Numerical and the MU radar estimations of gravity wave enhancement and turbulent ozone fluxes near the tropopause

Abstract

Abstract.It is shown with a numerical simulation that a sharp increase in the vertical temperature gradient and BruntVäisälä frequency near the tropopause may produce an increase in the amplitudes of internal gravity waves (IGWs) propagating upward from the troposphere, wave breaking and generation of stronger turbulence. This may enhance the transport of admixtures between the troposphere and stratosphere in the middle latitudes. Turbulent diffusion coefficient calculated numerically and measured with the MU radar are of 1-10 m 2 /s in different seasons in Shigaraki, Japan (35 • N, 136 • E). These values lead to the estimation of vertical ozone flux from the stratosphere to the troposphere of (1-10)×10 14 , which may substantially add to the usually supposed ozone downward transport with the general atmospheric circulation. Therefore, local enhancements of IGW intensity and turbulence at tropospheric altitudes over mountains due to their orographic excitation and due to other wave sources may lead to the changes in tropospheric and total ozone over different regions.

Generation of mountain wave‐induced mean flows and turbulence near the tropopause

“…He found higher levels of turbulence in the tropopause region and showed that breaking mountain waves were likely responsible. This is consistent with the MU (Middle and Upper atmosphere) radar observations over Japan by Gavrilov and Fukao (2004). Pavelin et al (2001) made similar measurements using both ground-based radar and radiosondes.…”

On the Wind and Turbulence in the Lower Atmosphere above Complex Terrain

“…Thus impenetrable for air tropopause has almost the same influence on the horizontal turbulence as the Earth's surface. It should be noted that the calculated vertical turbulence coefficients are in agreement with the measurements data [9]. (Figure 8).…”

“…The multifractal analyses revealed further scale breaks between gravity waves and turbulence. In [9] it is shown with a numerical simulation that a sharp increase in the vertical temperature gradient and Brunt-Väisälä frequency near the tropopause may produce an increase in the amplitudes of internal gravity waves propagating upward from the troposphere, wave breaking and generation of stronger turbulence. Turbulent diffusion coefficient calculated nu-  which may substantially add to the usually supposed ozone downward transport with the general atmospheric circulation.…”

Morphology of atmospheric refraction index variations at different altitudes from GPS/MET satellite observations

“…In addition, a sharp increase in vertical gradients of the background temperature at tropopause may change conditions of wave propagation, which leads to a corresponding increase in the amplitudes of gravity waves propagating from below. This was shown using numerical simulation by Gavrilov and Fukao (2004). Therefore, the problem of formation and in uence of sharp temperature gradients near the tropopause requires further studies.…”