半干旱雨养农田典型晴天感热、潜热的阶段差异

Changes of Sensible and Latent Heat on a Typical Clear Day on Dry-farming Land in Semi-arid Region during Different Development Phases of Crop

利用野外试验观测资料,就西北地区东部半干旱雨养农田典型晴天感热、潜热在作物不同生长时段的变化特征进行初步的探讨。结果表明:在作物不同生长阶段,我国西北地区东部半干旱雨养农田典型晴天的感热、潜热日变化特点基本相似,均表现为单峰型变化特征。从春季到夏季,感热的阶段变化表现为增加的趋势,而潜热的阶段变化与晴天前期的降水变化基本一致,呈波动趋势。在农田的地气能量交换中,植被的影响为主导因素时,主要表现为潜热交换方式,太阳辐射的影响为主导因素时主要表现为感热交换方式。农田典型晴天波恩比的阶段变化与晴天前期降水量的阶段变化有较好的反对应关系。降水的季节变化基本决定了农田水分的季节变化。

Based on the field observation data, changes of sensible heat and latent heat on dry-farming land in semi-arid region during different development phases of crop on a typical clear day are presented in this paper. The results show that the daily variations of sensible heat and latent heat under typical clear day are similar in different growth period of crop and exhibit the single peak character. The sensible heat showed a tendency of increase from spring to summer, but the change of latent heat was similar to precipitation in different development phases of crop and showed a figure of a wave.When the influence of vegetation was a central factor, the latent heat is main way in land-atmosphere energy exchange. When the influence of solar radiation was the central factor, the sensible heat is the main way. The precipitation and HS/LE were going in opposition during different development phases of crop.The seasonal change of precipitation turned the seasonal change of water in dry-farming land.