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IHY WB 2-3 Sep. 23, 2009. Forecast of Geomagnetic Storm based on CME and IP condition. R.-S. Kim 1 , K.-S. Cho 2 , Y.-J. Moon 3 , Yu Yi 1 , K.-H. Kim 3 1 Chungnam National University 2 Korea Astronomy and Space Science Institute 3 Kyunghee University. Geomagnetic storm.
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R.-S. Kim1, K.-S. Cho2, Y.-J. Moon3, Yu Yi1, K.-H. Kim3
1Chungnam National University
2Korea Astronomy and Space Science Institute
We use a two-step prediction for the storm forecast capability.
Source location (L) Earthward direction (D)
Initial speed (V) Magnetic field orientation of CME source region (M)
To improve the forecast capability of our model, we examine IP condition.
Gonzalez -Tsurutani empirical criteria (1987)
Bs ≥ 10 nT or Ey ≥ 5 mV/m for t ≥ 3 h
For the storms with Dst > -150 nT, 50% of the storms are satisfied.
For the storms with Dst ≤ -150 nT, 93% of the stronger storms are satisfied.
Our storm criteria is Dst ≤ -50 nT
We need to modify these criteria.
We select the criteria for moderate storms (Dst ≤ -50 nT)
Bz ≤ -5 nT or Ey ≥ 3 mV/m for t ≥ 2 h
For 64 events, 90% of the storms are in the IP criteria.
80% are correctly forecasted (51/64) (cf. CME parameter: 69%)
For 64 events
CME criteria: storm prediction formulae
IP criteria: Bz ≤ -5 nT or Ey ≥ 3 mV/m for t ≥ 2 hour
it can reduce the ambiguity of location caused by occulting disk.
Limitation of the forecast using CME parameter
We assumed that,
The effective acceleration ceases at some distance less than 1 AU and then CME travels with a constant speed to Earth (Gopalswamy et al, 2001).
The direction of the CME propagation (at C2 or C3 region) does not change through its travel to the Earth.
The magnetic field orientation of ICME has the same direction as in the CME source region.
The changes of CME characteristics increase the ambiguity in the storm forecast.
We used the plane-of-the-sky speed Error in predicted storm occurrence time.
We use the IP condition to increase the storm forecast capability.