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YEARTIME %f 2G4},x??GD},xG4},x??? add_ozone`3MIN(6.5e5*3.1536E7*1.81E35,OZONE*3.1536E7*1.81E35) X(A# *A~8 *GAm<  *A~8 *GAm<   s I0;c2e??I0;c2eI0;c2e???I0;c2e?NO 2E9*1.81E35 I0;c2e sI0;c2e??I0;c2eI0;c2eI0;c2eI0;c2e????NO20 %f 2I0;c2e??I@;c2eI0;c2e???I0;c2e add_ozone3MIN(2.4E7*3.1536E7*1.81E35,OZONE*3.1536E7*1.81E35)X(Av`*A~8 *GAm<  *A~8 *GAm<   s??????ClONO20 #f 6????? adding_NO27MIN(6.9E3*3.1536E7*1.81E35,add_ozone*3.1536E7*1.81E35)P*A~8 *GAm<  *A~8 *GAm<   s??????NO30 f ?????add_hv`7.2E3*3.1536E7*1.81E35  Iˊ~7c f#????? add_hv``7.2E3*3.1536E7*1.81E35  Iˊ~7c s%??????NO2`0 f&?????add_NO2.8E6*3.1536E7*1.81E35 J% 9. f)?????add_O1.7E6*3.1536E7*1.81E35 J8 f ,G4},x??GD},xG4},x???O2_other_sources O2_reservoir f DFȈ5]??FȈ5]FȈ5]???decay Cl_decaying m 3FȈ5]??FȈ5]FȈ5]??? Cl_decaying75$K !l#5@ԕ+??@g_o!@ԕ+==@2?CFC_in__lower_atmosphere$0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 "H f7@tfffff??@tfffff@tfffff??? production_of_CFCCFC_prod_from1931_to_2200## s:@tfffff??@dfffff@tfffff G40 ?!CFC's_in_Stratosphere0%"%!??????ə?ə?333333?333333?@ffffff@ffffff@@ffffff@&@.@2@7@<33333@@@>L@>fffff@D@@J @PY@T@W@[33333@^S33333@a333333@c@f@i33333@l\@o@rFfffff@tfffff@snfffff@s33333@rfffff@q@p{33333@oY@offfff@m@o@p񙙙@q@rq@si@s@p33333@qEjOv@k+a@k+a@fA [@fA [@[\(@[Xy=@@33332@@33333@@33333 m<@tfffff??@tfffff@tfffff???"transit_from_Lower_to_Upper18! c@y;@tfffff??@tfffff@tfffff ??? ?#CFC_prod_from1931_to_2200TIME  p@,@0@4@8@<@@@D@H@L@P@T@X@\@`@d@h@l@p@t@x@|@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@ @$@(@,@0@4@8@<@@@D@H@L@P@T@X@\@`@d@h@l@p@t@x@|@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ @@@@@@@@@@ @"@$@&@(@*@,@.@0@2@4@6@8@:@<@>@@@B@D@F@H@J@L@N@P@R@T@V@X@Z@\@^@`@b@d@f@h@j@l@n@p@r@t@v@x@z@|@~@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ @@@@@@@@@@ @"@$@&@(@*@,@.@0p??????ə?ə?333333?333333?@ffffff@ffffff@@ffffff@&@.@2@7@<33333@@@>L@>fffff@D@@J @PY@T@W@[33333@^S33333@a333333@c@f@i33333@l\@o@rFfffff@tfffff@snfffff@s33333@rfffff@q@p{33333@oY@offfff@m@o@p񙙙@q@rq@si@s@p33333@qEjOv@k+a@k+a@fA [@fA [@[\(@[Xy=@@33333@@33333@@33333!??????ə?ə?333333?333333?@ffffff@ffffff@@ffffff@&@.@2@7@<33333@@@>L@>fffff@D@@J @PY@T@W@[33333@^S33333@a333333@c@f@i33333@l\@o@rFfffff@tfffff@snfffff@s33333@rfffff@q@p{33333@oY@offfff@m@o@p񙙙@q@rq@si@s@p33333@qEjOv@k+a@k+a@fA [@fA [@[\(@[Xy=@@33333@@33333@@33333 Zl>KG4#??G4#G4#@R?$Cl_in_Stratosphere0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0%,KK f ?@tfffff??@tfffff@tfffff???Fd @@,% CFC_to_ClCFC's_in_Stratosphere/DT!!$!    g ==   ="a tV@V b$ N j#$% About STELLA&' 7"t@ #$%&' 7"t@ #$% &' 7"t@ #$%&' 7" M @;-C5#$%VVnM:\ES97-54\FLOW.pctܔ608O/FXߺ78 O/&XߺT()&' 7"t@ #$%&' 7"t@ #$%&' 7"t@   #$%&' 7"t @ g o#$%&' 7"t@d l#$%&' 7"t@W _#$%&' 7"t@O  W #$%&' 7"t@Y0 a#$%Stratospheric Ozone and CFCs&' 7"t@q ~|y#$%~Main Menu Introduction About STELLA Equations STELLA Model &' 7"N)@)K !S#$%&*TT .Fn n +, 7- .' 