Energetic Particles in the Atmosphere J.M. Wissing and M.-B. Kallenrode

ILWS 2011 Motivation

ILWS 2011 (Jackman et al, 2001) Motivation: Ozone depletion by precipitating particles altitudeO3 depletionduration >50 km35-40%~2 days 42 km 25 %~2 days 38 km10%>6 days 35 km5%>6 days Bastille day event July 14,

ILWS 2011  Which particle sources affect the atmosphere?  Where do these particles enter the atmosphere?  How does a comparatively small energy content cause a significant atmospheric reaction?  Are there effects besides Ozone change?  What are the main challenges in modeling atmospheric particles precipitation?  Which (kind of) models exist?  Do we really need them?  How accurate are these models? 4 Particle precipitation in general Main questions Modeling particle precipitation

ILWS 2011 Where do the Particles come from?

ILWS 2011 Where do the Particles come from?

ILWS magnetospheric solar Where do these particles precipitate into the atmosphere? (Wissing and Kallenrode 2009)

ILWS Primary effects What happens to the energetic particles in the atmosphere?  Exitation (e.g. aurora)  Ionization!  Secondaries  Bremsstrahlung  Cosmogenic isotopes

ILWS Primary effects What happens to the energetic particles in the atmosphere? (Quack, 2005) Bragg peak  Exitation (e.g. aurora)  Ionization!  Secondaries  Bremsstrahlung  Cosmogenic isotopes  interaction → vertical pattern!

ILWS Particle energy and it's main deposition altitude Entering the atmosphere (Wissing and Kallenrode 2009)

ILWS Atmospheric ionization at different places quiet event (Wissing and Kallenrode, 2009)

ILWS Atmospheric follow-ups due to ionization by precipitating particles Secondary effects  chemical impacts due to ionization production of radicals (NOx, HOx) Ozone depletion production of condensation nuclei cloud formation  physical impact due to ionization higher conductivity

ILWS 2011  ionization of most abundant species (N2, O2, NO, O)  forms radicals: NOx (N, NO) and HOx (H, HO) (Crutzen et al. 1975) 13 Production of NOx and HOx Secondary effect: Ozone depletion  e.g. NO > NO2 + O2 NO2 + O -> NO + 02 Crutzen (1970,1971) and JOHNSTON(1971)  „If you want to change the direction of a car the most energy-efficient solution is to tickle the driver.“ NOx and HOx catalytically destroy Ozone

ILWS 2011 Rohen et al., 2005  same forcing  but effect depends on hemisphere Secondary effect: Ozone depletion – single event  winter (NH): NOx is transported down into the Ozone layer.  other seasons/regions: NOx stays at high altitudes and is destroyed by sunlight North South 14

ILWS 2011 variation during solar cycle comparable in size with impact of UV-variation Sinnhuber et al., 2005 Secondary effect: Ozone depletion – solar cycle

ILWS 2011 Marsh & Svensmark, 2000 Secondary effect: Cloud formation due to GCRs  observation: cloud coverage below 3.2 km correlates with GCR variations (Svensmark and Friis- Christensen, 1997)  process: still under debate, possible link: enhanced aerosol nucleation due to presence of ions  the CLOUD labratory experiments at CERN support this hypotheses (Duplissy et al., 2009) 16

ILWS 2011  thunderstorms as dynamo  ionosphere/ground highly conductive  atmospheric ionization determines conductivity between ionosphere and ground 17 Global electric curcuit Secondary effect: Global electrical curcuit (Markson, 1978) Conductivity (=current) variation with solar activity!  solar max: low GCR-ionization in low latitudes high SEP-ionization in high latitudes  solar min: vise versa (e.g. Singh, Singh and Kamra, 2004) → Impact on lightning frequency? suggested by Schlegel et al. (2001)

ILWS Tertiary effects  Ozone is a radiation absorbing gas  Cloud coverage impacts the earth's radiation budget  different absorbtion: → e.g. UV radiation change on surface → impact on bisophere? → altitudinal temperature gradient changes! → impact on atmospheric circulation! Impact on radiation budget

ILWS 2011  above the atmosphere by satellite measurements 19 Determine particle flux How does a particle precipitation model work? Combine to energy deposition Calculate energy deposition  for single particles  of the full spectra

ILWS 2011 modelparticle source particle species and energy precipitation pattern used satellites internal mechanism resol ution areafix or variable Hardy et al. (1989) magnetosp heric p+ (30 eV–30 keV)globaldynamic, depending on Kp DMSP Callis (1997, 1998,...and Lambeth 1998) magnetosp heric e- (4.25–1050 keV)NH & SH auroral ovals POES-6, later 8 & 12 Walt et al. (1968) Jackman et al. (2001, 2005) solarp+ (1–300 MeV)polar cap (>60) staticGOES-11 and before range energy relation 1 h Schröter et al. (2006) solare- (0.5–5 MeV) p+ (0.29–440 MeV) polar cap staticIMP/GOESMonte Carlo (GEANT4) Fang et al. (2007) magnetosp heric p+ (30–240 keV)globaldynamicPOES- 15/16 AIMOSsolar & magnetosp heric e- (154eV–5MeV) p+(154eV–500MeV) alpha (4–500MeV) globaldynamic, depending on Kp POES- 15/16 GOES-10 or 11 Monte Carlo (GEANT4) 2 h Models for atmospheric particle precipitation (without GCRs) 20

ILWS Main challenge in modeling global particle precipitation (e.g. Wissing and Kallenrode, 2009) ?  No global ionization rates without intense interpolation!  e.g. cosine fits of actual measurements (Fang et al., 2007)  e.g. mean precipitation maps based on Kp-level (AIMOS model) missing data coverage

ILWS 2011  polar cap (dots): good satellite coverage → good agreement (factor 1)  auroral oval: interpolation → less accurate (mean underestimation: factor 0.5) 22 Setup (Wissing et al. 2011) How accurate are recent models for particle precipitation?  electron density derived from AIMOS ionizations and the GCM HAMMONIA  in comparison to: radar measurements  night time Results

ILWS 2011  daytime: sunlight dominates ionization  in the high atmosphere: benefit of a factor of 100 to 1000 in electron density at night  ion-chemistry depends on electron density 23 Do we really need precipitating particles in atmospheric modeling? (Wissing et al. 2011) without particles with particles

ILWS 2011 Unsolved questions in particle precipitation South Atlantic Anomaly More unsolved questions:  angular distribution of particle spectrum? (may cause shift in deposition altitude)  limitation of detectors: energy range, crosstalk (energy, species), degradation 24

ILWS 2011  global and wide energy range possible  electron density benefits (factor 1000)  allows calculation of follow-ups  main problems: SAA, spatial data coverage, missing angular distribution of p. particles, quality of particle measurements Modeling ionization Summary Effects on atmosphere  changes in electron density  conductivity, global electric curcuit  top-selling feature: Ozon depletion by catalytic reactions  in the stratosphere: few percents, but up to years  changes in cloud coverage?  changes in radiation budget → temperature gradients → circulation