Ozone depletion in the middle atmosphere during solar proton events in October 2003

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    to estimate the rates of ionelectron pair, odd-nitrogen and odd-hydrogen production. Our calculations show that the production of odd-hydrogen causes the ozone depletion by the factor 2 and more at the altitudes higher than 55 km. This depletion is in an agreement with

    et al., 1981; Solomon et al., 1981, 1983a; Jackman et al.,

    HOx1 +O!HOx+O2, x=0, 1. 2b

    tion of odd-nitrogen and odd-hydrogen through reactions

    selves by the traditional point of view in the calculationof the odd-nitrogen and odd-hydrogen inuence on theozone balance according to processes (1a,b) and (2a,b).The main goal of the paper is to study ozone concentrationdepletions observed in the middle atmosphere during SPEseries in October 2003.

    * Corresponding author. Tel.: +7 81555 79760.E-mail addresses: sunactivity@yahoo.se (Kh. Fadel), kirillov@pgi.

    kolasc.net.ru (A.S. Kirillov).

    Advances in Space Research 382000; Krivolutsky et al., 2001; Kirillov, 2004a). The odd-ni-trogen NOx and odd-hydrogen HOx can cause ozonedepletion in the mesosphere and stratosphere through thecatalytic cycles (including NO + NO2 and H + OH + HO2)(Brasseur and Solomon, 1984):

    NOx+O3!NOx1 +O2, 1aNOx1 +O!NOx+O2, x=1, 1band

    HOx+O3!HOx1 +O2, 2a

    in the middle atmosphere. Also it was concluded in(Kirillov, 2004a) that there is an eective production ofsinglet molecular oxygen (excited in metastable a1Dg orb1Rg states principally in vibrational level v = 0) and highlyvibrationally excited O2 (in ground X 3R

    g state, v > 20)

    in the middle atmosphere during solar proton events(SPEs).

    Here we do not consider, however, any role of electronicand vibration kinetics in chemical balance of the middleatmosphere. This is the complicated independent taskwhich is beyond the given study. So here we will limit our-measurements of O3 altitude proles made on POAM-3 satellite. 2006 COSPAR. Published by Elsevier Ltd. All rights reserved.

    Keywords: Solar proton event; Middle atmosphere; Ozone depletion; Odd-nitrogen; Odd-hydrogen

    1. Introduction

    Solar protons precipitating in the middle atmosphereproduce large amounts of odd-nitrogen, odd-hydrogenand electronically excited atoms and molecules (Rusch

    Moreover, solar protons and secondary electrons causethe eective electronic excitation of main atmospheric com-ponents N2 and O2 in inelastic collisions. It was proposedin (Toumi, 1993; Zipf and Prasad, 1998) that electronicallyexcited molecular oxygen could cause the sucient produc-Ozone depletion in the msolar proton even

    Kh. Fadel a, E.V. Vasha Swedish Institute of Space Physi

    b Polar Geophysical Institute, A

    Received 23 December 2004; received in revi


    A one-dimensional time-dependent model has been used to caatmosphere during solar proton precipitations in October 2003. W0273-1177/$30 2006 COSPAR. Published by Elsevier Ltd. All rights reservdoi:10.1016/j.asr.2006.04.015ddle atmosphere duringin October 2003

    yuk b, A.S. Kirillov b,*

    mea University, Kiruna, Sweden

    tity, Murmansk region, Russia

    form 18 April 2006; accepted 19 April 2006

    late the production and loss of minor components of the middlesed the solar proton uxes measured on the GOES-11 spacecraft


    (2006) 18811886ed.

  • ace2. The model

    The model considers a production of a set of minorcomponents in the middle atmosphere by the solar lightabsorption and by energetic proton and secondary electronimpacts. The set includes atomic oxygen O(3P, 1D), ozoneO3, atomic nitrogen N(

    4S, 2D), odd-nitrogen NOx (nitricoxide, nitrogen dioxide and trioxide), dinitrogen pentoxideN2O5, nitrous oxide N2O, odd-hydrogen HOx (atomichydrogen, hydroxyl and hydroperoxy radicals), even-hy-drogen H2Ox (molecular hydrogen, water vapor andhydrogen peroxide), HNOx (nitrous, nitric and peroxyni-tric acids), COx (carbon monoxide and dioxide), CHx(methyl and methane), CHxOy (formyl radical, formalde-hyde, methoxy and methylperoxy radicals and methylhydroperoxide), chlorine and bromide compounds: X2,X, HX, HOX, XO and XONO2 (here X = Cl or Br),unsymmetric ClOO and symmetric OClO chlorine diox-ides, chlorine oxides Cl2Ox (x = 13), BrCl. One hundredand thirty seven chemical reactions between the compo-nents are included in the model (Atkinson et al., 2005;Sander et al., 2003).

