heliospheric mhd models (for the lws community) lws workshop, boulder, co, march 23-26, 2004 dusan...
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Heliospheric MHD Models(for the LWS Community)
LWS Workshop, Boulder, CO, March 23-26, 2004
Dusan Odstrcil1,2 and Vic Pizzo2
1University of Colorado/CIRES, 2NOAA/Space Environment Center
Outline
• A. Heliospheric modeling
• B. Access to existing data sets
• C. Access to existing modeling system
• D. May 12, 1997 Interplanetary Event
• Conclusions
A. Heliospheric Modeling
Need for Heliospheric Simulations
Very little of the inner heliosphere can be directly sampled - many phenomena are of global scale; cannot be well understood by observations at a point or in a plane
Similar coronal ejecta may appear differently in the heliosphere due to their interactions with background solar wind or with other transient disturbances
Models are absolutely necessary for interpreting the available observations
Models will play a key role in space weather applications
Solar Wind Parameters
Large variations in plasma parameters between the Sun and Earth
Different regions involve different processes and phenomena
We distinguish between the coronal and heliospheric regions with an
interface located in the super-critical flow region (usually 18-30 Rs)
ENLIL – 3-D Solar Wind Model• Mathematical Description: - ideal magnetohydrodynamic (MHD) approximation - additional equations for injected mass and polarity tracking
• Method of Solution: - explicit finite-difference scheme - modified Lax-Friedrichs Total-Variation-Diminishing algorithm - parallelization by domain-decomposition
• Inputs: - Analytical, empirical, or numerical coronal models - NetCDF file format
• Outputs: - Distribution at specified time levels - Temporal evolution at specified positions - NetCDF file format
Currently Supported Input Data
• Analytic Models: - structured solar wind (bi-modal, tilted) - over-pressured plasma cloud (3-D) - magnetic flux-rope (3-D in progress)
• Empirical Models: - WSA source surface - SAIC source surface - CME cone model (location, diameter, and speed)
• Numerical Models: - SAIC coronal model (ambient + transient outflow)
Heliospheric Simulations• Using Available Data Sets: Visualize, analyze, and utilize a large collection of data sets
obtained during representative periods and events
• Using Available Modeling System: Prepare input data using existing initialization procedures
and data sets, and configure the existing numerical model
• Writing New Initialization Procedures: Develop new initialization procedures to produce input data
for the code, incorporate them into the ENKI portal, and run the existing numerical model
• Writing New Computational Procedures: Develop new computational procedures, incorporate them
into the ENLIL model as well as the ENKI portal, and use the existing initialization system to run the modified code
B. Access to Available Data Sets
Community Data Portal (CDP) –Storage Resources Broker (SRB)
CDP SRB
NCAR, Unidata NSF, UCSD, General Atomic
NCAR systems Multi-platform
NetCDF Multi-format
Web-based Installation needed
Community Data Portal
The Community Data Portal (CDP) is a collection of earth science datasets from NCAR, UCAR, UOP, and participating organizations
A central gateway to the large and diversified datasets in the following research areas: oceanic atmospheric space weather turbulence
Web-based portal with the following functionality: data search metadata browsing data download analysis and visualization
NCAR/SCD project supported by NSF/Cyberinfrastructure Strategic Initiative
Community Data Portal – Main Interface
[ http://dataportal.ucar.edu ]
Community Data Portal – Data Sets
Representative 3-D interactions in structured wind (hypothetic scenarios) Ambient solar wind for selected Carrington rotations (empirical models) Transient heliospheric disturbances for selected event (MURI, CISM, SHINE) driven by empirical models) Interplanetary consequences of coronal magnetic eruptions (coupled coronal and heliospheric numerical models)
Example – Providing a Global Context
Development of tools for utilizing multi-point in-situ observations Analysis of various in-situ observations for selected (computed) events
Example – Providing 3-D Density
Development of tools for utilizing multi-point remote observations Analysis of various remote observations for selected (computed) events
ICME
Earth
Stereo-A
Stereo-B
C. Access to Existing Modeling System
ENKI – Interface to ENLIL• Client-Based Approach: - runs locally - remote access via ssh and scp• Input Data: - initial and/or boundary values - run and batch parameters• Numerical Model: - parameters for CPP preprocessor
- array dimensions • Visualization: - interactive preview - standardized views• Data Management: - update source files - transfer input/output files• Project Management: - project review, report, and archiving
ENKI – Interface to ENLIL
ENKI – Interface to ENLIL
ENKI – Interface to ENLIL
Remote Visualization: ENKI-IDL
Preview of data before downloading processing and visualization, archiving, etc.
