To the question about perturbations of solar-terrestrial characteristics [CL]

http://arxiv.org/abs/1802.04348


Data obtained over the last three solar cycles have been analysed to reveal the relationships between the intensity of the photospheric field measured along the line of sight by the WSO group at heliolatitudes from -75 to 75 degrees and the intensity of the interplanetary magnetic field and absolute values of the perturbations of the different characteristics of the solar wind at the Earth orbit, and geomagnetic parameters. provided by the OMNI team.
The heliospheric and geomagnetic data are found to be divided into two groups characterized by their response to variability of the solar magnetic field latitudinal structures on short and on long time scales.

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E. Gavryuseva
Wed, 14 Feb 18
7/68

Comments: 14 pages, 6 Postscript figures. arXiv admin note: substantial text overlap with arXiv:1802.03135

Relations between variability of the photospheric and interplanetary magnetic fields, solar wind and geomagnetic characteristics [SSA]

http://arxiv.org/abs/1802.03135


Large scale solar magnetic field topology has a great influence on the structure of the corona, heliosphera and geomagnetic perturbations.
Data obtained over the last three solar cycles have been analysed to reveal the relationships between the photospheric field measured along the line of sight by the WSO group at 30 levels of heliolatitudes from -75 to 75 degrees and the interplanetary magnetic field The main aim of this first paper is to make a direct comparison between the basic structure and dynamics of the photospheric magnetic field and components and intensity of the interplanetary magnetic field % solar wind and geomagnetic parameters without using theoretical assumptions, models, physical expectations, etc.
The second paper by Gavryuseva, 2018d presents the raports between different characteristics of the solar wind at the Earth orbit, and geomagnetic parameters provided by the OMNI team. % Data obtained over the last three solar cycles have been analysed % to reveal the relationships % between the photospheric field measured along the line of sight % by the WSO group % at heliolatitudes from -75 to 75 degrees averaged over one year % and the interplanetary magnetic field, different characteristics % of the solar wind at the Earth orbit, and geomagnetic parameters. % provided by the OMNI team.
The heliospheric and geomagnetic data are found to be divided into two groups characterized by their response to variability of the solar magnetic field latitudinal structures on short and on long time scales.

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E. Gavryuseva
Mon, 12 Feb 18
13/53

Comments: 28 pages, 15 Postscript figures

Longitudinal structure of the photospheric magnetic field in the Carrington system [SSA]

http://arxiv.org/abs/1802.02692


The observations of the Sun have been performed over the years, even centuries- Whether are there active longitudes? If yes how stable are they? One of the first The Wilcox Solar Observatory data taken over three cycles N 21, N 22, N 23 have been used to reveal the longitudinal structure of the photospheric magnetic field. Mean over three cycles magnetic field distribution has been calculated in the North and in the South hemispheres as well as at 30 levels of latitude from -75 to 75 degrees. This study was performed using observations of the magnetic field taking into account its polarity or only intensity. The longitudinal structure of the magnetic field was calculated in the coordinate system rotating with Carrington rate. These structures were compared with a model of random longitudinal distribution of the magnetic field. Random character of the longitudinal structure was refused. The results agree with the presence of two active meridians seen in different phenomena of solar activity at longitudes separated by 150-170 degrees in the Carrington coordinate system.

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E. Gavryuseva
Fri, 9 Feb 18
50/57

Comments: 9 pages, 4 Postscript figures

Latitudinal structure and dynamic of the photospheric magnetic field [SSA]

http://arxiv.org/abs/1802.02450


Analysis of the structure and dynamics of the magnetic field of the Sun is fundamental for understanding of the origin of solar activity and variability as well as for the study of solar-terrestrial relations. Observations of the large scale magnetic field in the photosphere taken at the Wilcox Solar Observatory from 1976 up to 2007 have been analysed to deduce its latitudinal and longitudinal structures, its differential rotation, and their variability in time. This paper is dedicated to the analysis and dynamics of the latitudinal structure of the solar magnetic field over three solar cycles 21, 22, 23. The main results discussed in this paper are the following: the large scale latitudinal structure is antisymmetric and composed of four zones with boundaries located at the equator, -25 and + 25 degrees, stable over 10-11 years with a time delay of about 5-6 years in near-equatorial zones. The variability and North-South asymmetry of polarity waves running from the equator to the poles with 2-3 – year period was studied in detail.

