Page 148 - 《高原气象》2022年第5期

5 期 张 敏等：利用大涡模拟分析地表加热和动力作用对边界层结构的影响 1241

Analyze the Surface Thermodynamic and Dynamic Effects on the Atmospheric

Boundary Layer Structure by Large Eddy Simulation

1
ZHANG Min ，LIANG Jiening ，ZHANG Zhida ，ZHANG Lei 1，2
1
1
（1. Key Laboratory for Semi-Arid Climate Change of the Ministry of Education，College of Atmospheric Sciences，
Lanzhou University，Lanzhou 730000，Gansu，China；
2. Collaborative Innovation Center for Western Ecological Safety，Lanzhou University，Lanzhou 730000，Gansu，China）

Abstract：Atmospheric boundary layer structure affects the exchange of material and energy between the earth
and air，the dispersion of pollutants and human health. The boundary layer structure is significantly affected by
surface heating and dynamics，but it is difficult to separate the effects of each factor in practical observations，
which causes difficulties in parameterizing the boundary layer structure and atmospheric turbulence. Therefore，
using the large eddy module，WRF-LES，in the Weather Research and Forecasting Model（WRF），set up con‐
trol test（Test1），surface heat flux（Test2），low-level wind shear（Test3），surface roughness（Test4）tests and
test that change the above variables simultaneously（Test5）to investigate the effects of surface heating，low-lev‐
el wind shear and surface roughness on the boundary layer structure on the flat surface. The results were as fol‐
lows：（1）The surface heating，enhanced by 5 times，warmed up the boundary layer，enhanced convection，in‐
creased the thickness of the entrainment layer by 120. 8%，increased the turbulent kinetic energy of the full
boundary layer by 45. 7%，and increased the height of the thermodynamic and dynamic boundary layers by
28. 3% and 29. 9%，respectively. The strong vertical mixing facilitated the downward momentum transfer，
which increased the wind speed in the lower boundary layer and decreased in the middle and upper boundary lay‐
ers.（2）The 0. 5 times increase in wind shear in the lower layer increased the thermodynamic and dynamic
boundary layer heights by 11. 9% and -6%，respectively，and increased the entrainment zone thickness by
31. 2% and the full boundary layer turbulent kinetic energy by 25. 7%.（3）The 4 times increase in roughness af‐
fected the turbulent kinetic energy mainly in the lower layers. The change in height of the dynamic boundary lay‐
er was small，but the friction loss effect reduced the wind speed in the dynamic boundary layer. Meanwhile，it in‐
creased the entrainment effect near the top of the boundary layer，which increased the potential temperature in
the boundary layer. In a comprehensive view，the effects of surface heating and wind shear on turbulent kinetic
energy and boundary layer structure are more significant，while the effects of roughness are smaller and mainly
concentrated in the lower boundary layer. The simulation results can reflect to some extent the changing charac‐
teristics of the boundary layer structure under ideal conditions and are indicative for understanding scientific is‐
sues such as the influence of meteorological factors on pollution dispersion.
Key words：Large Eddy Simulation（LES）；atmospheric boundary layer turbulence；surface heat flux；wind
shear；roughness