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GLOBAL GEOMAGNETIC RESPONSE TO THE SHARP

MAGNETOSPHERE COMPRESSION AND IMF VARIATIONS ON OC­

TOBER 29, 2003

Solovyev S.I. , Moiseyev A. V. , Mullayarov V.A. (Yu.G.Shafer Institute o f Cosmophysical Research

and Aeronomy Russia 677891 Republic Sakha (Yakutia) Yakutsk, Lenin ave.,31), Du A. (Institute

o f geology and geophysics China ), Engebretson M. (Augsburg College USA 2211 Riverside Av­

enue Minneapolis, MN 55454-1338), Newitt L.R. (Geological Survey o f Canada, 1 Observatory

Crescent, Ottawa)

Analysis results o f the geomagnetic response during 30 min after SC o f the magnetic storm at

0611:30 UT on October 29, 2003 by using the global station chain are presented. The interaction

o f a shock with the Earth’s magnetosphere is accompanied by the increase o f the dynamic solar

wind pressure (Pd) and by the rise o f negative IMF Bz to -30 nT with the following change up to

positive values ~ -f 10 nT at 0617 UT. At the instant o f the northward turning o f the IMF Bz the

sharp decrease o f IMF By from

+2

to -38 nT is observed. The comparison with VLF-emission data

at Yakutsk (JL=3.3) is shown that ~ 15 s before the positive preliminary impulse (PI) onset, detected

almost in all time sectors and at all latitudes, the wide-band VLF-emission impulse is observed with

the shift o f the initial spectrum to higher frequencies. The estimation o f the propagation Alfven’s

velocity of a hydromagnetic impulse at

L <

4 gives

Va

~ 880 km/s. The main impulse (MI) of

SC during the first 5 min is characterized by the sharp intensification o f the westward electrojet in

the midnight-morning sector with maximum change of H-component o f geomagnetic field equal to

2000 nT at latitudes 65-70 degs and the eastward electrojet in the postnoon sector with maximum

change o f H-component equal to 700 nT at latitudes less/equal 65 deg. The northward turning

o f IMF Bz led to the new global intensification of the westward electrojet including the postnoon

sector at latitudes more/equal 70 deg. The expansion o f the westward electrojet in the premidnight

to the pole to latitudes ~ 80 deg with the velocity up to 5 km/s and to the east with the,velocity

~ 6 —13 km/s. It is supposed that the geomagnetic response o f electric currents to SC at the first 5

min is related to the rise o f Pd, magnetospheric convection and DP2 current system strengthening.

The following intensification o f the westward electrojet and its expansion in azimuth is the result

o f IMF Bz and By variations and the MIID-wave generation. The work was supported by RFBR

grant 03-05-39011-GFEN.

FORMATION OF THE NEW RADIATION BELT DURING OCTOBER-

NOVEMBER STORMS 2003

Shprits Yu. (UCLA, Los Angeles, USA)

Stochastic acceleration and loss of MeV electrons during October-November storms 2003 is re­

quired to explain intensive loss and formation o f a newr radiation belt in the slot region, near L=3.

Filling o f the slot region of the radiation belts is modeled with a combined pitch-angle, energy

diffusion code. We find that pitch angle distributions attain equilibrium shapes. Energy dependent

lifetimes are on the scale o f a day for MeV electrons and on the scale of a few hours for keV elec­

tron population, which provide a source for chorus emissions. We show that the energy diffusion

driven by whistler mode waves is capable of accelerating electrons up to energies of 3 MeV on the

time scales o f few days which is consistent with Polar and Sampax observations.

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