Line data Source code
1 : !----------------------------------------------------------------------------
2 : ! For calculating background ionization due to star light, geo-corona radiation
3 : ! Applicable to high altitudes of WACCM and WACCMX
4 : ! Module created by Francis Vitt 14 Feb 2013
5 : ! Background ionization algorithm provided by Stan Solomn
6 : !----------------------------------------------------------------------------
7 : module photo_bkgrnd
8 :
9 : use shr_kind_mod, only : r8 => shr_kind_r8
10 : use mo_chem_utls, only : get_rxt_ndx
11 : use ppgrid, only : pver
12 :
13 : implicit none
14 :
15 : private
16 : public :: photo_bkgrnd_calc
17 : public :: photo_bkgrnd_init
18 :
19 : integer :: jo_ndx, jo2_ndx, jn2_ndx, jn_ndx, jno_ndx
20 :
21 : contains
22 :
23 : !----------------------------------------------------------------------------
24 : ! look up corresponding reaction rate indices
25 : !----------------------------------------------------------------------------
26 0 : subroutine photo_bkgrnd_init()
27 0 : jo_ndx = get_rxt_ndx( 'jeuv_1' ) ! O + hv -> Op + e
28 0 : jo2_ndx = get_rxt_ndx( 'jeuv_5' ) ! O2 + hv -> O2p + e
29 0 : jn2_ndx = get_rxt_ndx( 'jeuv_6' ) ! N2 + hv -> N2p + e
30 0 : jn_ndx = get_rxt_ndx( 'jeuv_10') ! N2 + hv -> N + Np + e
31 0 : jno_ndx = get_rxt_ndx( 'jno_i' ) ! NO + hv -> NOp + e
32 0 : end subroutine photo_bkgrnd_init
33 :
34 : !----------------------------------------------------------------------------
35 : ! Adds background ionization rates to WACCM's photolysis rates
36 : !----------------------------------------------------------------------------
37 0 : subroutine photo_bkgrnd_calc(f107, o_den, o2_den, n2_den, no_den, zint, rates, &
38 0 : qbko1_out, qbko2_out, qbkn2_out, qbkn1_out, qbkno_out )
39 :
40 : ! arguments
41 : real(r8), intent(in) :: f107
42 : real(r8), intent(in) :: o_den(:) ! N density (molecules/cm^3)
43 : real(r8), intent(in) :: o2_den(:) ! O2 density (molecules/cm^3)
44 : real(r8), intent(in) :: n2_den(:) ! N2 density (molecules/cm^3)
45 : real(r8), intent(in) :: no_den(:) ! NO density (molecules/cm^3)
46 : real(r8), intent(in) :: zint(:) ! interface height (km)
47 :
48 : real(r8), intent(inout) :: rates(:,:) ! photolysis rates (sec-1)
49 :
50 : real(r8), intent(out), optional :: qbko1_out(:) ! rate (cm-3 sec-1) of O + hv -> Op + e
51 : real(r8), intent(out), optional :: qbko2_out(:) ! rate (cm-3 sec-1) of O2 + hv -> O2p + e
52 : real(r8), intent(out), optional :: qbkn2_out(:) ! rate (cm-3 sec-1) of N2 + hv -> N2p + e
53 : real(r8), intent(out), optional :: qbkn1_out(:) ! rate (cm-3 sec-1) of N + hv -> Np + e
54 : real(r8), intent(out), optional :: qbkno_out(:) ! rate (cm-3 sec-1) of N2 + hv -> NOp + e
55 :
56 : ! local vars
57 : real(r8), parameter :: km2cm = 1.e5_r8
58 : integer, parameter :: nmaj = 3
59 :
60 : real(r8) :: zmaj(nmaj,pver)
