黄河流域旱涝年地面热量收支变化特征

CHARACTERISTICS OF HEAT BALANCE AT THE GROUND SURFACE DURING SUMMER DROUGHT/FLOOD PERION IN YELLOW RIVER VALLEY

根据北京、郑州３年热量平衡观测资料，建立波文（Ｂｏｗｅｎ）比计算模式。并用此模式及辐射计算式等估计黄河流域８年５－８月地面月辐射收支、蒸发耗热、湍流热交换量和土壤热交换量，并比较分析旱涝年它们的差异以及随旱涝（用降水距平表示）的变化。

An empirical rnodel, for estimating Bowen ratio through the agency monthly meanair temperature, vapour pressure and ground surface temperature,is proposed on thebasis of the heat balance data measured at Beijing and Zhengzhou in period of 1958-1960. The monthly sums of latent and sensible heat are estimated using the energybalance with Bowen ratio method for the months from May to August of eight years inYellow River valley. The relationships between each component of energy balance anddrought/flood are analysed. The main resuIts are as follows:(1) The monthly amounts of net radiation averaged during the May-August periodand monthly mean sensible heat for the same period, which of drought year areobviously greater than flood year. The departures decrease with increasing precipitationamounts,but the sensible heat is more sensitive to the precipitation departure than netradiation。(2) The averaged monthly totals of latent heat decrease from east to west in YellowRiver valley.(3)The monthly sums of soil heat exchange in summer in the drought years aremostly greater than that of flood years , but are only 4%-6%net radiation.