Quantifying the sources of increasing stratospheric water vapour concentrations
<p>According to satellite measurements from multiple instruments, water vapour (<span class="inline-formula">H<sub>2</sub>O</span>) concentrations, in most regions of the stratosphere, have been increasing at a statistically significant rate of <span class=...
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Copernicus Publications
2025-05-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/25/5199/2025/acp-25-5199-2025.pdf |
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| author | P. E. Sheese K. A. Walker C. D. Boone D. A. Plummer |
| author_facet | P. E. Sheese K. A. Walker C. D. Boone D. A. Plummer |
| author_sort | P. E. Sheese |
| collection | DOAJ |
| description | <p>According to satellite measurements from multiple instruments, water vapour (<span class="inline-formula">H<sub>2</sub>O</span>) concentrations, in most regions of the stratosphere, have been increasing at a statistically significant rate of <span class="inline-formula">∼1</span> <span class="inline-formula">%</span>–5 <span class="inline-formula">%</span> per decade since the early 2000s. Previous studies have estimated stratospheric <span class="inline-formula">H<sub>2</sub>O</span> trends, but none have simultaneously quantified the contributions from all main sources (temperature variations in the tropical tropopause region, changes in the Brewer–Dobson circulation, and changes in methane (<span class="inline-formula">CH<sub>4</sub></span>) concentrations and oxidation) at all latitudes. Atmospheric Chemistry Experiment–Fourier Transform Spectrometer (ACE-FTS) measurements are used to estimate altitude-/latitude-dependent stratospheric <span class="inline-formula">H<sub>2</sub>O</span> trends from 2004–2021 due to these sources. Results indicate that rising temperatures in the tropical tropopause region play a significant role in the increases, accounting for <span class="inline-formula">∼1</span> <span class="inline-formula">%</span>–4 <span class="inline-formula">%</span> per decade in the tropical lower mid-stratosphere and in the mid-latitudes below <span class="inline-formula">∼20</span> <span class="inline-formula">km</span>. By regressing to ACE-FTS <span class="inline-formula">N<sub>2</sub>O</span> concentrations, it is found that, in the lower mid-stratosphere, general circulation changes have led to both significant <span class="inline-formula">H<sub>2</sub>O</span> increases and significant <span class="inline-formula">H<sub>2</sub>O</span> decreases on the order of 1 <span class="inline-formula">%</span>–2 <span class="inline-formula">%</span> per decade depending on the altitude/latitude region. Making use of measured and modelled <span class="inline-formula">CH<sub>4</sub></span> concentrations, the increase in <span class="inline-formula">H<sub>2</sub>O</span> due to <span class="inline-formula">CH<sub>4</sub></span> oxidation is calculated to be <span class="inline-formula">∼1</span> <span class="inline-formula">%</span>–2 <span class="inline-formula">%</span> per decade above <span class="inline-formula">∼30</span> <span class="inline-formula">km</span> in the Northern Hemisphere and throughout the stratosphere in the Southern Hemisphere. After accounting for these sources, there are still regions of the mid-latitude lower mid-stratosphere that exhibit significant residual <span class="inline-formula">H<sub>2</sub>O</span> trends increasing at 1 <span class="inline-formula">%</span>–2 <span class="inline-formula">%</span> per decade. Results indicate that these unaccounted-for increases could potentially be explained by increases in upper-tropospheric molecular hydrogen.</p> |
| format | Article |
| id | doaj-art-8b6b36bd51d64d92bd1a9bdad2f65519 |
| institution | DOAJ |
| issn | 1680-7316 1680-7324 |
| language | English |
