GITM and Non-hydrostatic processes Yue Deng Department of Physics University of Texas, Arlington

Ionosphere/Thermosphere Processes Courtesy of Joseph Grebowsky, NASA GSFC Electrodynamics & particle Sun Tides and Gravity Waves

The Global Ionosphere-Thermosphere Model (GITM) GITM solves for: 6 Neutral & 5 Ion Species 6 Neutral & 5 Ion Species Neutral winds Neutral winds Ion and Electron Velocities Ion and Electron Velocities Neutral, Ion and Electron Temperatures Neutral, Ion and Electron Temperatures Ridley, A., Deng, Y., and Toth, G. (2006), J. Atmos. Solar-Terr. Phys., 68,

GITM Features: Flexible grid resolution Flexible grid resolution Can have non-hydrostatic solutions Can have non-hydrostatic solutions Coriolis Coriolis Vertical Ion Drag Vertical Ion Drag Non-constant Gravity Non-constant Gravity Massive heating in auroral zone Massive heating in auroral zone Runs in 1D and 3D Runs in 1D and 3D Solves in altitude coordinates Solves in altitude coordinates Vertical winds for each major species with friction coefficients Vertical winds for each major species with friction coefficients Non-steady state explicit chemistry Non-steady state explicit chemistry Variety of high-latitude and Solar EUV drivers Variety of high-latitude and Solar EUV drivers Fly satellites through model Fly satellites through model Time step: 2 seconds Time step: 2 seconds

Why Non-hydrostatic? The vertical momentum equation: The vertical momentum equation: Non-hydrostatic effects (deep convection) have been investigated in the low atmosphere using WRF. How about its effect on the upper atmosphere? Non-hydrostatic effects (deep convection) have been investigated in the low atmosphere using WRF. How about its effect on the upper atmosphere? Currently, no conclusive interpretation about the observed large vertical winds (more than 100 m/s) and density disturbance in thermosphere. [Rees et al., 1984; Smith et al., 1995; Innis et al., 1999; Aruliah et al., 2005] Currently, no conclusive interpretation about the observed large vertical winds (more than 100 m/s) and density disturbance in thermosphere. [Rees et al., 1984; Smith et al., 1995; Innis et al., 1999; Aruliah et al., 2005] Offer the opportunity to simulate acoustic waves and give a more realistic description of high-frequency gravity waves Offer the opportunity to simulate acoustic waves and give a more realistic description of high-frequency gravity waves Hydrostatic equilibrium

Study 1: idealized case Vsw=400km/s, IMF(Bz)=-1nT, F10.7=100, HPI=3GW  00 UT: Bz -1  -20 nT  CPCP: 45  180 kV  Integrated JH increases by 20 times.  After 1 hour, Bz changes back to -1 nT. Deng, Y., and et. al., GRL (2008)

Temporal variations of the buoyancy acceleration (300 km)

Time vs. altitude distribution ( S, E) during 15 min:  There is a positive disturbance propagating from low altitudes to high altitudes with increasing amplitude.  Buoyancy~2 m/s 2 at 400km, close to 25% of g (8.7m/s 2 ).  Phase speed, direction and frequency show that it is highly likely an acoustic wave. Buoyancy acceleration

Vertical wind Neutral density  Vertical neutral wind > 100 m/s at 300 km altitude.  Neutral density increase by 100% above 300 km.

Influence on the acoustic-gravity wave propagation: Non-hydrostatic dispersion relation for GW : [ Monin & Obukhov, 1958 ] where k and m are horizontal and vertical wave numbers; and are the wave and buoyancy intrinsic frequencies. The last term on RHS vanishes in hydrostatic situation. The conditions for wave to be reflected and ducted are: in the nonhydrostatic in the hydrostatic cases. [ Akmaev, 2011 ] When, the same wave behaves differently in hydrostatic and non-hydrostatic models. Study 2:

T = 3 min T = 3 min T = 6 min T = 6 min T = 12 min T = 12 min  During the first 12 minutes, acoustic waves are propagating upward  T > 12 minutes, most disturbance is below 200 km, which indicates that the wave got reflected or ducted above that.

Momentum flux decreases dramatically above 150 km. Dissipated GW accelerate background neutral wind. Magnitude and vertical depth of body force are Consistent with Vadas & Liu, (2009) Deng, et. al., 2014

Tsunami Imaging March 26, 2014Physics Dept Colloquium UT Arlington

Courtesy of Attila Komjathy, Xing Meng, JPL GITM simulation

Mars Titan Exo-planets 3. Planetary Atmosphere

Discovery rate of exo-planets

Exo-planets: habitable zone Kasting et al. 1993

Atmosphere escape is a hydrodynamic process Early Martian Upper Atmosphere (Tian, Kasting, & Solomon 2009)

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