Subjects: Geosciences >> Space Physics submitted time 2016-05-13
Abstract： The nightly and seasonal variability of gravity wave activity and spectra in the mesopause over Beijing are studied with 3 years of sodium lidar observations. From the linear layer density response to gravity wave forcing, the lidar data were analyzed to get the atmospheric density perturbations and their spectra. The atmospheric density perturbation, density variance for fluctuations with vertical scales between 2 and 10 km, and amplitudes of density perturbation spectra at m = 2pi/8, 2pi/4, m = 2pi/1.5, m = 2pi/1,and omega = 2pi/60,omega = 2pi/40,2pi/25 all exhibit large nightly variability as well as large seasonal variations, with the semiannual maxima occurring near the solstice. The mean RMS atmospheric density perturbation over Beijing are 5.8%, which are obviously larger in summer than that in winter and the maxima occur near the solstice. The m spectra show power law shapes, and their range of variation is between -1.97 and -3.67 with an annual mean value of -3.02, and omega spectra is between -1.06 and -2.08 with an annual mean value of -1.92, respectively. It is concluded that the reaction of the Qinghai-Tibet Plateau and the background wind may be the main reason of the gravity wave behaviors at Beijing.
Peer Review Status:
Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-04
Abstract： Based on the long-term observations from Beijing sodium lidar of Chinese Meridian Project, 162 monochromatic gravity waves was distinguished in the sodium layer during the 2208 hours' observation in 253 nights (from 2010 April to 2011 September). The vertical wavelength, wave period, wave amplitude and its growth factor of every monochromatic gravity wave were precisely extracted with the method derived by Yang et al. (2008). Statistical results reveal that there are systematic relationships between those wave parameters, and they respectively are λz=0.226Tob0.530, KE=6.66×10-10 kZ-3.091 and KE=8.97×10-6 fob-1.696 Those results partially agree well with the results predicted by Gardner's (1994) diffusive filtering theory. However, it is found incorrect to regard the wave-induced eddy diffusivity as the only main damping processes of gravity waves. It is suggested that the damping processes caused by other possible factors also play important roles in the saturation and dissipation mechanisms of gravity waves. ©, 2015, Chinese Society of Astronautics. All right reserved.
Peer Review Status:Awaiting Review
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