Q14 Do changes in the Sun and volcanic eruptions affect the ozone layer ?

1. Q14Do changes in the Sun andvolcaniceruptionsaffecttheozonelayer? Claudia Mignani

2. Q14 Do changes in the Sun and volcaniceruptionsaffecttheozonelayer? Changes in the Sun: • Solar radiation ↑ → O3 ↑ O2 + hν → 2 O O + O2 + M → O3 + M Volcanic eruption: • Volcanic particles (sulfate particles) ↑ → solar transmission ↓ → O3 ↓ But: ozone response depends on the amount of equivalent effective stratospheric chlorine (EESC): Low EESC → ozone decreases slightly High EESC → ozone decreases significantly

3. Q14 Dochangesin the Sun and volcaniceruptionsaffecttheozonelayer? Changes in the Sun: • 11-year solar cycle → O3 variation: 1 – 2% Volcanic eruption: • Mt. Agung(1963, EESC low) → O3unaffected • El Chichón(1982, EESC high) Mt. Pinatubo (1991, EESC very high) → O3 temporarily ↓ until volcanic particles (short residence time) are removed by natural processes  Changes in the sun and volcanic eruptions affect the ozone layer but they cannot account for the continuous long-term decrease of global ozone over the last three decades