astrid maute, art richmond, ben foster

High Altitude Observatory (HAO) – National Center for Atmospheric Research (NCAR)

The National Center for Atmospheric Research is operated by the University Corporation for Atmospheric Researchunder sponsorship of the National Science Foundation. An Equal Opportunity/Affirmative Action Employer. 18 March 200322 May 2007

Astrid Maute, Art Richmond, Ben Foster

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

Outline

SAMSI meeting 22 May 2007

•Description of the system

•Thermosphere-Ionosphere-Electrodynamics

General Circulation Model (TIE-GCM)

•Our Experiment

Electron and Neutral Density

SAMSI meeting 22 May 2007

Day-night difference

Spatial Variation: Equator

SAMSI meeting 22 May 2007

2001-09-10,7:30-8:03, long=67., F10.7=245

b0

B

[nT

]

100

-10

-20

-30-40

observations

mag. latitude [deg]

p.approxfor.correct

-40 -20 0 20 40

H at 12 SLT

upward ExB drift at magn. equator

CHAMP satellite at 12 LTMagnetic perturbation

on the ground

[Luehr et al. 2003]

H northwardD eastward

Spatial Variation: High Latitude

SAMSI meeting 22 May 2007

field-aligned current

coupling to the magnetosphere

closed field lines

open field lines

[Richmond et al. 2000]

night

+/- electric potential

Geomagnetic grid

SAMSI meeting 22 May 2007

geomagnetic equator

[Richmond 1995]

Geomagnetic / Geographic Grid

SAMSI meeting 22 May 2007

equivalent current

geomagnetic equator

17 UT 13 UT

magnetic perturbationat 12 LT

[Doumbia et al. 2007]

• D eastward

geog. longitude

• Variation with longitude

Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIE-GCM)

SAMSI meeting 22 May 2007

•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.

TIE-GCM: Interacting Physics

SAMSI meeting 22 May 2007

Global Electrodynamo

Thermosphere Ionosphere

tides at the lower boundary

high latitude electric fields

solar radiation, auroral precipitation, ion flux at

upper boundary

neutral windsion drag

conductivities

ion composition

neutral composition

neutral temperature & wind

ion drag

input parameters

internal parameters + many others

TIE-GCM: How the models is used

SAMSI meeting 22 May 2007

•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

[Flyer of TIME-GCM]

Joule heating [mW/m2] for 18. Oct. 1995 storm

Difference in temperature after doubling global CO2 concentration

TIE-GCM: “tuning” the model

SAMSI meeting 22 May 2007

•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

Observations

SAMSI meeting 22 May 2007

•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

Local time

[Scherliess et al. 1999]

Jicamarca 1968-92 Kp<3

Sa > 150

100 < Sa < 150

Sa < 100

Empirical models

SAMSI meeting 22 May 2007

•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 B in our experiment

MSIS and IRI

SAMSI meeting 22 May 2007

Our First Plan

SAMSI meeting 22 May 2007

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), B, drift velocities, MSIS

(composition, temperature)

Our Experiment

SAMSI meeting 22 May 2007

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 B, drift velocities at different stations

Why these parameters?

SAMSI meeting 22 May 2007

LT

LT

[Fesen et al. 2000]

prereversal enhancement in the early

evening

no influence on daytime

tides influence the daytime drift,

as well as time and magnitude of

early evening peak

nighttime changes

Influence of tidal modes on B

SAMSI meeting 22 May 2007

H H D D

observationbackground

(2,2)(2,3)(2,4)(2,5)(2,6)

tidal modes

phase shift: 0 & 3 hrs

Fuquene (geog. lat./long. = 5.3o/ -74.o)

•determine tidal amplitude and phase•least square fitting to magnetic perturbations around the world

Datatypes

SAMSI meeting 22 May 2007

Conditions: solar minimum, quite time, equinox

Use data from B, drift velocities at different stations

JRO

ARC MU

STSMH

drift velocities

magnetic perturbation

Example:B

HAO colloquium 8 September 2004

SJG

FRD

FUQ

PIL

HUA

TRW

AIA

mag

n. la

titud

e

60

40

20

0

-20

-40

-600 6 12 18 24

MLT

HAmerican sector

PET

MGD

KAK

KORGUA

PMG

BRS

TOO

H

mag

n. la

titud

e

60

40

20

0

-20

-40

-600 6 12 18 24

MLT

100 = 30 nT

TIEGCM

Observations

Asian/Australian sector

30 TIE-GCM runs

SAMSI meeting 22 May 2007

• 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

30 TIE-GCM runs

SAMSI meeting 22 May 2007

SAMSI meeting 22 May 2007

SAMSI meeting 22 May 2007

SAMSI meeting 22 May 2007

SAMSI meeting 22 May 2007

SAMSI meeting 22 May 2007