极地上空的臭氧空洞-保护环境ppt课件

1、Jan. 10, 2003 - local noon, Kiruna, Sweden1Jan. 14, 2003 Southern Norway2Polar Stratospheric OzoneDr. Paul A. Newman/People/Newman/NASAs Goddard Space Flight CenterIPY WebcastNASA GSFCNov. 3, 20213Ozone Basic FactsO3 = Ozone is composed of 3 oxygen atoms.O3 concentrations are small (peak concentrati

2、ons are about 10 parts per million at an altitude of about 32 km (20 miles).O3 absorbs harmful solar ultraviolet radiation. A necessary condition for life.O3 is mainly found in the the stratosphere.O3 at the ground is a problem! Inhalation of ozone for very small concentrations can cause lung proble

3、ms .Mass: (Billion Metric Tons)Sun1,9900,000,000,000,000,000Earth5,980,000,000,000Global atmosphere5,300,000Global ozone3OxygenOzone4Atmospheric CompositionNitrogen78.1%Oxygen20.9%Argon0.9%Water1.4% (tropics) 0.2% (poles) 0.0004% (stratosphere)CO20.0360% O30.001% (stratosphere) 0.00001% (troposphere

4、)5180200220240260280300Temperature (K)020406080100Altitude (km)TroposphereStratosphereMesosphereThermosphereAtmospheric StructureAltitude (miles)100203040506081oF45oF9oF-27oF-63oF-99oF-oF6020406080100Altitude (km)TroposphereStratosphereMesosphereThermosphereAtmospheric StructureAltitude (miles)10020

5、30405060Airliners fly at 30,000-40,000 feet7020406080100Altitude (km)TroposphereStratosphereMesosphereThermosphereAtmospheric StructureAltitude (miles)1002030405060ER-2 flies at 70,000 feet8020406080100Altitude (km)TroposphereStratosphereMesosphereThermosphereAtmospheric StructureAltitude (miles)100

6、2030405060OxygenOzone9Ozone (parts per million)020406080100Altitude (km)TroposphereMesosphereThermosphereOzone FactsAltitude (miles)100203040506090% of ozone is in the stratosphere0246810Ozone (parts per million)020406080100Altitude (km)StratosphereMesosphereThermosphereOzone FactsAltitude (miles)10

7、020304050600246810% of ozone is in the troposphere11Digression: Dobson Unitsozone layer3 mm = 300 Dobson UnitsTotal Ozone is a measure of the total column amount above us. Measured in Dobson UnitsIf we bring all of the ozone above us down to the Earths surfaceThe thickness would be about 3 millimete

8、rs (0.1 inches) = 300 Dobson Units (approximately the global average)100 Dobson Units = 1 millimeter in thicknessThe Dobson Unit is a convenient unit of measurement for total column ozone21012Ozone (part per million)020406080100Altitude (km)StratosphereOzone FactsAltitude (miles)100203040506002468UV

9、c - 100% AbsorptionUVb - 90% AbsorptionUVa - 50% Absorption & ScatteringOzone is the Earths natural sunscreen13UV Health FactsUV pluses: produces vitamin D in the skin - necessary to maintain levels of calcium and phosphorus (10-15 minutes twice a week)UV minuses:Eye damage: cataracts, photokerititu

10、s (snowblinding), ocular cancers Skin cancers: basal, squamous, melanomaphotoagingDamage to various land speciesDamage to aquatic speciesIncreased pollution levels in urban environmentsCataractMelanomaMexico City14Large polar ozone losses result from chlorine and bromine compounds that are mainly hu

11、man produced15CFC-12 released in troposphereCarried into stratosphere in the tropics by slow rising circulationCFC-12 photolyzed in stratosphere by solar UV, releasing ClCl catalytically destroys O3Cl reacts with CH4 or NO2 to form non-reactive HCl or ClONO2PolarlossChlorine Pathway16Source GasesCl

12、is much more abundant than Br, but Br is about 60 times more effective at O3 destructionFrom Ozone FAQ - see /ozone/faq.shtml17Atmospheric Chlorine Trends from NOAA/ERL - Climate Monitoring DivisionUpdated Figure made by Dr. James Elkins from Trends of the Commonly Used Halons Below Published by But

13、ler et al. 1998, All CFC-113 from Steve Montzka (flasks by GC/MS), and recent updates of all other gases from Geoff Dutton (in situ GC). 50 years102 years5 years42 years85 yearsCFC-11 CCl4CFC-113CFC-12 CH3CCl318Polar Stratospheric CloudsCentral, Sweden January 14, 2003 - P. Newman19Solomon et al. (1

14、986), Wofsy and McElroy (1986), and Crutzen and Arnold (1986) suggest reactions on cloud particle surfaces as mechanism for activating ChlorinePSCHClClONO2HNO3Cl2Cl2 is easily photolyzed by UV & blue/green lightHNO3 is sequestered on PSCAntarctic ozone hole theory20Polar Ozone Destruction1. O3 + Cl

15、ClO + O2Only visible light (blue/green) needed for photolyzing ClOOClNo oxygen atoms requiredNet: 2O3 + h 3O22 O33 O23. ClOOCl+h2 Cl+O22. 2 ClO + M ClOOCl + M21Antarctic Measurements Aurora over Halley Bay Station, Antarctica, 75.6S 26.5E Brunt Ice Shelf, Coats Land 105 days of continuous darkness,

16、twice per year re-supply Population: 65 in summer, 15 in winter22October Antarctic Ozone pre-198523October Antarctic Ozone24TOMS - August 31, 2003Orange/Yellow indicates higher ozone levels. Blue colors indicate low ozone valuesDark color over pole shows the extent of polar night, no ozone observati

17、onsAntarctic ozone hole is defined as the region covered by low ozone values 25Ozone Hole AreaN. America1st observed SH major warming (2002)Sep. 21, 2021Sep. 30, 202110/25/202126October Average Ozone Hole27March Average total ozone28Arctic & Antarctic Trends29Whats being done?30What Can You Do?Avoid

18、 excessive solar exposure (limit sun between 11AM and 2PM).Wear and encourage others to wear sunscreen (SPF rating of 15). Even with sunscreen, prolonged exposure is not smart. Check your skin regularly.Wear sunglasses that screen UV. Hats and other coveringsMake note of the UV index on the news or

19、web: /sunwise/uvindex.html31Atmospheric Chlorine Trends from NOAA/ERL - Climate Monitoring DivisionUpdated Figure made by Dr. James Elkins from Trends of the Commonly Used Halons Below Published by Butler et al. 1998, All CFC-113 from Steve Montzka (flasks by GC/MS), and recent updates of all other gases from Geoff Dutton (in situ GC). 50 years102 years5 years42 years85 yearsCFC-11 CCl4CFC-113CFC-12 CH3CCl3U. S. CFC production stopped by President George Bush i