Direct effects of particle precipitation and ion chemistry in the middle atmosphere

Transcription

1 Direct effects of particle precipitation and ion chemistry in the middle atmosphere P. T. Verronen Finnish Meteorological Institute, Earth Observation Helsinki, Finland

2 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, March

3 Energetic particle precipitation Earth s magnetic field directs charged particles into polar regions EPP affects both ionosphere and middle atmosphere ISSI Georgieva, Bern, March

4 Different types of particle precipitation From a presentation by Randall et al., 2008 ISSI Georgieva, Bern, March

5 SPE: example of geomagnetic cutoff Rodger et al., Journal of Geophysical Research (2006) ISSI Georgieva, Bern, March

6 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, March

7 Sodankylä Ion and Neutral Chemistry (SIC) ISSI Georgieva, Bern, March

8 SIC: D-region ion chemistry 36 positive ions, 29 negative ions, 400 reactions ISSI Georgieva, Bern, March

9 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., ISSI Georgieva, Bern, March

10 SIC: example of HO x production paths N 2 + p + (E) N e + p + (E E) N O 2 O N 2 O O 2 + M O M O 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, March

11 SIC: example of HNO 3 production paths N 2 + p + (E) N 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, March

12 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, March

13 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, March

14 Outstanding issue: nitric acid in CCMs From Jackman et al., Atmos. Chem. Phys., 2008 ISSI Georgieva, Bern, March

15 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, March

16 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, March

17 SIC vs. MLS: nitric acid, December 2006 SPE Before (left), during (middle), and after (right) the SPE forcing Altitude (km) Dec 2006 SIC MLS Mixing ratio (ppbv) Dec Mixing ratio (ppbv) Dec hpa Mixing ratio (ppbv) The model overestimates the HNO 3 increase on Dec 9 at km. Below 50 km the agreement is OK. For more details, see Verronen et al., J. Geophys. Res., ISSI Georgieva, Bern, March

18 MLS: HNO 3 (top) and CO (bottom) Daily avarages at approx. 60 km (2500 K) ISSI Georgieva, Bern, March

19 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 OH observations: data version 3.30 Useful range up to hpa ( 90 km). Mesospheric data have been validated by Pickett et al., JGR, Data are averaged at N, for day and night separately. MLS was the first instrument that provided continuous and global observations of mesospheric HO x. ISSI Georgieva, Bern, March

20 SIC vs. MLS: hydroxyl, January 2005 OH (1/cm3) 8 x OH at 66 km MLS SIC with SPE SIC without SPE OH (1/cm3) 3 x Difference: SIC MLS Night Daytime Day in 2005/01 ISSI Georgieva, Bern, March

21 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 OH 70 O 3 Altitude (km) 60 Altitude (km) Latitudes 69N 70N 40 Latitudes 71N 72N Longitudes 49W 27E OH concentration (cm 3 ) x 10 6 Longitudes 35W 41E Relative change of ozone (%) From Verronen et al., Geophys. Res. Lett., 2006 ISSI Georgieva, Bern, March

22 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, March