Protection without poison: why tropical ozone maximizes in the interior of the atmosphere
<p>The number density of ozone, <span class="inline-formula">[O<sub>3</sub>]</span>, maximizes around 26 km in the tropics, protecting life from harmful ultraviolet (UV) light without poisoning it at the surface. Textbooks explain this interior maximum with tw...
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Copernicus Publications
2025-04-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/25/4349/2025/acp-25-4349-2025.pdf |
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| author | A. Match E. P. Gerber S. Fueglistaler |
| author_facet | A. Match E. P. Gerber S. Fueglistaler |
| author_sort | A. Match |
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| description | <p>The number density of ozone, <span class="inline-formula">[O<sub>3</sub>]</span>, maximizes around 26 km in the tropics, protecting life from harmful ultraviolet (UV) light without poisoning it at the surface. Textbooks explain this interior maximum with two paradigms: (1) the <i>source-controlled paradigm</i> explains <span class="inline-formula">[O<sub>3</sub>]</span> as maximizing where its source maximizes between abundant photons aloft and abundant <span class="inline-formula">[O<sub>2</sub>]</span> below, and (2) the <i>source</i> <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="57ee8123d9c9aefcf23d9c7f6463c158"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-25-4349-2025-ie00001.svg" width="8pt" height="14pt" src="acp-25-4349-2025-ie00001.png"/></svg:svg></span></span> <i>sink competition paradigm</i>, inspired by the Chapman cycle, explains ozone as scaling with <span class="inline-formula">[O<sub>2</sub>]</span> and the photolytic source <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="073414a2b77546d8d5847ae97897d626"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-25-4349-2025-ie00002.svg" width="8pt" height="14pt" src="acp-25-4349-2025-ie00002.png"/></svg:svg></span></span> sink ratio. However, each paradigm's prediction for the altitude of peak <span class="inline-formula">[O<sub>3</sub>]</span> is off by 10 km, reflecting their well-known omission of ozone sinks from catalytic cycles and transport. We present a minimal, steady-state theory for the tropical stratospheric <span class="inline-formula">[O<sub>3</sub>]</span> maximum, accurate to within 1 km and formulated in terms of the dominant ozone sinks. These sinks are represented simply by augmenting the Chapman cycle with linear damping of O and O<span class="inline-formula"><sub>3</sub></span>, leading to the Chapman<span class="inline-formula">+</span>2 model. The Chapman<span class="inline-formula">+</span>2 model correctly simulates peak tropical <span class="inline-formula">[O<sub>3</sub>]</span> at 26 km, yet this peak is not explained by either paradigm. Instead, the peak is newly explained by the transition from an O-damped regime aloft to an O<span class="inline-formula"><sub>3</sub></span>-damped regime below. An explicit analytical expression is derived for ozone under gray radiation. This theory accurately predicts an interior maximum of ozone and correctly predicts that an increase in top-of-atmosphere UV light will lead to a downward shift in the peak <span class="inline-formula">[O<sub>3</sub>]</span> due to a downward shift in the regime transition, a result not even qualitatively predicted by the existing paradigms.</p> |
| format | Article |
| id | doaj-art-5f3dd187f7bb49809995e422fb228a31 |
| institution | OA Journals |
| issn | 1680-7316 1680-7324 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | Copernicus Publications |
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| series | Atmospheric Chemistry and Physics |
| spelling | doaj-art-5f3dd187f7bb49809995e422fb228a312025-08-20T02:24:34ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242025-04-01254349436610.5194/acp-25-4349-2025Protection without poison: why tropical ozone maximizes in the interior of the atmosphereA. Match0E. P. Gerber1S. Fueglistaler2Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USACenter for Atmosphere Ocean Science, Courant Institute of Mathematical Sciences, New York University, New York, NY, USAProgram in Atmospheric and Oceanic Sciences, and Department of Geosciences, Princeton University, Princeton, NJ, USA<p>The number density of ozone, <span class="inline-formula">[O<sub>3</sub>]</span>, maximizes around 26 km in the tropics, protecting life from harmful ultraviolet (UV) light without poisoning it at the surface. Textbooks explain this interior maximum with two paradigms: (1) the <i>source-controlled paradigm</i> explains <span class="inline-formula">[O<sub>3</sub>]</span> as maximizing where its source maximizes between abundant photons aloft and abundant <span class="inline-formula">[O<sub>2</sub>]</span> below, and (2) the <i>source</i> <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="57ee8123d9c9aefcf23d9c7f6463c158"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-25-4349-2025-ie00001.svg" width="8pt" height="14pt" src="acp-25-4349-2025-ie00001.png"/></svg:svg></span></span> <i>sink competition paradigm</i>, inspired by the Chapman cycle, explains ozone as scaling with <span class="inline-formula">[O<sub>2</sub>]</span> and the photolytic source <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="073414a2b77546d8d5847ae97897d626"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-25-4349-2025-ie00002.svg" width="8pt" height="14pt" src="acp-25-4349-2025-ie00002.png"/></svg:svg></span></span> sink ratio. However, each paradigm's prediction for the altitude of peak <span class="inline-formula">[O<sub>3</sub>]</span> is off by 10 km, reflecting their well-known omission of ozone sinks from catalytic cycles and transport. We present a minimal, steady-state theory for the tropical stratospheric <span class="inline-formula">[O<sub>3</sub>]</span> maximum, accurate to within 1 km and formulated in terms of the dominant ozone sinks. These sinks are represented simply by augmenting the Chapman cycle with linear damping of O and O<span class="inline-formula"><sub>3</sub></span>, leading to the Chapman<span class="inline-formula">+</span>2 model. The Chapman<span class="inline-formula">+</span>2 model correctly simulates peak tropical <span class="inline-formula">[O<sub>3</sub>]</span> at 26 km, yet this peak is not explained by either paradigm. Instead, the peak is newly explained by the transition from an O-damped regime aloft to an O<span class="inline-formula"><sub>3</sub></span>-damped regime below. An explicit analytical expression is derived for ozone under gray radiation. This theory accurately predicts an interior maximum of ozone and correctly predicts that an increase in top-of-atmosphere UV light will lead to a downward shift in the peak <span class="inline-formula">[O<sub>3</sub>]</span> due to a downward shift in the regime transition, a result not even qualitatively predicted by the existing paradigms.</p>https://acp.copernicus.org/articles/25/4349/2025/acp-25-4349-2025.pdf |
| spellingShingle | A. Match E. P. Gerber S. Fueglistaler Protection without poison: why tropical ozone maximizes in the interior of the atmosphere Atmospheric Chemistry and Physics |
| title | Protection without poison: why tropical ozone maximizes in the interior of the atmosphere |
| title_full | Protection without poison: why tropical ozone maximizes in the interior of the atmosphere |
| title_fullStr | Protection without poison: why tropical ozone maximizes in the interior of the atmosphere |
| title_full_unstemmed | Protection without poison: why tropical ozone maximizes in the interior of the atmosphere |
| title_short | Protection without poison: why tropical ozone maximizes in the interior of the atmosphere |
| title_sort | protection without poison why tropical ozone maximizes in the interior of the atmosphere |
| url | https://acp.copernicus.org/articles/25/4349/2025/acp-25-4349-2025.pdf |
| work_keys_str_mv | AT amatch protectionwithoutpoisonwhytropicalozonemaximizesintheinterioroftheatmosphere AT epgerber protectionwithoutpoisonwhytropicalozonemaximizesintheinterioroftheatmosphere AT sfueglistaler protectionwithoutpoisonwhytropicalozonemaximizesintheinterioroftheatmosphere |