DELAY TIMES BETWEEN GEOEFFECTIVE DELAY TIMES BETWEEN GEOEFFECTIVE SOLAR DISTURBANCES AND SOLAR DISTURBANCES AND

GEOMAGNETIC INDICESGEOMAGNETIC INDICES

Y. D. PARK1, Y. -J. MOON1, I. S. KIM2, H. S. YUN3

1.Korea Astronomy Observatory, Daejeon, KOREA

2. Sternberg State Astronomical Institute, Moscow Univ. RUSSIA

3. Seoul National Univ. Seoul, KOREA

I. INTRODUCTION

Geomagnetic Activities are associated with Solar Active Features(DSF, CME, Flares….)

Solar activity - Geomagnetic activities research : Gosling et al.( 1991), Gosling(1997), Hudson et al.(1998), Zarro et al.(1999), Sterning et al.(2000), Gilbert et al.(2000)…..

Primary mechanisms are not fully understood Gosling suggestion (1993 “Solar Flare Myth”) : geomagnetic a

ctivities by fast CMEs are not necessarily associated with solar flares.

Delay times of solar disturbances Several cases using simple correlation tools (e.g., Joselyn and McIn-tos

h, 1981; ; Wright, 1983a; 1983b; Mikhailusta and Gnevyshev, 1985;Wat

anabe and Schwenn, 1989). Joselyn and McIntosh(1981) : flare- geomagnetic storm relation 3 years

data. Wright(1983a, 1983b) disappearing prominences and Ap index.

Quantitative characteristics of delay times of geoeffective solar disturbances, using data taken for several decades.

Cross-correlation measure of point series data most probable delay time

Estimate the most probable time for major X-ray flares and disappearing filaments to travel from the Sun to the Earth.

Investigate delay time between SSC(storm sudden commencement)s and major geomagnetic storms.

Examined the dependence of correlation on the characteristics of solar disturbances such as their strengths, durations and locations.

II. DATA

NGDC – more than 2 solar cycle 4836 solar X-ray flares stronger than M1 class recorded from Sep.

1, 1975 to Dec. 31,1999 1651 disappearing filaments occurred from Jan. 1, 1992 to Dec. 31,

1999 793 SSCs recorded from Sep. 1, 1975 to Dec. 31, 1999, 408 major geomagnetic storms from Sep.1, 1975 to Dec. 31, 1999.

III. RESULT and DISCUSSION

Examined relationships solar flares - disappearing filaments, - SSCs. X-ray flares duration –SSC

X-ray flares strength –SSC

Flare duration should be a more significant factor than strengthFlare duration should be a more significant factor than strength

traveling time of flare disturbance on heliolongitude

The cross-correlation between DSFs and SSC

Cross-correlation : DSFs of heliolongitudes - SSCs.

Cross-correlation : SSCs - starting time of major

geomagnetic storms

High correlation appearing at zero time lag

SSCs are a good sign of initiation of major

geomagnetic storms.

Positive correlation

most of geomagnetic storms take place in about

one and half days after SSCs occur.

Cross-correlation : SSCs - starting time of major

geomagnetic storms

VI. SUMMARY and CONCLUSION

1. The most probable traveling time of a solar disturbance from the Sun to the Earth is estimated to be about 2 days for solar major (X and M class) flares and about 3 days for disappearing filaments.

1. The most probable traveling time of a solar disturbance from the Sun to the Earth is estimated to be about 2 days for solar major (X and M class) flares and about 3 days for disappearing filaments.

1. Long-duration flares are better correlated with SSCs than short duration flares are. This is consistent with that long-duration flares are frequently associated with CMEs and coronal and/or interplanetary shocks.

1. Long-duration flares are better correlated with SSCs than short duration flares are. This is consistent with that long-duration flares are frequently associated with CMEs and coronal and/or interplanetary shocks.

1. The traveling times of solar disturbances strongly depend on the heliolongitude where they originate. The disturbances associated with flares and laments located at the middle west longitude are approximately two times faster than those associated with flares located at the middle east longitude.

1. The traveling times of solar disturbances strongly depend on the heliolongitude where they originate. The disturbances associated with flares and laments located at the middle west longitude are approximately two times faster than those associated with flares located at the middle east longitude.

1. We have confirmed that solar disturbances associated with flares and disappearing laments at the western limb can hardly reach the Earth. Finally, our results are expected to be used as quantitative input parameters for predicting solar-terrestrial effects(e.g., Lundstedt, 1992).

1. We have confirmed that solar disturbances associated with flares and disappearing laments at the western limb can hardly reach the Earth. Finally, our results are expected to be used as quantitative input parameters for predicting solar-terrestrial effects(e.g., Lundstedt, 1992).

1. The traveling times of solar disturbances strongly depend on the heliolongitude where they originate. The disturbances associated with flares and laments located at the middle west longitude are approximately two times faster than those associated with flares located at the middle east longitude.

1. We have confirmed that solar disturbances associated with flares and disappearing laments at the western limb can hardly reach the Earth. Finally, our results are expected to be used as quantitative input parameters for predicting solar-terrestrial effects(e.g., Lundstedt, 1992).