Astrid Maute, Art Richmond, Ben Foster

1. Astrid Maute, Art Richmond, Ben Foster The NCAR Themosphere-Ionosphere-Electrodynamics General Circulation Model: Problems in Developing a Realtistic Model 22 May 2007

2. Outline • Description of the system • Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) • Our Experiment SAMSI meeting 22 May 2007

3. Electron and Neutral Density Day-night difference SAMSI meeting 22 May 2007

4. Spatial Variation: Equator H at 12 SLT 2001-09-10,7:30-8:03, long=67., F10.7=245 10 0 -10 b0 B [nT] -20 observations -30 -40 mag. latitude [deg] -40 -20 0 20 40 CHAMP satellite at 12 LT Magnetic perturbation on the ground [Luehr et al. 2003] upward ExB drift at magn. equator DH northward DD eastward SAMSI meeting 22 May 2007

5. Spatial Variation: High Latitude field-aligned current open field lines coupling to the magnetosphere night closed field lines +/- electric potential [Richmond et al. 2000] SAMSI meeting 22 May 2007

6. Geomagnetic grid geomagnetic equator [Richmond 1995] SAMSI meeting 22 May 2007

7. Geomagnetic / Geographic Grid equivalent current geomagnetic equator magnetic perturbation at 12 LT 13 UT 17 UT geog. longitude • Variation with longitude • DD eastward [Doumbia et al. 2007] SAMSI meeting 22 May 2007

8. Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIE-GCM) • Self-consistently calculates neutral and ion densities, composition, velocities, temperatures, along with electric fields and currents, between 97 and 500 km, assuming vertical hydrostatic equilibrium. • Basic resolution is 5x5 degrees horizontally, ½ scale height (3-30 km) • vertically, dimensioned 73(longitude) x 36 (latitude) x 29 (height) • 1-day simulation uses ~ 3 minutes on bluevista, with 3-minute time step. SAMSI meeting 22 May 2007

9. TIE-GCM: Interacting Physics high latitude electric fields Global Electrodynamo neutral winds conductivities ion drag ion drag ion composition Thermosphere Ionosphere neutral composition solar radiation, auroral precipitation, ion flux at upper boundary tides at the lower boundary neutral temperature & wind input parameters internal parameters + many others SAMSI meeting 22 May 2007

10. TIE-GCM: How the models is used • Studies of geomagnetic storms • Yearlong runs for seasonal studies • Model runs with daily varying input (e.g. using NCEP data) • Generic input parameters to study certain effects Joule heating [mW/m2] for 18. Oct. 1995 storm Difference in temperature after doubling global CO2 concentration [Flyer of TIME-GCM] SAMSI meeting 22 May 2007

11. TIE-GCM: “tuning” the model • Lots of parameters which would need tuning or could be improved • Simplification of parameters, e.g. ignore latitudinal variation, seasonal dependence • Model response is not necessarily linear, i.e. cannot “tune” for one parameter after another SAMSI meeting 22 May 2007

12. Observations Jicamarca 1968-92 Kp<3 Sa > 150 100 < Sa < 150 Sa < 100 Local time [Scherliess et al. 1999] • Local with varying local time and location • Dependence on season, solar cycle and activity • Datatypes: neutral wind, electron density, magnetic field, drift velocity, neutral density SAMSI meeting 22 May 2007

13. Empirical models • International Reference Ionosphere (IRI) model • Mass-Spectrometer-Incoherent-Scatter (MSIS) model • Global, can define specific conditions Log10 Ne [1/cm3] at 12 LT at equator IRI 2001 TIE-GCM • Electron density (Ne) in TIE-GCM 40 to 60% too low depending on altitude • Increase of DB in our experiment SAMSI meeting 22 May 2007

14. MSIS and IRI SAMSI meeting 22 May 2007

15. Our First Plan • Initial plan was to vary 7 parameters: • Tidal input (2,2) and (2,4) mode with amplitude and phase 4 parameters • Eddy diffusion • Burnside factor • Nighttime electron density • Use data from IRI (electron density height and magnitude of peak density), DB, drift velocities, MSIS (composition, temperature) SAMSI meeting 22 May 2007

16. Our Experiment • Reduce to 3 parameters: • Tidal input (2,2) migrating mode with amplitude and phase • Range for amplitude [0,360] m and phase [0,12] hrs • Nighttime electron density (internal parameter) • Range for log10 Ne [3,4] 1/cm3 • Use data from DB, drift velocities at different stations SAMSI meeting 22 May 2007

17. Why these parameters? prereversal enhancement in the early evening no influence on daytime nighttime changes LT tides influence the daytime drift, as well as time and magnitude of early evening peak [Fesen et al. 2000] LT SAMSI meeting 22 May 2007

18. Influence of tidal modes on DB D H D H Fuquene (geog. lat./long. = 5.3o/ -74.o) observation background • determine tidal amplitude and phase • least square fitting to magnetic perturbations around the world (2,6) tidal modes (2,5) (2,4) phase shift: 0 & 3 hrs (2,3) (2,2) SAMSI meeting 22 May 2007

19. Datatypes Conditions: solar minimum, quite time, equinox Use data from DB, drift velocities at different stations STS MH ARC MU JRO magnetic perturbation drift velocities SAMSI meeting 22 May 2007

20. Example: B H H 60 60 MGD FRD PET 40 40 KAK SJG 20 20 FUQ GUA HUA 0 0 KOR magn. latitude magn. latitude PMG PIL -20 -20 TRW 100 = 30 nT BRS -40 -40 TIEGCM TOO AIA -60 -60 Observations 0 6 12 18 24 0 6 12 18 24 MLT MLT American sector Asian/Australian sector HAO colloquium 8 September 2004

21. 30 TIE-GCM runs • Amplitude of (2,2) migrating tide: [0,360] m • Phase of (2,2) migrating tide: [0,12] hrs • Nighttime electron density: log10 Ne [3,4] 1/cm3 Error on our code: electrons and ions not in balance SAMSI meeting 22 May 2007

22. 30 TIE-GCM runs SAMSI meeting 22 May 2007

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