Ionosphere-atmosphere interaction (during solar proton events) Pekka T. Verronen Finnish Meteorological Institute, Earth Observation, Helsinki, Finland Research seminar on Sun-Earth connections, Feb 22, 2006 P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 1 / 47 Contents 1 About middle atmosphere and ionosphere Ozone Catalysts NOx and HOx D region of ionosphere 2 Solar proton events, forcing from the Sun Increase in D-region ionization Production of NOx and HOx , and subsequent loss of ozone 3 Open questions Further reading P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 2 / 47 About middle atmosphere and ionosphere Outline 1 About middle atmosphere and ionosphere Ozone Catalysts NOx and HOx D region of ionosphere 2 Solar proton events, forcing from the Sun Increase in D-region ionization Production of NOx and HOx , and subsequent loss of ozone 3 Open questions Further reading P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 3 / 47 About middle atmosphere and ionosphere Middle atmosphere 120 120 110 110 100 100 Mesopause 90 90 80 80 70 70 60 60 Stratopause 50 50 Altitude [km] 40 40 30 30 20 Tropopause 20 10 10 0 0 10 15 20 100 200 300 400 10 10 10 −3 Temperature [K] Concentration [cm ] P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 4 / 47 About middle atmosphere and ionosphere Chemical composition Main middle atmospheric constituents are N2 (78%) and O2 (21%), the remaining 1% is mostly argon. Minor constituents, such as O3 and CO2, play important role in atmospheric chemistry, and heating and cooling processes. Constituents are either produced in the ground level and transported into the middle atmosphere, or produced in-situ by photochemical processes. Some have extra-terrestrial origin. P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 5 / 47 About middle atmosphere and ionosphere Chemical composition II Continuity equation Time-dependent concentration of an atmospheric species j can be solved from the continuity equation ∂n j = P − L n − ∇ · (n v¯ ) (1) ∂t j j j j j where nj = concentration, t = time, Pj = local production rate, Lj nj = local loss rate, and v¯j = velocity. Transport Winds, air parcel transport Diffusion, mixing of gases P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 6 / 47 About middle atmosphere and ionosphere Dissociation/ionization at alt. zo (see present. by K. Kauristie) Z qj (zo, χ) = I(λ, zo, χ) ηj (λ) σj (λ) nj (zo) dλ, (2) λ I(λ, zo, χ) = photon flux, σj (λ) = cross section, nj (zo) = gas concentration, ηj = efficiency, λ = wavelength, χ = zenith angle. Chemical reactions For a two-body reaction A + B → C + D (3) the reaction rate R is obtained from R = k[A][B], (4) k is the T-dependent reaction rate coefficient (from lab. work), while [A] and [B] are the concentrations of constituents A and B. P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 7 / 47 About middle atmosphere and ionosphere Ozone Outline 1 About middle atmosphere and ionosphere Ozone Catalysts NOx and HOx D region of ionosphere 2 Solar proton events, forcing from the Sun Increase in D-region ionization Production of NOx and HOx , and subsequent loss of ozone 3 Open questions Further reading P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 8 / 47 About middle atmosphere and ionosphere Ozone Ozone is a key constituent in the atmosphere A minor gas Abundance ≤ 10 ppmv Absorbs UV radiation Important to the thermal balance and dynamics Protects life on Earth The ozone layer Located at 15–35 km Affected by CFC gases Ozone hole at Antarctica P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 9 / 47 About middle atmosphere and ionosphere Ozone Ozone chemistry and transport Catalytic destruction Chapman, [1930] XO + O → X + O2 O2 + hν → O + O X + O3 → XO + O2 O + O2 + M → O3 + M Net : O3 + hν → O2 + O O + O3 → 2O2 O + O3 → 2O2 X can be Br, Cl, OH, or NO Distribution by transport Production depends upon solar light, strongest in the equator Highest amount are found in the polar regions Chemical loss processes require solar radiation P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 10 / 47 About middle atmosphere and ionosphere Ozone Total ozone column EOS-Aura/OMI instrument P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 