Using Potential Field Models

to Learn About CME Coronal

Context and Consequences

•J.G. Luhmann and Yan Li (Space Sciences Lab, UCB)

•C.N. Arge (CIRES, U. of Colorado and NOAA-SEC)

•X-P. Zhao and Yang Liu (Stanford University)

•O.C. St.Cyr (NASA GSFC and CUA)

•Nathan Rich (NRL and Interferometrics Inc.)

Active region distributions can be simple or complex

(synoptic maps from SOHOMDI of CR 1915-1917, 1934-1936, and 1960-1962)

The potential field The potential field source surface model source surface model reproduces the reproduces the coronal holes and coronal holes and shows the helmet shows the helmet streamer belt and streamer belt and active region field active region field connections for connections for CR1915. (CR1915. (SOHO EIT SOHO EIT map from NRL map from NRL LASCO websiteLASCO website))

The potential field The potential field source surface model source surface model reproduces the reproduces the coronal holes and coronal holes and shows the helmet shows the helmet streamer belt and streamer belt and active region field active region field connections for connections for CR1936. (CR1936. (SOHO EIT SOHO EIT map from NRL map from NRL LASCO websiteLASCO website))

09/26/96 LASCO C2, SXT, and PFSS09/26/96 LASCO C2, SXT, and PFSS

26 September 1996 Haol CME: 26 September 1996 Haol CME:

““Model” and SOHO EIT/LASCO imageModel” and SOHO EIT/LASCO image

Halos may be secondary streamer cylinders produced as a transient phase

(right panel from ISTP website at GSFC)

(bottom: hypothetical backside view)

05/12/98 LASCO C2, SXT, and PFSS05/12/98 LASCO C2, SXT, and PFSS

CR1936 PFSS Views During CMEsCR1936 PFSS Views During CMEs

What We’ve LearnedWhat We’ve Learned

• For simple CMEs, PFSS models allow For simple CMEs, PFSS models allow visualization of the surrounding corona.visualization of the surrounding corona.

• Complex CMEs are more challenging, Complex CMEs are more challenging, but the PFSS model still provides the but the PFSS model still provides the helmet streamer belt context.helmet streamer belt context.

• It would be good to try some of the same It would be good to try some of the same boundary conditions in global MHD boundary conditions in global MHD models.models.