Thermosphere and Ionosphere Modeling for Mars MGCMMTGCM Stephen

Thermosphere and Ionosphere Modeling for Mars (MGCM-MTGCM) Stephen W. Bougher (UM) Jared Bell Tami Mc. Dunn Brian Steers James R. Murphy (NMSU) 10/6/2020 1

Outline q Why thermosphere-ionosphere modeling is important for Mars (volatile escape & evolution). q Capabilities and limitations of the coupled NCAR/Michigan MGCM-MTGCM framework. q Validation of the MGCM-MTGCM; key features simulated that match available measurements. q Details of SWIM model challenge: inputs to and outputs from the MGCM-MTGCM. q Future SWIM model challenge: ancient Mars. 10/6/2020 2

Martian Atmospheric Regions and Processes 10/6/2020 3

Interaction of Models : Volatile Escape 10/6/2020 4

Mars Upper Atmosphere GCMs q MGCM-MTGCM (e. g. Bougher et al. , 01; 04; 06): • • Flux coupled separate models spanning 0 -300 km NCAR (TIGCM) and NASA Ames (MGCM) heritage. q Mars Whole Atmosphere Climate Model (MWACM) (e. g. Bougher et al; 07 -08) • • Ground to exosphere code (0 -300 km). Earth GITM heritage. Under development q LMD-GCM (e. g. Angelat-i-Coll et al; 04; Gonzalez-Galindo et al. , 05) • • Ground to exosphere code (0 -240 km) LMD/AOPP MGCM heritage; LMD/IAA teaming. q ASPEN (e. g. Crowley et al. 04; 05) • • Troposphere to thermosphere (14 -300 km) NCAR TIME-GCM heritage q GM 3 (e. g. Moudden et al. , 04; 05) • • 10/6/2020 Ground to thermosphere code (0 -160 km) Canadian MET model heritage. 5

MTGCM Formulation and Structure v Altitude range: ~70 -300 km (dayside). Pbot=1. 32 -microbar v 5 x 5º latitude-longitude grid (pole-to-pole) v Pressure vertical coordinate (1/2 -H intervals): 33 -levels v Major Fields: T, U, V, W, O, CO, N 2, CO 2, Z v PCE ions Fields: CO 2+, NO+, CO+, Ne v Current Minor Fields: O 2 and Ar v Future NOx Fields: N(4 S), N(2 D), NO (NO nightglow) v Fox & Sung (2001) ion-neutral chemical reactions & rates. v O, CO and O 2 sources and losses explicitly calculated. v Tion and Telec (empirically based) from Fox [1993]. v NLTE CO 2 15 -micron cooling scheme and near IR heating rates adapted from M. Lopez-Valverde (pc. 2000) 10/6/2020 6

Input Parameters for MTGCM v F 10. 7 ~ 70, 130, 200. Solomon UV routine (2. 4 -225. 0 nm) v Factor for heliocentric distance = 1. 38 -1. 67 (seasonal) v Mars obliquity = ± 25º (seasonal) v Q-Efficiency (EUV, UV) = 22% (after Fox et al. , 1995) v K(O-CO 2) = 3. 0 x 10 -12 cm 3/sec (at 300 K) v Kzz ≤ 1. 0 -1. 5 x 107 cm 2/sec. Prandtl # = 1. 0 v Assumes Grav = 3. 5 m/s 2 over domain v Timestep = 120. 0 secs v PE secondary ionization factors utilized 10/6/2020 7

Coupled MGCM-MTGCM q. Flux coupled codes: NASA Ames MGCM (0 -90 km) and NCAR- Michigan MTGCM (~70 -300 km), linked across an interface at 1. 32 -microbars on a regular 5 x 5º grid. q. Fields passed upward at interface (T, U, V, Z) on 2 -min time-step intervals. No downward coupling enabled. q. Coupling captures upward propagating migrating & nonmigrating tidal oscillations, as well as in-situ solar EUV-UVIR heating (migrating tides). q. Ls = 60 -120 (~Aphelion) & Ls = 270 -300 (~Perihelion) v. Empirical TES horizontal dust distributions (LAT vs LON). v. Conrath parameter scheme used to specify vertical dust distributions (mixed to ~20 -60 km). v. Circulation sensitive to vertical dust dist. (Bell et al. 2007) 10/6/2020 8

Martian Lower Atmos. Dust Opacities for Three Consecutive TES Years (Bell et al. , 2007) 10/6/2020 9

