Ozone Depletion in the Stratosphere: The Ozone Hole, Study notes of Earth Sciences

Download Ozone Depletion in the Stratosphere: The Ozone Hole and more Study notes Earth Sciences in PDF only on Docsity! T i # 9 op c OZONE DEPLETION IN THE STRATOSPHERE (cont.) 51 55 i Cl N t see pp - n ass o es The real answer: The ozone hole is: a depletion of -- ozone in the lower stratosphere -- that has occurred with increasing severity each spring (since measurements begin in 1970s) NOTE: the “Key Concepts” are all provided on p 55 The chemical reaction theory: The destruction of stratospheric ozone is catalyzed by chlorine from CFCs . This has destabilized h “ d ” t e stea y state formerly in place in the stratosphere h l th t l Ch w en on y e na ura apman mechanism was occurring. Key Concept WHY ANTARCTICA? The ozone "hole(s)" have a unique REGIONALITY and SEASONALITY : WHERE: it is most severe over Antarctica WHEN: during the Southern Hemisphere’s SPRING (Sep, Oct) NOTE : a less severe depletion (not a true hole) occurs over the Arctic in the Northern Hemisphere Key Concept SPRING (Feb, Mar) WHERE: i th mapp ng e OZONE HOLE: D b U ito son n s On this image, it is LARGER! ☺ ? POLAR STRATOSPHERIC CLOUDS OVER ANTARCTICA [Go to movie clip] HOW DEEP DOES THE HOLE GET? The intensity of ozone depletion varies from year to year. The value of 85 Dobson Units on October 8, 2006 was the d l t d dsecon owes ever recor e by satellite measurements. Nearly ALL of the ozone in the layer 8-13 miles above the Earth's surface was destroyed! 2006 also saw the second LARGEST sustained ozone hole In this critical layer, the instrument measured a record . http://www.sciencedaily.com/releases/2006/10/061019162053.htm low of only 1.2 DU! ☺ Over time, the AVERAGE SIZE OF THE HOLE has gotten LARGER: http://toms.gsfc.nasa.gov/eptoms/dataqual/oz_hole_avg_area_v8.jpg ☺ “Previously, the hole had only opened over Antarctica and the surrounding ocean. “Citing data from NASA , atmospheric research scientist Stephen Wood said the hole covered 11.4 million square miles - an area more than three times the size of the United States - on Sept 9 and 10 ☺ . . “For those two days, the hole extended over Punta Arenas, a southern Chilean city of about 120,000 people, exposing residents to very high A "solar stoplight" in Punta levels of ultraviolet radiation Arenas announces an orange alert, the second highest of four levels, and warns people to limit their exposure to the sun between noon and 3 p m . “ findings showed a . . to a maximum of 21 minutes. . . . city being exposed to the ozone hole for the first time.” ☺a woman and her child are bundled up against the sun http://ozonewatch.gsfc.nasa.gov/ Update of graphs on p 53 in Class Notes 2008 see also: http://macuv.gsfc.nasa.gov/ p 53 Arctic ozone depletion also takes place! There are concerns that an “Arctic Ozone Hole” may develop that is similar to the severe Antarctic Hole “An Arctic Ozone Hole, if similar in size to the Antarctic Ozone Hole could expose over 700+ million people , , wildlife and plants to dangerous UV ray levels. The likely hood of this happening seems inevitable based on the deterioration of ozone layer caused by the effects of global warming on the upper atmosphere.” http://www.theozonehole.com/arcticozone.htm ☺ Record Low Temperatures in A ti O L Fi t Si f rc c zone ayer - rs gns o Ozone Loss 28 January 2005 Press Release Record low temperatures in Arctic ozone layer - first signs of ozone loss The first signs of ozone loss have now been observed in the Arctic this winter, and large scale l t d t if th ld diti osses are expec e o occur e co con ons persist. . . . . http://www.theozonehole.com/recordlow.htm Wh t i i ifi t b t th d t a s s gn can a ou e a e September 16th with respect to the topic of ozone? http://fp.arizona.edu/kkh/nats101gc/selftest_bonus.htm Why can’t we just ship the “bad ozone” in the troposphere up to the stratosphere to ‘fill the hole’? • Ozone is increasing in the troposphere due to car exhaust etc (“bad ozone”) but , , only at the rate of about 1% per year, • Hence stratospheric levels of “good ozone” are going down at a rate faster than ozone is being added in the troposphere. Key Concept The Discover of the Ozone Hole issues a warning http://www.theozonehole.com/discoverer.htm OZONE DEPLETION & CLIMATE CHANGE What – if anything – is scientifically inaccurate about this cartoon? YOU TUBE The OZONE & THE MONTREAL PROTOCOL http://www.youtube.com/watch?v=Dn3KvZ_Xyqs&eurl=ht tp://www.theozonehole.com/discoverer.htm EPILOGUE THE OZONE DEPLETION STORY TIES TOGETHER MANY OF THE CONCEPTS YOU’VE LEARNED IN THE COURSE THUS FAR: > the nature of matter, e.g., chemical reactions and photon interaction with atoms ☺ > th l t ti t e e ec romagne c spec rum --especially the wavelengths of UV di tira a on ☺ > the vertical structure of the atmosphere 100 90k Thermosphere 4 80r 705 60F Mesosphere BO Peown rrr rrr rrr rrr rrr rrr rrr cnr cr 40°F Stratosphere 30 20r 10 Troposphere I i i i 0 180 200 220 240 260 280 300 Temperature (K) (b) Altitude (km) > the ever changing - nature of science th l . . . e ear y theory was right b t f th u or e wrong reasons (it was hypothesized that ozone destruction would be caused by “super sonic transport” jets ☺ flying in stratosphere) > Preconceived ideas influencing one’s observations and the . . . surprise of discovery! ☺