TIPEX高原东南部近地层湍流参数的分析

摘要

The characteristics of the turbulence spectrum, turbulence variance, and turbulence flux at Qamdo overthe Southeastern Tibetan Plateau measured during the TIPEX experiment from 18 May to 30 June 1998are analyzed by the eddy correlation method. During periods of intense convection, most of the spectraof the 3D winds, temperature, and humidity follow a power law with a slope of -2/3. The normalizedvariances of the 3D winds in relation to z/L satisfy the similarity law but the normalized variances oftemperature and humidity are related to z/L by a -1/3 power law only in unstable conditions. In near-neutral stratification, σu/u* and σy/u* at Qamdo and Gerze are nearly constant in rugged terrain andσw/u* at Qamdo and Gerze is similar to the value found in plains, which indicates that the, effects oflandform on vertical turbulence is not significant over the southeast and western Tibetan Plateau. Duringthe dry period, the sensible heat dominates, comprising 81% of the heat intensity, with the other 19%being latent heat; during the wet period on the other hand, the latent heat accounts for about 64% ofthe available energy and the sensible heat only around 36%. The maximum intensity of the heating of airoccurs in the middle of the Plateau during the summertime.%利用第二次青藏高原科学试验(TIPEX)涡旋相关法资料,计算和分析了高原东南部湍流谱、三维风速、温度和湿度归一化的方差和近地面湍流通量.结果表明,白天在不稳定层结条件下,大部分湍流谱基本能满足-2/3次方定律.三维风速、温度和湿度归一化的方差与稳定度的关系在不稳定条件下基本服从1/3次方定律,温度和湿度方差在稳定层结下与稳定度1/3次方定律的关系不显著.昌都和改则中性层结下的A、B值比平原地区大,与起伏地形的值接近,高原东南部和西部的C值没有显著差异,与在平原地区的差异不大,表明观测区的地形对垂直方向的湍流没有明显影响.昌都干期的热源强度以感热为主(81%),潜热约占19%,湿期的热源强度有所增大;潜热占64%,感热占36%.与高原其它站的观测结果相比表明,夏季最大加热强度出现在高原中部.