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Modeling the Upper Atmosphere and Ionosphere with TIMEGCM Geoff Crowley

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Modeling the Upper Atmosphere and Ionosphere with TIMEGCM

Geoff Crowley

Atmospheric & Space Technology Research Associates (ASTRA)

www.astraspace.net

TIMEGCM: Thermosphere-Ionosphere-Mesosphere-Electrodynamics-General Circulation Model

ASPEN: Advanced SPace ENvironment Model

ASPEN-TIMEGCM

Temperatures, Chemistry & Winds

So it’s Easy …….. Right?

Think I’ll develop another GCM this afternoon

Tides

Temperature

Gravity Waves

Winds

E-fields

Composition

Electron Density

Joule Heating

Particle Heating

Solar EUV

Chemical Heating

Boundary Conds

Diffusion Coeffs

Chemistry

Solar EUV

Important Inputs to the Thermosphere – Ionosphere System

Solar EUV Input

OUTPUT

High Latitude Inputs

E-fields Particles

Neutral density Composition Temperature Wind Electron density

Dynamo E-fields

Coupled Thermosphere –Ionosphere-Electrodynamics

Tides and Gravity Waves

MODEL - QUIET - 12UT

Neutral Temperature 12 UT

MODEL - %DIFFERENCE (Storm – Quiet)

MODEL - STORM - 12UT

MODEL - QUIET - 12UT

Meridional Wind 12 UT

MODEL - %DIFFERENCE (Storm – Quiet)

MODEL - STORM - 12UT

Most Realistic High Latitude Inputs

Data Inputs:

180 magnetometers

3 DMSP satellites

X SuperDARNs

325 (11/21)

324 (11/20)

323 (11/19)

322 (11/18)

325 (11/21)

324 (11/20)

323 (11/19)

322 (11/18)

Time runs right to left

325 (11/21)

324 (11/20)

322 (11/18)

323 (11/19)

325 (11/21)

324 (11/20)

323 (11/19)

322 (11/18)

325 (11/21)

324 (11/20)

323 (11/19)

322 (11/18)

TIMEGCM+AMIE

Vertical Coordinate System

If Zp is the pressure level (usually ranging from –17 to +5), and Po is the base pressure

P = Po exp (-Zp) (ASPEN has 88 pressure levels; 30 to 600 km)

Density is

r = Po exp (-Zp) Mbar / (Kb T),

where Kb is the Boltzman constant (gas constant / Avogadro number). Units depend on the choice of Po and Kb. If Kb = 1.38e-16 erg/K then density is in g/cm3.

Horizontal Coordinates

-87.5S (5) +87.5N latitude ; -180E (5) +180E longitude (72*36 grid points)

Molecular conduction radiation advection adiab. heating

Many terms

Energy equation

The leap-frog method is employed with vertical thermal conductivity treated implicitly to second order accuracy. This leads to a tridiagonal scheme requiring boundary conditions at the top and bottom of the domain as implied by the differential equation. Advection is treated implicitly to fourth order in the horizontal, second order in the vertical

Cooling Terms

O(3P) 63 mm O(3P) fine structure

NO 5.3 mm Nitric Oxide

CO2 15 mm Carbon Dioxide

O3 9.6 mm Ozone

Km Molecular Conduction

DIFKT Eddy Diffusion Cooling

Heating Terms

QEUVEUV (1-1050 Å) (EUVEFF= 5%)

QSRCO2 -Schumann-Runge continuum (1300 -1750 Å)

QSRBO2 -Schumann-Runge bands (1750-2000 Å)

QO3O3- Lyman a (1215.67 Å)

O3- Hartley, Huggins and Chappuis (203-850 nm)

QO2O2- Lyman a (1215.67 Å)

O2 Herzberg (2000-2420 Å)

QNCExothermic neutral-neutral chemistry

(NOX, HOX, OX, CH4, O(1D) quench, CLX)

Atomic O recombination

Heating from O(1D) quenching

QICExothermic ion-neutral chemistry

QANon-Maxwellian auroral electrons (AUREFF= 5%)

QPPhotoelectrons (X-rays, EUV, and Night) (EFF=5%)

QEICollisions between e-, ions and neutrals

QDH 4th order diffusion heating

QGW Gravity Waves

QM Viscous Dissipation

QJ Joule heating

QTTotal Heating

Dynamical terms

Adiabatic cooling

Horizontal Advection

Vertical Advection

NEUTRAL GAS HEATING

Figure 2. Diurnal global mean deg K/day

a)

b)

c)

d)

e)

f)

Global Mean Heating and Cooling Terms (Solar Min.)

275 km

150

150

120

103

90

90

50

Neutral Temperature

Heating (K/day)

Cooling (K/day)

Heating (K/day)

Cooling (K/day)

SMAX

SMAX

Effect of Season On Heating (SMAX)

Equinox

Solstice

Vert. adv.

