Astrid Maute, Art Richmond, Ben Foster

1
The NCAR Themosphere-Ionosphere-Electrodynamics
General Circulation Model Problems in Developing
a Realtistic Model

• Astrid Maute, Art Richmond, Ben Foster

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
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
17 UT
13 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
tides at the lower boundary
solar radiation, auroral precipitation, ion flux
at upper 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

• 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
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
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
23
SAMSI meeting
22 May 2007
24
SAMSI meeting
22 May 2007
25
SAMSI meeting
22 May 2007
26
SAMSI meeting
22 May 2007
27
SAMSI meeting
22 May 2007