Exploring the Mars Upper Atmosphere With Aerobraking Accelerometers Aerobraking Spacecraft Vertical Structures Seasonal (Ls) Coverage F 10. 7 (at Earth) MGS 1 (1997 -1998) 7 -months 400 (~115 -160 km) 180 -300 70 -90 (MIN) MGS 2 (1998 -1999) 4. 5 -months 1200 (~110 -160 km) 30 -95 130 -150 (MOD) Odyssey (2001 -2002) ~3 -months 650 (~95 -150 km) 260 -310 ~175 -200 (MAX) MRO (2006) 5 -months 900 (~95 -170 km) 35 -109 80 -100 (MIN) 10/6/2020 10

Accelerometer Temp. Variations at 120 km (Bougher et al. , 2006) 10/6/2020 11

Zonal Mean Temperatures and Dynamical Heating Terms from MGCM-MTGCM : (a) MGS 2 (Ls = 90), and (b) ODY (Ls = 270) Temperatures (K) Winter Heating/Cooling (K/day) Summer S +400 K/d Summer 10/6/2020 Winter 800 -2000 K/d 12

MTGCM: No Lower Boundary Forcing (Ls = 270): Temperatures (K) and adiabatic heat/cooling (K/day). Summer Bell et al. (2007) Winter polar warming gone Meridional winds reduced (by ~50%) Reduced max heating (+400 K/d) 10/6/2020 13

MRO Nightside (SLT = 3 -4, LAT=0 -40ºS) and MGS 2 Dayside (LST = 15 -17, LAT= ± 40º) (Keating et al. , 2007) Dayside Mis-Match : • HP > HD issue • O/CO 2 ratio differences? • EUV efficiency ~ 20% needed? 10/6/2020 14 7

MTGCM Thermal Balances: Dayside MGS 2 (LAT = 22. 5ºS LST = 1500) ADIA COND 10/6/2020 QEUV 15

Earth-Mars Comparative Response to Long-Term Changes in Solar flux (Forbes et al. , 2007) Mars - MGS Ls variation removed Earth - msise 90 40 o latitude 10/6/2020 Mars is ~36% - 50% as responsive to solar flux received at the planet, compared to Earth, consistent with Forbes et al. (2006) 16

MGS Comparison with DTM-Mars and MTGCM Results (Forbes et al. , 2007) Latest MTGCM result -50 o 1400 LT (Bougher) DTM Noon MGS orbit ~370 x 425 km periapsis near -40 o to -60 o 1400 LT MGS Fit DTM Midnight 10/6/2020 17

MTGCM Temperature Profiles: Ls = 90 -120; LST = 2. 6 -4. 8; LAT = 17 S-16 S Mc. Dunn et al. , 2007; 2008 10/6/2020 18

MTGCM Z. M. Heat Balance Terms: Ls = 90 -120; LST = 2. 6 -4. 8; LAT = 17 S-16 S COND ADIA CIR Mc. Dunn et al. , 2007; 2008 Rate (K/day) 10/6/2020 19

Dust Storm Impacts: Density at 130 km (Bougher et al. , 1999) MGS Orbit Number 10/6/2020 20

MTGCM Inputs to SWIM Model Challenge v F 10. 7 ~ 130 (solar moderate fluxes) v Ls = 180º; Ds-m = 1. 466 AU (Equinox) v TES Mapping Year #1 dust opacities (Smith, 2004) v Q-Efficiency (EUV, UV) = 22% (Fox et al. , 1995) v K(O-CO 2) = 3. 0 x 10 -12 cm 3/sec (at 300 K) v Kzz ≤ 1. 0 x 107 cm 2/sec. Prandtl # = 1. 0 10/6/2020 21

MTGCM Outputs for SWIM Model Challenge v. SZA Method – – – Neutral Fields (6) = T, O, CO, N 2, CO 2, XTOT Ion Fields (3) = O 2+, O+, Ne Altitudes ~ 100 to 260 by 5. 0 km Longitudes = -180 to 180º by 5º SLT = 0 to 12 to 24 hours (at Latitude = 2. 5 N) SZA = 180 to 180º v. Constant Altitude (Lat vs Lon) Method – – – 10/6/2020 Same fields (6 -neutral and 3 -plasma) plus O 2+ production. Altitudes ~ 100 to 260 by 5. 0 km Longitudes = -180 to 180º by 5º Latitudes = -87. 5 S to +87. 5 N by 5º 22

Conclusions and Summary q 3 -D thermosphere-ionosphere model outputs are important for volatile escape & evolution studies (hybrid, MHD, airglow, exosphere, sputtering, etc) q MGCM-MTGCM validation is ongoing using aerobraking (MGS/Odyssey/MRO), drag (MGS) and stellar occultation (MEX) datasets. Reasonable. q MGCM-MTGCM outputs are provided for SWIM model challenge (present day). 2 -D and 3 -D grids. q Future SWIM model challenge: ancient Mars. 10/6/2020 23