Direct effects of particle precipitation and ion chemistry in the middle atmosphere P. T. Verronen Finnish Meteorological Institute, Earth Observation Helsinki, Finland
Contents of presentation 1. Middle atmospheric effects of energetic particle precipitation (EPP) 2. Sodankylä Ion and Neutral Chemistry Model (SIC) Analysis of the ion chemistry scheme Parameterization of EPP-related changes in HO x and NO y 3. SIC model versus MLS/Aura observations: SPEs of January 2005 and December 2006 Production of HNO 3 and OH 4. Summary ISSI Georgieva, Bern, 24 28 March 2014 2
Energetic particle precipitation Earth s magnetic field directs charged particles into polar regions EPP affects both ionosphere and middle atmosphere ISSI Georgieva, Bern, 24 28 March 2014 3
Different types of particle precipitation From a presentation by Randall et al., 2008 ISSI Georgieva, Bern, 24 28 March 2014 4
SPE: example of geomagnetic cutoff Rodger et al., Journal of Geophysical Research (2006) ISSI Georgieva, Bern, 24 28 March 2014 5
Effects of energetic particle precipitation (EPP) energetic particles precipitate into atmosphere N( 2 D) N 2 + O + O 2 + O 4 + O 2+ (H 2 O) HO 3 + (H 2 O) n NO x HO x Ozone loss Ozone connects to temperature and dynamics ISSI Georgieva, Bern, 24 28 March 2014 6
Sodankylä Ion and Neutral Chemistry (SIC) ISSI Georgieva, Bern, 24 28 March 2014 7
SIC: D-region ion chemistry 36 positive ions, 29 negative ions, 400 reactions ISSI Georgieva, Bern, 24 28 March 2014 8
Changes in hydrogen and nitrogen species Particles precipitate into middle atmosphere Positive ion chemistry dissociates N 2 and H 2 O Negative ion chemistry redistributes NO y (inside the blue box) From Verronen and Lehmann, Ann. Geophys., 2013. ISSI Georgieva, Bern, 24 28 March 2014 9
SIC: example of HO x production paths N 2 + p + (E) N + 2 + e + p + (E E) N + 2 + O 2 O + 2 + N 2 O + 2 + O 2 + M O + 4 + M O + 4 + H 2O O + 2 (H 2O) + O 2... O + 2 (H 2O) 2 + H 2 O H 3 O + (OH)H 2 O + O 2 H 3 O + (OH)H 2 O + H 2 O H + (H 2 O) 3 + OH H + (H 2 O) 3 + H 2 O + M H + (H 2 O) 4 + M H + (H 2 O) 4 + e H + 4H 2 O Net : H 2 O OH + H ISSI Georgieva, Bern, 24 28 March 2014 10
SIC: example of HNO 3 production paths N 2 + p + (E) N + 2 + e + p + (E E) O 2 + O 2 + e O 2 + O 2 O 2 + O 3 O 3 + O 2 O 3 + CO 2 CO 3 + O 2 CO 3 + NO 2 NO 3 + CO 2 NO 3 + H 2O + M NO 3 (H 2O) + M NO 3 (H 2O) + HNO 3 NO 3 (HNO 3) + H 2 O NO 3 (HNO 3) + H + (H 2 O) 4 HNO 3 + HNO 3 + 4H 2 O Net : H 2 O + O 3 + NO 2 OH + HNO 3 + O 2 ISSI Georgieva, Bern, 24 28 March 2014 11
P/Q: relative production/loss rates from SIC P/Q = (ionic production - ionic loss) / ionization rate H 2 O becomes the limiting factor at upper altitudes At night: more negative ions, more HNO 3 production ISSI Georgieva, Bern, 24 28 March 2014 12
P/Q: relative production/loss rates from SIC P/Q = (ionic production - ionic loss) / ionization rate Note: Zero net change of NO y (incl. HNO 3 ) by negative ion chemistry Net production of NO x is by positive ion chemistry ISSI Georgieva, Bern, 24 28 March 2014 13
Outstanding issue: nitric acid in CCMs From Jackman et al., Atmos. Chem. Phys., 2008 ISSI Georgieva, Bern, 24 28 March 2014 14
MLS/Aura observations Microwave Limb Sounder, measures emissions at mm and sub-mm wavelengths Launched in July 2004 into a near-polar orbit, observations cover latitudes between 82 S 82 N, day and night Can be used to monitor temperature and more than 15 trace gases, including O3, OH, and HNO3 First satellite instrument providing continuous observations of mesospheric OH and HO2 ISSI Georgieva, Bern, 24 28 March 2014 15
