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A global model of meteoric metals and smoke particles: An update

Wuhu Feng , John Plane, Martyn Chipperfield, Erin Dawkins, Daniel Marsh, Charles Bardeen, Diego Janches , David Nesvorny, Chester Gardner, Josef Hoffner , et al. A global model of meteoric metals and smoke particles: An update. Model for metal layers and MSPs

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A global model of meteoric metals and smoke particles: An update

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  1. Wuhu Feng, John Plane, Martyn Chipperfield, Erin Dawkins, Daniel Marsh, Charles Bardeen, Diego Janches, David Nesvorny, Chester Gardner, Josef Hoffner, et al. A global model of meteoric metals and smoke particles: An update • Model for metal layers and MSPs • Validation of model results • Sensitivities/uncertainties • Long term trend • MSP formation and its impact

  2. WACCM/CARMA IDP Whole Atmosphere Community Climate Model • 0-140 km (detailed cemistry/dynamics) • GEOS5, MERRA, ECMWF Community Aerosol and Radiation Model for Atmosphere • Detailed microphysics, 28 bins (0.2-102 nm) Metal chemistry for neutral and ions Feng et al. (2013): WACCM-Fe Marsh et al. (2013): WACCM-Na Plane et al. (2014): WACCM-K Langowski et al. (2015): WACCM-Mg Plane et al. (2015): Mesosphere and Metals http://www.see.leeds.ac.uk/~earfw Ablation MIF Metal Chemistry Modules (Fe, Si, Na, Mg, Ca, K) WACCM (metals) CARMA (MSP) Lidar, rocket and satellite Deposition

  3. Meteoric ablation: Source of metals • Large uncertainty in IDP (2-300 tonnes/day) • Source of metal layer • Re-condense into MSP Mass=5µg, SZA=35o, V=21 km/s • Chemical ablation model (CABMOD) profiles • Different metals are released at different altitudes

  4. Processes Ablations (Source) Aurora Tides PMCs PSCs MLT Metals Photolysis Radiation Clouds Meteoric Smoke Particles (nm) Chemistry Dynamics Aerosol Deposition circulations, gravity waves etc. Emissions

  5. Global picture (Na, K) Observations (ODIN-OSIRIS) Model Na Marsh et al. (2013) K Dawkins et al. (2015)

  6. Global picture (Mg, Mg+) Observations (SCIAMACHY) WACCM-Mg model Mg Mg+ Langowski et al. (2015)

  7. Locations of Ground-based Lidar metal measurements

  8. Seasonal, Diurnal variations 54N Lidar 54N WACCM-K Plane et al. (2014) Feng et al. (2015) Plane et al. (2014)

  9. Sensitivity of top layer: DR of FeO+ +e Bones et al. (2015) Feng et al. (2013) FeO+ + e– >Fe + O 3e-7*sqrt(200./T) Bones et al. (2015): 5.5e-7*sqrt(298/.) • Neutralisation of Fe+ pathway has been revisited • Lab: Dissociative Recombination of FeO+ with electron density

  10. FeOH photolysis and reactions with H FeOH + H  Fe + H2O  FeO + H2 • New calculated J(FeOH) = 6.2 × 10-3 s-1 which is ~100 times larger than used in Feng et al (2013) • Two Channels of FeOH + H are updated in WACCM-Fe

  11. Sensitivity of bottom layer Viehl et al. (in prep) • New updates (J(FeOH), 6.2 × 10-3 s-1 and k) improve the bottom layer

  12. Long-term trends in the metal layers Dawkins et al. (to be submitted)

  13. Solar cycle response

  14. Meteoric Input Function

  15. Sensitivity of Fe layer using different MIF

  16. Calcium 18N Model fails to capture the observed maximum summer Ca layer for the high latitudes (further investigation is required)

  17. Silicon ions comparison with rocket 10xMIF Control simulation • Model is able to produce the peak Si+ density and altitude in the upper mesospheric lower thermosphere. • Model underestimates Si + density in the bottom layer compared with rocket measurement (N2 + ?)

  18. Fe, Si, Na, Mg neutral/ion/reservoir species 4 dominant reservoir species used to form MSP (18 extra reactions) Meteoric elements in MSP ratios Fe : Mg : Na : Si7 : 2 : 2 : 3

  19. Meteoric smoke formation pathways • Exothermic polymerisation reactions H = -157 kJ mol-1 NaHCO3 + Fe(OH)2 Mg(OH)2 + Mg(OH) 2 H = -268 kJ mol-1 2. Condensation reactions with Si(OH)4 produce silicates Mg(OH)2 + Si(OH)4 + H2O H = -61 kJ mol-1 FeOH+ Si(OH)4 + H2O H = -21 kJ mol-1

  20. Meteoric smoke particle concentration 115 • The smoke material explicitly formed by metal chemistry enters the model in the smallest size bin (0.2 nm) • Seasonal variation in MSP concentration. • Largest MSP concentration (10,000 cm-3) matches rocket data. 95 80 hPa 60 40 20 15 5.5

  21. HO2 uptake on MSPs

  22. Summary and conclusions • Mesospheric metal Chemistry into a 3D NCAR CESM model. The first self-consistent global model of MSP from metal chemistry is still under validation. • MIF varied to match lidar/satellite measurements (there are still large uncertainties) • Recent a few updates in the model improve the upper and bottom Fe layers. • The MSP has impact on the stratosphere/lower mesosphere. • Still a big challenge to host a large MIF into model.

  23. HNO3 uptake on MSPs Frankland et al. (2015)

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