COMMENTS: If the disturbance in the IMF, which started on July 26 at 2230UT
is associated with the halo CME on July 25th, then it seems that the CME speed was significantly
The height-time plot for this event shows a wide range of speeds and for the prediction we
ususlly take speed measured at about 20 solar radii (~700km/s). Now that we know the travel
time, the initial speed can be estimated according to the Gopalswamy et al., 2000, GRL, 27 plot (Fig 3):
for the travel time of about 34 hours the initial speed should be about 1300 km/s.
Then the Bz is estimated to be between -20 ... -34 nT (about -25nT according to ACE data),
while the Dst index should drop by 177 ... 244 nT (Dst decreased by ~170 nT from -32nT to -200nT).
CME's Source Region is NOAA AR0653 ; P0= 8.2879988; Day of Year # 207
CME Appeared at 6 Solar Radii on 20040725 at 1518 UT
CME Arrived at 20 Solar Radii on 20040725 at 1830 UT