CAUSES AND LESSONS OF THE 20 NOVEMBER 2003

GEOMAGNETIC SUPERSTORM

V.Grechnev, A.Uralov, G.Rudenko, I.Myshyakov, V.Fainshtein, Ya.Egorov, A.Afanasyev (Institute of Solar-Terr.

Phys., Irkutsk, Russia)V.Slemzin (Lebedev Physical Institute FIAN, Moscow, Russia)

I.Chertok, B.Filippov, A.Belov (IZMIRAN, Moscow, Russia)M.Temmer (Kanzelhöhe Observatory, Graz University, Austria)

B.Jackson (University of California, San Diego, USA) N.Prestage (Culgoora Solar Observatory, Australia)

Magnetic flux in source region, 1020 Mx

r 0.67

18–20.11.2003

18–20.11.2003 Event: Challenges & Significance

•Moderate 18.11.2003 solar eruptive event…

•…caused the 20.11.2003 geomagnetic storm, most severe in almost quarter a century

•Relations between parameters of the event and its geomagnetic outcome deviate from all known correlations

•Hazards of geomagnetic storms for industrial systems urge one to find out causes of extreme geomagnetic effect of this event

•We search for causes of the 20.11.2003 superstorm by comparing with extreme 2829.10.2003 event of preceding rotation of this activity complex (in different AR)

Chertok et al. 2013, Sol. Phys. 282, 175

Several Papers Addressed Enigmatic 18–20.11.2003

Geoeffective Event: 1. Gopalswamy, Yashiro, Michalek et al. (2005, GRL 32, L12S09)2. Yurchyshyn, Hu, and Abramenko (2005, Space Weather 3, S08C02) 3. Yermolaev, Zeleny, Zastenker et al. (2005, Geomag. Aeron. 45, 20)4. Ivanov, Romashets, Kharshiladze (2006, Geomag. Aeron. 46, 275)5. Möstl, Miklenic, Farrugia et al. (2008, Ann. Geophys. 26, 3139) 6. Srivastava, Mathew, Louis, Wiegelmann (2009, JGR 114, A03107)7. Chandra, Pariat, Schmieder et al. (2010, Solar Phys. 261, 127) 8. Kumar, Manoharan, and Uddin (2011, Solar Phys. 271, 149)9. Lui (2011, Space Sci. Rev. 158, 43)10. Marubashi, Cho, Kim et al. (2012, JGR 117, A01101) 11. Cerrato, Saiz, Cid et al. (2012, J. Atm. Sol.-Terr. Phys. 80, 111)

– assumed (i) ‘simple’ eruption and (ii) correspondence of magnetic cloud and pre-eruption structure in handedness

However, there is no satisfactory explanation to:1. Strongest field in magnetic cloud (MC)2. Different helicity signs in MC and its presumed solar source3. Different directions of the magnetic field in MC and its source (>

90)4. Particularities of CME – see further

CMEs • Two CMEs: CME1 and halo CME2 • Most studies associate magnetic cloud

with eruptive filament and CME2 • However: “halo” was a shock trace,

while CME2 was not Earth-directed

Shock• Halo: shock trace• CME2 body: expanding arcade• Core not visible

Filament eruption and CME2

•Filament eruption in H line•Filaments and CME2 are similar in direction and

shape•However, CORONAS-F/SPIRIT (304 Å): filament has

not left Sun but transformed into Y-like cloud:– Filament and “Y” similar in kinematics and masses;– CME2 was coreless.

• Grechnev, Chertok, Slemzin et al. (2005, JGR 110, A09S07): “filament failed to become a CME core”.

Parameter 28–29.10.2003

18–20.11.2003

Flare >X17 M3.9CME speed 2450 km/s 1660 km/s

Source magnetic flux phot 870870 1020 Mx 130130 1020 MxICME transit speed 2200 km/s 865 km/s

Total magnetic field |B|, nT

4747 nTnT 5656 nTnT

Bz –30 nT –46 nTGeomagnetic Dst index –353 nT –422 nT

Forbush decrease 28 28 %% 44..7 7 %%

Comparison of 28–29.10.2003 and 18–20.11.2003 events

•Moderate Forbush decrease with strong magnetic Moderate Forbush decrease with strong magnetic field field small size small size of magnetic cloud of magnetic cloud ((MCMC))

•Strong field Strong field BB with ordinary magnetic flux with ordinary magnetic flux = = BB AA smallsmall cross section cross section AA of MCof MC

– Confirmed by three reconstructions of MC, Confirmed by three reconstructions of MC, e.g.e.g.::

MCs on 29 October and 20 November in the same scalein the same scale

Reconstructions of MC cross sections from ACE data (Yurchyshyn et al., 2005)

Where were the boundaries of near-Earth magnetic cloud?• Usually MC is considered as a ‘cold magnetic

reservoir’. Its boundaries are traditionally determined by the conditions: < 1– Smooth rotation of magnetic field– Low proton temperature– Axial field has constant direction

