内蒙古奈曼流动沙丘下垫面近地面能量收支研究

Energy budget in the surface layer over movable dune at Naiman in Inner Mongolia

利用2000年7月18日～8月12日在内蒙古奈曼流动沙丘下垫面取得的大气边界层观测资料,分析了地表能量收支各项的日变化、总体输送系数日变化及其与稳定度的关系;比较了涡旋相关法、波文比-能量平衡法所得到的感热通量.得到奈曼流动沙丘下垫面平均地面阻曳系数Cd为4.69×10^-3;感热通量总体输送系数Ch为2.25×10^-3.在近中性层结条件下,Cd和Ch分别为4.83×10^-3和1.34×10^-3.近地面层湍流方差在不稳定层结下均满足Monin-Obukhov相似理论.

The Naiman region （42°58＇N, 120°43＇E） is located in the southwest area of Zhelimu league, Inner Mongolia, China, which belongs to semiarid region. The annual precipitation is about 400 mm. On the basis of data observed over movable dune in Naiman from July 18 to August 12, 2000, diurnal variation of the surface energy budget and the bulk transfer coefficients, the relation between the bulk transfer coefficients and the stability, the relation between the non-dimensional turbulent variances and the stability, were analyzed. The sensible heat fluxes, which were calculated with the eddy correlation and Bowen ratio methods respectively, were compared. At most time, the sensible heat flux calculated with the eddy correlation was smaller than that with Bowen ratio method. Over movable dune, diurnal variation of the surface energy budget was obvious. At the daytime, most of the net radiation contributed to sensible heat flux and the soil heat flux, the ratio of the sensible heat flux to the net radiation was larger than that of the soil heat flux. The average bulk transfer coefficients of momentum and sensible heat were and respectively. The value of the bulk transfer coefficient of momentum was higher than that of the bulk transfer coefficient of sensible heat. Under the near neutral stratification, the average values of Cd and Ch were 4.83 × 10^ -3 and 1.34 × 10^ -3 respectively. The turbulent variances in the surface layer are satisfied the Monin-Obukhov similarity theory under the unstable stratification.