冬季中层顶区域重力波谱特性

使用DYANA试验期间19枚(Chaff火箭在81-105km高度范围测量的高分辨率水平速度数据,研究标量水平速度垂直波数谱在冬季的谱特性.分析结果显示冬季平均垂直波数谱有-3.02的谱斜率,这与各种饱和理论预测的-3谱斜率很一致,提供了饱和重力波谱在冬季的观测证据.与各种饱和理论比较表明,这个冬季谱的谱振幅与线性饱和理论预测的谱振幅完全一致,但是总是小于非线性饱和理论预期的、激光雷达测量的谱振幅.这个冬季谱与最近得到的夏季饱和重力波谱一道,共同表明我们的观测结果支持了线性饱和理论,而不管季节,地理位置和高度范围的不同.由这个冬季谱估计的盛行垂直波长为15km,它比夏季的12.8km盛行垂直波长稍大.

CHARACTERISTICS OF GRAVITY WAVE SPECTRUM IN THE WINTER MESOPAUSE REGION

This paper utilizes horizontal velocity data with high resolution measured by 19 chaff rockets in the 80-105 km region during the DYANA campaign to study char-acteristics of vertical wavenumber spectrum of scalar horizontal velocity in winter. Results show that the mean vertical wavenumber spectrum in winter has a spec-tral slope of -3.02, which is quite consistent with the -3 spectral slope predicted by various saturation theories, therefore, this provides an observational evidence of a saturated gravity wave spectrum in winter. Comparison with various saturation theories shows that spectral amplitude of the winter spectrum is perfectly consistent with that spectral amplitude predicted by the linear saturation theory, but it is always lower than those spectral amplitudes predicated by the nonlinear saturation theories and measured by lidars. The winter spectrum, together with a saturated gravity wave spectrum in the polar summer obtained recently, shows collectively that our observational results support the linear saturation theory re-gardless of different seasons, different geographical locations, and different height regions. Dominant vertical wavelength of the winter spectrum is estimated to be 15km, which is slightly larger than the dominant vertical wavelength of 12.8km measured in summer.