Geography Reference
In-Depth Information
4.2.1.3 Simulation with WRF Model
WRF model is a next-generation mesoscale model developed by a group of sci-
entists from different institutes (Hernández-Ceballos et al. 2012 ).It consists of
three parts, including pre-processing module of mode (WPS), main module of
model (ARW), and assimilation module of mode and post-processing tools of
mode data (WRF-VAR). The ARW is used to analyze the impacts of land use/
cover change on the land surface heat flux in this study. This study calculates the
flux of momentum, sensible heat, latent heat and radiation, etc. between the land
surface and the atmosphere from the perspective of the water balance and energy
balance with WRF model. Based on the Noah land surface parameterization
scheme, and focused on the sensible heat flux and latent heat flux, the study reveals
the impacts of the future land use change on the regional climate change.
The land net radiation is the energy source of near-surface temperature change,
and the latent heat flux and sensible heat flux are two key components of the land
surface energy balance. Both of them are closely related with the efficient energy
of the land surface and are influenced by the land surface characteristics and soil
water and heat conditions. Besides, under the condition of certain land surface net
radiation the underlying surface influences the temperature through influencing the
sensible heat flux, latent heat flux, and soil heat flux.
Rn ¼ H þ LE þ G
ð 1 : 1 Þ
Where Rn is the land surface net radiation, H is the sensible heat flux, LE is the
latent heat flux, and G is the soil heat flux.
The land surface net radiation heavily depends on the sensible heat flux and
latent heat flux since there is generally very limited heat flux into soil, and the
underlying surface can directly influence the latent heat flux and consequently
indirectly influence the near-surface temperature. Therefore, this study has mainly
focused on the influence of land use change on the latent heat flux and sensible
heat flux. Since the temperature is generally very low in the spring and winter in
Northeast China, this study has only calculated the sum of the latent heat flux and
sensible heat flux in the summer and autumn.
The parameterization scheme of the WRF model in this study includes the Noah
land surface parameterization scheme, CAM3 radiation scheme, WSM3-class
simple ice microphysics (MP) scheme, Grell-Devenyi ensemble scheme for
cumulus convection, and YSU boundary layer scheme. The data of the lateral and
boundary conditions came from the NCEP/FNL, being updated every 6 h. This
dataset has been constructed and updated since July of 1999 with the data
assimilation of almost all kinds of observation data (e.g., the remote sensing data
and ground-based observation data), it has the spatial resolution of 1 9 1 and the
vertical height of 27 layers. The NCEP/FNL dataset has higher accuracy and
spatial resolution and includes more kinds of environmental variables than the
datasets of NCEP I, NCEP II, and EAR40. The land surface parameters in WRF
model under different conditions of land cover were adjusted according to the
result of scenario analysis of the future land use change.
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