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| Dynamical Tropopause Variability and Potential Vorticity Streamers in the Northern Hemisphere —— A Climatological Analysis | |
| 作者姓名： | Olivia MARTIUS Cornelia SCHWIERZ Michael SPRENGER |
| 作者单位： | Institute for Atmospheric and Climate Science ETH Zurich，8092 Zurich，Switzerland，Institute for Atmospheric Science，School of Earth and Environment，Leeds University，Leeds LS2 9JT，UK，Institute for Atmospheric and Climate Science，ETH Zurich，8092 Zurich，Switzerland |
| 摘 要： | This study presents a 44-year climatology of potential vorticity （PV） streamers in the Northern Hemisphere based upon analyses of the ERA-40 reanalysis data set. A comparison to an existing 15-year climatology yields very good agreement in the locations of PV streamer frequency maxima, but some differences are found in the amplitude of frequencies. The climatology is assessed with the focus on links between PV streamer frequencies and the synoptic- and planetary-scale variability of the dynamical tropopause. A comprehensive overview is provided on where （zonally） and when （seasonally） short-term variability throughout the extra-tropical and sub-tropical tropopause is enhanced or reduced. Several key processes that influence this variability are discussed. Baroclinic processes, for example, determine the variability in the storm-track areas in winter, whereas the Asian summer monsoon significantly influences the variability over Asia. The paper also describes links between the frequency of PV streamers in the extra-tropical and subtropical tropopause and three major northern hemisphere teleconnection patterns. The observed changes in the PV streamer frequencies are closely related to concomitant variations of PV and its gradient within the tropopause region. During opposite phases of the North Atlantic Oscillation the location of the streamer frequency maxima shifts significantly in the Atlantic and European region in both the extra-tropics and subtropics. The influence of ENSO on the streamer frequencies is most pronounced in the subtropical Pacific. |
| 关 键 词： | 罗斯比波 远距对比 北半球 电子流 |
| 收稿时间： | 18 February 2009 |
Dynamical tropopause variability and potential vorticity streamers in the Northern Hemisphere — A climatological analysis |
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| Olivia MARTIUS,Cornelia SCHWIERZ,Michael SPRENGER.Dynamical tropopause variability and potential vorticity streamers in the Northern Hemisphere — A climatological analysis[J].Advances in Atmospheric Sciences,2008,25(3):367-380. | |
| Authors: | Olivia Martius Cornelia Schwierz Michael Sprenger |
| Abstract: | This study presents a 44-year climatology of potential vorticity (PV) streamers in the Northern Hemi sphere based upon analyses of the ERA-40 reanalysis data set. A comparison to an existing 15-year clima tology yields very good agreement in the locations of PV streamer frequency maxima, but some differences are found in the amplitude of frequencies. The climatology is assessed with the focus on links between PV streamer frequencies and the synoptic- and planetary-scale variability of the dynamical tropopause. A comprehensive overview is provided on where (zonally) and when (seasonally) short-term variability throughout the extra-tropical and sub-tropical tropopause is enhanced or reduced. Several key processes that influence this variability are discussed. Baroclinic processes, for example, determine the variability in the storm-track areas in winter, whereas the Asian summer monsoon significantly influences the variability over Asia. The paper also describes links between the frequency of PV streamers in the extra-tropical and sub tropical tropopause and three major northern hemisphere teleconnection patterns. The observed changes in the PV streamer frequencies are closely related to concomitant variations of PV and its gradient within the tropopause region. During opposite phases of the North Atlantic Oscillation the location of the streamer frequency maxima shifts significantly in the Atlantic and European region in both the extra-tropics and subtropics. The influence of ENSO on the streamer frequencies is most pronounced in the subtropical Pacific. |
| Keywords: | Rossby wave breaking PV streamer Northern Hemisphere teleconnection indices dynamical tropopause |
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