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Thermosphere and Ionosphere Modeling for Mars (MGCM-MTGCM)

Thermosphere and Ionosphere Modeling for Mars (MGCM-MTGCM). Stephen W. Bougher (UM) Jared Bell Tami McDunn Brian Steers James R. Murphy (NMSU). Outline. Why thermosphere-ionosphere modeling is important for Mars (volatile escape & evolution).

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Thermosphere and Ionosphere Modeling for Mars (MGCM-MTGCM)

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  1. Thermosphere and Ionosphere Modeling for Mars (MGCM-MTGCM) Stephen W. Bougher (UM) Jared Bell Tami McDunn Brian Steers James R. Murphy (NMSU)

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

  3. Martian Atmospheric Regions and Processes

  4. Interaction of Models : Volatile Escape

  5. Mars Upper Atmosphere GCMs • 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. • 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 • 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. • ASPEN (e.g. Crowley et al. 04; 05) • Troposphere to thermosphere (14-300 km) • NCAR TIME-GCM heritage • GM3 (e.g. Moudden et al., 04; 05) • Ground to thermosphere code (0-160 km) • Canadian MET model heritage.

  6. MTGCM Formulation and Structure • Altitude range: ~70-300 km (dayside). Pbot=1.32-microbar • 5x5º latitude-longitude grid (pole-to-pole) • Pressure vertical coordinate (1/2-H intervals): 33-levels • Major Fields: T, U, V, W, O, CO, N2, CO2, Z • PCE ions Fields: CO2+, O2+, N2+, NO+, CO+, O+, Ne • Current Minor Fields: O2 and Ar • Future NOx Fields: N(4S), N(2D), NO (NO nightglow) • Fox & Sung (2001) ion-neutral chemical reactions & rates. • O, CO and O2 sources and losses explicitly calculated. • Tion and Telec (empirically based) from Fox [1993]. • NLTE CO2 15-micron cooling scheme and near IR heating rates adapted from M. Lopez-Valverde (pc. 2000)

  7. Input Parameters for MTGCM • F10.7 ~ 70, 130, 200. Solomon UV routine (2.4-225.0 nm) • Factor for heliocentric distance = 1.38-1.67 (seasonal) • Mars obliquity = ±25º (seasonal) • Q-Efficiency (EUV, UV) = 22% (after Fox et al., 1995) • K(O-CO2) = 3.0 x 10-12 cm3/sec(at 300K) • Kzz ≤ 1.0-1.5 x107 cm2/sec. Prandtl # = 1.0 • Assumes Grav = 3.5 m/s2 over domain • Timestep = 120.0 secs • PE secondary ionization factors utilized

  8. Coupled MGCM-MTGCM • 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 5x5º grid. • Fields passed upward at interface (T, U, V, Z) on 2-min time-step intervals. No downward coupling enabled. • Coupling captures upward propagating migrating & non-migrating tidal oscillations, as well as in-situ solar EUV-UV-IR heating (migrating tides). • Ls = 60-120 (~Aphelion) & Ls = 270-300 (~Perihelion) • Empirical TES horizontal dust distributions (LAT vs LON). • Conrath parameter scheme used to specify vertical dust distributions (mixed to ~20-60 km). • Circulation sensitive to vertical dust dist. (Bell et al. 2007)

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

  10. Exploring the Mars Upper Atmosphere With Aerobraking Accelerometers

  11. Accelerometer Temp. Variations at 120 km (Bougher et al., 2006)

  12. Zonal Mean Temperatures and Dynamical Heating Terms from MGCM-MTGCM :(a) MGS2 (Ls = 90), and (b) ODY (Ls = 270) Temperatures (K) Heating/Cooling (K/day) Summer Winter S +400K/d Summer Winter 800-2000K/d

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

  14. MRO Nightside (SLT = 3-4, LAT=0-40ºS) and MGS2 Dayside (LST = 15-17, LAT= ± 40º)(Keating et al., 2007) Dayside Mis-Match : • HP > HD issue • O/CO2 ratio differences? • EUV efficiency ~ 20% needed? 7

  15. MTGCM Thermal Balances: Dayside MGS2 (LAT = 22.5ºS LST = 1500) ADIA COND QEUV

  16. Earth-Mars Comparative Response to Long-Term Changes in Solar flux (Forbes et al., 2007) Mars - MGS Ls variation removed Earth - msise90 40o latitude Mars is ~36% - 50% as responsive to solar flux received at the planet, compared to Earth, consistent with Forbes et al. (2006)

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

  18. MTGCM Temperature Profiles: Ls = 90-120; LST = 2.6-4.8; LAT = 17S-16S McDunn et al., 2007; 2008

  19. MTGCM Z.M. Heat Balance Terms: Ls = 90-120; LST = 2.6-4.8; LAT = 17S-16S COND ADIA CIR McDunn et al., 2007; 2008 Rate (K/day)

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

  21. MTGCM Inputs to SWIM Model Challenge • F10.7 ~ 130 (solar moderate fluxes) • Ls = 180º; Ds-m = 1.466 AU (Equinox) • TES Mapping Year #1 dust opacities (Smith, 2004) • Q-Efficiency (EUV, UV) = 22% (Fox et al., 1995) • K(O-CO2) = 3.0 x 10-12 cm3/sec(at 300K) • Kzz ≤ 1.0 x107 cm2/sec. Prandtl # = 1.0

  22. MTGCM Outputs for SWIM Model Challenge • SZA Method • Neutral Fields (6) = T, O, CO, N2, CO2, XTOT • Ion Fields (3) = O2+, O+, Ne • Altitudes ~ 100 to 260 by 5.0 km • Longitudes = -180 to 0 to 180º by 5º • SLT = 0 to 12 to 24 hours (at Latitude = 2.5N) • SZA = 180 to 0 to 180º • Constant Altitude (Lat vs Lon) Method • Same fields (6-neutral and 3-plasma) plus O2+ production. • Altitudes ~ 100 to 260 by 5.0 km • Longitudes = -180 to 0 to 180º by 5º • Latitudes = -87.5S to +87.5N by 5º

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

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