    Since the reaction of nitrous oxide with electronicallyexcited atomic oxygen

    N2O+O (1D)!NO+NO 3

    is the main production channel of odd-nitrogen in thestratosphere during quiet period (Jackman et al., 1980)we input N2O concentrations according to (Olsen et al.,2001). The source of odd-hydrogen is the direct photolysisof H2O and by the reactions (Solomon et al., 1983b; Crut-zen, 1997)

    H2O+O (1D)!OH+OH, 4

    H2 +O (1D)!H+OH. 5

    The concentrations of even hydrogen H2O and H2 weretaken equal to 6 ppmv and 0.5 ppmv, respectively, (Robleand Dickinson, 1989), decreasing at altitudes higher than70 km and lower than 40 km for H2O (Gunson et al.,1990; Zhou et al., 1997). So concentration proles ofN2O, H2O and H2 are taken as invariable in time in ourcalculations.

    Also we consider concentration proles for carbon diox-ide CO2 and methane CH4 as invariable. Data for CO2were taken according to (Zaragoza et al., 2000) and forCH4 according to (Gunson et al., 1990; Zhou et al.,1997). Seasonal variation of long-lived trace gases (Sum-mers et al., 1997) are neglected in our consideration.

    We input initial concentration proles for chlorine com-pounds HCl, HOCl, ClO and ClONO2 according to(Michelsen et al., 1996; Zander et al., 1996). Initial concen-tration proles for bromine compounds Br2, Br, HBr,HOBr, BrO, BrONO2 and BrCl were taken according to

    1882 Kh. Fadel et al. / Advances in SpBrO proles measured in (Harder et al., 1998) and normal-ised to be in agreement with model data of Lary (1996).Dierent spectral intervals of the solar light are impor-tant in the dissociative processes of O2 and minor compo-nents, so the solar spectral irradiance in visible andultraviolet regions used in the model calculations was takenaccording to (Mount and Rottman, 1981; Nicolet, 1989).Absorption cross sections for major gas O2 and minorcomponents were taken mainly according to (Atkinsonet al., 2005; Finlayson-Pitts and Pitts, 2000; Sander et al.,2003). All spectrum diapason 120900 nm is divided inthe intervals with the width of 1 nm. The decrease of theintensity of solar light in the every interval was calculatedaccording to exponential LambertBeer law where theoptical depth at the altitude h includes the contributionof all atmospheric components having non-zero cross sec-tions of solar light absorption.

    To calculate the rates of ionelectron pair production byprecipitated particles we use the following formula for ratesof solar proton energy dissipated in cubic centimeter persecond at the altitude h (Dorman, 1975, chapter 6):

    wh qhAZ EmaxEmin

    Z p2


    f E Em1 Am 1 Xcos h


    2p sin hdEdh: 6Here q is the density of the atmosphere, f(E) is the energeticspectrum of solar protons, X is the respective depth ing/cm2, Emin = 1 MeV, Emax = 400 MeV and parameters Aand m are equal to 242 and 0.75, respectively. The rate ofionelectron pair production is related with the valuew(h) by the relation

    qh whQ

    ; 7

    where Q is equal to 35 eV. Here we suggest the isotropicdistribution of solar protons on the pitch angle h in allour calculations.

    The continuity non-stationary equations

    oniot o


    onioh 1

    ToToh 1Hi


    P i Lini 8

    are solved for minor components of the middle atmo-sphere. Here ni and Hi is the concentration and the scaleheight of the ith component, D is the diusion coecient,T is the temperature, Pi and Li are the production and lossrates of the ith component. The production and loss ratesinclude the contributions from dissociative processes relat-ed with solar light inelastic scattering, chemical reactions,production of minor components in collisions of protonsand secondary electrons with main atmospheric compo-nents. Diusion coecient adopted in our study was takenaccording to (Crutzen et al., 1978). Upper and lower bor-ders in our calculation are at 90 km and 20 km, respective-ly. Border conditions are given uxes at 90 km andphotochemical equilibrium at 20 km. The time integrationof Eq. (8) were carried out explicitly, in which case the spa-

    Research 38 (2006) 18811886tial derivative terms are only evaluated at known time (pre-ceding step in time) (Rood, 1987). Time and altitude steps

  • is suggested for spectral interval 120145 nm (Stief et al.,1975). The cross section for solar Lyman-a line (121.6 nm)is equal to 2 1017 cm2 (Sonnemann et al., 1977).

    Absorption spectrum of carbon dioxide CO2 was takenaccording to (Thompson et al., 1963) for the spectral inter-val 120200 nm. The quantum yield of 1.0 for the process

    CO2 + hm!CO+O (1D)is suggested for spectral interval 120167 nm (Lin and Bau-er, 1969).

    3. Experimental data on solar protons

    Ionization eects in middle atmosphere in late October,2003 were caused by the SPEs of 28 and 29 October. Char-acteristics of the parent solar ares are presented in Table1. Fig. 1 shows intensity proles of solar protons with ener-gies >10 MeV, >30 MeV and >100 MeV as measured atGOES-11 spacecraft. Two maxima on the intensity curvescorrespond to the two SPEs: on 28 and 29 October. Byarrows at the time axis are shown the times of the relevantares (Table 1). The date, the time of X-ray maximum(probable moment of particle acceleration), are impor-tance and heliocoordinates are shown in respective col-umns of Table 1.

    The dierential energy spectra of solar protons werederived using the GOES-11 dat