Plot 1-D profiles and 2-D contours or surfaces of 1-D, 2-D, or 3-D data
D. May 12, 1997 Interplanetary Event
Global Solar and Coronal Observations
Remote solar observations of the photospheric magnetic field Remote coronal observations of
the white-light scattered on density structures
Ambient Solar Wind Models
SAIC 3-D MHD steady state coronal model based on photospheric field maps
CU/CIRES-NOAA/SEC 3-D solar wind model based on potential
and current-sheet source surface empirical models
May 12, 1997 Halo CME
Running difference images fitted by the cone model
CME Cone Model
[ Zhao et al., 2001 ]
Best fitting for May 12, 1997 halo CME
• latitude: N3.0• longitude: W1.0• angular width: 50 deg
• velocity:650 km/s at 24 Rs
(14:15 UT)• acceleration: 18.5 m/s2
Boundary Conditions
Ambient Solar WindAmbient Solar Wind
+ Plasma Cloud
Latitudinal Distortion of ICME Shape
ICME propagates into bi-modal solar wind
Radial Compression of ICME Structure
Fast stream follows the ICME
Evolution of Density Structure
ICME propagates into the enhanced density of a streamer belt flow
Propagation of Energetic Particles
IMF line connected to Earth by-passes the shock structure
=>Interplanetary CME-driven shock
cannot generate energetic particles observed at Earth
IMF line connected to Earth passes through the shock structure
=>Quasi-perpendicular shock can
generate energetic particles under certain circumstances
Early time Later time
Energetic Particles & Radio Emission
Important effect occurs away from the Sun-Earth line
Enhanced shock interaction together with quasi-perpendicular propagation relative to IMF lines favors particle acceleration and generation of radio emission
Global view Detailed view
Evolution of Parameters at Earth
May 12, 1997 – Interplanetary Shock
• Shock propagates in a fast stream and
merges with its leading edge
Distribution of parameters in equatorial plane Evolution of velocity on Sun-Earth line
0.2 AU
0.4 AU
0.6 AU
0.8 AU
1.0 AU
Fast-Stream Position
Ambient state before the CME launch
Disturbed state during the CME launch
Ambient state after the CME launch
Case A1 Case A3
[ SAIC maps -- Pete Riley ]
Effect of Fast-Stream Position
Case A1 Case A3
Earth : Interaction region followed by shock and CME (not observed)
Earth : Shock and CME (observedbut 3-day shift is too large)
Fast-Stream Evolution
Ambient state before the CME launch
Disturbed state during the CME launch
Ambient state after the CME launch
Case A2 Case B2
[ SAIC maps -- Pete Riley ]
Effect of Fast-Stream Evolution
Case A2 Case B2
Earth : Interaction region followed by shock and CME (not observed)
Earth : Shock and CME (observedbut shock front is radial)
Conclusions – 1 of 2
• It becomes possible to:
- simulate ambient solar wind parameters
- estimate arrival of shock and ejecta
- provide a global context
• It is not possible to:
- reproduce detail locations of stream boundaries
- reproduce an internal magnetic structure of ICMEs
Conclusions – 2 of 2
• Key areas needing development:
- consensus on what mechanisms lead to and launch CME
- how to characterize the inputs given the sparse nature of
the observations
- improved treatment of reconnection
- self-consistent (or at least much improved) inclusion of
energetic particles on global scale
- framework for modeling, visualization, and analysis