Simulation Of Land-Atmosphere Interaction And Boundary Layer Structure Over Heterogeneous Underlying Surface In Beijing

The research of land-atmosphere interactions over heterogeneous surface has became a hot subject. We use WRF/UCM (urban canopy model) to simulate the boundary layer structure, turbulence and energy balance of urban and rural districts of Beijing. Differences of the variables between urban and suburban districts are compared.The results showed that:(1) Observed radiation the radiation of the four-component analog four-component goodness of fit, the correlation coefficient of up to0.999in winter; summer soil heat flux correlation coefficient of only0.837in the four-component energy, latent heat flux net radiation, sensible heat flux results than radiation components low, the correlation coefficient between0.837-0.999, soil heat flux12:00-15:30when the deviation larger than the other periods, this is because in the period from analog lower than the measured net radiation, net radiation mode at the same time the energy value of the the summer energy distribution of the sensible heat flux and latent heat flux is overestimated.(2) A sense of urban surface heat exchange to achieve maximum360.34W/m2water underlying surface is approximately50.34W/m2at.14:00in summer the Yanshan Mountains during the day14:30up to298.80W/m2, the city’s largest mountain, followed by the smallest body of water;14:00, vegetation underlying surface latent heat flux reaches its maximum465.89W/m2the urban surface latent heat flux maximum of only52.34W/m2, water reaches minimum53.33W/m2, water at night maximum of248.30W/m2; urban soil heat flux reached around midday, about275.20W/m2, the water soil heat flux throughout the day are small because large specific heat capacity of the water body itself; vegetation underlying surface soil heat flux diurnal variation between in-35-65W/m2; urban surface net radiation maximum560.22W/m2, net radiation of the underlying surface of the surrounding vegetation maximum value of about548.20W/m2, the the water net radiation maximum of about762.21W/m2.(3) Yanshan Mountains sensible heat flux around midday reached most about139.80W/m2, the city most about125.90W/m2at14:10in winter, water body of14:30is just4.87W/m2; urban latent heat flux value only1.5W/m2appear in13:40, the water13:50a maximum of22W/m2, Yanshan latent heat flux during the day transpiration significantly up to22.84W/m2at13:30; urban soil heat flux in noon, the most about148.98W/m2, soil heat flux of water throughout the day to0W/m2; the urban net radiation11:30hours maximum, a maximum of271W/m2vegetation underlying surface net radiation The230W/m2water net radiation and its surface temperature is reverse, date of maximum amplitude, between changes in-123-328W/m2.(4) The city at11:00hours mixing layer height of200meters in winter, to1000meters in15:00, while the suburbs underlying surface mixing layer height in the the11:00mixing layer height of200meters to15:developed00to600m, which is a plus due to the heat of the city prompted the city’s atmosphere the junction becomes unstable, heat island effect is conducive to produce heat convection and urban surface roughness and uneven buildings on flow Summer Urban mechanical disturbance, trigger turbulence and uplift the city over the mixed layer to rise faster development in the mixing layer height of200meters in9:00and17:00hours, with the surface gradually warming unstable stratification gradually upward development inversion layer disappeared completely, up to1650m; suburbs9:00when the mixed layer height of100m17:00when growth to1750m,11:00-14:00than the same when times urban boundary layer height low200m or so, the surface potential temperature from11:00hours to296.8K and14:00when growth to304.6K, and Urban considerable.(5) Turbulence activity in the city and suburbs at14:00when the maximum in winter, which is due to the higher surface temperature thermal action along with a large, turbulent kinetic energy of the urban surface vertical development to1100m, value of0.59m2·s-2, the outskirts of the vertical development to1100m, and a maximum of of0.37m2·s-2; Summer City12:00hours, the city’s turbulent kinetic energy development to1100m,500m at a maximum of0.76m2·s-2; turbulence in the suburbs kinetic energy development to the maximum vertical development to1100m, and a peak of0.57m2·s-2.