61 : real(r8) :: zno(pver)
62 : real(r8) :: zvcd(nmaj,pver)
63 : real(r8) :: delz(pver)
64 : real(r8) :: qbko1(pver)
65 : real(r8) :: qbko2(pver)
66 : real(r8) :: qbkn2(pver)
67 : real(r8) :: qbkn1(pver)
68 : real(r8) :: qbkno(pver)
69 :
70 : integer :: k
71 :
72 0 : zmaj(1,:) = o_den(:)
73 0 : zmaj(2,:) = o2_den(:)
74 0 : zmaj(3,:) = n2_den(:)
75 0 : zno(:) = no_den(:)
76 :
77 : ! thickness of each layer (cm)
78 0 : delz(1:pver-1) = km2cm*(zint(1:pver-1) - zint(2:pver))
79 0 : delz(pver) = delz(pver-1)
80 :
81 0 : zvcd(:,:) = 0._r8
82 :
83 : ! intergate column above each layer
84 0 : do k = 2,pver
85 0 : zvcd(1,k) = zvcd(1,k-1) + delz(k) * o_den(k)
86 0 : zvcd(2,k) = zvcd(2,k-1) + delz(k) * o2_den(k)
87 0 : zvcd(3,k) = zvcd(3,k-1) + delz(k) * n2_den(k)
88 : enddo
89 :
90 : ! invoke Stan's background ionization method -- returns rates (cm-3 sec-1)
91 0 : call qback (zmaj,zno,zvcd,f107,nmaj,pver,qbko1,qbko2,qbkn2,qbkn1,qbkno)
92 :
93 : ! divide by densities to get photolysis rates (sec-1)
94 0 : if (jo_ndx>0) rates(:,jo_ndx) = rates(:,jo_ndx) + qbko1(:)/o_den(:)
95 0 : if (jo2_ndx>0) rates(:,jo2_ndx) = rates(:,jo2_ndx) + qbko2(:)/o2_den(:)
96 0 : if (jn2_ndx>0) rates(:,jn2_ndx) = rates(:,jn2_ndx) + qbkn2(:)/n2_den(:)
97 0 : if (jn_ndx >0) rates(:,jn_ndx) = rates(:,jn_ndx) + qbkn1(:)/n2_den(:)
98 0 : if (jno_ndx>0) rates(:,jno_ndx) = rates(:,jno_ndx) + qbkno(:)/no_den(:)
99 :
100 : ! for diagnostics
101 0 : if (present(qbko1_out)) qbko1_out(:) = qbko1(:)
102 0 : if (present(qbko2_out)) qbko2_out(:) = qbko2(:)
103 0 : if (present(qbkn2_out)) qbkn2_out(:) = qbkn2(:)
104 0 : if (present(qbkn1_out)) qbkn1_out(:) = qbkn1(:)
105 0 : if (present(qbkno_out)) qbkno_out(:) = qbkno(:)
106 :
107 0 : endsubroutine photo_bkgrnd_calc
108 :
109 : !----------------------------------------------------------------------------
110 : ! Private Method
111 : !----------------------------------------------------------------------------
112 : !
113 : ! Stan Solomon, 11/88, 11/92
114 : ! Comment updated 3/05
115 : ! New version uses updated TIE-GCM and TIME-GCM qinite.F formulation, 1/13
116 : !
117 : ! Estimates background ("nighttime") ionization rates.
118 : ! Four components are used:
119 : ! Geocoronal Lyman-beta 102.6 nm (ionizes O2 only)
120 : ! Geocoronal He I 58.4 nm
121 : ! Geocoronal He II 30.4 nm
122 : ! Geocoronal Lyman-alpha 121.6 nm (ionizes NO only)
123 : !
124 : ! Definitions:
125 : !
126 : ! zmaj major species O, O2, N2 at each altitude
127 : ! zno nitric oxide at each altitude
128 : ! zvcd vertical column density for each major species above each altitude
129 : ! photoi photoionization rates for each state, species, altitude
130 : ! f107 solar 10.7 cm radio flux activity index
131 : ! jm number of altitude levels
132 : ! nmaj number of major species (3)
133 : ! nst number of states
134 : !