11 / 47 About middle atmosphere and ionosphere Ozone Ozone yearly mean for 2003 Envisat/GOMOS instrument O3 mixing ratio 100 8 5 10 6 9 7 7 7 6 2 1 0.2 8 8 0 8 7 7 8 9 6 6 90 4 5 7 9 0.1 4 5 3 3 4 2 2 3 65 1 1 0.5 0.4 0.4 0.3 0.3 0.5 0.3 0.5 80 0.2 0.4 8 0.5 0.2 0.2 0.4 0.3 0.5 0.40.3 1 1 70 1 7 0.055176 60 6 0 0.2 2 2 2 50 3 5 0.1 3 Altitude [km] 4 4 3 0.5 5 5 10.4 0.3 6 4 40 7 7 4 6 6 7 8 9 8 30 0.055176 5 8 3 9 5 7 65 4 2 4 3 4 3 2 0.2 0 3 20 0.5 1 2 2 0.2 0.30.4 1 1 0.40.5 0.1 0.40.5 10 0.3 0.3 1 −80 −60 −40 −20 0 20 40 60 80 Latitude P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 12 / 47 About middle atmosphere and ionosphere Catalysts NOx and HOx Outline 1 About middle atmosphere and ionosphere Ozone Catalysts NOx and HOx D region of ionosphere 2 Solar proton events, forcing from the Sun Increase in D-region ionization Production of NOx and HOx , and subsequent loss of ozone 3 Open questions Further reading P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 13 / 47 About middle atmosphere and ionosphere Catalysts NOx and HOx Odd nitrogen and odd hydrogen Odd hydrogen HOx = (H + OH + HO2) Odd nitrogen NOx = (N + NO + NO2) Are chemically active, main catalysts of ozone loss in the upper stratosphere (NOx) and mesosphere (HOx). Particle precipitation in the polar regions contributes to their production −→ Important role in Sun-Earth connection. P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 14 / 47 About middle atmosphere and ionosphere Catalysts NOx and HOx NOx production OHx production In the stratosphere, and From water vapour lower thermosphere 1 1 H2O + O( D) → 2OH N2O + O( D) → 2NO + ∗ H2O + hν → OH + H N2 + hν → N2 + e ∗ ∗ e + N2 → 2N + e OHx loss N + O2 → NO + O “Cannibalistic” reactions, such as NOx loss Requires solar radiation OH + HO2 → H2O + O2 NO + hν → N + O Short chemical lifetime, transport can be neglected N + NO → N2 + O P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 15 / 47 About middle atmosphere and ionosphere Catalysts NOx and HOx Odd nitrogen profiles NO at noon, equinox, high latitude, SIC model x 100 Production from N N 2 NO NO 90 2 80 70 Altitude[km] 60 50 40 Production from N O 2 30 5 6 7 8 9 10 10 10 10 10 Concentration [cm−3] P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 16 / 47 About middle atmosphere and ionosphere Catalysts NOx and HOx Odd hydrogen profiles HO at noon, equinox, high latitude, SIC model x 100 Dynamical control 90 Decrease of H O 2 80 70 Altitude[km] 60 50 40 H OH HO 2 30 5 6 7 8 9 10 10 10 10 10 Concentration [cm−3] P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 17 / 47 About middle atmosphere and ionosphere D region of ionosphere Outline 1 About middle atmosphere and ionosphere Ozone Catalysts NOx and HOx D region of ionosphere 2 Solar proton events, forcing from the Sun Increase in D-region ionization Production of NOx and HOx , and subsequent loss of ozone 3 Open questions Further reading P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 18 / 47 About middle atmosphere and ionosphere D region of ionosphere Ionospheric D-region Lowest region of the ionosphere, at 60–90 km, overlaps with the mesosphere, relatively low electron density: 102 − 104 cm−3 Chemically much more complex than the regions above, because minor neutrals become important Ionization sources Specialities Lyman-α multitude of ions EUV negative ions hard X-rays cluster ions particle precipitation complex chemistry P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 19 / 47 About middle atmosphere and ionosphere D region of ionosphere Quiet-time ionization rates 120 110 100 90 Altitude [km] 80 N2 (EUV/X−ray) O2 (EUV/X−ray) 70 NO (Lyman−alpha) O2(1Dg) (EUV) N2 (GCR) N2 (photoelectrons) 60 4 5 6 7 8 9 10 10 10 10 10 10 10 10 Ionisation rate [m−3 s−1] P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 20 / 47 About middle atmosphere and ionosphere D region of ionosphere Charge balance recombination recombination ionisation neutral side ionic side X+ e- attachment X- detachment P. T. Verronen (FMI, Earth Observation) Ionosphere-atmosphere interaction Sun-Earth connections 21 / 47 About middle atmosphere and ionosphere D region of ionosphere Positive ion reactions P.