祁连山海北高寒湿地微气象日变化特征

Diurnal Changes of Micro-Climate in Haibei Alpine Wetland in the Qilian Mountains

利用2004年的观测资料分析了青海海北高寒湿地微气象要素的日变化特征,结果表明,辐射、热量平衡各分量日平均变化中,瞬时最高值出现在中午,最低在早晨。地面长波有效辐射日最高出现在中午,日最低出现在下午。地面反射率表现出早晚高白天低的"U"型分布状况,1月日最低达0.68,而7月日最低仅为0.12。动量通量、垂直风速、水平风速、摩擦速度等均在下午大,夜间到清晨小。垂直风速除10月全天为上升运动外,其他月份夜间还出现下沉运动,而且冬季明显。海北高寒湿地夏季热强明显,冷季热强减弱。因湿地长久积水,地温日变化平稳,40 cm地温<0℃的维持时间不到2个月,60 cm地温全年均>0℃,即季节冻结层浅薄。

Based on the measured data, diurnal changes of micro-meteorology in Haibei alpine wetland in 2004 were analyzed in this paper. The results were as follows： The maximum and minimum instantaneous values of diurnal averaged variations of radiation and the components of heat energy balance were observed at the noon and sunrise, respectively. The maximum and minimum values of the surface longwave effective radiation were observed at the noon and sunset in a day, respectively. The surface surface albedo showed the variations of the ＂U＂ type in a day, which was lower in daytime than in morning and evening. Its diurnal minimum values in January and July were 0.68 and 0.12, respectively. The other parameters of micro-meteorology, such as moment flux, vertical wind speed, horizontal wind speed, friction velocity, were hight in the afternoon and low from night to morning in a day. The vertical wind spe＇ed ascended in a whole-day in October, while descended in nighttime in other months, especially in winter. The Haibei alpine wetland had the strong heat source in summer, while became weak in the cold season. The soil temperatures of Haibei alpine wetland smoothly varied because its surface was covered by water for a long time. The period of soil temperature below 0℃ at the depths of 40 cm was less than two months, and that of 60 cm above 0℃ was all the year, which meant the seasonal frozen layer was thin.