The First Space-Weather Numerical Forecasting Model & Reconstruction of Halo CMEs

1. The First Space-Weather Numerical Forecasting Model &Reconstruction of Halo CMEs Xuepu Zhao http://sun.stanford.edu/~xuepu xpzhao98@yahoo.com NAOC Oct. 20, 2011

2. 1. The first space-weather numerical forecasting model • NSF Press Release, 26 Jan 2011: CISM’s New Space Weather Forecasting Model Going Operational use in fall 2011 with NWS • Pizzo, V., et al., Wang-Sheeley-Arge-Enlil-Cone Model Transitions to Operations, Space Weather, 9, S03004,doi:10.1029/2011SW000663 • Schultz, C., Space Weather Model Moves Into Prime Time, Space Weather, 9, S03005,doi:10.1029/2011SW000669 • Schultz, C., Space Weather Model Moves Into Prime Time, Space Weather, 9, S03005,doi:10.1029/2011SW000669

3. The new forecasting model will provide forecasters • with a one-to-four day advance warning of • high-speed streams of solar plasma and • Earth-directed coronal mass ejections. The model • make it possible to narrow the ICME arrival-time • window from 1- or 2-day to 6-8 hours. • This transition draws upon contribution mainly • from NSF’s Center for Integrated Space Weather • Modeling (CISM). CISM was established in August 2002 and made up of 11 member institutions. Its goal is to integrate, improve, and systematically validate a physics-based numerical simulation model for operational forecast use.

4. CISM Solar thrust: (1) Model boundary conditions (Stanford, UCB) (2) MSA model (SAIC) (3) WSA solar wind model (NOAA-SWPC) (4) Cone models of halo CMEs (Stanford) (5) Active region models (UCB,Stanford) (6) CME models (SAIC) (7) ENLIL CME propagation model (NOAA-SWPC) (8) Solar energetic particle models (UCB)

5. 2. Improvement of CISM’s prediction model MASX Magnetic Synoptic maps GONG, MWO MDI, HMI WSA* ENLIL* HCCSSA? SIP-CESE? • White-light Halo CMEs • Automatic determination of elliptical outlines SIP-AMR-CESE? Circular Cone* Elliptic Cone?

6. 3. Reconstruction of halo CMEs • The model-CME launched at the inner boundary of ENLIL model is obtained using the circular cone model (Zhao et al., 2002; Xie, 2005). However, Most of halo CMEs cannot be correctely reconstructed by the circular model. I’d like to talk about the elliptic model that can be used to correctely invert 3-D properties from all types of halo CMEs (Zhao, 2008; 2011).

7. 3.1Halo Parameters and Classification of Halo CMEs • Halo CMEs with flares or filament eruptions associated, Earth-directed Halo CMEs, are major cause of severe geomagnetic storms and crucial for space weather. • Halo CMEs may be expressed as ellipses • A 2-D ellipse can be characterized by FIVEhalo parameters(See following figure): Dse, α– the location of ellipse center SAxh,SAyh – Shape of ellipses ψ – orientation of ellipses

8. Definition of five Halo Parameters: Dse—distance from disk center to ellipse center α—angle between Xh & Xc’ SAxh, SAyh— Semi axes Ψ—oriention angle between Yc’ & Sayh or Xc’ & SAxh Zh Y Yc’ SAyh ψ SAxh Xh α Dse Xc’

9. A B Three Types of Halo CMEs C C Ψ = 0 => FOUR halo parameters C C There are 3 (10%) Type A halos among 30 halo CMEs

10. 3.2 Circular and Elliptic Halo Models • It is impossible to invert 3-D properties of halo CMEs from observed 2-D halo images if there is no additional data source and/or assumptions about the 3-D CME structure. • Most of CMEs are believed to be 3-D magnetized plasma clouds with configuration of flux ropes.

12. Limb CMEs (CMEs with propagation direction near the plane of the sky) show loop-like with two ends anchored on the solar surface, suggesting that the 3-D CMEs may be obtained by rotating the loop, i.e., circular or elliptic conical shells. The following figure shows a cone in the heliospheric coordinate system XhYhZh. • Zh from Sun to Earth, XhYh denptes the • sky plane.

13. Rc Central axis: Rc, λ, φ(θ, α), size: ω Yc || Yc’

14. 3.3 Cone Model Parameters • Circular cone model: 4 model parameters Location of the cone base center: Rc, λ, φ Size of circular cone base: ω • Elliptic cone model: 6 parameters: Location of the cone base center: Rc, λ, φ Size of elliptic cone base: ωy, ωz Orientation of elliptic cone base: χ

15. Zh SAx Cone base || YcZc plane Dse =Rc cos θ SAy=yc > SAx=zc sinθ Only Type A for circular cone model

16. 4. Improved Elliptic Cone Model • Halo CMEs are assumed to be CMEs with propagation direction near the Sun-Earth line. 2-D elliptic halos are projection of 3-D CMEs in the plane of the sky. White-light coronagraph data from SOHO & STEREO confirmed the assumption.

17. 4.1Predicted and observed halo

18. 4.2 Relationship between model and halo parameters

20. 4.3 Inversion equation system

21. Halo parameters: α, Dse, ψ, SAx, SAy Model parameters: α, β, Rc, χ, ωy, ωz Eq. (7) can be used to find out Rc, ωy, χ, and ωz from Dse, ψ, SAx, Say if β can be specified. β is found out based on given α and the location of associated flare or filament eruption.

24. 5. Summary • The improved inversion equation system can be used to invert model parameters for all three types of halo CMEs with all kinds of propagation directions. • It is necessary to automatically identify the outline for halo CMEs so that the reconstruction of 3-D CME is rather objective and reliable.

25. Thank you!