135 : ! al photon flux at 102.6 nm, 58.4 nm, 30.4 nm
136 : ! flyan photon flux at 121.6 nm
137 : ! sa absorption cross sections for O, O2, N2 at each wavelength
138 : ! si ionization cross sections for O, O2, N2 at each wavelength
139 : ! flyan photon flux at 121.6 nm
140 : ! salyao2 absorption cross section for O2 at 121.6 nm
141 : ! silyano ionization cross section for NO at 121.6 nm
142 : ! bn2p branching ratio for N2+ from ionization of N2
143 : ! bn1p branching ratio for N+ from ionization of N2
144 : ! tau optical depth
145 : ! qbko1 production rate of O+
146 : ! qbko2 production rate of O2+
147 : ! qbkn2 production rate of N2+
148 : ! qbkn1 production rate of N+
149 : ! qbkno production rate of NO+
150 : !
151 : ! All units cgs.
152 : !
153 : !
154 0 : subroutine qback (zmaj,zno,zvcd,f107,nmaj,jm,qbko1,qbko2,qbkn2,qbkn1,qbkno)
155 :
156 : ! args:
157 : integer, intent(in) :: nmaj,jm
158 : real(r8), intent(in) :: f107
159 : real(r8), intent(in) :: zmaj(nmaj,jm), zno(jm), zvcd(nmaj,jm)
160 : real(r8), intent(out) :: qbko1(jm),qbko2(jm),qbkn2(jm),qbkn1(jm),qbkno(jm)
161 :
162 : ! local vars:
163 : real(r8) :: al(3), sa(3,3), si(3,3)
164 : real(r8) :: salyao2, silyano, bn2p, bn1p
165 : real(r8) :: flyan
166 : real(r8) :: tau
167 : integer :: j,l
168 :
169 : data al /1.5e7_r8, 1.5e6_r8, 1.5e6_r8/
170 :
171 : data sa / 0._r8, 1.6e-18_r8, 0._r8, &
172 : 10.2e-18_r8, 22.0e-18_r8, 23.1e-18_r8, &
173 : 8.4e-18_r8, 16.0e-18_r8, 11.6e-18_r8/
174 :
175 : data si / 0._r8, 1.0e-18_r8, 0._r8, &
176 : 10.2e-18_r8, 22.0e-18_r8, 23.1e-18_r8, &
177 : 8.4e-18_r8, 16.0e-18_r8, 11.6e-18_r8/
178 :
179 : data salyao2/8.0e-21_r8/
180 : data silyano/2.0e-18_r8/
181 : data bn2p/0.86_r8/
182 : data bn1p/0.14_r8/
183 :
184 : !
185 : ! Calculate Lyman-alpha 121.6 nm geocoronal flux as a function of F10.7:
186 : !
187 0 : flyan = 5.E9_r8*(1._r8+0.002_r8*(f107-65._r8))
188 : !
189 : ! Loop over altitudes:
190 : !
191 0 : do j=1,jm
192 : !
193 : ! Calculate optical depth and ionization rates for major species:
194 : !
195 0 : qbko1(j)=0._r8
196 0 : qbko2(j)=0._r8
197 0 : qbkn2(j)=0._r8
198 0 : qbkn1(j)=0._r8
199 0 : do l=1,3
200 0 : tau=(sa(1,l)*zvcd(1,j)+sa(2,l)*zvcd(2,j)+sa(3,l)*zvcd(3,j))
201 0 : qbko1(j) = qbko1(j) + al(l)*si(1,l)*zmaj(1,j)*exp(-tau)
202 0 : qbko2(j) = qbko2(j) + al(l)*si(2,l)*zmaj(2,j)*exp(-tau)
203 0 : qbkn2(j) = qbkn2(j) + bn2p*(al(l)*si(3,l)*zmaj(3,j)*exp(-tau))
204 0 : qbkn1(j) = qbkn1(j) + bn1p*(al(l)*si(3,l)*zmaj(3,j)*exp(-tau))
205 : enddo
206 : !
207 : ! Calculate optical depth of Ly-alpha, and ionization rate of NO:
208 : !
209 0 : tau = salyao2*zvcd(2,j)
210 0 : qbkno(j) = flyan*silyano*zno(j)*exp(-tau)
211 :
212 : enddo
213 :
214 0 : return
215 : end subroutine qback
216 :
217 : end module photo_bkgrnd
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