Variability and trends in the potential vorticity (PV)-gradient dynamical tropopause
<p>The dynamical tropopause acts as a transport barrier between the tropical upper troposphere and extratropical lowermost stratosphere and is characterized by steep gradients in potential vorticity (PV) along an isentropic surface. Hence, the latitudinal separation between the dynamical tropo...
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Copernicus Publications
2024-12-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/24/13653/2024/acp-24-13653-2024.pdf |
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| author | K. Turhal K. Turhal F. Plöger F. Plöger J. Clemens J. Clemens T. Birner T. Birner F. Weyland P. Konopka P. Hoor |
| author_facet | K. Turhal K. Turhal F. Plöger F. Plöger J. Clemens J. Clemens T. Birner T. Birner F. Weyland P. Konopka P. Hoor |
| author_sort | K. Turhal |
| collection | DOAJ |
| description | <p>The dynamical tropopause acts as a transport barrier between the tropical upper troposphere and extratropical lowermost stratosphere and is characterized by steep gradients in potential vorticity (PV) along an isentropic surface. Hence, the latitudinal separation between the dynamical tropopause in the Northern Hemisphere and Southern Hemisphere can be used as a metric of upper-tropospheric width for assessing climate change impacts. Here, we obtain the PV-gradient-based dynamical tropopause (PVG tropopause) from four meteorological satellite-era reanalyses (ERA5, ERA-Interim, JRA-55, MERRA-2) and investigate its climatology, variability and long-term trends from 1980 to 2017. Our results show a distinct seasonal cycle with larger PV values and a poleward movement of the PVG tropopause in summer. The climatological tropopause PV values are substantially different between different reanalyses, but the tropopause latitude is similar. Significant interannual variability in the PVG tropopause latitude is related to the El Niño–Southern Oscillation (ENSO) and weaker variability also to the quasi-biennial oscillation (QBO) and is consistently represented in reanalyses. In particular, El Niño correlates with equatorward shifts in the PVG tropopause and hence a decrease in upper-tropospheric width. Long-term trends in the PVG tropopause over the period 1980–2017 exhibit a distinct vertical structure with poleward shifts below 340 <span class="inline-formula">K</span> potential temperature, equatorward shifts between 340 and 370 <span class="inline-formula">K</span>, and poleward shifts between 370 and 380 <span class="inline-formula">K</span>. This consistent widening at lower levels and narrowing in the upper troposphere also exhibit considerable zonal variability with the strongest upper-tropospheric narrowing over the eastern Pacific.</p> |
| format | Article |
| id | doaj-art-8feee13f0ddb47fcbb48424249f221fa |
| institution | Kabale University |
| issn | 1680-7316 1680-7324 |
| language | English |
| publishDate | 2024-12-01 |
| publisher | Copernicus Publications |
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| series | Atmospheric Chemistry and Physics |
| spelling | doaj-art-8feee13f0ddb47fcbb48424249f221fa2024-12-11T07:08:08ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242024-12-0124136531367910.5194/acp-24-13653-2024Variability and trends in the potential vorticity (PV)-gradient dynamical tropopauseK. Turhal0K. Turhal1F. Plöger2F. Plöger3J. Clemens4J. Clemens5T. Birner6T. Birner7F. Weyland8P. Konopka9P. Hoor10Institute of Climate and Energy Systems, Stratosphere (ICE-4), Forschungszentrum Jülich, Jülich, GermanyInstitute for Atmospheric and Environmental Research, University of Wuppertal, Wuppertal, GermanyInstitute of Climate and Energy Systems, Stratosphere (ICE-4), Forschungszentrum Jülich, Jülich, GermanyInstitute for Atmospheric and Environmental Research, University of Wuppertal, Wuppertal, GermanyInstitute of Climate and Energy Systems, Stratosphere (ICE-4), Forschungszentrum Jülich, Jülich, GermanyInstitute for Atmospheric and Environmental Research, University of Wuppertal, Wuppertal, GermanyMeteorological Institute, Ludwig-Maximilians-Universität München, Munich, GermanyInstitute of Atmospheric Physics, Deutsches Zentrum für Luft- und Raumfahrt (German Aerospace Center), Oberpfaffenhofen, GermanyInstitute for Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, GermanyInstitute of Climate and Energy Systems, Stratosphere (ICE-4), Forschungszentrum Jülich, Jülich, GermanyInstitute for Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, Germany<p>The dynamical tropopause acts as a transport barrier between the tropical upper troposphere and extratropical lowermost stratosphere and is characterized by steep gradients in potential vorticity (PV) along an isentropic surface. Hence, the latitudinal separation between the dynamical tropopause in the Northern Hemisphere and Southern Hemisphere can be used as a metric of upper-tropospheric width for assessing climate change impacts. Here, we obtain the PV-gradient-based dynamical tropopause (PVG tropopause) from four meteorological satellite-era reanalyses (ERA5, ERA-Interim, JRA-55, MERRA-2) and investigate its climatology, variability and long-term trends from 1980 to 2017. Our results show a distinct seasonal cycle with larger PV values and a poleward movement of the PVG tropopause in summer. The climatological tropopause PV values are substantially different between different reanalyses, but the tropopause latitude is similar. Significant interannual variability in the PVG tropopause latitude is related to the El Niño–Southern Oscillation (ENSO) and weaker variability also to the quasi-biennial oscillation (QBO) and is consistently represented in reanalyses. In particular, El Niño correlates with equatorward shifts in the PVG tropopause and hence a decrease in upper-tropospheric width. Long-term trends in the PVG tropopause over the period 1980–2017 exhibit a distinct vertical structure with poleward shifts below 340 <span class="inline-formula">K</span> potential temperature, equatorward shifts between 340 and 370 <span class="inline-formula">K</span>, and poleward shifts between 370 and 380 <span class="inline-formula">K</span>. This consistent widening at lower levels and narrowing in the upper troposphere also exhibit considerable zonal variability with the strongest upper-tropospheric narrowing over the eastern Pacific.</p>https://acp.copernicus.org/articles/24/13653/2024/acp-24-13653-2024.pdf |
| spellingShingle | K. Turhal K. Turhal F. Plöger F. Plöger J. Clemens J. Clemens T. Birner T. Birner F. Weyland P. Konopka P. Hoor Variability and trends in the potential vorticity (PV)-gradient dynamical tropopause Atmospheric Chemistry and Physics |
| title | Variability and trends in the potential vorticity (PV)-gradient dynamical tropopause |
| title_full | Variability and trends in the potential vorticity (PV)-gradient dynamical tropopause |
| title_fullStr | Variability and trends in the potential vorticity (PV)-gradient dynamical tropopause |
| title_full_unstemmed | Variability and trends in the potential vorticity (PV)-gradient dynamical tropopause |
| title_short | Variability and trends in the potential vorticity (PV)-gradient dynamical tropopause |
| title_sort | variability and trends in the potential vorticity pv gradient dynamical tropopause |
| url | https://acp.copernicus.org/articles/24/13653/2024/acp-24-13653-2024.pdf |
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