Nitric acid: comparisons Modeling: Sodankylä Ion and Neutral Chemistry Uses MLS temperatures, neutral density, and water vapor. 80 N/December January, no diurnal variations. Results reduced to MLS altitude resolution using averaging kernels. Observations: data version 3.30, SZA > 100 (night-time) Data are daily means, uncertainty is standard error of the mean. Useful range up to 1.5 hpa ( 50 km) in normal conditions, but can be extended into mesosphere when high amounts are observed. Mesospheric HNO 3 data have not been validated. Comparison is made with the highest amount of HNO 3 observed after the peak of SPE forcing, assuming that it is least affected by dynamics. ISSI Georgieva, Bern, 24 28 March 2014 16
SIC vs. MLS: nitric acid, December 2006 SPE Before (left), during (middle), and after (right) the SPE forcing Altitude (km) 85 80 75 70 65 60 55 50 45 06 Dec 2006 SIC MLS 40 2 0 2 4 Mixing ratio (ppbv) 85 80 75 70 65 60 55 50 45 09 Dec 2006 40 2 0 2 4 Mixing ratio (ppbv) 85 11 Dec 2006 0.005 80 0.010 75 0.022 70 0.046 65 0.100 60 0.147 0.215 55 0.316 50 0.464 0.681 45 1.000 hpa 40 2 0 2 4 Mixing ratio (ppbv) The model overestimates the HNO 3 increase on Dec 9 at 60 65 km. Below 50 km the agreement is OK. For more details, see Verronen et al., J. Geophys. Res., 2011. ISSI Georgieva, Bern, 24 28 March 2014 17
MLS: HNO 3 (top) and CO (bottom) Daily avarages at approx. 60 km (2500 K) ISSI Georgieva, Bern, 24 28 March 2014 18
Odd hydrogen: comparisons Modeling: Sodankylä Ion and Neutral Chemistry Uses MLS temperatures, neutral density, and water vapor. Latitudes >60 N, solar proton events of January 2005 and December 2006. OH observations: data version 3.30 Useful range up to 0.0032 hpa ( 90 km). Mesospheric data have been validated by Pickett et al., JGR, 2008. Data are averaged at 65 75 N, for day and night separately. MLS was the first instrument that provided continuous and global observations of mesospheric HO x. ISSI Georgieva, Bern, 24 28 March 2014 19
SIC vs. MLS: hydroxyl, January 2005 OH (1/cm3) 8 x OH at 66 km 106 6 4 2 0 MLS SIC with SPE SIC without SPE 2 15 16 17 18 19 20 21 22 23 24 OH (1/cm3) 3 x Difference: SIC MLS 106 2 1 0 1 Night Daytime 2 15 16 17 18 19 20 21 22 23 24 Day in 2005/01 ISSI Georgieva, Bern, 24 28 March 2014 20
SIC vs. MLS: OH 90 Case I : January 18, 12:10 LT MLS/Aura SIC model 90 Case I : January 18, 21:20 LT GOMOS/Envisat SIC model 80 80 70 OH 70 O 3 Altitude (km) 60 Altitude (km) 60 50 50 40 Latitudes 69N 70N 40 Latitudes 71N 72N Longitudes 49W 27E 30 0 1 2 3 4 5 6 OH concentration (cm 3 ) x 10 6 Longitudes 35W 41E 30 90 60 30 0 30 60 90 Relative change of ozone (%) From Verronen et al., Geophys. Res. Lett., 2006 ISSI Georgieva, Bern, 24 28 March 2014 21
Ion chemistry and its effects in models Although there are uncertainties, the understanding of ion chemistry seems reasonably good for particle effect modelling. Our full knowledge is not used when parameterizing ion chemistry in 3-D atmospheric models, typically: HO x and NO x production is included, HNO 3 and HNO 2 production is not included, Chlorine activation is not included (Winkler et al., Geophys. Res. Lett., 2009). Two ways to include ion chemistry: Parameterization. Simple and good in all situations? Full ion chemistry. Computationally too expensive? ISSI Georgieva, Bern, 24 28 March 2014 22