Recombination

Production

molecular diffusion

eddy diffusion

Horiz. advection

Continuity equation

The leap-frog method is employed leading to a tridiagonal scheme requiring boundary conditions at the top and bottom of the domain.

Nitrogen Chemistry (Simplified for This Talk)

Each species equation includes horizontal and vertical advection, photo-chemical production and loss, and vertical molecular and eddy diffusion.

Neutral Species

The model includes 15 separate neutral species, not counting some excited states which are also tracked.

O, N2, O2, CO2, CO, O3, H, H2, H2O, HO2,

N, NO, NO2, Ar, and He.

Ionized Species

The model includes 6 ion species

O+, N+, O2+, N2+, NO+, and H+

with ionization primarily from solar EUV and x-rays, together with auroral particles.

Momentum equations

Zonal velocity

Rayleigh friction

Pressure gradients

Coriolis

gravity wave drag

ion drag

momentum advection

Viscosity (Molecular and Eddy)

Meridional velocity

The Leap frog method is employed with vertical molecular viscosity treated implicitly to second order accuracy. Since the zonal and meridional momentum equations are coupled through Coriolis and off-diagonal ion drag terms, the system reduces to a diagonal block matrix scheme, where (2 x 2) matrices and two component vectors are used at each level. Boundary conditions for the zonal (u) and meridional ( v) wind components are needed at the top and bottom of the model.

Momentum Forcing Terms

(u,v) = neutral velocity (cm/s)

(ui, vi) = ion velocity (cm/s)

Pressure gradients

f = 2 W sin(colatitude) (s-1) part of Coriolis forcing

Molecular viscosity = Km (g/cm/s)

Eddy viscosity (vertical) = DIFKV (g/cm/s)

Momentum advection

GWU, GWV = gravity wave drag

RAYK = Rayleigh friction

lij = ion drag tensor (must have units of s-1)

Balance of Forces

NUMERICAL EXPERIMENTS

a)

b)

c)

d)

Electric Potential

Electron Density

Conjugate Enhancements

AMIE

, Q, E

TIMEGCM

Ne

Ne

Background Ne

IDA4D

TIMEGCM-IDA3D-AMIE interaction

FAC

- Self-consistently coupled - each output feeding the input of the other.
- Each algorithm has strengths that address the weaknesses of others.
- Coupled together, a more accurate specification of ionosphere and thermospheric state variables is obtained.
- Output: complete, data-driven specification (and prediction) of ionospheric and thermospheric state variables. Particularly:
- High latitude conductances
- High latitude field aligned currents (FAI)
- High latitude potentials
- High latitude Joule heating
- Global Electron density, neutral winds, neutral composition etc.

EFFECT OF ADDING IDA4D ELECTRON DENSITY TO TGCM NEUTRALS

SH

50

AMIE

ASPEN

IDA3D/ASPEN

0

GUVI Binned

GUVI Raw

Figure 4. Comparisons of Hall Conductance from GUVI, ASPEN, IDA3D/ASPEN, and AMIE for November 20, 2003 for GUVI orbit 10564 (~17:29 UT) in apex magnetic latitude and magnetic local time coordinates.

MODEL COUPLING #2 Extension to Plasmasphere/Inner Magnetos.

SAMI3 (ionos-plasmasphere)

RCM (inner magnetosphere)

TIMEGCM

MODEL COUPLING #3 Addition of Hydrogen Geocorona

SAMI3 (ionos-plasmasphere)

RCM (inner magnetosphere)

Hydrogen Geocorona

(2-4 RE)

TIMEGCM

MODEL COUPLING #4 Coupling to Lower Atmosphere??

SAMI3 (ionos-plasmasphere)

RCM (inner magnetosphere)

Hydrogen Geocorona

(2-4 RE)

TIMEGCM

NOGAPS

NCEP

http://uap-www.nrl.navy.mil/dynamics/html/nogaps.html

How to Think About About

Upper Atmosphere GCMs

- They are numerical laboratories
- Can do controlled (numerical) experiments
- They approximate reality
- Good “first stop” for atmospheric predictions
- Useful framework for understanding a system
- Useful framework for data analysis, and can be studied for mechanisms
- Useful place to test ideas (what if …..)
- Necessary first step to space-weather forecasting

- Summary
- Thermosphere-Ionosphere-Mesosphere-Electrodynamics-General Circulation Model
- 30-600 km
- Fully coupled thermodynamics, chemistry
- Inputs - tidal, solar, high latitude
- Outputs
- Neutral: Temp, Wind, Density, Composition
- Ionosphere: Electron density, ions (dynamo E-field)

- Extensively Validated
- Various model coupling studies
- Provides useful background fields and test-bed
- e.g. gravity wave propagation