Modeling the Upper Atmosphere and Ionosphere with TIMEGCM Geoff Crowley Atmospheric & Space...
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Transcript of Modeling the Upper Atmosphere and Ionosphere with TIMEGCM Geoff Crowley Atmospheric & Space...
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