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Polar Stratospheric Clouds (PSC)

Polar Stratospheric Clouds (PSC). Patrick Shaw SIO 209 May 15, 2009. Zondlo et al., 2000. Cirrus in general. Cover 30% of earth’s surface at all times Upper troposphere generally has low T, high RH and enough CCN to form large coverage of ice crystal clouds

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Polar Stratospheric Clouds (PSC)

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  1. Polar Stratospheric Clouds(PSC) Patrick Shaw SIO 209 May 15, 2009

  2. Zondlo et al., 2000

  3. Cirrus in general • Cover 30% of earth’s surface at all times • Upper troposphere generally has low T, high RH and enough CCN to form large coverage of ice crystal clouds • Diversity of formation regions makes for variety of unique particle size, density and morphology • Optically thin  allows most in sun, traps IR out

  4. PSC’s in particular • Form at poles because of extremely low T in winter • Reaction site where reservoir chlorine compounds are converted into ozone-destroying chlorine radicals • Type 1 – ice + liquid nitric acid and water mixtures formed at ~195 K • Type 2- less common, water-ice crystals at < 187K

  5. PSC classification Zondlo et al., 2000

  6. http://www.atm.ch.cam.ac.uk/tour/psc.html

  7. Sudden creation of Type 1 http://www.atm.ch.cam.ac.uk/tour/psc.html

  8. Sudden creation of Type 2 http://www.atm.ch.cam.ac.uk/tour/psc.html

  9. Chemistry Denoxification occurs on PSC drops, resulting (…) in the net reaction: ClO + NO2 + M -> ClONO2 + M As clouds grow, they attain enough mass to deposit out and remove nitrogen compounds with them. This increases the ClO in the net equation, and promotes ozone destruction once sunlight is available to catalyze active Cl compounds. http://www.atm.ch.cam.ac.uk

  10. Measuring Ozone (toms.nasa.gsfc.com)

  11. Antarctic vs. Arctic • Antarctic has stronger polar vortex  lowest stratosphere T during winter, prone to PSC formation and ozone depletion • Arctic has weaker polar vortex, but standing lee waves may still process enough air to deplete N. Hemisphere ozone layer • If GHG-induced climate change makes stratosphere colder, as predicted, more PSC may form, and N. Hemisphere ‘mini’ ozone hole may grow

  12. Can infer vortex strength, and thus effect of PSC, from Total Ozone Mapping Spectrometer data: (toms.nasa.gsfc.com)

  13. From http://www.jpl.nasa.gov/releases/2004/108.cfm

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