【作者】 李宝乐；

【导师】 左洪超；

【作者基本信息】 兰州大学 ， 气象学， 2013， 硕士

【摘要】 非均匀下垫面和大气的相互作用是当今全球气候变化中的热点学科。本文利用WRF模式,选取单层城市冠层参数化方案,模拟了北京城市及郊区边界层结构、湍流特征及能量平衡特征,并对比了两者差异。结果表明：(1)冬季观测的辐射四分量与模拟的辐射四分量吻合度较好,相关系数可达0.999；在能量四分量中,夏季土壤热通量的相关系数仅为0.837,潜热通量、净辐射、感热通量结果较辐射分量低,相关系数在0.837—0.999之间,土壤热通量在12：00-15：30时偏差较其它时段大,这是因为在该时段模拟的净辐射低于实测净辐射,同时模式高估了夏季能量分配于感热通量和潜热通量的能量值。(2)夏季14：00时城市下垫面的感热交换达到最大值360.34W/m2,而水体下垫面约为50.34W/m2,燕山山脉地白天在14：30可达298.80W/m2,城市最大,山区次之,水体最小；14：00时,植被下垫面的潜热通量达到最大值465.89W/m2,城市下垫面的潜热通量最大值仅为52.34W/m2,水体达到日最小值53.33W/m2,水体夜间最大值达248.30W/m2；城市土壤热通量在正午前后达到最大,约275.20W/m2,水体土壤热通量全天都很小的原因是由于水体本身的比热容大：植被下垫面土壤热通量日变化在-35-65W/m2之间；城市下垫面的净辐射最大值为560.22W/m2,周围植被下垫面的净辐射最大值约为548.20W/m2,水体净辐射最大值约为762.21W/m2,(3)冬季燕山山脉感热通量正午前后达到最大约139.80W/m2,城市在14：10达到最大约125.90W/m2,水体14：30仅有4.87W/m2；城市潜热通量最大值仅1.5W/m2出现在13：40,水体13：50出现最大为22W/m2,燕山的潜热通量白天蒸腾显著达22.84W/m2出现在13：30；城市土壤热通量在中午达到最大约148.98W/m2,水体的土壤热通量全天为OW/m2；城市净辐射11：30时达到最大,最大值为271W/m2,此时植被下垫面的净辐射为230W/m2水体净辐射与其表面温度呈反向变化,日振幅最大,在-123-328W/m2之间变化。(4)冬季城市在11：00时混合层高度为200米,至15：00时发展到1000米,而郊区下垫面混合层高度在11：00时混合层高度为200米,至15：00时发展到600m,这是由于城市的热能促使城市大气层结变得不稳定,热岛效应有利于产生热力对流并且再加上城市下垫面的粗糙度较大和参差不齐的建筑物对气流有机械扰动、触发湍流和抬升作用,使城市上空混合层上升发展速度较快,夏季城市在9：00时混合层高度为200米,17：00时随着地表逐渐升温不稳定层结逐渐向上发展逆温层完全消失,增长到1650m；郊区在9：00时混合层高度为100m,17：00时增长至1750m,其中11：00时—14：00时均比同一时次城市的边界层高度低200m左右,地表位温从在11：00时为296.8K,14：00时增长至304.6K,与城市相当。(5)冬季城市与郊区的湍流活动在14：00时均达到最大,这是由于此时地表温度较高热力作用随之较大,城市地表处湍流动能垂直发展到1100m,值达到0.59m2·s-2,郊区垂直发展到1100m,最大值为0.37m2·s-2；夏季城12：00时,城市的湍流动能发展到1100m,500m处最大值达0.76m2·s-2；郊区的湍流动能发展到最大,垂直发展到1100m,峰值为0.57m2·s-2。更多还原

【Abstract】 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.更多还原