1. A New Methodology to Predict the Axial ICME Magnetic Field at 1 AU
M. K. Georgoulis1 & S. Patsourakos2
1 RCAAM of the Academy of Athens Physics Dept., University of Ioannina
To appear as Near-Sun and 1 AU Magnetic Field of Coronal Mass Ejections: a Parametric Study, S. Patsourakos & M. K. Georgoulis, A&A, in press (arXiv )

2. Objective and Steps of the Study
To best constrain the ICME axial magnetic field (B0) at 1 AU using solar observations and heliospheric propagation. ICME axis orientation not examined at this stage
SOLAR
Focus on CME source active regions and calculate their magnetic helicity
Aim to identify eruption-related helicity changes (ideally)
NEAR-SUN
Follow the helicity conservation principle and attribute helicity changes to eruptions
Forward-fit CME axis, orientation & radius
INNER-HELIOSPHERIC
Propagate B0 in inner heliosphere by using a power-law heliocentric fall-off function
Constrain power-law index by demanding agreement at L1
Credit: Demoulin & Dasso (2009)

3. Monte-Carlo modeled Near-Sun CME B0
Lundquist
flux rope
Credit: Thernisien et al. (2009)

4. Extrapolated ICME B0 at 1 AU
From an initial αB ∊ [-2.7, 1.0], an optimal agreement with observations is achieved for αB ≃ -1.6
Typical B0-values at 1 AU (L1) between in the range (10, 40) nT

5. Summary and limitations
MAIN FINDINGS
For the first time, diagnostics used from solar photosphere to L1
Ballpark agreement between measured/modeled axial fields of Mcs at L1 and findings hereby
Inner heliospheric radial fall-off power-law index constrained at ~ -1.6
Typical ICME B0-values at (10, 40) nT
LIMITATIONS
At this stage, analysis is not automated
ICME axis orientation not examined
Further assumptions toward assigning helicity to near-Sun CMEs and forward-modeling parameters