1. Extreme Event Symposium 2004 MAGNETOSPHERIC EFFECT in COSMIC RAYS DURING UNIQUE MAGNETIC STORM IN NOVEMBER 2003 1. Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Moscow, Russia 2. NPolar Geophysical Institute, Russia. 3. Nuclear and Particle Physics Section, Physics Dpt., University of Athens, Greece A.Belov (1), L. Baisultanova, E.Eroshenko (1), V.Yanke (1) V.Pchelkin (2), H.Mavromichalaki (3), A.Belov (1), L. Baisultanova, E.Eroshenko (1), V.Yanke (1), V.Pchelkin (2), H.Mavromichalaki (3),

2. Records in 2003 Earth’s Magnetosphere WhenWhat 29 October Mostly disturbed day of Cycle (Ap=204) 29-30 October Three 3-hourly intervals with Kp=9 o during 2 days 29-31 October Ap = 204,191,116 –mostly disturbed 3-day interval over the history October Mostly disturbed MONTH of Cycle (Ap=34.7 ) 20 November Dst= -472 nT Dst= -472 nT –second value over history Dst= -472 nT 2003 Mostly disturbed YEAR of Cycle (Ap=21.7)

3. Some reasons of specific interest to the magnetospheric effect in CR study 1. On the physical point of view: creation, evolving and decay of the magnetosphere current systems, global interaction of cosmic radiation with the geomagnetic field 1. On the physical point of view: creation, evolving and decay of the magnetosphere current systems, global interaction of cosmic radiation with the geomagnetic field 2. Cosmic ray variations caused by the cut off rigidity changes during the big magnetic storm, should be correctly excluded from the initial NM data to study primary CR variations. 2. Cosmic ray variations caused by the cut off rigidity changes during the big magnetic storm, should be correctly excluded from the initial NM data to study primary CR variations. 3. Checking of the current system models on different steps of the magnetic storm. Incorporation directly CR data for this analysis is important to study the global effect of the current systems on the particle trajectories as for initial phase of magnetic storm (associated with currents in the magnetopause, when cut off rigidity increases relatively to the quite level, so for the main phase, when cut off rigidity decreases significantly. 3. Checking of the current system models on different steps of the magnetic storm. Incorporation directly CR data for this analysis is important to study the global effect of the current systems on the particle trajectories as for initial phase of magnetic storm (associated with currents in the magnetopause, when cut off rigidity increases relatively to the quite level, so for the main phase, when cut off rigidity decreases significantly.

4. Interaction of solar wind disturbance with the Earth magnetosphere

5. Results of disturbed magnetosphere What such disturbances result is well seen even from the label of the Institute which hold this Symposium Aurora oval moving to the equator

6. Cosmic Ray variations in 2003 The most significant series of Forbush effects (FEs), exceeded series in July 2000 and March- April 2001, occurred in Oct-Nov 2003. The most significant series of Forbush effects (FEs), exceeded series in July 2000 and March- April 2001, occurred in Oct-Nov 2003. AR486 was mostly productive with geoeffective events during 13 days. The greatest was FE on 29.10 after exclusively fast CME (up to 2125 km/s) from the flare X17/2B. AR486 was mostly productive with geoeffective events during 13 days. The greatest was FE on 29.10 after exclusively fast CME (up to 2125 km/s) from the flare X17/2B.

7. Conditions Two AR: 501 (484) and 508 (486) ; 18 Nov.: the last big flare in group 508 (M4 at 09:23 UT ); Two long lasted flares in the center of disk (M3.2/2N N00W18, at 07:16 UT, maximum at 07:54 UT; and M3.9/, onset at 08:12 UT, maximum at 08:31 UT ); Powerful and extremely effective CMEs ; Severe magnetic storm associated possibly with all three CMEs started on 20.11 after 12 UT; IMF intensity reached 60 nT and Bz~-57nT; Dst-index fall down to -472 nT ; Aurora - even in the Athens (Rc=8.34 GV)

8. Magnetospheric effects Aurora in Athens on 20 November 2003.

9. Geomagnetic activity during severe storm on 20.11.03 Geomagnetic field variations and wavelet spectrum of H-c In November 20, 2003 observed in Moscow (IZMIRAN)

10. Magnetospheric effect in CR on 20.11.03 Counting rate at different NMs uncorrected for magnetospheric effect. FD is moderate despite of severe magnetic storm

11. METHODS Neutron Monitors Stations used in this analysis Data from 39 NMs : 15 high latitudinal ( 10GV Global Survey Method (GSM): 1. Coupling coefficients- beyond the athmosphere; 2. Trajectory calculations-beyond magnetosphere ; 3. Spherical analysis-to select different harmonics; Counting rate—> isotropic part+3D anisotropy +magn+err:

12. Correction CR variations for magnetospheric effect

13. Comparison of obtained dRc with Dst-index Comparison of obtained dRc with Dst-index

14. Correlation between cut off rigidity variations dRc and Dst-index Correlation between cut off rigidity variations dRc and Dst-index

15. Latitudinal dependences of dRc for each hour during event on 20.11.04 Maximum in latitudinal distribution of dRc is found around 7-8 GV (usually 3-4 GV) that means ring current to be located at 3R from the Earth center.

16. Comparison experimental results with calculations by the last Tsyganenko model 1.Good agreement under Rc>6 GV; 2.2. Disagreement at Rc<6GV may be caused by inadequacy of model under great magnetospheric disturbances; 3. Experimental methods applied to other magnetic storms gives the classical latitudinal dRc variations with the maximum around 3-4GV dRc variations in dependence on cut-off rigidity in the maximum of geomagnetic storm 20.11.03, derived from experimental CR data (circles) and calculated by the Tsyganenko (T01storm) model (red).

17. SUMMARY Exclusively large effect in CR was observed during the main phase of the 20.11.04 geomagnetic storm; Latitudinal distribution of the cut off rigidity variations was obtained for each hour during the main and recovery phases of this magnetosphere storm. A peculiarity of this event is that maximum magnetospheric effect is observed at low latitude stations (7-8 GV) on the contrary with usual observations at low latitudes (3-4GV); The ring current system during this event was at more close distance from Earth (apparently about 3 Earth’s radii) than it usually observed; Calculations of the Rc variations by the last “storm” model of the magnetospheric magnetic field showed a good agreement with the experimental results under Rc>6 GV. A discrepancy under less rigidities may be caused by the model inadequacy under greatest magnetospheric disturbances.

18. THE END