塔克拉玛干沙漠腹地近地层湍流能谱特征分析

利用塔克拉玛干沙漠腹地近地层湍流观测资料,计算并分析了不同稳定层结条件的湍流速度谱、温度谱及局地各向同性特征。结果表明,湍流速度谱和温度谱在惯性副区均满足Kolmogorov的-2/3指数规律,且稳定条件的相关系数更高;速度谱满足湍流各向同性的低频限制理论。近中性条件的温度谱和弱不稳定条件的速度谱在高频段有尾部上翘现象;稳定情况下的v谱和近中性条件的u谱、T谱在低频处也有上翘现象。沙漠腹地水平湍流尺度范围介于森林和草地之间,不稳定层结比稳定层结的谱峰更偏向低频端,且峰值尺度更大。

Characteristics of Surface-Layer Turbulence Spectra over the Taklimakan Desert Hinterland

In different atmospheric stable stratification condition, the turbulence spectral characteristics were calculated and analyzed according to the data obtained at the height of 10 meters over the Taklimakan Desert hinterland. Results indicated that velocity and temperature spectra followed the -2/3 law in the higher frequency while the correlation were closer under the stable atmosphere condition than unstable. The velocity spectra fit lower frequency limit for isotropy. It was found that "v" spectra at the stable, "u" spectra and "T" spectra at near neutral were tail upwarping in low-frequency while velocity spectra at the weak unstable and "T" spectra at near neutral were the same phenomena in high-frequency. The values of horizontal peak wavelength in desert hinterland were between the value in forest and in grassland, the peak frequency values were lower under the unstable condition.