北京上空高分辨率气球探空观测的温度垂直波数谱

Vertical Wavenumber Spectra of Temperature From High-Resolution Balloon Soundings Over Beijing

使用分辨率为10 m的温度剖面检查2．90～8．01 km和14．65～19．76 km高度范围内归一化温度扰动谱的谱特性,并且将它们与模式谱比较．结果表明,在波数9．8×10^(-4)～2．5×10^(-2)-m^(-1)范围内,对流层的垂直波-数谱有约1．9的平均谱斜率；低平流层的垂直波数谱有约-2．2的平均谱斜率．这两个平均谱斜率大大偏离了目前饱和谱模式和普适大气谱模式表示的-3．0和-2．4谱斜率,并且认为是目前气球测量中曾经观测到的最平谱斜率．在波数9．8×10^(-4)～2．5×10^(-2)m^(-1)范围内,对流层和低平流层的平均谱振幅比饱和谱模式的谱振幅分别大24倍和5倍,这也与饱和谱模式以及目前文献中的观测结果有很大不同．这些较大平均谱振幅与最平的平均谱斜率一道共同表明,观测的温度谱并不遵循目前的饱和谱模式和普适大气谱模式．

This study utilizes the vertical profiles of temperature with a high resolution of 10 m to examine spectral character of normalized temperature fluctuations in the 2.90～8.01 km and 14.65～19.76 km altitude ranges and to compare them with model spectra. Six vertical wavenumber spectra of normalized temperature fluctuations in the troposphere and six vertical wavenumber spectra of normalized temperature fluctuations in the lower stratosphere are presented. Results indicate that mean spectral slopes in the wavenumber range of 9.8 × 10^-4 ～ 2.5 × 10^-2m^-1 are about -1.9 in the troposphere and about -2.2 in the lower stratosphere. The two mean spectral slopes are diverge significantly from the value of -3.0 predicted by current saturation models and from the value of -2.4 predicted by a ＂universal＂ atmospheric spectrum model as well as are believed to be the shallowest slopes ever measured by balloon-borne radiosonde soundings. Mean spectral amplitudes in the wavenumber range of 9.8 × 10^-4 ～ 2.5 × 10^-2m^-1 are about 24 times in the troposphere and 5 times in the lower stratosphere larger than the predicted saturated spectral amplitudes. The two mean spectral amplitudes are also significantly different from the saturation models and those measurements in current literature. The larger spectral amplitudes, together with the shallowest slopes, show collectively that the observed temperature spectra do not obey current gravity wave saturation models and ＂universal＂ atmospheric spectrum model.