The influence of energetic particle precipitation on Antarctic stratospheric chlorine and ozone over the 20th century

• Published in: Atmospheric Chemistry and Physics
• Main Authors: V. Maliniemi, P. Arsenovic, A. Seppälä, H. Nesse Tyssøy
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2022
• Subjects: Physics; QC1-999; Chemistry; QD1-999; Antarctic; The Antarctic; Antarc*
• Online Access: https://doi.org/10.5194/acp-22-8137-2022; https://doaj.org/article/b458352124c1473ea55e979d87039467

Chlorofluorocarbon (CFC) emissions in the latter part of the 20th century reduced stratospheric ozone abundance substantially, especially in the Antarctic region. Simultaneously, polar stratospheric ozone is also destroyed catalytically by nitrogen oxides (NO x = NO + NO 2 ) descending from the mesosphere and the lower thermosphere during winter. These are produced by energetic particle precipitation (EPP) linked to solar activity and space weather. Active chlorine (ClO x = Cl + ClO) can also react mutually with EPP-produced NO x or hydrogen oxides (HO x ) and transform both reactive agents into reservoir gases, chlorine nitrate or hydrogen chloride, which buffer ozone destruction by all these agents. We study the interaction between EPP-produced NO x , ClO and ozone over the 20th century by using free-running climate simulations of the chemistry–climate model SOCOL3-MPIOM. A substantial increase of NO x descending to the polar stratosphere is found during winter, which causes ozone depletion in the upper and mid-stratosphere. However, in the Antarctic mid-stratosphere, the EPP-induced ozone depletion became less efficient after the 1960s, especially during springtime. Simultaneously, a significant decrease in stratospheric ClO and an increase in hydrogen chloride – and partly chlorine nitrate between 10–30 hPa – can be ascribed to EPP forcing. Hence, the interaction between EPP-produced <math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">NO</mi><mi>x</mi></msub><mo>/</mo><msub><mi mathvariant="normal">HO</mi><mi>x</mi></msub></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="51pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="98ca2d0ce39eb5edb37137915c5f828d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-8137-2022-ie00001.svg" ...