A global model of meteoric metals and smoke

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. q Model for metal layers and MSPs q Validation of model results q Sensitivities/uncertainties q Long term trend q MSP formation and its impact

WACCM/CARMA Whole Atmosphere Community Climate Model IDP • 0 -140 km (detailed cemistry/dynamics) • GEOS 5, MERRA, ECMWF Ablation Community Aerosol and Radiation Model for Atmosphere MIF • Detailed microphysics, 28 bins (0. 2 -102 nm) Metal chemistry for neutral and ions Metal Chemistry Modules (Fe, Si, Na, Mg, Ca, K) Feng et al. (2013): WACCM-Fe Marsh et al. (2013): WACCM-Na WACCM (metals) Plane et al. (2014): WACCM-K CARMA (MSP) Langowski et al. (2015): WACCM-Mg Plane et al. (2015): Mesosphere and Metals http: //www. see. leeds. ac. uk/~earfw Deposition Lidar, rocket and satellite

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

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

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

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

Locations of Ground-based Lidar metal measurements

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

Sensitivity of top layer: DR of Fe. O+ +e Fe. O+ Feng et al. (2013) Bones et al. (2015): + e– >Fe + O 3 e-7*sqrt(200. /T) 5. 5 e-7*sqrt(298/. ) Bones et al. (2015) • Neutralisation of Fe+ pathway has been revisited • Lab: Dissociative Recombination of Fe. O+ with electron density

Fe. OH photolysis and reactions with H Fe. OH + H Fe + H 2 O Fe. O + H 2 • New calculated J(Fe. OH) = 6. 2 × 10 -3 s-1 which is ~100 times larger than used in Feng et al (2013) • Two Channels of Fe. OH + H are updated in WACCM-Fe

Sensitivity of bottom layer Viehl et al. (in prep) • New updates (J(Fe. OH), 6. 2 × 10 -3 s-1 and k) improve the bottom layer

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

Solar cycle response K OSIRIS Lidar (Kborn) WACCM F 10. 7 -0. 25 (p<0. 01) -0. 11 (p=0. 32) -0. 19 (p<0. 05) T @ 87 km -0. 35 (p<0. 01) -0. 22 (p<0. 05) -0. 53 (p<0. 01) T @ 90 km -0. 34 (p<0. 01) -0. 24 (p<0. 05) -0. 52 (p<0. 01) T @ 95 km 0. 08 (p=0. 39) 0. 15 (p=0. 18) -0. 09 (p=0. 34) Na OSIRIS WACCM F 10. 7 0. 05 (p=0. 63) -0. 01 (p=0. 93) T @ 87 km 0. 33 (p<0. 01) 0. 50 (p<0. 01) T @ 90 km 0. 32 (p<0. 01) 0. 47 (p<0. 01) T @ 95 km 0. 01 (p=0. 95) -0. 14 (p=0. 13)

Meteoric Input Function

Sensitivity of Fe layer using different MIF

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

Silicon ions comparison with rocket Control simulation 10 x. MIF Ø Model is able to produce the peak Si+ density and altitude in the upper mesospheric lower thermosphere. Ø Model underestimates Si + density in the bottom layer compared with rocket measurement (N 2 + ? )

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 : 3

Meteoric smoke formation pathways 1. Exothermic polymerisation reactions Na. HCO 3 + Fe(OH)2 H = -157 k. J mol-1 Mg(OH)2 + Mg(OH) 2 H = -268 k. J mol-1 2. Condensation reactions with Si(OH)4 produce silicates Mg(OH)2 + Si(OH)4 + H 2 O H = -61 k. J mol-1 Fe. OH+ Si(OH)4 + H 2 O H = -21 k. J mol-1

Meteoric smoke particle concentration 115 h. Pa 95 80 60 40 20 15 5. 5 Ø The smoke material explicitly formed by metal chemistry enters the model in the smallest size bin (0. 2 nm) Ø Seasonal variation in MSP concentration. Ø Largest MSP concentration (10, 000 cm-3) matches rocket data.

HO 2 uptake on MSPs

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

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