| Autor: |
Koval, Andrey V., Didenko, Kseniia A., Ermakova, Tatiana S., Gavrilov, Nikolai M., Golovko, Anastasia G. |
| Zdroj: |
Climate Dynamics; Jan2025, Vol. 63 Issue 1, p1-14, 14p |
| Abstrakt: |
Using the mechanistic nonlinear Middle and Upper Atmosphere Model “MUAM”, the influence of solar activity (SA) on the dynamics of the mesosphere and lower thermosphere (MLT) area and thermosphere is considered from the point of view of the interaction of the mean atmospheric circulation with planetary waves (PWs) and tides. This interaction is analyzed within the Transformed Eulerian Mean approach and interpreted by calculating the Eliassen-Palm flux and the residual mean meridional circulation (RMC). Two ensembles of hydrodynamic fields for January, consisting of 16 model runs, corresponding to high and low SA, are considered. It is shown that with increasing solar influence at high SA, wave activity decreases in the layer between 100 and 170 km, while in higher layers an increase in wave activity occurs. This behavior may be explained by a number of factors contributing to the weakening PWs and increasing tides. Among them are an increase in temperature, viscosity and vertical temperature gradients at high SA. At the same time, the dominant role of tides in the change of wave activity in the thermosphere is detected, while the PW amplitudes and their EP fluxes have significantly smaller values. An analysis of the thermosphere dynamic regime at increasing SA shows that the strengthening of the RMC above 200 km is determined by changes in the mean Eulerian circulation. Modifications of the dynamic and temperature regime of the thermosphere caused by SA lead to changes in RMC in the MLT of up to 10%. The main role in these changes is played by increasing reflection of PWs above 100 km altitude due to increasing vertical temperature gradients at high SA. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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