黄土高原陆-气相互作用预试验及其晴天地表能量特征分析

详细介绍了在2004年8月24日～9月11日在甘肃平凉进行的陆-气相互作用野外预试验，对观测仪器进行了对比和标定，并利用观测资料，初步分析了黄土高原塬上裸地、塬上和塬下玉米地的地表净辐射各分量、感热、潜热和地热流的特征。由于作物（玉米）的存在，降低了地表反射率，使白天地面向上短波减少，同时向上长波也减少，增大了地表净辐射，地表潜热明显增大，玉米地白天向下的地热流和夜晚向上的地热流都比裸地小。与塬上相比，塬下玉米地的向下短波略小，向上短波明显偏小，向上长波基本一致；净辐射只在中午附近略小，地热流上午偏小，下午偏大，夜晚基本一致；感热和潜热在白天基本一致；塬下玉米地在凌晨明显存在负感热通量。

A Primary Field Experiment of Land-Atmosphere Interaction over the Loess Plateau and Its Ground Surface Energy in Clear Day

We introduce a primary field experiment of land-atmosphere interaction over the Loess Plateau in Pingliang, Gansu from 26 August to 11 September 2004. The data from different instruments are compared and calibrated. Using the data of this experiment, the characteristicsof four components of net radiation, sensible heat, latent heat and soil heat flux on ground surface are analyzed. Comparing with the bare soil surface, the vegetation (corn) reduces the surface albedo and the upward short-wave radiation from ground surface; it also reduces the upward long-wave radiation from ground surface. As a result, the net radiation from the vegetation is higher than that from the bare soil surface. The latent heat flux from the vegetation is obvious larger than that from the bare soil surface. The downward soil heat at day and the upward soil heat at night from surface soil under the corn are smaller than the ones under the bare ground. Comparing with the one from the corn field over mesa, the downward short-wave radiation is little smaller and the upward short-wave radiation is obvious smaller from the flat ground cornfield. The upward long-wave radiation from the corn field over mesais almost sameasthe one from the flat ground corn field beneath mesa. The net radiationis a little smallerat noon from the bottom flat ground corn field beneath mesathan the corn field over mesa. The soil heat flux is smaller in the morning and larger in the afternoon and same at night from the flat ground corn field beneath itthan the corn field over mesa. There are not obvious differences of the sensible and latent heat fluxes between the flat ground beneath mesa and the corn field over mesa in daytime. There are obvious negative sensible heat fluxes in very early morning from the flat ground corn field beneath mesa.