PARAMETERS IN MAGNETIC CLOUDS AT 1 AU Luciano Rodriguez 1 Jimmy J Masias Meza 2 Sergio Dasso 2 Pascal Demoulin 3 Andrei Zhukov 14 Adriana Gulisano 25 ID: 589328
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TYPICAL PROFILES AND DISTRIBUTIONS OF PLASMA AND MAGNETIC FIELDPARAMETERS IN MAGNETIC CLOUDS AT 1 AU
Luciano Rodriguez[1], Jimmy J. Masias-Meza[2], Sergio Dasso[2], Pascal Demoulin[3], Andrei Zhukov[1][4], Adriana Gulisano[2][5], Marilena Mierla[1][6],Emilia Kilpua[7], Matthew West[1], Dana Lacatus[6], Alin Razvan Paraschiv[6], Miho Janvier[8][1]Solar-Terrestrial Centre of Excellence - SIDC, Royal Observatory of Belgium, [2]Universidad de Buenos Aires, [3]Observatoire de Paris, [4]Moscow State University, [5]Instituto Antártico Argentino, [6]Institute of Geodynamics of the Romanian Academy, [7]University of Helsinki, [8]Institut d'Astrophysique Spatiale
ESWW13, November 2016,
OstendeSlide2
Introduction: Magnetic C
loudsZurbuchen and Richardson, 2006
Kataoka
and Miyoshi, 2006Slide3
Introduction: method
Superposed epoch analysis of 63 MCs at L1 (1998-2006), in order to find the typical profiles in plasma and magnetic field parameters0149…0149…
…
MC #1
MC #63
MC #1
MC #63
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B
Avg
. 0
Avg
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1
Avg
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49
…
MC
Avg
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Profiles of 63 MCs at L1
Timenα/nprmsBoBO+7/O+6NVBTβRodriguez et al., 2016 (Solar Physics)
Sheath region
Asymmetric peak
Minimum T
Speed gradient
Minimum
β
Maximum
n
α
Maximum O
+7
/O
+6
Minimum
rmsBobSlide5
Desnsity peaks at the
trailing edge of MCs3 most likely causesHigh speed stream compressionExpansionIntrinsic processes at the SunThe peak in density is observed in 22 out of 63 MCsSlide6
Expansion
MCs are expanding structures. This expansión can create peaks in density. VBTβNSlide7
Compression from a trailing
HSSA HSS trailing the clouds is compressing them from the back creating peaks in densityVBTβNSlide8
Intrinsic processes at the
SunVBTβNFor some events no expansión nor trailing HSS were detected, for them the density peak could have solar originSlide9
MC events with
density peaksHigh speed streams are the most likely cause, with 17 out of 22 events having themSlide10
Conclusions
The peak in the magnetic field magnitude inside magnetic clouds is not symmetric, due to the MC expansion, a possible spatial asymmetry within the flux rope, and its interaction with the surrounding solar wind.The proton temperature, the magnetic field fluctuations and the plasma β are low throughout the duration of the MC.The expansion of the cloud is marked by the negative slope of the speed profile and the low proton temperature.The O+7/O+6 profile is clearly enhanced throughout the duration of the MC.The O+7/O+6 and the α-to-proton ratio present typical ICME values for a period extended well beyond the defined flux rope rear boundary.A log-normal distribution function can be used to describe the distribution of plasma and magnetic field parameters near the center of MCs. There are proton density peaks observed around the trailing edge of a significant fraction of the studied MCs (22 out of 63). The scenario with overtaking fast flows is sufficient to explain most of the observed proton density peaks.Slide11
ExtraSlide12
Log-normal distributions