2.1.5 Urban planning
Urban planning is concerned with the design and development of urban
environments, including population control, transport management, and
building distributions. The energy consumption, water usage, and the
building construction in a city are closely related to urban planning,
which have important effects on the weather and climate by affecting the
energy, water cycle, and urban meteorology. In CAS-LSM, the schemes of
AHR, UWU, and urban roughness height (and height variations) were
incorporated to consider the effects of these processes.
AHR was treated as part of the sensible heat flux that affected the
energy balance equation. AHR could be divided into four components: AHR
from vehicles, the building sector, industry, and human metabolism
(Sailor and Lu 2004), representing the major sources of waste heat in
the urban environment. As anthropogenic heat is closely tied to energy
consumption (Sailor 2011), the AHR from vehicles, buildings, and
industry could be estimated by listing all kinds of energy consumption
(including coal, coke, crude oil, gasoline, kerosene, diesel, fuel oil,
natural gas, and electric power). For UBU, a simple UBU scheme,
including urban irrigation and road sprinkling, was incorporated into
the CAS-LSM model based on the scheme described by Zeng et al. (2017).
Here, ecological and farmland irrigations were both treated as urban
irrigation, and the road sprinkling scheme was activated at night during
the summer when water was applied to the impervious road layer to
accelerate evaporation. For the urban roughness height, this parameter
is affected by building construction, and the spatial distribution of
urban building heights, which can affect the heat and momentum
variables. Here, the scheme was based on the work of Millward-Hopkins et
al. (2011). It is worth noting that because urban planning is currently
used only in the regional setup, it was set as an option in the model
and not used in the global coupled simulations.