塔克拉玛干沙漠南缘近地层风温湿廓线与能量交换特征

Characteristics of wind, temperature, humidity profiles and energy exchange in the surface layer in the southern edge of Taklimakan Desert

塔克拉玛干沙漠南缘属于荒漠-绿洲生态过渡区,地表性质时空变化较大,下垫面性质和水热特征均较特别,所以开展该地区微气象要素特征研究对区域未来气候变化的认知具有重要意义。利用青藏高原北侧陆-气相互作用观测站2022年实测气象要素数据,分析了塔克拉玛干沙漠南缘生态过渡区风、温、湿廓线结构、辐射通量及能量交换特征。结果表明:(1)塔克拉玛干沙漠南缘各季节风速、温度、比湿均随高度上升发生明显变化,其中在温度和比湿廓线中出现了逆温和逆湿现象,逆温层和逆湿层高度均达到了30 m,最大平均风速发生在春季,为6.23 m·s^(-1),最大平均温度和比湿均在夏季,分别为28.93℃与6.36 g·kg^(-1)。(2)四季地表辐射平衡以正值为主,各辐射分量峰值大小及出现时间存在差异,其中向下短波辐射受到沙尘天气影响,表现为春季>秋季>夏季>冬季;地表反照率与太阳高度角和土壤湿度呈负相关,其年均值为0.326,12月最大,8月最小,分别为0.366与0.297。(3)感热、土壤热通量及净辐射四季变化明显,潜热变化平稳,以0 W·m^(-2)为中心上下波动,能量消耗以感热为主;四季能量闭合率分别为76%、82%、53%与48%,表现为夏季>春季>秋季>冬季。(4)有效能量四季变化明显,白天为正值,地面为热源,表明地面向大气输送热量,夜间则相反,表现为春季>夏季>秋季>冬季。研究结果可为未来塔克拉玛干沙漠南缘陆面过程参数化提供科学依据,进而提升对该地区陆面过程的认识。

The southern edge of the Taklimakan Desert of China belongs to the desert-oasis ecological transition zone,and the temporal and spatial changes in land surface properties are significant.The underlying surface properties and hydrothermal characteristics are unique.Therefore,it is of great significance to investigate the characteristics of micrometeorological elements in this region for future climate change.Based on meteorological element data measured through the land-atmosphere interaction observatory on the northern side of the Tibetan Plateau in 2022,the wind,temperature,and humidity profile structure,radiation flux,and energy exchange characteristics of the ecological transition zone on the southern edge of the Taklimakan Desert were analyzed.The results show the following:(1)The wind speed,temperature,and specific humidity of the southern margin of the Taklimakan Desert change significantly with increasing altitude,and the temperature and specific humidity profiles of the inversion and humidity inversions occur in the temperature and specific humidity profiles,the heights of the inversion layer and the inversion humidity layer reach 30 m,the maximum average wind speed occurs in spring at 6.23 m·s^(−1),and the maximum average temperature and specific humidity are 28.93℃and 6.36 g·kg^(−1) in summer,respectively.(2)The surface radiation balance of the four seasons is mainly positive,and there are differences in the peak size and occurrence time of each radiation component,among which downward shortwave radiation is affected by sand and dust weather,which is manifested in spring>autumn>summer>winter.The surface albedo was negatively correlated with the solar altitude angle and soil moisture,with an annual average of 0.326,with the highest in December(0.366)and the lowest in August(0.297).(3)Sensible heat,soil heat flux,and net radiation changed significantly in the four seasons;the latent heat changed steadily,fluctuating up and down with 0 W·m^(−2) as the center,and the energy consumption was dominated by sensible heat.The energy closure rates of the four seasons were 76%,82%,53%,and 48%,respectively,which were manifested in summer>spring>autumn>winter.(4)The effective energy varies significantly in the four seasons,with positive values during the day and heat sources on the ground,indicating that the ground transports heat to the atmosphere,whereas,at night,it is the opposite,exhibiting spring>summer>autumn>winter.These findings can provide a scientific basis for the parameterization of land surface processes in the southern edge of the Taklimakan Desert in the future and improve the understanding of land surface processes in this area.