Q14Do changes in the Sun and volcanic eruptions affect the ozone layer?

Claudia Mignani

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

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 effectivestratospheric chlorine (EESC):

Low EESC → ozone decreases slightly High EESC → ozone decreases significantly

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

Changes in the Sun:• 11-year solar cycle

→ O3 variation: 1 – 2%

Volcanic eruption:

• Mt. Agung (1963, EESC low)

→ O3 unaffected• 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 affectthe ozone layer but they cannot account for thecontinuous long-term decrease of global ozoneover the last three decades