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 Wuhu Feng, John Plane, Martyn Chipperfield, Erin Dawkins, Daniel Marsh, Charles Bardeen, Diego Janches, David Nesvorny, Chester Gardner, Josef Hoffner, et al.

WACCM/CARMA Whole Atmosphere Community Climate Model km (detailed cemistry/dynamics) GEOS5, MERRA, ECMWF Community Aerosol and Radiation Model for Atmosphere Detailed microphysics, 28 bins ( 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 WACCM (metals) CARMA (MSP) MIF Ablation IDP Deposition Metal Chemistry Modules (Fe, Si, Na, Mg, Ca, K) Lidar, rocket and satellite

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

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

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

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

Locations of Ground-based Lidar metal measurements

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

Sensitivity of top layer: DR of FeO + +e 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 Bones et al. (2015)

FeOH photolysis and reactions with H New calculated J(FeOH) = 6.2 × s -1 which is ~100 times larger than used in Feng et al (2013) Two Channels of FeOH + H are updated in WACCM-Fe FeOH + H  Fe + H 2 O  FeO + H 2

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

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

Solar cycle response K OSIRISLidar (Kborn)WACCM F (p<0.01)-0.11 (p=0.32)-0.19 (p<0.05) 87 km (p<0.01)-0.22 (p<0.05)-0.53 (p<0.01) 90 km (p<0.01)-0.24 (p<0.05)-0.52 (p<0.01) 95 km 0.08 (p=0.39)0.15 (p=0.18)-0.09 (p=0.34) Na OSIRISWACCM F (p=0.63)-0.01 (p=0.93) 87 km 0.33 (p<0.01)0.50 (p<0.01) 90 km 0.32 (p<0.01)0.47 (p<0.01) 95 km 0.01 (p=0.95)-0.14 (p=0.13)

Meteoric Input Function

Sensitivity of Fe layer using different MIF

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

 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 (N 2 + ?) Silicon ions comparison with rocket Control simulation 10xMIF

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 : Si 7 : 2 : 2 : 3

1.Exothermic polymerisation reactions NaHCO 3 + Fe(OH) 2   H = -157 kJ mol -1 Mg(OH) 2 + Mg(OH) 2   H = -268 kJ mol Condensation reactions with Si(OH) 4 produce silicates Mg(OH) 2 + Si(OH) 4  + H 2 O FeOH+ Si(OH) 4  + H 2 O  H = -61 kJ mol -1  H = -21 kJ mol -1 Meteoric smoke formation pathways

hPa  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 Meteoric smoke particle concentration

HO 2 uptake on MSPs

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.

Frankland et al. (2015) HNO 3 uptake on MSPs