7"t@R0 Z#$% Introduction&' 7"td@d0\#$%0CFCs have been used industrially as aerosol propellants, solvents and refrigerants. The use of CFCs leads to their release into the atmosphere since even "sealed" refrigeration units leak into the air. Considered chemically inert in the troposphere, the only escape route for these compounds is transport to the stratosphere. Here CFCs undergo photolytic dissociation by ultraviolet light and are converted to a form that destroys ozone molecules. In this form, it is estimated that one chlorine ion is capable of destroying 100,000 ozone molecules. &' 7"ND z#$%&*An n +, 7-MORE.' 7"NKDK C#$%&*A n n +, 7- MAIN MENU.' 7"NE@E$g =,o#$%&*n n +, 7-Button.' 7"t@] Ar I#$%Every STELLA model is composed of several parts which helps make a mental model explicit. One of the basic parts of the model is the STOCK which represents an accumulation. &' 7"t_ @_ IzWQ#$%zStocks are filled and depleted by FLOWS. Flows are activities represented by double lines or pipes, with arrows pointing to the direction of the flow. One end of a flow may be represented by a cloud which indicates an infinite supply of material. The other end of the flow corresponds to a sink. The STELLA model will do the calculations for the regulation of the flow. &' 7"N #D # V   ^#$%&*zAn n +, 7-NEXT.' 7"NYDY| Q#$%&*An n +, 7-NEXT.' 7"N?e@?ea 7]i#$%&*n n +, 7-Button.' 7"tK@KC#$%CONNECTORS will carry information or show relationships between stocks and are represented by a single line with an arrow pointing in the direction of the relationship. &' 7" M @`-h5#$%"M:\ES97-54\CONNECT.pct608O/FXߺ7B=8 O/ =XߺT()&' 7"NZeDZe R]#$%&*FAR n n +, 7- MAIN MENU.' 7"t@$#$%STELLA Model &' 7" M @|#$%M:\ES97-54\SUN2.pctܔ608O/FXߺ7o8 O/oXߺT()&' 7"Nw@w oz#$%&*n n +, 7-Button.' 7"t@uf}#$%f Measurements indicate that chlorine of anthropogenic origin now dominates in the stratosphere. This model examines some of the chemistry related to the destruction of ozone and the effect of decreasing the production of chlorine compounds. The threat to the ozone layer is real. The damage has been done and will continue to affect future generations.&' 7" MM @M- E5#$%M:\ES97-54\SUN.pctܔ608O/FXߺ78 O/XߺT()&' 7" M ? @ ? ! 7& #$%*M:\ES97-54\STOCK.pctܔ608O/FXߺ78 O/ XߺT()&' 7"t@@@~"8#$%In the stratosphere, three cycles with HOx , NOx , ClOx are important. Each of the cycles and their role in the STELLA model are given. HOx cycle : Cl + O3 --> ClO + O2 OH + O3 --> HO2 + O2 HO2 + ClO --> HOCl + O2 HOCl + hv --> OH + Cl &' 7"t@;L#:CT#$%:Circles represent CONVERTERS which perform calculations. &' 7" MT @T!