1 Energetic Particle Impacts in the Atmosphere Charley Jackman 1, Dan Marsh 2, Cora Randall 3, Stan Solomon 2 1 Goddard Space Flight Center 2 National Center for Atmospheric Research 3 University of Colorado Sun-to-Ice Kickoff Meeting San Diego, California 2 November 2011

A Simplified Overview of the Particle-to-Nitrates Chain 2 Energetic particles enter the atmosphere, predominantly in the polar regions Mostly electrons and protons Penetration depth depends on energy (more energy — deeper penetration) Particles impact atmospheric gases, causing ionization, dissociation, excitation Most important process is ionization, which also leads to dissociation, excitation Ionization produces secondary electrons Secondary electrons dissociate molecules, primarily molecular nitrogen (N 2 ) The majority of nitrogen atoms are left in excited metastable states (N( 2 D), N( 2 P)) Excited N react with molecular oxygen (O 2 ) to produce nitric oxide (NO) NO is long-lived at night, esp. in the polar winter, and can be transported downward NO reacts with odd-oxygen, particularly ozone (O 3 ) to produce nitrogen dioxide (NO 2 ) NO 2 reacts with O 3 and hydroxyl radical (OH) to produce nitric acid (HNO 3 ) HNO 3 attaches to water (H 2 O) Acidified water enters troposphere and ultimately precipitates?

A Few Words About Photons 3

troposphere mesosphere stratosphere H+H+ e-e- thermosphere NO Direct EffectIndirect Effect Direct Effect: High-energy particles sporadically produce NO x directly in stratosphere Indirect Effect: Lower energy particles routinely produce NO x in MLT NO x can descend to stratosphere during polar night Direct and Indirect Effects of Particle Precipitation

Electron Precipitation 40 o 50 o 60 o 70 o 80 o Medium & high energy electrons  subauroral zone [~55-65 o geom. lat.] 90 o N geomagnetic Lower energy Auroral electrons  auroral zone [~62-75 o geomag. lat.]

Proton Precipitation 40 o 50 o 60 o 70 o 80 o 90 o N geomagnetic Solar protons Polar Caps >~60 o geomag. lat. Very intense solar events push polar cap boundaries Equatorward

Altitude (km) Troposphere Stratosphere Mesosphere Thermosphere 1 MeV proton 100 MeV proton 10 MeV proton Middle Atmosphere 1 keV electron 10 keV electron 100 keV electron (Bremsstrahlung X-rays can penetrate further) 1 MeV electron 1 GeV proton (mostly GCRs)

9 Ionization in the Northern Polar Cap During the 2003 “Halloween” Storm

First Satellite Observations of NOx Generated by Energetic Particles Northern Hemisphere, Based on Russell et al., 1984 EPP is the ONLY source of mesospheric NO x in the polar winter

11 HALOE NOx and O 3 Measurements

12 NO x (NO+NO 2 ) in SH Polar Vortex in Sep./Oct UARS HALOE Mean Altitude (km) from Randall et al. (2001) Interannual Variability NO x (ppbv)

WACCM NO x (NO+NO 2 ) vmr 55 km 27-Oct Oct Oct-2003 Polar vortex edge MIPAS NO x (NO+NO 2 ) in km (Northern Hemisphere) Enhancements by Halloween 2003 Solar Energetic Particles Geomagnetic pole from López-Puertas et al. [2005a]

MIPAS HNO 3 Change (ppbv) in o N (night) Relative to 26 Oct Primary (?): OH + NO 2 + M  HNO 3 + M ΔHNO 3 from López-Puertas et al. [2005b, updated]

15 Whole Atmosphere Community Climate Model (WACCM) A single-code synthesis of CAM, MOZART, and the TIME-GCM WACCM v.4 extends from the surface to ~140 km altitude Released as part of NCAR CESM, online documentation, regular community workshops, etc. Interdivisonal NCAR development group (ACD, CGD, HAO) WACCM-SD “specified dynamics” incorporates measured troposphere- stratosphere dynamical state, enabling event- specific studies. WACCM-X development in progress to eXtend to ~500 km, including full thermosphere-ionosphere coupling Now a working group of the CESM

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The Role of Dynamics in Odd-Nitrogen Distributions 17 NO y transport by: Diffusion (4 orders of magnitude in vmr with height from km) Residual Circulation

18 Pressure (hPa) WACCM - NO y % change60-90 o S J A S O N D J F M A M J Year 2000 Year 2001 Nov SPE Apr SPE

19 Pressure (hPa) WACCM - Ozone % change60-90 o S J A S O N D J F M A M J Year 2000 Year 2001 Ozone decrease  more NO y -induced O 3 loss Ozone increase  NO y interferes with Cl and Br chemistry

20 Comparison of HALOE Measurements to WACCM Simulation

21 Comparison of NOAA-SBUV Ozone Measurements to WACCM Simulation 15-35% depletion

Comparison of MIPAS Measurements to WACCM Simulation “Halloween Storm,” Funke et al., Atmos. Chem. Phys., 2010

NO x enhances larger family NO y N, NO, NO 2, NO 3, N 2 O 5, HNO 3, HO 2 NO 2, ClONO 2, BrONO 2 ) –Lifetimes can be long (~months to years) Recent Work on Other Constituent Observations N 2 O Production (MIPAS): Funke et al. (2008a,b) HCl Destruction (HALOE): Winkler et al. (2009) N 2 O 5 Production (MIPAS): López-Puertas et al. (2005b); Jackman et al. (2008) HO 2 NO 2 Production (MIPAS): Funke et al. (2011) CO Destruction (MIPAS): Funke et al. (2011)

High Energy Particle Precipitation in the Atmosphere (HEPPA) 24 International affiliation that studies energetic particle transport and effects Primarily the middle-atmosphere community Conferences every two years or so, generally in attractive venues Next meeting is October 8~12, High Altitude Observatory, Boulder, Colorado