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E. Gavryuseva
Thu, 8 Feb 18
6/43

Comments: 23 pages, 10 Postscript figures

Rotation of the photospheric magnetic field through solar cycles 21, 22, 23 [SSA]

http://arxiv.org/abs/1802.02461


Rotation of the large scale solar magnetic field has a great importance for the understanding of solar dynamic, for the search of longitidinal structure and for the study of solar-terrestrial relations. 30-year long observations taken at the Wilcox Solar Observatory (USA) in 21-23 cycles have been analysed carefully to deduce magnetic field rotation rate at different latitudes in both hemispheres and its variability in time. The WSO data appear to indicate that additionally to the differential rotation along the latitudes there are running waves of fast rotation of the magnetic field. These torsional waves are running from the poles to the equator with a period of 11 years. The rotation of the magnetic field (RMF) is almost rigid at latitudes above 55 degrees in both hemispheres. The rotation rate in the sub-polar regions is slower when the magnetic field is strong there (during minima of solar activity), and faster when the magnetic field changes polarity (during maxima of solar activity).

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E. Gavryuseva
Thu, 8 Feb 18
27/43

Comments: 8 pages, 3 Postscript figures

Magma ascent in planetesimals: control by grain size [EPA]

http://arxiv.org/abs/1802.02157


Rocky planetesimals in the early solar system melted internally and evolved chemically due to radiogenic heating from aluminum-26. Here we quantify the parametric controls on magma genesis and transport using a coupled petrological and fluid mechanical model of reactive two-phase flow. We find the mean grain size of silicate minerals to be a key control on magma ascent. For grain sizes larger than ~1 mm, melt segregation produces distinct radial structure and chemical stratification. This stratification is most pronounced for bodies formed at around 1 Myr after Ca,Al-rich inclusions. These findings suggest a link between the time and orbital location of planetesimal formation and their subsequent structural and chemical evolution. According to our models, the evolution of partially molten planetesimal interiors falls into two categories. In the global magma ocean scenario, the whole interior of a planetesimal experiences nearly complete melting, resulting in turbulent convection and core-mantle differentiation by the rainfall mechanism. In the magma sill scenario, segregating melts gradually deplete the deep interior of the radiogenic heat source. In this case, magma may form melt-rich sills beneath a cool and stable lid, while core formation would proceed by percolation. Our findings suggest that grain sizes prevalent during the internal-heating stage governed magma ascent in planetesimals. Regardless of whether evolution progresses toward a global magma ocean or segregated magma sills, our models predict that temperature inversions due to rapid aluminum-26 redistribution are limited to bodies formed earlier than ~1 Myr after CAIs. We find that if grain size was smaller than ~1 mm during peak internal melting, only elevated solid-melt density contrasts (such as found for the reducing conditions in enstatite chondrite compositions) would allow substantial melt segregation to occur.

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T. Lichtenberg, T. Keller, R. Katz, et. al.
Thu, 8 Feb 18
30/43

Comments: 14 pages, 6 figures, 1 table; associated video file at this http URL

Expected Precision of Europa Clipper Gravity Measurements [EPA]

http://arxiv.org/abs/1801.08946


The primary gravity science objective of NASA’s Clipper mission to Europa is to confirm the presence or absence of a global subsurface ocean beneath Europa’s Icy crust. Gravity field measurements obtained with a radio science investigation can reveal much about Europa’s interior structure. Here, we conduct extensive simulations of the radio science measurements with the anticipated spacecraft trajectory and attitude (17F12v2) and assets on the spacecraft and the ground, including antenna orientations and beam patterns, transmitter characteristics, and receiver noise figures. In addition to two-way Doppler measurements, we also include radar altimeter crossover range measurements. We concentrate on +/-2 hour intervals centered on the closest approach of each of the 46 flybys. Our covariance analyses reveal the precision with which the tidal Love number k2, second-degree gravity coefficients C20 and C22, and higher-order gravity coefficients can be determined. The results depend on the Deep Space Network (DSN) assets that are deployed to track the spacecraft. We find that some DSN allocations are sufficient to conclusively confirm the presence or absence of a global ocean. Given adequate crossover range performance, it is also possible to evaluate whether the ice shell is hydrostatic.

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A. Verma and J. Margot
Tue, 30 Jan 18
55/70

Comments: N/A