NSSC OpenIR  > 空间科学部
Comparison of horizontal velocity spectra derived from chaff rockets with saturation models
Wu, Y. F.; Xu, J. Y.; 北京8701信箱
Department空间天气学国家重点实验室
Source PublicationJournal of Geophysical Research-Atmospheres
2006
Volume111Issue:D13Pages:D13109
ISSN0148-0227
Language英语
KeywordGravity-wave Spectrum Starfire Optical-range Lower Thermosphere Middle Atmosphere Mesopause Region Testing Theories Number Spectra Lower Stratosphere Mac Epsilon Foil Chaff
AbstractWe present vertical wave number spectra of wind fluctuations using data with a height resolution of 25 m observed near the mesopause by 64 chaff rockets. Direct measurement of Brunt-Vaisala frequency allows accurate calculations of spectral amplitude and local Richardson number. Individual vertical wave number spectra reveal considerable variability in both slope and amplitude, which is not consistent with the predictions of various saturation models. Mean vertical wave number spectra observed at different locations and seasons show great similarities. While the spectral amplitude predicted by the linear saturation model or saturated-cascade model is comparable to the spectral amplitude of the observed mean spectrum, those spectral amplitudes predicted by other saturation models are larger than the observed mean amplitude within a factor of 3. However, mean vertical wave number spectra observed at 69 degrees N exhibit significant seasonal variation with a shallower slope of - 2.40 and a larger spectral amplitude of 2.6 x 10(5) (m(2)/s(2))/(cyc/m) at m = 1/(4 km) in winter compared to that spectrum observed in summer. Very large mean wind shears, as high as 42 - 77 m/s/km, are observed to be present at several heights near the mesopause. Such strong mean shear profiles, together with the Brunt-Vaisala frequency squared N-2 profiles, act collectively to produce dynamical instability regions of local Richardson number Ri smaller than 0.25. These regions are found to correlate well with the saturated gravity wave spectra. In contrast, the stable region of local Richardson number Ri larger than 0.4 observed at high latitude in winter is found to associate with an unsaturated gravity wave spectrum.
Indexed BySCI
Funding Project中国科学院空间科学与应用研究中心
Document Type期刊论文
Identifierhttp://ir.nssc.ac.cn/handle/122/1056
Collection空间科学部
Corresponding Author北京8701信箱
Recommended Citation
GB/T 7714
Wu, Y. F.,Xu, J. Y.,北京8701信箱. Comparison of horizontal velocity spectra derived from chaff rockets with saturation models[J]. Journal of Geophysical Research-Atmospheres,2006,111(D13):D13109.
APA Wu, Y. F.,Xu, J. Y.,&北京8701信箱.(2006).Comparison of horizontal velocity spectra derived from chaff rockets with saturation models.Journal of Geophysical Research-Atmospheres,111(D13),D13109.
MLA Wu, Y. F.,et al."Comparison of horizontal velocity spectra derived from chaff rockets with saturation models".Journal of Geophysical Research-Atmospheres 111.D13(2006):D13109.
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