Stratospheric Ozone Depletion

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Does ozone hole occur in the north pole (Arctic)? • The Arctic winter stratosphere is generally warmer than the Antarctic by ~10k. – Caused by the water mass covering the Arctic. • The warmer temperature results in less PSCs and shorter presence time. • The less abundant and less persistent PSCs dramatically reduce the extent of denitrification. – PSCs in the Arctic does not have sufficient time to settle out of the stratosphere. – PSCs releases their HNO 3 back to the stratosphere, making ClOx polar cycle less efficient. • Conclusion: <strong>Ozone</strong> depletion is less dramatic in the Arctic compared with the Antarctic.
Summary on ozone hole • Massive ozone loss requires both very cold temperature (to form PSCs) and sunlight (to photolyze reactive chlorine to produce Cl atoms). • Denitrification is required to prevent reformation of reservoir species once photolysis ensures. • Denitrification occurs when PSCs containing HNO 3 settling out of the stratosphere. • The massive springtime loss of ozone in the Antarctic stratosphere (the <strong>Ozone</strong> hole) is conclusively linked to anthropogenic halogens. • Virtually all inorganic chlorine is converted into active chlorine every winter in both the Antarctic and Arctic stratosphere as a result of heterogeneous reactions of reservoir species on polar stratospheric clouds (PSCs).
Page 1 and 2: Environmental Chemistry Part 2 Atmo
Page 3 and 4: The ozone layer
Page 5 and 6: Ultraviolet protection by ozone The
Page 7 and 8: Typical ozone column values • Tot
Page 9 and 10: Ozone formation and destruction in
Page 11 and 12: Prediction by Chapman theory vs. Ob
Page 13 and 14: The important catalysts for stratos
Page 15 and 16: Chlorine atom Sources: Photolysis o
Page 17 and 18: Chlorine atom (Continued) Terminati
Page 19 and 20: The two-sided effect of NOx • NOx
Page 21 and 22: Numbering system for CFCs and HCFCs
Page 23: The discovery of the ozone hole •
Page 26 and 27: Features of the ozone hole • Ozon
Page 28 and 29: Polar vortex • The polar vortex i
Page 30 and 31: Why do PSCs occur at heights of 15-
Page 32 and 33: PSCs promote the conversion of inor
Page 34 and 35: Active Cl species can rapidly yield
Page 36 and 37: How does the polar ClOx cycle stop?
Page 38 and 39: Denitrification by PSCs enhances po
Page 40 and 41: Summary of the roles played by PSCs
Page 42 and 43: Schematic of photochemical and dyna
Page 46 and 47: Summary on ozone hole (Continued)
Page 48 and 49: What influences ODP? • Lifetime i
Page 50 and 51: ODPs of Selected Compounds Compound

Stratospheric Ozone Depletion

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