scostep 2010 (stp12) - Leibniz-Institut für Atmosphärenphysik an der ...

STP12 Abstracts
Berlin, 12 - 16 July 2010
SCOSTEP Symposium 2010
The Relation Between Coronal Holes and CMEs During the Rise, Maximum and
Declining Phases of the Solar Cycle 23
Mohamed Amaal 1 , Gopalswamy Nat 2 , Jung Hyewon 1 , Makela Pertti 1 , Akiyama Sachiko 1 , Yashiro
Seijie 1 , Xie Hong 1
1 The catholic University of America, 2 Goddard Space Flight Center
We investigate the influence of coronal holes on the propagation of CM Es through
considering both ICM Es categories with and without flux rope structures, i.e. magnetic
clouds (M Cs) and non magnetic clouds (non-M Cs), during the three phases of the solar cycle
23 and compare the results obtained with that of the driverless shocks reported previously by
Gopalswamy et al., 2009b. The results show that the correlation coefficient in the case of M C
events is very high at the rise phase (~0.99), while it is for declining phase ~-0.62. This result
confirms the correspondence between the non-radial motion during the rise phase of the solar
cycle and the existence of the higher magnetic field strength in the solar regions of the polar
coronal holes during this phase. For the maximum phase the correlation coefficient in case of
magnetic clouds is ~-0.30. The correlation coefficient values are found to be much less for
non magnetic clouds during the three phases; with the highest value turned to be for the
declining phase (ccd=-0.2). The difference between measured position angle (M PA) and the
influence position angle (FPA) s pointing, (∆ψ), is found to be in the case 3 where the CH is
located between the eruption region and disk center ~35o for the non-M Cs in the maximum
phase and in case 2 where the disk center is located between the CH and eruption region ~34o
for the non-M Cs events in the rise phase which is consistent with the value of ∆ψ for
driverless shocks given by Gopalswamy et al., (2009b) (where ∆ψ≤ 37o). These results
together with the average influence parameter value (Favd=2.5 G) which is found to be the
highest compared to the other two phases and also to the M Cs average values suggest that the
non M Cs is resembling in their behavior the driverless shocks (which have been proven by
Gopalswamy et al., (2009a,b) to be deflected by the near by CH s away from the Sun-Earth
line) and that the non M Cs may have flux rope structure as the M Cs do have but this
structure is hidden from observation due to the deflection by CH s. This finding may have
bearing on the idea that all CM Es may be flux ropes and the difference is only due to the
viewing angle variation.