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Coupling processes of various timescales in the middle atmosphere
Kuchař, Aleš ; Pišoft, Petr (advisor) ; Koucká Knížová, Petra (referee) ; Thiéblemont, Rémi (referee)
The thesis deals with the manifestation of coupling processes of various timescales in the middle atmosphere. Longer and shorter timescales are represented here by the 11-year solar cycle (SC) and orographic gravity waves (oGWs) considered on the intraseasonal timescale of the north hemisphere winter, respectively. The first two chapters deal with the application of rigorous attribution the variability of temperature, ozone and circulation characteristics in the stratosphere and lower mesosphere with regard to the SC using multiple nonlinear techniques (support vector regression and neural networks) besides the multiple linear regression approach. The aliasing of the SC with volcanic eruptions or the El Niňo Southern Oscillation is qualitatively assessed and its impact on conclusions about the top-down coupling mechanisms discussed. The last chapter examines the role of parametrized oGWs in the lower stratosphere. The Himalayan hotspot reveals common features with sudden stratospheric warmings such as the residual circulation amplification leading to a warming and ozone enrichment in the polar latitudes of the lower stratosphere.
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Climate characteristics of higher atmospheric levels
Kuchař, Aleš ; Pišoft, Petr (advisor) ; Žák, Michal (referee)
This work investigates the climatic characteristics of the upper atmosphere. The characteristics that were analyzed include air temperature, speed and direction of the zonal wind, geopotential height and total column of ozone or its mixing ratio in the individual levels of pressure. Data from projects NCEP/NCAR and ERA-40 reanalysis were used for these purposes. The data are present in a graphic form, particularly in the average monthly maps during 1978−2007 for the first one and during 1978−2002 for the second one with azimuthal projection for each hemisphere for the levels of 300, 100, 10 and 30 hPa. The results obtained are described and interpreted by a research of available literature.
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Vertical variability of the 11 years solar cycle influence within the middle and higher atmosphere
Kuchař, Aleš ; Pišoft, Petr (advisor) ; Laštovička, Jan (referee)
This work investigates changes implied by variability of temperature, zonal wind and ozone mixing ratio during the eleven-year cycle in the stratosphere and lower mesosphere. The analysis is performed by using multiple linear regression of the MERRA reanalysis dataset for the period 1979-2012. Furthermore, we describe possibilities of available dataset, which can be also considered for the study of the upper atmosphere. Results of this study show a qualitative agreement with other related studies in the stratosphere, we find substantial differences especially in the ozone concentrations above the stratopause. It has been shown more intensive sudden stratospheric warming during solar maxima and the associated impact on the Brewer-Dobson circulation in all fields of meteorological variables.
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Coupling processes of various timescales in the middle atmosphere
Kuchař, Aleš ; Pišoft, Petr (advisor) ; Koucká Knížová, Petra (referee) ; Thiéblemont, Rémi (referee)
The thesis deals with the manifestation of coupling processes of various timescales in the middle atmosphere. Longer and shorter timescales are represented here by the 11-year solar cycle (SC) and orographic gravity waves (oGWs) considered on the intraseasonal timescale of the north hemisphere winter, respectively. The first two chapters deal with the application of rigorous attribution the variability of temperature, ozone and circulation characteristics in the stratosphere and lower mesosphere with regard to the SC using multiple nonlinear techniques (support vector regression and neural networks) besides the multiple linear regression approach. The aliasing of the SC with volcanic eruptions or the El Niňo Southern Oscillation is qualitatively assessed and its impact on conclusions about the top-down coupling mechanisms discussed. The last chapter examines the role of parametrized oGWs in the lower stratosphere. The Himalayan hotspot reveals common features with sudden stratospheric warmings such as the residual circulation amplification leading to a warming and ozone enrichment in the polar latitudes of the lower stratosphere.
|
|
|
Vertical variability of the 11 years solar cycle influence within the middle and higher atmosphere
Kuchař, Aleš ; Pišoft, Petr (advisor) ; Laštovička, Jan (referee)
This work investigates changes implied by variability of temperature, zonal wind and ozone mixing ratio during the eleven-year cycle in the stratosphere and lower mesosphere. The analysis is performed by using multiple linear regression of the MERRA reanalysis dataset for the period 1979-2012. Furthermore, we describe possibilities of available dataset, which can be also considered for the study of the upper atmosphere. Results of this study show a qualitative agreement with other related studies in the stratosphere, we find substantial differences especially in the ozone concentrations above the stratopause. It has been shown more intensive sudden stratospheric warming during solar maxima and the associated impact on the Brewer-Dobson circulation in all fields of meteorological variables.
|
|
|
Climate characteristics of higher atmospheric levels
Kuchař, Aleš ; Pišoft, Petr (advisor) ; Žák, Michal (referee)
This work investigates the climatic characteristics of the upper atmosphere. The characteristics that were analyzed include air temperature, speed and direction of the zonal wind, geopotential height and total column of ozone or its mixing ratio in the individual levels of pressure. Data from projects NCEP/NCAR and ERA-40 reanalysis were used for these purposes. The data are present in a graphic form, particularly in the average monthly maps during 1978−2007 for the first one and during 1978−2002 for the second one with azimuthal projection for each hemisphere for the levels of 300, 100, 10 and 30 hPa. The results obtained are described and interpreted by a research of available literature.
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