Toward Forecasting Space Weather

Tamas GombosiThe University of Michigan

Isradynamics 2010 Conference

Ein Bokek (Dead Sea), Israel

April 11-16, 2010

Space Weather

Space weather: conditions in geospace that can have adverse effects on space-borne and ground-based technological systems and can endanger human life or health.

(courtesy of Doug Biesecker, NOAA SWPC)

Modeling the Space Weather System

Disparate time scales

Disparate spatial scales

Disparate physics

……

☞ Model coupling is needed

Coupled Space Weather Models

Space Weather Modeling Framework (SWMF)Centered at the University of Michigan

Enables flexible Sun-to-Earth model chain

Single executable

Center for Integrated Space Weather Modeling (CISM) coupled model

Centered at Boston University

Enables Sun-to-Earth model chain

Multiple executables

Integrated Magnetosphere-Ionosphere ModelCentered at the University of New Hampshire

Couples a global magnetosphere, an ionosphere-thermosphere, a radiation belt and a ring current model

Single executable

Freely available at http://csem.engin.umich.edu

SWMF Capabilities: Physics

Fluid Equations

Compressible HD

Ideal MHD

Semi-relativistic MHD

Resistive MHD

Single-fluid Hall MHD

Two-fluid Hall MHD

Multi-species (Hall) MHD

Multi-fluid (Hall) MHD

Anisotropic pressure

Heat conduction

Additional PhysicsMultiple materials

Non-ideal EOS

RadiationGray diffusion

Multigroup diffusion

Source termsGravity, mass loading, chemistry, photo-ionization, recombination, etc…

Various resistivity models

Semi-empirical coronal heating

Alfven wave energy transport and dissipation

Self-consistent turbulence

SWMF Capabilities: Numerics

Time integration SchemesLocal time-stepping for steady state

Explicit (with Boris correction)

Explicit/implicit

Semi-implicit

Point-implicit

GridsBlock-adaptive tree

Cartesian

Generalized grids including spherical, cylindrical, toroidal

TVD SolversRoe

HLLD

HLLE

Artificial-wind

Rusanov

LimitersKoren (3rd order)

MC

Beta

Div(B) control8-wave

Hyperbolic/parabolic scheme

Projection

Staggered grid (CT)

Ray tracingFast & parallel

Synthetic imagesWhite light coronagraph

EUV LOS171Å, 195Å, 284Å

X-ray radiographs

Tomography

SWMF Capabilities: Framework

Source code:

250,000 lines of Fortran in the currently used models

34,000 lines of Fortran 90 in the core of the SWMF

13,000 lines of Fortran 90 in the wrappers and couplers

User manual with example runs and full documentation of input parameters

Fully automated nightly testing on 9 different machine/compiler combinations

SWMF runs on any Unix/Linux based system with a Fortran 90 compiler, MPI library, and Perl interpreter

Simulation and Tomography

2005 05 14 21:03 2005 05 15 21:05 2005 05 16 21:00 2005 05 17 21:05

2005 05 18 21:00 2005 05 19 21:05 2005 05 20 21:00 2005 05 21 0306

2005 05 21 21:05 2005 05 22 21:05 2005 05 23 21:00 2005 05 24 21:05

2005 05 25 21:00 2005 05 26 21:05 2005 05 27 21:00 2005 05 27 23:44

ne=106

ne=5x105

Frazin et al., 2008

Thermodynamic Solar Wind Model(van der Holst, Oran and Sokolov)

Sub-photosphere modelMultigroup radiation transport

MHD

Magnetic flux emergence

Low corona (1R☉r<2.5 R☉)

γ=5/3, single temperature

Heat conduction

Transport and dissipation of total energy of Alfvénic turbulence (E±)

Wave dissipation represents sources for the plasma momentum and internal energy

Additional coronal heating is obtained from the “unsigned flux” model (Abbett 2007) and observed X-ray luminosity (Pevtsov 2003)

Corona (2.5R☉<r<20R☉)

γ=5/3, separate ion and electron temperatures

Transport and dissipation of frequency resolved Alfvén wave intensity, I±(ω)

Kolmogorov spectrum is assumed at the inner boundary

Observational inputs:Magnetogram driven potential field extrapolation (synoptic maps from GONG or MDI)

Density and temperatures near the sun are predicted by the DEMT (Differential Emission Measure Tomography) results of Vasquez and Frazin (2009).

Solar X-ray luminosity (EIT, STEREO)

Boundary Conditions for CR2077with no Free ParametersGONG magnetogram WSA relation

STEREO/EUVI Differential Emission Measure Tomography (Vasques & Frazin)

CR2077: Two State Solar Wind

In the fast windElectrons are cold (due to adiabatic cooling)

Ions are hot (due to Alfvén wave heating)

In the slow windElectrons are hot (due to heat conduction)

Ions are cold (no Alfvén wave heating)

Radial velocity

Ion temperature Electron temperature

New Low Corona Model EIT 171Å EIT 195Å EIT 284Å SXT AlMg

Old SC modelsynthesis

New LC modelsynthesis

Observation:Aug 27, 1997

CR1913

Downs et al., ApJ, 712, 1219, 2010

Halloween Storm Simulation: Early Phase

Alfvénic Turbulence and SEP Acceleration

Recent Hinode observations imply that MHD turbulence might be the source that powers, accelerates and heats the solar windToday it is possible to use many dimensional models (>3D)We developed a coupled solar wind-turbulence-SEP model

Separate transport equation is solved for turbulenceWave stress tensor and energy appear in the solar wind momentum and energy equationsEnergetic particles are accelerated by interaction with turbulence

t=7m t=80m t=137m

Sokolov et al., 2009

FTE Simulation (Kuznetsova)

Resolution at the dayside magnetoapuse is 1/16 RE (400 km)

Total number of cells in the simulation is 20 million

Solar wind parameters: n = 2 cm–3

T = 20,000 K

Vx = 300 km/s

B = 5 nT

IMF Turning From Northward (θ = 0∘) to IMF clock angle θ < 120∘

Theta = 120o

Pressure

Subsolar FTE Structure

Cluster

View from South

Component Reconnection Near Sub-Solar Region (Y ~ 0 – 2 RE)And Anti-Parallel Reconnection at Flanks (Y ~ 12 - 15 RE)

View from the Sun

Z-slice

Y-slice

X-slice

FTE at flanks (Y = 12 Re) is connected to FTE at the subsolar region ( Y = 0 ).