Abstract
Using a set of near space high-resolution balloon data released in Hami, Xinjiang, we explored the spectral characteristics of temperature fluctuations and three-dimensional wind field fluctuations. As different from previous studies, which were based on radiosondes, we have increased the height range of spectral analysis to the stratosphere (38 km), which can explore the variation of spectral features with altitude, and can analyze higher wavenumber regions. The results show that horizontal wind field disturbances are isotropic, meridional and zonal winds have relatively consistent spectral structures, while vertical wind fluctuations have completely different spectral structures, which cannot be explained by the existing “universal spectrum” theory. The observed spectrum of horizontal wind field can be explained well by the “wind-shifting” theory. The ratio of spectral kinetic energy to potential energy is approximately constant only in the high wavenumber region but it varies at different height intervals. This study is a necessary extension of the observation for the characteristics of the vertical wavenumber spectrum in northwestern China, and it is also an experimental observation of spectral characteristics using radiosonde data at higher altitudes.
Highlights
A gravity wave is an important form of atmospheric motion
Previous studies have shown that the gravity waves in the middle and upper atmosphere are mainly generated in the troposphere and the lower stratosphere [1], which can cause significant temperature and wind field disturbances
In order to explain the variation of the amplitude and slope of the vertical wavenumber spectrum with height, we explore the effect of the background wind field on the wavenumber spectrum according to the “wind shifting” theory proposed by Echermann [12]
Summary
A gravity wave is an important form of atmospheric motion. It is a wave whose restoring force is gravity generated in the atmosphere with stable stratification. Gravity waves generated in the lower atmosphere increase in amplitude as the height increases, and when the amplitude reaches a certain level, they break up due to convective instability or dynamic instability, and are considered to have reached saturation. Space-based devices such as satellites cover a wide range, the resolution is too low to reflect small-scale disturbances At present it is mainly measured by mesosphere-stratosphere-troposphere (MST) radar and middle-upper atmosphere (MU) radar [9,10], rocket detection [11,12], lidar measurements, and balloon observations [13,14,15,16] to obtain mesoscale fluctuations in different regions. We analysis the vertical wavenumber spectrum characteristics of gravity waves in Hami, Xinjiang using near space high-resolution balloon data and extract the spectrum characteristics of gravity waves from temperature field and three-dimensional wind field. Our work is a necessary extension to obtain the characteristics of the gravitational wavenumber spectrum in northwest China by radiosonde data
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