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那曲高寒草地总体输送系数及地面热源特征
The Bulk Transfer Coefficient and Characteristics of Surface Heat Source on Alpine Grassland at Naqu
【摘要】 利用中国科学院那曲高寒气候环境观测研究站那曲/BJ观测点的野外观测数据,估算了青藏高原那曲地区典型高寒草地下垫面的热量和水汽总体输送系数以及地表大气相对湿度因子,在此基础上利用中国气象局那曲气象站1980—2016年的常规业务观测数据,采用总体输送法计算并分析了那曲高寒草地地表通量特征。研究结果表明:(1)那曲/BJ观测点地表大气相对湿度因子γ的数值在33%~62%,9月最大,2月最小,热量和水汽输送系数CH和Cλ的季节变化范围分别在1.6×10-3~2.7×10-3和1.0×10-3~2.0×10-3,两者存在较大的差异。(2) 1980—2016年那曲高寒草地感热通量总体呈现减弱趋势,而潜热通量呈现增强趋势,导致地面热源变化趋势不明显;分阶段来看,感热通量的变化在2004年前后发生转折,转折点前后的趋势为先减弱后增加,潜热通量在1994—2005年下降趋势明显,这也导致地面热源在1995—2005年有一个明显的减少。(3)年内季节变化上潜热通量相较于感热通量更明显,地面热源的季节变化更依赖于潜热通量的季节变化。
【Abstract】 Based on the data from the Naqu Station of Plateau Climate and Environment in the Northern QinghaiTibetan Plateau,this paper investigates the relative humidity close to the underlying surface and the bulk transfer coefficient over the underlying surface of typical alpine grassland in the Naqu area of the Qinghai-Tibetan Plateau.On this basis,using the conventional observation data from the Naqu Weather Station of the China Meteorological Administration from 1980 to 2016 to calculate and analyze the characteristics of surface fluxes over alpine grassland in Qinghai-Tibetan Plateau.The results suggest that:(1) The monthly average of the relative humidity close to the underlying surface at Naqu Station is between 33% and 62%,the highest is in September,and the lowest is in February,the monthly mean bulk transfer coefficient for heat CH at Naqu Station vary from 1.6×10-3 to 2.7×10-3,and the monthly mean bulk transfer coefficient for vapor Cλ at Naqu Station vary from 1.0×10-3 to2.0×10-3.(2) The surface fluxes at Naqu area from 1980 to 2016 are calculated,the annually averaged sensible heat fluxes H showed a weakening trend,while the latent heat fluxes showed an increasing trend,which led to the inconspicuous trend of surface heat source.In stages,the mutation of sensible heat fluxes occurred in 2004,the trend before and after the turning point was firstly weakened and then increased,the latent heat fluxes decreased significantly from 1994 to 2005,which led to a significant reduction in surface heat source from 1995 to 2005.(3) The seasonal variation of latent heat fluxes at Naqu Station is more obvious than the change in sensible heat fluxes,the seasonal variation of the surface heat source is more dependent on the seasonal variation of latent heat fluxes.
【Key words】 Qinghai-Tibetan Plateau; surface heating; relative humidity close to the underlying surface; bulk transfer coefficient;
- 【文献出处】 高原气象 ,Plateau Meteorology , 编辑部邮箱 ,2019年03期
- 【分类号】P433
- 【被引频次】5
- 【下载频次】144