| publishDate | 2025-05-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj-art-8b6b36bd51d64d92bd1a9bdad2f655192025-08-20T03:08:18ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242025-05-01255199521310.5194/acp-25-5199-2025Quantifying the sources of increasing stratospheric water vapour concentrationsP. E. Sheese0K. A. Walker1C. D. Boone2D. A. Plummer3Department of Physics, University of Toronto, Toronto, CanadaDepartment of Physics, University of Toronto, Toronto, CanadaDepartment of Chemistry, University of Waterloo, Waterloo, CanadaCanadian Centre for Climate Modelling and Analysis, Environment and Climate Change Canada, Montreal, Canada<p>According to satellite measurements from multiple instruments, water vapour (<span class="inline-formula">H<sub>2</sub>O</span>) concentrations, in most regions of the stratosphere, have been increasing at a statistically significant rate of <span class="inline-formula">∼1</span> <span class="inline-formula">%</span>–5 <span class="inline-formula">%</span> per decade since the early 2000s. Previous studies have estimated stratospheric <span class="inline-formula">H<sub>2</sub>O</span> trends, but none have simultaneously quantified the contributions from all main sources (temperature variations in the tropical tropopause region, changes in the Brewer–Dobson circulation, and changes in methane (<span class="inline-formula">CH<sub>4</sub></span>) concentrations and oxidation) at all latitudes. Atmospheric Chemistry Experiment–Fourier Transform Spectrometer (ACE-FTS) measurements are used to estimate altitude-/latitude-dependent stratospheric <span class="inline-formula">H<sub>2</sub>O</span> trends from 2004–2021 due to these sources. Results indicate that rising temperatures in the tropical tropopause region play a significant role in the increases, accounting for <span class="inline-formula">∼1</span> <span class="inline-formula">%</span>–4 <span class="inline-formula">%</span> per decade in the tropical lower mid-stratosphere and in the mid-latitudes below <span class="inline-formula">∼20</span> <span class="inline-formula">km</span>. By regressing to ACE-FTS <span class="inline-formula">N<sub>2</sub>O</span> concentrations, it is found that, in the lower mid-stratosphere, general circulation changes have led to both significant <span class="inline-formula">H<sub>2</sub>O</span> increases and significant <span class="inline-formula">H<sub>2</sub>O</span> decreases on the order of 1 <span class="inline-formula">%</span>–2 <span class="inline-formula">%</span> per decade depending on the altitude/latitude region. Making use of measured and modelled <span class="inline-formula">CH<sub>4</sub></span> concentrations, the increase in <span class="inline-formula">H<sub>2</sub>O</span> due to <span class="inline-formula">CH<sub>4</sub></span> oxidation is calculated to be <span class="inline-formula">∼1</span> <span class="inline-formula">%</span>–2 <span class="inline-formula">%</span> per decade above <span class="inline-formula">∼30</span> <span class="inline-formula">km</span> in the Northern Hemisphere and throughout the stratosphere in the Southern Hemisphere. After accounting for these sources, there are still regions of the mid-latitude lower mid-stratosphere that exhibit significant residual <span class="inline-formula">H<sub>2</sub>O</span> trends increasing at 1 <span class="inline-formula">%</span>–2 <span class="inline-formula">%</span> per decade. Results indicate that these unaccounted-for increases could potentially be explained by increases in upper-tropospheric molecular hydrogen.</p>https://acp.copernicus.org/articles/25/5199/2025/acp-25-5199-2025.pdf |
| spellingShingle | P. E. Sheese K. A. Walker C. D. Boone D. A. Plummer Quantifying the sources of increasing stratospheric water vapour concentrations Atmospheric Chemistry and Physics |
| title | Quantifying the sources of increasing stratospheric water vapour concentrations |
| title_full | Quantifying the sources of increasing stratospheric water vapour concentrations |
| title_fullStr | Quantifying the sources of increasing stratospheric water vapour concentrations |
| title_full_unstemmed | Quantifying the sources of increasing stratospheric water vapour concentrations |
| title_short | Quantifying the sources of increasing stratospheric water vapour concentrations |
| title_sort | quantifying the sources of increasing stratospheric water vapour concentrations |
| url | https://acp.copernicus.org/articles/25/5199/2025/acp-25-5199-2025.pdf |
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