Chelpanov M. A., Zolotukhina N.A. Institute of Solar-Terrestrial Physics, Irkutsk, Russia

Subauroral heliosphere-Subauroral heliosphere-geosphere coupling geosphere coupling during November 2004 during November 2004

ionospheric storms: F2-region, ionospheric storms: F2-region, North-East AsiaNorth-East Asia

Chelpanov M. A., Chelpanov M. A., Zolotukhina N.A.Zolotukhina N.A.

Institute of Solar-Terrestrial Institute of Solar-Terrestrial Physics, Irkutsk, RussiaPhysics, Irkutsk, Russia

Purposes of the studyPurposes of the study

The main object of our study The main object of our study is is disturbances of the F2-layer of the disturbances of the F2-layer of the subauroral ionosphere, developed on subauroral ionosphere, developed on November 7-11, 2004 in the East Asian November 7-11, 2004 in the East Asian sector.sector.

We consider two negative phases of the We consider two negative phases of the ionosphere storm and find out reasons for ionosphere storm and find out reasons for differences in the duration of the negative differences in the duration of the negative phase.phase.

Measurements in the Measurements in the restricted sector 190restricted sector 190oo to to

211211oo geomagnetic longitude geomagnetic longitude

Station Station geomagnetic geomagnetic

coordinates coordinates1 1 Kotel'nyy (KTN) Kotel'nyy (KTN) 65.21 65.21

195.55195.552 2 LANL-97A (LANL-97A (L7) L7) 63.90 63.90

210.88210.883 3 Chokurdakh (CHD) 62.04 Chokurdakh (CHD) 62.04

206.71206.714 4 Tixie (TIK) 61.81 Tixie (TIK) 61.81

193.49193.495 5 Zyryanka (Zyryanka (ZYK) ZYK) 57.58 57.58

211.02211.026 6 Zhigansk (Zhigansk (ZGN) ZGN) 56.81 56.81

190.70190.707 7 Yakutsk (Yakutsk (YAK) 52.39 YAK) 52.39

196.25196.258 8 Magadan (MGD) Magadan (MGD) 50.68 50.68

210.94210.94

Series of the November Series of the November 2004 superstorms2004 superstorms

The leading edge of the solar wind The leading edge of the solar wind irregularities propagated past WIND spacecraft irregularities propagated past WIND spacecraft at 02 UT on November 7, and approached the at 02 UT on November 7, and approached the

Earth at 02:58 UTEarth at 02:58 UT

Series of the November Series of the November 2004 superstorms: Kp, 2004 superstorms: Kp, SYM-H, AU, AL indices SYM-H, AU, AL indices

Two negative substorm Two negative substorm effectseffects

Neutral thermosphere Neutral thermosphere densitiesdensities

Thermosphere mass Thermosphere mass densities predicted by densities predicted by

MSIS model and MSIS model and densities derived from densities derived from

GRACE satellite data for GRACE satellite data for altitude 350 km near altitude 350 km near

noon-midnight meridian.noon-midnight meridian.

from Burke et alfrom Burke et al., 2007., 2007 During the second During the second

substorm mass densities substorm mass densities even less than even less than

these duringthese during the first one. the first one.

Outer conditions: IMFOuter conditions: IMFThe first The first

difference:difference:the first phase the first phase

developed at developed at southward southward

IMFIMF, the second , the second one one began at began at

northward northward IMFIMF and 3 and 3

hours later the hours later the IMF turned to IMF turned to

the south.the south.

Outer conditions: By, density Outer conditions: By, density and speedand speed

The second differenceThe second difference: : solar wind velocitysolar wind velocity during the second event was 150 km/s higher during the second event was 150 km/s higher than that during the first one.than that during the first one.

Pc5 geomagnetic Pc5 geomagnetic pulsationspulsations

The third The third differencedifference::

the second the second negative phase negative phase

was accompanied was accompanied by intense by intense

geomagnetic geomagnetic pulsations of the pulsations of the

Pc5 range.Pc5 range.

Auroral electrojetsAuroral electrojets

The negative storm effects in Yakutsk occurred in The negative storm effects in Yakutsk occurred in the north-west electrojet region, southward of the north-west electrojet region, southward of unstable currents i. e. in the south-westward reverse unstable currents i. e. in the south-westward reverse convection regionconvection region

Reverse convection Reverse convection regionregion

Model calculation Model calculation (Heelis (Heelis et al., 2009)et al., 2009) reveals that reveals that in the north-west in the north-west electrojet regionelectrojet region electron electron density and altitude of the density and altitude of the F2 layer decrease.F2 layer decrease.

ResultsResultsBoth negative phases occurred in Both negative phases occurred in conditions ofconditions of

the morning-noon magnetosphere contracted the morning-noon magnetosphere contracted to the geostationary orbit radiusto the geostationary orbit radius

negative By component of the IMFnegative By component of the IMF the reverse convection region.the reverse convection region.

Differences in conditions of the second Differences in conditions of the second negative storm effect arenegative storm effect are the negative phase with prolonged the negative phase with prolonged

ionosphere effect began at northward Bz ionosphere effect began at northward Bz component of the IMFcomponent of the IMF

high speed of the solar windhigh speed of the solar wind accompanying by generating of geomagnetic accompanying by generating of geomagnetic

pulsations of the Pc5 band.pulsations of the Pc5 band.

in both cases one of the reasons for negative in both cases one of the reasons for negative phase development was critical frequency and phase development was critical frequency and F2 altitude depletion in the strong reverse F2 altitude depletion in the strong reverse convection region;convection region;

high-latitude reconnection occurring in the high-latitude reconnection occurring in the north morning magnetosphere at the north morning magnetosphere at the northward IMF and ULF-waves of the Pc5 northward IMF and ULF-waves of the Pc5 band amplified the electromagnetic energy band amplified the electromagnetic energy entrance to the subauroral ionosphere;entrance to the subauroral ionosphere;

Amplification of energy entering the Amplification of energy entering the ionosphere-thermosphere system has led to ionosphere-thermosphere system has led to the long-lived disturbed composition zone the long-lived disturbed composition zone which is supposed to be a reason for the which is supposed to be a reason for the morning-noon negative storm effect.morning-noon negative storm effect.

ConclusionsConclusions

Thank you!Thank you!