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Variability of the Brewer-Dobson Circulation
Kupčihová, Zuzana ; Pišoft, Petr (advisor) ; Kozubek, Michal (referee)
The middle atmosphere transport is mostly controlled by a large-scale meridional circulation, namely the Brewer-Dobson circulation. In this thesis, climatology and variability of the Brewer-Dobson circulation and the middle atmosphere has been analysed using the Canadian Middle Atmosphere Model (CMAM30-Ext). A number of key variables are used including the age of air, residual velocities, residual stream function, temperature and zonal wind. The analysis of the climatology of the age of air shows, in particular, that young air gets generated near the tropical tropopause, which then travels poleward. The residual stream function shows that the Brewer-Dobson circulation dominates the winter hemispheres around the solstices and becomes nearly symmetrical, with respect to the equator, around the equinoxes. The empirical orthogonal function analysis is applied to explore the modes of variability in the middle atmosphere. The analysis identifies, in particular, the semi-annual oscillation, the quasi-biennial oscillation with moderate explained variance compared to the variance explained by the annual cycle. In addition, the analysis also reveals the emergence of the solar cycle. Powered by TCPDF (www.tcpdf.org)
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Variability of the Brewer-Dobson Circulation
Kupčihová, Zuzana ; Pišoft, Petr (advisor) ; Kozubek, Michal (referee)
The middle atmosphere transport is mostly controlled by a large-scale meridional circulation, namely the Brewer-Dobson circulation. In this thesis, climatology and variability of the Brewer-Dobson circulation and the middle atmosphere has been analysed using the Canadian Middle Atmosphere Model (CMAM30-Ext). A number of key variables are used including the age of air, residual velocities, residual stream function, temperature and zonal wind. The analysis of the climatology of the age of air shows, in particular, that young air gets generated near the tropical tropopause, which then travels poleward. The residual stream function shows that the Brewer-Dobson circulation dominates the winter hemispheres around the solstices and becomes nearly symmetrical, with respect to the equator, around the equinoxes. The empirical orthogonal function analysis is applied to explore the modes of variability in the middle atmosphere. The analysis identifies, in particular, the semi-annual oscillation, the quasi-biennial oscillation with moderate explained variance compared to the variance explained by the annual cycle. In addition, the analysis also reveals the emergence of the solar cycle. Powered by TCPDF (www.tcpdf.org)
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