• Not all of these were the case in 20.11.2003 MC:– Proton temperature varied within a wide range– Not everywhere << 1 – Axial field changed direction

ACE Interplanetary Data

• Regions Bz >0 (A & C) belong to MC • These regions neglected previously indicate disconnection of

MC from the Sun • Linear velocity profile self-similar expansion;

– compensation for expansion produces ‘snapshot’ of MC

•Solid vertical line: shock front

•Dashed vertical line: sharp density increase of suprathermal electrons in both directions – MC boundary

•Bz > 0 in regions A,C: regular continuation of region B

‘Snapshot’ of MC from ACE Data

• Variations of B components correspond to pass of spheromak; Bz changed sign twice

• MC size ≈ 0.2 AU • Balans of Bz total magnetic fluxes in regions

B (6.21020 Mx) and A+C (+5.21020 Mx)

Cf. Ivanov & Kharshiladze (1985, Solar Phys. 98, 379)

3-D Reconstructions of Heliospheric Density Distribution

from SMEI Data

• Neither ICME1 nor ICME2 met Earth and could cause superstorm

• Expansion angle of spheromak SGS 14

29 October: typical flux rope

20 November: compact ICME different from a

torus perpendicular to ecliptic plane spheromak

Weak Expansion of Spheromak

• Disconnection from Sun• Orientations of CME1

and CME2 estimated from ice-cream cone model

• Spheromak expanded in dense tails of CME1 and CME2 being restricted laterally

• Magnetic field in spheromak 20% higher than in flux rope with the same surface pressure

CME1

CME2

EarthSun

Causes of Superstorm

• Weak expansion of disconnected spheromak (within cone 14) + magnetic flux conservation strong field in spheromak

• Almost exactly southward orientation of the magnetic field vector in MC: negative Bz 0.8|В|

• Central impact of MC on Earth’s magnetosphere

• To meet Earth with expansion angle 14, CME should be launched near solar disk center

• LASCO could not detect it: appearance in C2 field of view at r > 16R – scattered light meager

• Support from different observations

Dynamic Radio Spectrum and GOES/SXI Images

• Initial size of CME: ring structure near solar disk center in SXI images

•Aparent expansion in SXI images corresponds to frequency drift of type IV burst

•Final speed of radial expansion 100 km/s, average MC speed 865 km/s angle 14

•Type II bursts: traces of shock waves•Low-frequency envelope of type IV burst –

plasma frequency in expanding volume: n 1/r3, fp n½

NS

Direction of eruption

Null point

NN

NN

SSSS

Reason for Transformation of Erptive Filament into Y-like Cloud

•Pass of eruptive filament through null point of coronal magnetic field

•Orientations of fields allow reconnection of filament only with west section of quadrupole, a dipole “bridge”

•Subsequent formation of spheromak in interaction between magnetic fields of filament and dipole bridge

Filament contacts itself, reconnection,

two tongues of Y-like cloud form

Filament portion “attached” to bridge

disconnects to form a torus

Torus moving up stretches bridge.

Reconnection between legs of bridge and its

forced eruption

Field lines of vertical torus scatter along

horizontal one. Then pair of linked tori

evolves into spheromak

Reconnection and Formation of Right-handed Spheromak

Collision of left-left-handed handed filament

with dipole bridge dipole bridge

Right-handedRight-handed pair of linked tori forms

t4

Y

Y

t5

N

S

t6

t7

t8

S

t3

AR503

t2t1

N

Probable Solar Source Region: EIT 195 Å and Extrapolation from MDI

Magnetogram

• Development of dimming in AR 503 and southward indicates eruption of dipole bridge

• Magnetic field in erupted dipole directed almost exactly south (80), which corresponds to MC and opposite to axial field of filament

• Magnetic flux in bases of erupted bridge (dimmings) at a height of 30 Mm (~111020 Mx) is close to estimated one in magnetic cloud (5.51020 Mx, Möstl et al., 2008) and sufficient to provide strong field actually observed near Earth

Particularities of the Event. Results and Consequences

•Anomalous eruption: mass dispersal over large area due to reconnection between magnetic field in filament and corona.

•Outer halo of fast CME was a shock trace and did not indicate its earthward direction.

•Radio bursts reflected in detail eruptive processes and presented kinematics of eruptive structures and shock waves.

•CME solar source region presented comprehensive information about magnetic cloud, however:

•Helicity sign of magnetic cloud might not correspond to own helicity of pre-eruption structure.

•Conception of magnetic cloud as a cold flux rope is not universal.

•Atypically weak ICME expansion increases geomagnetic effect.

This study is presented in four companion papers “A Challenging Solar Eruptive Event of 18 November 2003 and the Causes of the 20 November Geomagnetic Superstorm” (Solar Physics).

Comments

Filament is attached to its inversion line

Morphological Reason for Transformation of Eruptive Filament

into Y-like CloudChange in connectivity of inversion lines Br(h) at a height of 140 Mm