陇中黄土高原植被覆盖和裸露下垫面地表通量和总体输送系数研究

A Study on Surface Flux and the Bulk Transfer Coefficients over Middle Gansu Region of Loess Plateau under the Wheat and Bare Fields

通过对陇中黄土高原地区地表观测资料的分析,研究了该地区地表能量收支各项的平均日变化、小麦不同生长阶段的热通量日变化、总体输送系数平均日变化及其与稳定度的关系。结果表明:该地区白天潜热通量在净辐射通量的分配中所占的份额最大,其次为感热通量,土壤热通量最小;随着小麦的生长,潜热通量在净辐射通量的分配中所占的份额增加,感热通量则呈下降趋势,波文比呈下降趋势;在10m高度处,在小麦地动量总体输送系数Cd的平均值为6.03×10-3,感热总体输送系数Ch的平均值为3.40×10-3;在裸地,动量总体输送系数Cd的平均值为5.18×10-3,感热总体输送系数Ch的平均值为4.08×10-3。在同一观测高度上,Cd小麦>Cd裸地,Ch小麦<Ch裸地。

Using the observed data in the middle Gansu region of Loess Plateau, the average diurnal variation of surface energy budget and the bulk transfer coefficients, the relation between the bulk transfer coefficients and the stability and the diurnal variation of the heat flux of the wheat filed during various growing stages are studied. The results show that： In the daytime, most of the net radiation is spent for the latent heat flux, the second is for the sensible heat flux and the soil heat flux is least. The net radiation spent for the latent heat flux increases with growth of the wheat and the net radiation spent for the sensible heat flux decreases at the same time. Bowen ratio decreases with growth of the wheat. At the heights of 10 m, in the wheat field, the average bulk momentum and the sensible heat transfer coefficients are respectively equal to 6.03×10^-3 and 3.40×10^-3, in the bare soil, they are 5.18 ×10^-3 and 4.08×10^-3. At the same observation height, Cd wheat field〉Cd bare soil, Ch wheat field〈Cd naked bare soil.