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Solar wind effect on the propagation of CME-associated interplanetary shocks

Solar wind effect on the propagation of CME-associated interplanetary shocks. 김관혁 , 문용재 , 조경석 한국천문연구원. Sun-Earth Connection. Interplanetary (IP) space:. Near-Earth space/Earth ionosphere:. Solar wind (V, N)/IMF (B) variations. Compressed magnetosphere. IP shock+ Magnetic cloud.

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Solar wind effect on the propagation of CME-associated interplanetary shocks

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  1. Solar wind effect on the propagation of CME-associated interplanetary shocks 김관혁, 문용재, 조경석 한국천문연구원

  2. Sun-Earth Connection Interplanetary (IP) space: Near-Earth space/Earth ionosphere: Solar wind (V, N)/IMF (B) variations Compressed magnetosphere IP shock+ Magnetic cloud Magnetic storms (Ring current) Substorms (Aurora) Atmospheric heating CME Time Averaged MP SW dynamic pressure Time Compressed MP ~500-800 km/s N > 10 /cc RC ~400 km/s N < 10 /cc ExB flows 15 10 5 5 Dawn-Dusk E field Geosynchronous orbit 10 Dst 15 Recovery Phase Main Phase

  3. Magnetospheric responses to interplanetary (IP) shocks on Nov. 26, 2000 ACE (~230 RE) B Bz Near-Earth Space ACE (~230 RE) N Vsw Near-Earth Space KAK (L ~ 1.3) ground station Earth Sudden commencement (SC) Sudden impulse (SI)

  4. Data and event selection • IP shocks identified from SC/SI at the Earth and by examining SW/IMF data at the ACE satellite during 2000-2002 (solar maximum). • SC/SI events identified from the 1-min SYM-H data. • IP shocks driven by halo/partial halo CMEs identified from SOHO/LASCO. • CME initial speeds and CME onset times obtained from the CME catalog [Yashiro et al., 2004] • 56 CME-IP shock (SC/SI) pairs. • The events are mostly selected from the published archival data in the CME-IP shock studies [Cane and Richardson, 2003; Manoharan et al., 2004].

  5. Empirical shock arrival (ESA) model [Gopalswamy et al., 2004] Empirical CME arrival model [Gopalswamy et al., 2001], based on aconstant IP acceleration a = 2.193-0.0054Vcme Empirical shock arrival model [Gopalswamy et al., 2004] Acceleration-cessation distance: 0.76 AU

  6. Constant (mean) IP acceleration in ESA model [Gopalswamy et al., 2001] a = 2.193-0.0054VCMEfrom Helios 1/PVO and P78-1 at ~0.6-0.9 AU during 1979-1984

  7. ESA model prediction and observed shock arrival times N = 56 events |DT|  12 hours (34 events) |DT| > 12 hours (22 events) 91% (31 of 34 events) in 400-1300 km/sec 34 (61%) events predicted within 12 hours from ESA model ESA model prediction

  8. Is there a systematic dependence of the IP shock travel time deviations from the ESA model? Examine the deviations of shock arrival times from ESA model (T = Tobs-Tmod) with respect to CME initial speed (VCME),IP shock speed (VSH), and solar wind speed (VSW) just before IP shock VSH Solar wind speed VSW Time

  9. Deviations (T =Tobs-Tmod) of shock arrival times from the ESA model (Tobs-Tmod) vs. VCME VCME: CME initial speed from SOHO/LASCO (Tobs-Tmod) vs. (VCME-VSH) VSH: IP shock speed observed at ACE (1 AU) (Tobs-Tmod) vs. (VCME-VSW) VSW: Solar wind speed just before IP shock at ACE (1 AU)

  10. Revised ESA model [Texp-Tmod = a + bVCME] ESA model vs. Observation 400  VCME 1300 km/s ~61% (34 events) of 56 events within 12 hours from perfect agreement ~80% (45 events) of 56 events within 12 hours from perfect agreement

  11. Revised ESA model [Texp-Tmod = a + b(VCME-VSH)] Revised ESA model [Texp-Tmod = a + b(VCME-VSW)] ~90% of 56 events within 12 hours from perfect agreement ~90% of 56 events within 12 hours from perfect agreement

  12. Summary-1 • We evaluated the empirical shock arrival (ESA) model [Gopalswamy et al., 2004], based on a constant IP acceleration, using 56 CME-IP shock (SC/SI) pairs during 2000-2002. • Out of 56 CME-IP shock (SC/SI) pairs, ~61% (34 events) were predicted within 12 hours from the ESA model. • Most of the events (91%, 31 of 34 events) within 12 hours were in a range of VCME of 400-1300 km/s. • We find a systematic dependence of the IP shock travel time deviations from the ESA model. • This systematic dependence indicates that the constant IP accelerationin the ESA model is not reasonably well applied for all VCME but for VCME in the range of 400-1300 km/s.

  13. Summary-2 • Revised ESA model using T vs. VCME, T vs. (VCME-VSH), and T vs. (VCME-VSW) regressions predicts ~80%, ~90%, and ~90% of 56 events within 12 hours from perfect agreement. • We suggest that further study of solar wind effect on the propagation of IP shock associated with slower (VCME < 400 km/s) and faster (VCME > 1300 km/s) CMEs is required to improve the prediction accuracy of the IP shock arrival times at 1 AU, which is the first step in space weather forecasting.

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