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

Simulating Mars and EarthSimulating Mars and Earth

Temperatures, Chemistry & Winds

Think I’ll develop another GCM this afternoon

So it’s Easy …….. Right?

Simplified Physics of Upper AtmosphereSimplified Physics of Upper Atmosphere

Composition

Temperature Winds

E-fields

Electron Density

Diffusion Coeffs

Boundary Conds

Chemistry

Joule Heating Particle Heating

Solar EUV Chemical HeatingTides

Gravity Waves

Solar EUV

Important Inputs to the Thermosphere – Ionosphere System

Solar EUV Input

Coupled Thermosphere –Ionosphere-Electrodynamics

Tides and Gravity Waves

High Latitude Inputs

E-fields Particles

Neutral density Composition Temperature Wind Electron densityDynamo E-fields

OUTPUT

Neutral Temperature 12 UT

MODEL - %DIFFERENCE (Storm – Quiet)

MODEL - QUIET - 12UT

MODEL - STORM - 12UT

Meridional Wind 12 UT

MODEL - %DIFFERENCE (Storm – Quiet)

MODEL - QUIET - 12UT

MODEL - STORM - 12UT

180 magnetometers

3 DMSP satellites

X SuperDARNs

Data Inputs:

Most Realistic High Latitude Inputs

325 (11/21) 324 (11/20) 323 (11/19) 322 (11/18)

325 (11/21) 324 (11/20) 323 (11/19) 322 (11/18)

325 (11/21) 324 (11/20) 323 (11/19) 322 (11/18)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

Time runs right to left

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

= 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)

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

Energy equation

ppp

e

p

i

po

s

c

Q

Hc

RTTV

c

aT

c

aT

sK

H

1

scp

ge

t

T+

ω−∇⋅−−−⎟

⎠⎞

⎜⎝⎛ ε+

∂∂

∂∂

=∂∂ −

Molecular conduction radiation advection adiab. heating

Many terms

Heating Terms

QEUV EUV (1-1050 Å) (EUVEFF= 5%)

QSRC O2 -Schumann-Runge continuum (1300 -1750 Å)

QSRB O2 -Schumann-Runge bands (1750-2000 Å)

QO3 O3- Lyman a (1215.67 Å)

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

QO2 O2- Lyman a (1215.67 Å)

O2 Herzberg (2000-2420 Å)

QNC Exothermic neutral-neutral chemistry

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

Atomic O recombination

Heating from O(1D) quenching

QIC Exothermic ion-neutral chemistry

QA Non-Maxwellian auroral electrons (AUREFF= 5%)

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

QEI Collisions between e-, ions and neutrals

QDH 4th order diffusion heating

QGW Gravity Waves

QM Viscous Dissipation

QJ Joule heating

QT Total Heating

Cooling Terms

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

NO 5.3 m Nitric Oxide

CO2 15 m Carbon Dioxide

O3 9.6 m Ozone

Km Molecular Conduction

DIFKT Eddy Diffusion Cooling

Dynamical terms

Adiabatic cooling

Horizontal Advection

Vertical Advection

NEUTRAL GAS HEATING

50

103

90

Neutral Temperature

120

150

275 km

Figure 2. Diurnal global mean deg K/day

a) b)

Global Mean Heating and Cooling Terms (Solar Min.)

Heating (K/day) Cooling (K/day)Heating (K/day) Cooling (K/day)

150

90

Effect of Season On Heating (SMAX)

SMAX SMAX

Equinox Solstice

Continuity equation

{ } ( ){ } RSdz

dV

dz

dezK

dz

deL

T

T

m

m

dz

de

dt

d zz125.0

0

N

1z

2

−+Ψ

ω−Ψ∇•−Ψ

+Ψα⎟⎠⎞

⎜⎝⎛τ−=

Ψ −−−

molecular diffusion eddy diffusion Horiz. advection

Vert. adv.

Production

Recombination

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

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.

GWU + F + u + + t

cosr

g u vu RAYK* ) tan

r

u + (f +

s

u

H

) K+ K(

s

P

eg =

t

uxIxxIxyxxuxy

EM

o

s

λνλλ∂∂

φ−∇⋅−−λ−νλ−φ

∂∂

∂∂

∂∂ rr

GWV+ F + + u z

r

g v RAYK* u) tan

r

u + (f

s

H

)K + K(

s

P

eg =

tIyyIyxxxxy

EM

o

s

φν νλλ−φ∂

∂−ν∇⋅−ν−λ−λ−φ−

∂ν∂

∂∂

∂ν∂ rr

Viscosity (Molecular and Eddy)

Coriolis

gravity wave drag

Pressure gradientsRayleigh friction

ion drag momentum advection

Momentum Forcing Terms

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

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

Pressure gradients

f = 2 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

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

Balance of Forces

a) b)

c) d)

Electron Density

NUMERICAL EXPERIMENTS

Electric Potential

Conjugate Enhancements

MODEL COUPLING #1 MODEL COUPLING #1 ASPEN-IDA3D-AMIE (AIA)ASPEN-IDA3D-AMIE (AIA)

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.

AMIE

TIMEGCM

IDA4D

Ne

Background Ne

Ne

, Q, E

TIMEGCM-IDA3D-AMIE interaction

FAC

GUVI Raw GUVI Binned

ASPEN IDA3D/ASPENAMIE

50

0

H

EFFECT OF ADDING IDA4D ELECTRON DENSITY TO TGCM NEUTRALS

Conductance Affects Field Aligned Conductance Affects Field Aligned Currents from AMIECurrents from AMIE

TIMEGCM

RCM (inner magnetosphere)

SAMI3 (ionos-plasmasphere)

MODEL COUPLING #2 MODEL COUPLING #2 Extension to Plasmasphere/Inner Magnetos.Extension to Plasmasphere/Inner Magnetos.

TIMEGCM

RCM (inner magnetosphere)

SAMI3 (ionos-plasmasphere)

MODEL COUPLING #3 MODEL COUPLING #3 Addition of Hydrogen GeocoronaAddition of Hydrogen Geocorona

Hydrogen Geocorona

(2-4 RE)

TIMEGCM

RCM (inner magnetosphere)

SAMI3 (ionos-plasmasphere)

MODEL COUPLING #4 MODEL COUPLING #4 Coupling to Lower Atmosphere??Coupling to Lower Atmosphere??

Hydrogen Geocorona

(2-4 RE)NOGAPS

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

NCEP

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

SummaryThermosphere-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