$L)#$%~M:\ES97-54\CONVERTR.pct08O/FXߺ78 O/2 XߺT()&' 7" Mu @uL70%mT#$%M:\ES97-54\CLCYCLE.PCT608O/FXߺ7~ 8 O/ XߺT()&' 7"NdHDdH &\@#$%&*An n +, 7-NEXT.' 7"tH@HN !'d2d )#$%dNOx cycle: Cl + O3 --> ClO + O2 ClO + NO --> Cl + NO2 NO2 + O --> NO + O2 &' 7" M f @ f p*( ^ x#$%M:\ES97-54\CYCLE2.PCT6/W!o#FXߺ/g7W! o#* g7XߺT()&' 7"NR DR s ^ )J { f#$%&*2A2_ n n +, 7-NEXT.' 7"t9#@9#*"#$%ClOx cycle: Cl + O3 --> ClO + O2 NO + O3 --> NO2 + O2 ClO + NO2 --> ClONO2 ClONO2 + hv --> Cl + NO3 NO3 + hv --> NO + O2 &' 7" M @ -+|"#$%n_ M:\ES97-54\CYCLE3.PCT66/-FXߺ). / - XߺT()&' 7"N.D.Q ,&{Y#$%&*_ A_ n n +, 7- MAIN MENU.' 7"ty@y3$- q;#$% Equations&' 7"t @ . #$% Problem : If human use of CFCs is reduced to zero, how long will it take for the destruction of the ozone layer to cease? With the Montreal Protocols in place, this STELLA model can predict when this will occur. In building this model, three assumptions were made: &' 7"N9tD9tY /1la#$%&*_ A_ n n +, 7-NEXT.' 7" D8 @0+V!#$% Graph 1&' 7"t@$1#$%Stratospheric Ozone and CFC's&' 7"RG5@2?P#$%&/hh 2!?.!01,  ' 7"Rn5@3fw#$%&/2?.01,  ' 7"R5@4'#$%&/2#?.#01,  ' 7"t@P 5}X$#$%}The units in the model are as follows: ~rates: molecules/year ~amounts: number molecules in the stratosphere &' 7"ND- 65#$%&* A_ n n +,-RUN.' 7"NDDD 7<#$%&* A_ n n +,-PAUSE.' 7"NDDD 8<#$%&* A_ n n +,-STOP.' 7"ND* 92#$%&* A_ n n +,-RESUME.' 7"N D J :R#$%&*B_ AN_ n n +, 7- MAIN MENU.' 7"R6Q@;#$%&/2 ?. 01,  ' 7"t@<  #$%1. The rates of formation and destruction of ozone are equal. 2. In calculating the volume of the stratosphere, a spherical earth is assumed. 3. Data reflect noontime values at mid-latitudes and at 30 km altitude. &' 7drmd 2plwh,u2plwh,2plwh,2plwh,2plwh,_2plwh,O2plwh, H ,NL ;@ 8CN" s@o#$%&' " s@6#$%&' " d@ #$%&' " f%@y&xs. '!H#p$%#c$c9&' " f@y;FM#$%#&' " sP@@{#$%&' " sUx@Ef #$%&' " s_tx@4Sp2#$%&' " c,6@Ti $*#$%&' " sx@ #$%&' " f:@ yNkv#AF$%#0[0[&' " aw,*]@ !<d:#$%&' " fd8 @ y.rp.0G#TT$%#B&' " s @ X#$%&' " fU" @y #$%#q&' " a`;!@[6&"#$%&' " s# @4J#$%&' " f  @ym/#$%# S&' " a`@!#$%&' " d:#@1CZ#$%&' " fX x@y*.2(#2~$%#q&' " sQx@&b#$%&' " cx@.#$%&' " sS@W>i#$%&' " sA@Z,W#$%&' " fx@yx_50 /#g-$%# Z&' " a @ #$%&' " a`@[#$%&' " s B@-#$%&' " f@y!=6sO#).$%#cc&' " a@ #$%&' " s8@#w#$%&' " f{N@ y\!#>>$%#v&' " ayB 1@!,~G#$%&' "t@k " s#$% NO SINK&' " fCJ@#yX-$#::$%#R&' " aG?#A'@$B<,D#$%&' " sF@%\#$%&' " f-@&y>'#FF$%#&' " a,&& @'!1#$%&' " d@(}#$%&' " fYT@)y b!*1#DD$%#]&' " adZ)1!@*_U&6#$%&' " dW,@+N`#$%&' " fd?@,yL+ #TT$%#&' " DW, @- Jn#$% CFC vs OZONE&' " aC 8j@.b2#$%&' " cx(@/0#$%&' " a$/ ?{@0b>#$%&' " dE)@1<Ne#$%&' " aCN@2M(]e#$%&' " m@3y@8I#$%#j&' " ag:?wQ@4#$%&' " lN@5t#$%&' " d`7@6Wi#$%&' " f @7y`BP6=#h:$%#<d&' " d3@8#$%&' " D@9 0R#$% DATA TABLE&' " sv!@:h4#$%&' " c#@;_DA=#$%&' " m"@<yZjS#bb$%#   &' " a;7@=#$%&' " lt$@>l+#$%&' " f%@?yh4C#`$%#W&' " cB @@)8[#$%&' """ cs?@Cf H#$%&' " fR@Dy MCEJM#$%#r&' " dD@Ez#$%&' " c<x@F mG#$%&' " aF kT@Gj7G#$%&' " aiC!@Hn"#$%&' " ce3@IXJ#$%&' " a_IDS@JNd#$%&' "t@: K B#$% HO2 SINK&' "t@i Lq#$%NO SINK&' " aNDA;@MK#$%&' drmdCB &66B?22=޺_ -= 3ZZZ==&= =@0@0.!@4@&'CFC PRODUCTION VS. 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