作物叶面蒸腾与棵间蒸发分摊系数的计算方法

Calculation Method of the Ratio between Crop Leaf Transpiration and Soil Evaporation from Farmland

依据在冬小麦和玉米冠层表面及冠层内部下方土壤表面的净辐射观测资料,建立了一个能较准确地反映叶面蒸腾与棵间土壤蒸发分摊系数物理变化规律的较实用的计算模式,结果表明,分摊系数(a)随叶面积指数(LAI)增加而增加,且具有明显的日变化,a在中午最小、早、晚稍大,这种日变化受叶气孔调节的影响。

Based on the measured net radiation data above the canopy and on the soil surface under the crop canopy in winter wheat and summer corn field, a calculation model of the ratio between crop leaf transpiration and soil evaporation from farmland has been established in this paper. The model can express the physical varing laws of the ratio correctly and is practical and useful. The research result shows that the ratio between leaf transpiration and soil evaporation a is increased with the leaf area index increasing, has a daily change and is higher in mid-noon and lower in the early morning and near night. The daily change process is influenced by leaf stomata movement.