The First Space-Weather Numerical Forecasting Model & Reconstruction of Halo CMEs Xuepu Zhao NAOC Oct. 20, 2011

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: /2011SW Schultz, C., Space Weather Model Moves Into Prime Time, Space Weather, 9, S03005,doi: /2011SW Schultz, C., Space Weather Model Moves Into Prime Time, Space Weather, 9, S03005,doi: /2011SW000669

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.

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 )

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

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).

3.1 Halo 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 FIVE halo parameters (See following figure): Dse, α – the location of ellipse center SAxh,SAyh – Shape of ellipses ψ – orientation of ellipses

Dse SAxh SAyh Xc’ Yc’ Xh Zh α ψ 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 Y

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

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.

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.

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

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

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

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.

4.1 Predicted and observed halo

4.2 Relationship between model and halo parameters

4.3 Inversion equation system

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.

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.

Thank you!