Radiosonde Observations of Vertical Wavenumber Spectra
for Gravity Waves in the Lower Atmosphere Over Central
China
Shao Dong Zhang(张绍东)1,2, Chunming Huang(黄春明)1,2, and Fan Yi1,2
1
School of Electronic Information, Wuhan University, Wuhan, People’s Republic of
China
2
Key Laboratory of Geospace Environment and Geodesy, Ministry of Education,
Wuhan, People’s Republic of China
Vertical wavenumber spectra of inertial gravity waves in the troposphere and
lower stratosphere over six stations at latitudes from 10oN to 40oN were statistically
studied by using the data from Radiosonde observation on a twice daily basis at 0800
and 2000 LT. Statistically, the observations show considerable conformity between the
spectral characters of zonal and meridional wind disturbances: spectral slopes at the
spectral tails exhibit a consistent value of about -3, moreover, these slopes and
spectral intensities are roughly independent on location, which coincides well with
decades of previous observations. As to the spectral structures for the temperature
disturbances, although their slopes are geographically independent as well as those of
the horizontal wind disturbances, their values are statistically larger than -3. And, the
maximum spectral intensity of the temperature disturbance decreases poleward, which
may be due to the intensive convection in the lower latitudinal region. Except the
universalities, the spectral structures also exhibits departures and variations: smaller
height coverage tends to yield a shallower vertical wavenumber spectrum; more
important is that in the case of strong shear due to the tropospheric jet, there usually
occurs smaller and larger spectral slopes for the horizontal wind and temperature
disturbances, respectively. And this departure seems to be persistent and
climatological rather than transitory, indicating the significant impacts of the sheared
background winds on the spectral structures of gravity waves.
1