巴丹吉林沙漠典型湖泊湖气界面水一热交换特征

利用2012年8月-2013年7月在巴丹吉林沙漠腹地典型湖泊上用涡动相关系统观测的湍流资料,分析了湍流方差统计特征、微气象特征,计算了湍流热通量和湖泊蒸发量,初步结论为：①湖面上局地环流复杂,湍流三维风速的标准差与稳定度(Z/L)之间满足1/3次律。②湖面辐射分量具有明显季节变化和日变化特征,结冰期和非结冰期能量分配不同,冬季湖泊将储存的能量向大气传递;潜热通量和感热通量季节变化存在差异,但均有明显的昼夜变化特征。③湖气界面的感热通量在不同的月份也存在差异,感热以湖泊向大气传递为主;潜热通量夏半年远大于冬半年,在一天中6:00-8:00时处于最低值,15:00-16:00时达到峰值,在冬季会出现潜热向下输送现象。感热通量和潜热通量日变化呈负相关,湖面有效能量主要分配给潜热,湖泊同周围环境以水汽交换为主。④湖面平均蒸发速率为3.97 mm/d,累计蒸发量为1450±10 mm/a,同期的蒸发量是降水量的20多倍,湖泊主要靠地下水补给。这些结论可为进一步研究巴丹吉林沙漠腹地湖泊群的水循环及补给来源提供参考。

Water-heat exchange over a typical lake in Badain Jaran Desert,China

Using turbulence data from August 2012 to July 2013 collected through the eddy covariance system over a closed lake in the Badain Jaran Desert, this study analyzed the characteristics of the turbulence variance, meteorological elements, and turbulent heat fluxes, and calculated the evaporation of the lake. The results show that: local circulation on the lake showed a diurnal variation; standard deviation of the three-dimensional wind speed versus stability(Z/L) was in agreement with the "1/3" law, and support the Monin-Obukov similarity theory. Each component of the radiation fluxes has clearseasonal and diurnal variations. Energy distribution differed during ice period and non-ice period. The lake transfers the stored energy to the atmosphere in the winter. Latent heat flux has clearseasonal variation and sensible heat flux did not change significantly, but both showed significant diurnal variations. Sensible heat flux has periodic positive and negative diurnal variation from March to August. It was mainly delivered from the lake to the atmosphere from September to January, and had no significant diurnal variation from December to February. Latent heat flux in the summer was much larger than in the winter. It was lowest in a day at 6:00-8:00 and reached the peak at 15:00-16:00. Sensible and latent heat flux diurnal variationsshow anegative correlation. Effective energy of the lake was mainly allocated for latent heat flux. The average evaporation was 3.97 mm/d and the cumulative evaporation was 1450±10 mm a year. The total evaporation exceeded the cumulative precipitation 20-folds during the same period. The existence of the lake not only relies on rainfall and runoff from the local area, but also groundwater replenishment. The results of this study may provide some references for the lake water circulation and sources in the BadainJaran Desert.