Long-term changes in the thermodynamic structure of the lowermost stratosphere inferred from reanalysis data
<p>The lowermost stratosphere (LMS) plays an important role in stratosphere–troposphere coupling and the Earth's radiation balance. This study investigates the effects of long-term changes in the tropopause and the lower-stratospheric isentropic structure on the mass of the LMS. We compar...
Saved in:
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-01-01
|
| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/25/1227/2025/acp-25-1227-2025.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1832582888947712000 |
|---|---|
| author | F. Weyland P. Hoor D. Kunkel T. Birner T. Birner F. Plöger F. Plöger K. Turhal K. Turhal |
| author_facet | F. Weyland P. Hoor D. Kunkel T. Birner T. Birner F. Plöger F. Plöger K. Turhal K. Turhal |
| author_sort | F. Weyland |
| collection | DOAJ |
| description | <p>The lowermost stratosphere (LMS) plays an important role in stratosphere–troposphere coupling and the Earth's radiation balance. This study investigates the effects of long-term changes in the tropopause and the lower-stratospheric isentropic structure on the mass of the LMS. We compare five modern reanalyses: ERA5, ERA-Interim, MERRA-2, JRA-55 and JRA-3Q. The focus is on changes after 1998, which marks the anticipated beginning of stratospheric ozone recovery. The trend analysis is performed with a dynamic linear regression model (DLM), capable of modeling non-linear trends. According to our study, isentropic pressure in the lower stratosphere (here 380–430 <span class="inline-formula">K</span>) shows negative trends in the tropics and positive trends in the extratropics. In the Northern Hemisphere (NH), we find that the extratropical tropopause is rising, accompanied by decreasing pressure at an average rate of <span class="inline-formula">−</span>1 <span class="inline-formula">hPa</span> per decade. Additionally, our results indicate that the tropical tropopause in the NH has expanded poleward by 0.5<span class="inline-formula">°</span> latitude between 1998–2019. In the Southern Hemisphere (SH) extratropics, the lapse rate tropopause shows a downward tendency of up to <span class="inline-formula">+</span>2 <span class="inline-formula">hPa</span> per decade after 1998, consistent across all reanalyses except JRA-3Q. The tropical tropopause and the cold point is rising, accompanied by decreasing pressure at a rate of ca. <span class="inline-formula">−</span>0.5 <span class="inline-formula">hPa</span> per decade in all reanalyses. The sign of the tropical tropopause potential temperature trends, however, differs across the reanalyses. This can be attributed to contrasting (absolute) temperature trends in the tropical tropopause region, such as at the 100 <span class="inline-formula">hPa</span> pressure level. Consistent with the upward and poleward trend of the NH tropopause, the mass of the LMS decreases by 2 <span class="inline-formula">%</span>–3 <span class="inline-formula">%</span> for 1998–2019 if a fixed isentrope (380 <span class="inline-formula">K</span>) is chosen as the upper LMS boundary. In ERA5, as well as MERRA-2 and ERA-Interim, this mass decline disappears if dynamical upper LMS boundaries are used that take the upward trends of the tropical tropopause into account.</p> |
| format | Article |
| id | doaj-art-ea548c5d61144cb0b2c417871a38a9f3 |
| institution | Kabale University |
| issn | 1680-7316 1680-7324 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj-art-ea548c5d61144cb0b2c417871a38a9f32025-01-29T07:41:17ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242025-01-01251227125210.5194/acp-25-1227-2025Long-term changes in the thermodynamic structure of the lowermost stratosphere inferred from reanalysis dataF. Weyland0P. Hoor1D. Kunkel2T. Birner3T. Birner4F. Plöger5F. Plöger6K. Turhal7K. Turhal8Institute for Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, GermanyInstitute for Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, GermanyInstitute for Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, GermanyMeteorological Institute, Ludwig-Maximilians-Universität München, Munich, GermanyInstitute for Physics of the Atmosphere, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, 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, Germany<p>The lowermost stratosphere (LMS) plays an important role in stratosphere–troposphere coupling and the