Dynamical and thermal effects of nonsteady nonlinear acoustic-gravity waves propagating from tropospheric sources to the upper atmosphere

• Published in: Advances in space research Vol. 56; no. 9; pp. 1833 - 1843
• Main Authors: Gavrilov, Nikolai M., Kshevetskii, Sergey P.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2015
• Subjects: Acoustic-gravity waves; Altitude; Atmosphere; Computer simulation; Heating; Horizontal; Nonlinear interactions; Nonlinearity; Numerical modeling; Surface waves; Upper atmosphere; Wave drag; Wave propagation; Numerical modeling; Nonlinear interactions; Wave drag; Atmosphere; Acoustic-gravity waves
• ISSN: 0273-1177; 1879-1948
• DOI: 10.1016/j.asr.2015.01.033

•Direct numerical simulation of atmospheric acoustic-gravity waves is made.•Dissipating initial wave pulse produces the mean heating and winds above 200km.•Later, waves may produce convective instability and jet streams at 100–120km. We performed numerical simulations of nonlinear AGW propagation to the middle and upper atmosphere from a plane wave forcing at the Earth’s surface with period τ=2×103s. After activating the surface wave forcing, initial pulse of acoustic and very long gravity modes in a few minutes can reach altitudes above 100km. Dissipation of this initial pulse produces substantial mean heating and wave-induced mean winds at altitudes above 200km. This may influence AGW propagation and produce enhanced vertical gradients of temperature, horizontal velocity and increased wave dissipation in the lower part of the wave-induced mean flows helping their downward expansions. Later, AGWs may produce layers of convective instability and peaks of the wave-induced jets at altitudes 100–120km. Shorter AGWs with smaller horizontal wave speeds produce smaller mean heating and wave-induced mean velocities in the upper atmosphere at fixed amplitudes and periods of the surface wave excitation. Numerical simulation of nonlinear AGW propagation helps better understanding the details of dynamical and thermal influence of waves coming from the troposphere on the mean temperature and wind in the middle and upper atmosphere.