Convection-driven Emergence of Small-Scale Magnetic Fields and their Role in Coronal Heating and Solar Wind Acceleration

2008 ◽  
Vol 679 (1) ◽  
pp. L57-L60 ◽  
Author(s):  
H. Isobe ◽  
M. R. E. Proctor ◽  
N. O. Weiss
Keyword(s):  
Solar Wind ◽  
Magnetic Fields ◽  
Coronal Heating ◽  
Small Scale ◽  
Solar Wind Acceleration

scholarly journals Magnetosheath-cusp interface

2004 ◽  
Vol 22 (1) ◽  
pp. 183-212 ◽  
Author(s):  
S. Savin ◽  
L. Zelenyi ◽  
S. Romanov ◽  
I. Sandahl ◽  
J. Pickett ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Solar Wind ◽  
Magnetic Fields ◽  
Large Scale ◽  
Traditional Approach ◽  
Qualitative Difference ◽  
Small Scale ◽  
Nonlinear Phenomena ◽  
Solar Wind Interaction ◽  
Linear Superposition

Abstract. We advance the achievements of Interball-1 and other contemporary missions in exploration of the magnetosheath-cusp interface. Extensive discussion of published results is accompanied by presentation of new data from a case study and a comparison of those data within the broader context of three-year magnetopause (MP) crossings by Interball-1. Multi-spacecraft boundary layer studies reveal that in ∼80% of the cases the interaction of the magnetosheath (MSH) flow with the high latitude MP produces a layer containing strong nonlinear turbulence, called the turbulent boundary layer (TBL). The TBL contains wave trains with flows at approximately the Alfvén speed along field lines and "diamagnetic bubbles" with small magnetic fields inside. A comparison of the multi-point measurements obtained on 29 May 1996 with a global MHD model indicates that three types of populating processes should be operative: large-scale (∼few RE) anti-parallel merging at sites remote from the cusp; medium-scale (few thousandkm) local TBL-merging of fields that are anti-parallel on average; small-scale (few hundredkm) bursty reconnection of fluctuating magnetic fields, representing a continuous mechanism for MSH plasma inflow into the magnetosphere, which could dominate in quasi-steady cases. The lowest frequency (∼1–2mHz) TBL fluctuations are traced throughout the magnetosheath from the post-bow shock region up to the inner magnetopause border. The resonance of these fluctuations with dayside flux tubes might provide an effective correlative link for the entire dayside region of the solar wind interaction with the magnetopause and cusp ionosphere. The TBL disturbances are characterized by kinked, double-sloped wave power spectra and, most probably, three-wave cascading. Both elliptical polarization and nearly Alfvénic phase velocities with characteristic dispersion indicate the kinetic Alfvénic nature of the TBL waves. The three-wave phase coupling could effectively support the self-organization of the TBL plasma by means of coherent resonant-like structures. The estimated characteristic scale of the "resonator" is of the order of the TBL dimension over the cusps. Inverse cascades of kinetic Alfvén waves are proposed for forming the larger scale "organizing" structures, which in turn synchronize all nonlinear cascades within the TBL in a self-consistent manner. This infers a qualitative difference from the traditional approach, wherein the MSH/cusp interaction is regarded as a linear superposition of magnetospheric responses on the solar wind or MSH disturbances. Key words. Magnetospheric physics (magnetopause, cusp, and boundary layers) – Space plasma physics (turbulence; nonlinear phenomena)

Investigation of the coronal heating through phase relation of solar activity indexes

2020 ◽  
Vol 37 ◽  
Author(s):  
K. J. Li ◽  
J. C. Xu ◽  
Z. Q. Yin ◽  
J. L. Xie ◽  
W. Feng
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
Phase Relation ◽  
Large Scale ◽  
Solar Rotation ◽  
Rotation Period ◽  
Magnetic Activity ◽  
Coronal Heating ◽  
Small Scale

Abstract The coronal heating problem is a long-standing perplexing issue. In this study, 13 solar activity indexes are used to investigate their phase relation with the sunspot number (SSN). Only three of them are found to statistically significantly lag the SSN (large-scale magnetic activity) by about one solar rotation period; the three indexes are total solar irradiance (TSI), the modified coronal index, and the solar wind velocity; the former two indexes may represent the long-term variation of energy quantity of the heated photosphere and corona, respectively. The Mount Wilson Sunspot Index (MWSI) and the Magnetic Plage Strength Index (MPSI), which reflect the large- and small-scale magnetic field activities, respectively, are also utilised to investigate their phase relations with the three indexes. The three indexes are found to be much more intimately related to MPSI than to MWSI, and MWSI statistically significantly leads TSI by about one rotation period. The heated corona is found to pulse perfectly in step with the small-scale magnetic activity rather than the large-scale magnetic activity; furthermore, combined with observations, our statistical evidence should thus attribute coronal heating firmly to small-scale magnetic activity phenomena, such as spicules, micro-flares, nano-flares, and others. The photosphere and the corona are synchronously heated, which should seemingly prefer magnetic reconnection heating to wave heating. In the long term, such a coronal heating way is inferred effective. Statistically, it is also small-scale magnetic activity phenomena that produce TSI enhancement. Coronal heating and solar wind acceleration are found to be synchronous, as standard models require.

Anisotropy and velocity of small-scale irregularities in the region of solar-wind acceleration

2000 ◽  
Vol 44 (9) ◽  
pp. 634-640 ◽  
Author(s):  
I. V. Chashei ◽  
A. I. Efimov ◽  
V. K. Rudash ◽  
M. K. Bird
Keyword(s):  
Solar Wind ◽  
Small Scale ◽  
Solar Wind Acceleration

scholarly journals Understanding coronal heating and solar wind acceleration: Case for in situ near-Sun measurements

2007 ◽  
Vol 45 (1) ◽  
Author(s):  
D. J. McComas ◽  
M. Velli ◽  
W. S. Lewis ◽  
L. W. Acton ◽  
M. Balat-Pichelin ◽  
...  
Keyword(s):  
Solar Wind ◽  
Coronal Heating ◽  
Solar Wind Acceleration

Integrating physics-based coronal heating and solar wind acceleration in a global MHD model

2013 ◽  
Author(s):  
Roberto Lionello ◽  
Marco Velli ◽  
Jon A. Linker ◽  
Zoran Mikić
Keyword(s):  
Solar Wind ◽  
Coronal Heating ◽  
Solar Wind Acceleration ◽  
Mhd Model

MULTI-SHELL MAGNETIC TWISTERS AS A NEW MECHANISM FOR CORONAL HEATING AND SOLAR WIND ACCELERATION

2015 ◽  
Vol 808 (1) ◽  
pp. 5 ◽  
Author(s):  
K. Murawski ◽  
A. K. Srivastava ◽  
Z. E. Musielak ◽  
B. N. Dwivedi
Keyword(s):  
Solar Wind ◽  
Coronal Heating ◽  
Solar Wind Acceleration
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