绿洲荒漠过渡带夏季晴天地表辐射和能量平衡及小气候特征

利用张掖试验基地2006年6月24日至7月17日的加密观测资料,系统分析了夏季典型晴天张掖绿洲荒漠过渡带地表辐射收支和地表能量平衡特征及小气候特征。结果表明:夏季晴天绿洲荒漠过渡带总辐射值还是比较大的,并且净辐射值也很大，这说明绿洲荒漠过渡带地表具有比较充足的可利用热能，为加热大气和土壤提供了必要的热能条件。在地表能量分配中，晴天绿洲荒漠过渡区主要用于大气运动引起的感热交换，其次是土壤交换，用于水蒸发相变的能量相对较小。近地层空气温度和湿度的变化刚好相反。气温白天随高度的增加而递增，夜晚随高度的增加而递减。近地层大气温度变化要比地表温度缓慢。白天土壤辐射增温，越接近地表增温越快，夜间辐射冷却，地表温度下降最为明显。近地层水平风速在白天较大，夜间逐渐减小。在绿洲荒漠过渡带全天以上升气流为主，水平风速随高度增加明显递增。

Characteristics of Surface Radiation and Energy Balance as Well Microclimate within Oasis-Desert Ecotone of Zhangye on Typical Clear Days in Summer

Based on the data intensively observed on June 24 to July 26, 2006 in Zhangye Arid Meteorology and Ecological Environment Experimental Station, the surface radiation balance, energy balance and microclimate were analyzed systemically for the oasis-desert ecotone of Zhangye on these typical clear days in summer. It is showed that the solar radiation is high (can reach 1 000 W5m-2) and the surface net radiation is also high, which indicates that the a vailable heat energy is so ample that the necessary condition is provided for heating the atmosphere and soil. During the courses of surface energy distribution, the most of energy is used for sensible heat exchange caused by atmospheric flow, the following is soil exchange, but the energy used for water evaporation is relatively low. The diurnal variation of air temperature in surface layer is contrary to that of humidity in oasis-desert ecotone. At daytime, the air temperature is increasing gradually with the increase of the height, and at night, the air temperature is decreasing gradually with the increase of the height. The diurnal variation of surface layer air temperature is far slower than that of surface temperature. At daytime, solar radiation can increase soil temperature, and the lower the soil layers is, the faster the soil temperature increases. At night, the soil temperature drops, especially in the soil layers near to the land surface，the drop of soil temperature is obvious. The horizontal wind speed of surface layer air is relatively large at daytime, and gradually decreases at night. The air vertical movement is downward in a whole day. Horizontal wind speed increase obviously with increasing height.