Earth's radiation balance. This study investigates the effects of long-term changes in the tropopause and the lower-stratospheric isentropic structure on the mass of the LMS. We compare five modern reanalyses: ERA5, ERA-Interim, MERRA-2, JRA-55 and JRA-3Q. The focus is on changes after 1998, which marks the anticipated beginning of stratospheric ozone recovery. The trend analysis is performed with a dynamic linear regression model (DLM), capable of modeling non-linear trends. According to our study, isentropic pressure in the lower stratosphere (here 380–430 <span class="inline-formula">K</span>) shows negative trends in the tropics and positive trends in the extratropics. In the Northern Hemisphere (NH), we find that the extratropical tropopause is rising, accompanied by decreasing pressure at an average rate of <span class="inline-formula">−</span>1 <span class="inline-formula">hPa</span> per decade. Additionally, our results indicate that the tropical tropopause in the NH has expanded poleward by 0.5<span class="inline-formula">°</span> latitude between 1998–2019. In the Southern Hemisphere (SH) extratropics, the lapse rate tropopause shows a downward tendency of up to <span class="inline-formula">+</span>2 <span class="inline-formula">hPa</span> per decade after 1998, consistent across all reanalyses except JRA-3Q. The tropical tropopause and the cold point is rising, accompanied by decreasing pressure at a rate of ca. <span class="inline-formula">−</span>0.5 <span class="inline-formula">hPa</span> per decade in all reanalyses. The sign of the tropical tropopause potential temperature trends, however, differs across the reanalyses. This can be attributed to contrasting (absolute) temperature trends in the tropical tropopause region, such as at the 100 <span class="inline-formula">hPa</span> pressure level. Consistent with the upward and poleward trend of the NH tropopause, the mass of the LMS decreases by 2 <span class="inline-formula">%</span>–3 <span class="inline-formula">%</span> for 1998–2019 if a fixed isentrope (380 <span class="inline-formula">K</span>) is chosen as the upper LMS boundary. In ERA5, as well as MERRA-2 and ERA-Interim, this mass decline disappears if dynamical upper LMS boundaries are used that take the upward trends of the tropical tropopause into account.</p>https://acp.copernicus.org/articles/25/1227/2025/acp-25-1227-2025.pdf |
| spellingShingle | F. Weyland P. Hoor D. Kunkel T. Birner T. Birner F. Plöger F. Plöger K. Turhal K. Turhal Long-term changes in the thermodynamic structure of the lowermost stratosphere inferred from reanalysis data Atmospheric Chemistry and Physics |
| title | Long-term changes in the thermodynamic structure of the lowermost stratosphere inferred from reanalysis data |
| title_full | Long-term changes in the thermodynamic structure of the lowermost stratosphere inferred from reanalysis data |
| title_fullStr | Long-term changes in the thermodynamic structure of the lowermost stratosphere inferred from reanalysis data |
| title_full_unstemmed | Long-term changes in the thermodynamic structure of the lowermost stratosphere inferred from reanalysis data |
| title_short | Long-term changes in the thermodynamic structure of the lowermost stratosphere inferred from reanalysis data |
| title_sort | long term changes in the thermodynamic structure of the lowermost stratosphere inferred from reanalysis data |
| url | https://acp.copernicus.org/articles/25/1227/2025/acp-25-1227-2025.pdf |
| work_keys_str_mv | AT fweyland longtermchangesinthethermodynamicstructureofthelowermoststratosphereinferredfromreanalysisdata AT phoor longtermchangesinthethermodynamicstructureofthelowermoststratosphereinferredfromreanalysisdata AT dkunkel longtermchangesinthethermodynamicstructureofthelowermoststratosphereinferredfromreanalysisdata AT tbirner longtermchangesinthethermodynamicstructureofthelowermoststratosphereinferredfromreanalysisdata AT tbirner longtermchangesinthethermodynamicstructureofthelowermoststratosphereinferredfromreanalysisdata AT fploger longtermchangesinthethermodynamicstructureofthelowermoststratosphereinferredfromreanalysisdata AT fploger longtermchangesinthethermodynamicstructureofthelowermoststratosphereinferredfromreanalysisdata AT kturhal longtermchangesinthethermodynamicstructureofthelowermoststratosphereinferredfromreanalysisdata AT kturhal longtermchangesinthethermodynamicstructureofthelowermoststratosphereinferredfromreanalysisdata |