黑河下游绿洲地表辐射平衡及小气候特征分析

Ground Energy Balance and Microclimate Characteristics in the Oasis of Lower Reaches of Heihe River

利用额济纳绿洲2004年5～10月微气象站观测资料，分析了该地区地表能量平衡及小气候特征．结果表明：在绿洲内太阳总辐射、光合有效辐射、净辐射有明显的季节变化及日变化，日峰值及月总量在7月份达到最高．地表能量平衡季节变化显著，5、8、9、10月份，地面能量交换基本以感热通量为主，Bowen比值在日间〉4；6、7月份，潜热蒸发是能量平衡的主要部分，Bowen比基本〈1．5～10月土壤热通量值始终较小，约占净辐射的15％～20％．绿洲内近地层风速基本在0～5m·s^-1之间，夜间风速变化很小，日间风速较大．随着土壤深度的增加，土壤温度变化趋势越来越缓慢，地表温度波动变化最大，而在40cm深处土壤温度日变化很小．

Using the meteorological data in Ejin Oasis from May to October 2005, the ground energy balance and microclimate characteristics have been analyzed. The results showed that global radiation, photosynthesis availability radiation （PAR） and net radiation had pronounced seasonal and daily variations in the oasis, and the maximum daily peak value and maximum month integral values appeared in July. The seasonal variation of the ground energy balance was obvious. In May, August, September and October, the sensible heat flux was the major portion in the ground energy exchange, and the Bowen Ratio was greater than 4 on day time; in June and July, the latent heat flux was the major portion in energy balance, and the Bowen Ratio was less than 1 on day time. Soil heat flux was always relatively small from May to October; about 15% to 20% of the net radiation. Wind velocity in the surface layer changed between 0 and 5 m · s^-1, and the variation of wind velocity was small in night and relatively large in daytime. The change of soil temperature decreased with soil depth increasing. Daily variation of soil temperature was large at the earth surface and slight at 40 cm depth.