c Subroutine QBACK c c Stan Solomon, 11/88, 11/92 c Comment updated 3/05 c New version uses updated TIE-GCM and TIME-GCM qinite.F formulation, 1/13 c c Estimates background ("nighttime") ionization rates. c Four components are used: c Geocoronal Lyman-beta 102.6 nm (ionizes O2 only) c Geocoronal He I 58.4 nm c Geocoronal He II 30.4 nm c Geocoronal Lyman-alpha 121.6 nm (ionizes NO only) c c Definitions: c c zmaj major species O, O2, N2 at each altitude c zno nitric oxide at each altitude c zvcd vertical column density for each major species above each altitude c photoi photoionization rates for each state, species, altitude c f107 solar 10.7 cm radio flux activity index c jm number of altitude levels c nmaj number of major species (3) c nst number of states c c al photon flux at 102.6 nm, 58.4 nm, 30.4 nm c flyan photon flux at 121.6 nm c sa absorption cross sections for O, O2, N2 at each wavelength c si ionization cross sections for O, O2, N2 at each wavelength c flyan photon flux at 121.6 nm c salyao2 absorption cross section for O2 at 121.6 nm c silyano ionization cross section for NO at 121.6 nm c bn2p branching ratio for N2+ from ionization of N2 c bn1p branching ratio for N+ from ionization of N2 c tau optical depth c qbo1 production rate of O+ c qbo2 production rate of O2+ c qbn2 production rate of N2+ c qbn1 production rate of N+ c qbno production rate of NO+ c c All units cgs. c c subroutine qback (zmaj,zno,zvcd,photoi,phono,f107,jm,nmaj,nst) c dimension zmaj(nmaj,jm), zno(jm), zvcd(nmaj,jm), > photoi(nst,nmaj,jm), phono(nst,jm) c dimension al(3), sa(3,3), si(3,3) c data al /1.5e7, 1.5e6, 1.5e6/ data sa / 0., 1.6e-18, 0., > 10.2e-18, 22.0e-18, 23.1e-18, > 8.4e-18, 16.0e-18, 11.6e-18/ data si / 0., 1.0e-18, 0., > 10.2e-18, 22.0e-18, 23.1e-18, > 8.4e-18, 16.0e-18, 11.6e-18/ data salyao2/8.0e-21/ data silyano/2.0e-18/ data bn2p/0.86/ data bn1p/0.14/ c c Calculate Lyman-alpha 121.6 nm geocoronal flux as a function of F10.7: c flyan = 5.E9*(1.+0.002*(f107-65.)) c c Loop over altitudes: c do j=1,jm qbo1 = 0. qbo2 = 0. qbn2 = 0. qbn1 = 0. c c Calculate optical depth and ionization rates for major species: c do l=1,3 tau=(sa(1,l)*zvcd(1,j)+sa(2,l)*zvcd(2,j)+sa(3,l)*zvcd(3,j)) qbo1 = qbo1+al(l)*si(1,l)*zmaj(1,j)*exp(-tau) qbo2 = qbo2+al(l)*si(2,l)*zmaj(2,j)*exp(-tau) qbn2 = qbn2+bn2p*(al(l)*si(3,l)*zmaj(3,j)*exp(-tau)) qbn1 = qbn1+bn1p*(al(l)*si(3,l)*zmaj(3,j)*exp(-tau)) enddo c c Calculate optical depth of Ly-alpha, and ionization rate of NO: c tau = salyao2*zvcd(2,j) qbno = flyan*silyano*zno(j)*exp(-tau) c c Increment ionization rate arrays with background ionization: c photoi(1,1,j) = photoi(1,1,j) + qbo1 photoi(1,2,j) = photoi(1,2,j) + qbo2 photoi(1,3,j) = photoi(1,3,j) + qbn2 photoi(6,3,j) = photoi(6,3,j) + qbn1 phono(1,j) = phono(1,j) + qbno c enddo c c return end