling it to The Air Pollution Model. The combined system was found to predict a realistic climatology of air temperatures and winds when compared with observations from Environmental Protection Authority monitoring stations. The model also produced a plausible partitioning of the urban energy budget when compared to urban flux-tower studies. Overall, the urban canyon parametrization appears to have reasonable potential for studying present and predicting changes in future Australian urban climates in regional climate simulations.

Comparative Analysis of Responses of Land Surface Temperature to Long-Term Land Use/Cover Changes between a Coastal and Inland City: A Case of Freetown and Bo Town in Sierra Leone

“…The rising temperature in response to the growth of both cities can be captured by the explanation that, as population grows, urbanization increases and the magnitude of the urban heat island also expands [58]. Similar findings were obtained in Australia between 1951 and 2003, where land cover changes produced statistically significant warming [59].…”

Enhanced modeling of latent heat flux from urban surfaces in the Noah/single-layer urban canopy coupled model

“…The urban canopy model developed by Ryu et al (2011) considered the impacts of urban surface water (the maximum water depth on roofs and roads was set to 1 mm). Thatcher et al (2012) introduced a simplified big-leaf model in the urban canopy model to determine the impacts of vegetation in urban street canyons. Kotthaus et al (2012) analyzed the contributions of anthropogenic sources to sensible and latent heat flux at building scales by observing the urban SEB.…”

The Hamburg Tornado (7 June 2016) from the perspective of low-cost high-resolution radar data and weather forecast model

“…In addition, effects of aerosols on the radiation and on the cloud microphysics are considered (Rotstayn and Lohmann, 2002;Rotstayn et al, 2011), which are shown to be important for the simulations of severe convective storms (Lompar et al, 2017). In order to account for processes within the urban canopy layer, CCAM employs a state-of-the-art urban parameterization based on the Town Energy Budget (TEB; Masson, 2000), approach denoted here as aTEB (Thatcher and Hurley, 2012;Luhar et al, 2014;Lipson et al, 2017), which is coupled to the Community Atmosphere Biosphere Land Exchange model (CABLE) land-surface scheme (Kowalczyk et al, 2013). Compared to the original approach by Masson (2000) aTEB has an improved representation of suburban areas, an in-canyon vegetation parameterization, an additional parameterization for air-conditioning and an improved thermal conduction model.…”