Atmospheric Chemistry Reactions

Natural Stratosphere

Chapman Mechanism


R1	O2 + hv -> 2O               J1     to be calculated
R2	O + O2 + m -> O3 + m        k2   = 6.0e-34/((temp/300)**2.3)
R3a	O3 + hv -> O(1D) + O2       J3a    to be calculated
R3b	O3 + hv -> O(3P) + O2       J3b    to be calculated
R4	O + O3 ->  2O2              k4   = 8.0e-12*exp(-2060./temp)

O(1D) Chemistry [Don't forget R3a]


R5	N2O + hv -> O(1D) + N2      J5     to be calculated
R6 	O(1D) + m -> O(3P) + m      k6   = 2.1e-11*exp(+100/temp)
R7a	O(1D) + H2O -> 2OH          k7a  = 2.2e-10
R7b	O(1D) + N2O -> 2NO          k7b  = 6.7e-11

HxOy Chemistry


R8	OH + O3 -> HO2 + O2         k8   = 1.6e-12*exp(-940/temp)
R9	HO2 + O3 -> OH + 2O2        k9   = 1.1e-14*exp(-500/temp)
R10	OH + O -> HO2               k10  = 2.2e-11*exp(+120/temp)
R11	HO2 + O -> OH + O2          k11  = 3.0e-11*exp(+200/temp)
R12	HO + HO2 -> H2O + O2        k12  = 4.8e-11*exp(+250/temp)
R13a	HO2 + HO2 -> H2O2 + O2      k13a = (2.3e-13*exp(+600/temp) +    
                                           nm*1.7e-33*exp(+1000/temp))

[NOTE: k13a is a 2-body + an effective 3-body rate coefficient]


R13b	OH + OH + m -> H2O2 + m     k13b = 6.9e-31/((temp/300)**0.8)
R14	H2O2 + hv -> 2OH            J14    to be calculated
R15	H2O2 + OH -> H2O + HO2      k15  = 2.9e-12*exp(-160/temp)

NOy Chemistry


R16 	NO + O3 -> NO2 + O2         k16  = 2.0e-12*exp(-1400/temp)
R17	NO2 + hv -> NO + O          J17    to be calculated
R18 	NO2 + O -> NO + O2          k18  = 6.5e-12*exp(+120/temp)
R19	OH + NO2 + m -> HNO3 + m    k19  = 2.6e-30/((temp/300)**3.2)
	[high pressure 2-body limit k19  = 2.4e-11/((temp/300)**1.3)]
R20	HNO3 + hv -> OH + NO2       J20    to be calculated
R21	OH + HNO3 -> H2O +          k21  = 7.2e-15*exp(785/temp)
                     NO2 + O
[NOTE - in the troposphere k21 is more complex]

Additional NOy Reactions for Class Information


R22	NO2 + O3 -> NO3 + O2        k22  = 1.2e-13*exp(-2450./temp)
R23a 	NO3 + hv -> NO + O2         J23a   to be calculated
R23b	NO3 + hv -> NO2 + O         J23b   to be calculated
R24a	NO3 + NO2 + m -> N2O5 + m   k24a = 2.2e-30/((temp/300)**3.9)
	[high pressure 2-body limit k24a = 1.5e-12/(temp/300)**0.7)]
R24b 	N2O5 -> NO2 + NO3           K24b = k24a/(2.7e-27*exp(11,000./temp))
R25	N2O5 + hv -> NO2 + NO3	    J25    to be calculated
R26	N2O5 + aerosol -> removal   k26    to be determined

Another Potential NOy Reservoir


R27a 	NO2 + HO2 + m -> HO2NO2 + m k27a = 1.8e-31/((temp/300)**3.2)
	[high pressure 2-body limit k27a = 4.7e-12/((temp/300)**1.4)]
R27b	HO2NO2 -> HO2 + NO2         k27b = k27a/(2.1e-27*exp(10,900/temp)
R28 	HO2NO2 + hv -> HO2 + NO2 J28 to be calc., though some ? about products
R29	HO2NO2 + OH -> products     k29  = 1.3e-12*exp(+380/temp)

Tropospheric Chemical Reactions [NOTE: All reactions that require O2 treat the O2 implicitly (O2). The O2 is NOT considered one of the reactants AND the rate coefficients are 2-body, except for J37 and J38 which are photodissociation rate coefficient.


R21     OH + HNO3 -> H2O +	    [The more complex form for the troposphere]
		     NO2 + O	    k21 = 7.2e-15*exp(785/temp) +
					  (1.9e-33*exp(725/temp)*nm(z))/
					  (1.0 + (1.9e-33*exp(725/temp)*nm(z)/
					  (4.1e-16*exp(1440/temp))))
R30	NO + HO2 -> NO2 + OH	    k30  = 3.7e-12*exp(250/temp)
R31     HNO3 or H2O2 -> deposition  k31  = 1e-5 (z = 0.0)
					 = 2e-6 (z = 5.0)
  					 = 6e-7 (z = 10.0)
          				 = 0.0  (z > 10.0)
R32	OH + CO (O2)-> CO2 + HO2    k32  = 1.5e-13*(1 + (0.6*nm(iz)/nm(1)))
R33     OH + CH4 (O2)-> H2O + CH3O2 K33  = 2.65e-12*exp(-1800/temp)
R34     CH3O2 + NO (O2)-> H2CO + HO2 
                          + NO2     K34  = 4.2e-12*exp(180/temp)
R35     CH3O2 + HO2 -> CH3OOH + O2  K35  = 3.8e-13*exp(800/temp)
R36    	H2CO + OH (O2)-> H2O + HO2
                             + CO   K36  = 1.0e-11
R37a 	H2CO + hv (O2)-> CO + 2HO2  J37a = pch2oa(iz) in Photocalc
R37b	H2CO + hv     -> CO + H2    J37b = pch2ob(iz) in Photocalc
R38	CH3OOH + hv (O2)-> H2CO + 
                           HO2 + OH J38  = pch3ooh(iz) in Photocalc
R39	CH3OOH + OH -> H2O + CH3O2  K39  = 3.8e-12*exp(200/temp)