Geoeffectiveness of interplanetary shocks, magnetic clouds, sector boundary crossings and their combined occurrence

2004 ◽  
Vol 31 (9) ◽  
pp. n/a-n/a ◽  
Author(s):  
E. Echer ◽  
W. D. Gonzalez
Keyword(s):  
Magnetic Clouds ◽  
Interplanetary Shocks ◽  
Sector Boundary ◽  
Boundary Crossings

scholarly journals A summary of WIND magnetic clouds for years 1995-2003: model-fitted parameters, associated errors and classifications

2006 ◽  
Vol 24 (1) ◽  
pp. 215-245 ◽  
Author(s):  
R. P. Lepping ◽  
D. B. Berdichevsky ◽  
C.-C. Wu ◽  
A. Szabo ◽  
T. Narock ◽  
...  
Keyword(s):  
Temperature Drop ◽  
Model Fitting ◽  
Sunspot Cycle ◽  
Flux Rope ◽  
Axial Current ◽  
Model Fit ◽  
Magnetic Clouds ◽  
Symmetric Model ◽  
Large Set ◽  
Interplanetary Shocks

Abstract. Interplanetary magnetic clouds (MCs) have been identified for the first 8.6 years of the WIND mission, and their magnetic field structures have been parameter-fitted by a static, force free, cylindrically-symmetric model (Lepping et al., 1990) with various levels of success. This paper summarizes various aspects of the results of the model fitting by providing: seven estimated model fit-parameter values for each of the 82 MCs found, their objectively determined quality estimates, closest approach vectors (in two coordinate frames), fit-parameter errors for the cases of acceptable quality (50 cases, or 61%), axial magnetic fluxes, axial current densities, and total axial current - as well as some examples of MC profiles for various conditions and "categories" for each case (e.g. Bz: N→S or S→N, etc.). MC quality is estimated from a quantitative consideration of a large set of parameters, such as the chi-squared of the model fit, degree of asymmetry of the B profile, and a comparison of two means of estimating radius. This set of MCs was initially identified by visual inspection of relevant field and plasma data. Each resulting MC candidate is then tested through the use of the MC parameter model, for various adjusted durations to determine the best fit, which helps to refine the boundary-times. The resulting MC set is called Set 1. Another, larger, set (Set 2) of MCs is identified through an automated program whose criteria are based on general MC plasma and field characteristics at 1AU determined through past experience. Set 1 is almost fully contained within Set 2, whose frequency of occurrence better matches that of the sunspot cycle than Set 1. The difference-set (Set 2-Set 1) is referred to as the magnetic cloud-like (MCL) set, whose members do not very well represent good flux ropes through modeling. We present a discussion of how a MC's front boundary is specifically identified in terms of multi-parameter considerations (i.e. any one or more of: increase in B, directional discontinuity, magnetic hole in B, drop in proton plasma beta, B-fluctuation level change, proton temperature drop, etc.), as well as through the application of the flux rope model. Also presented are examples of unusual MCs, as well as some commonly occurring relationships, such as the existence and frequency (approx. 1/2 the time) of upstream interplanetary shocks, and less frequent internal shocks.

scholarly journals A statistical study of interplanetary shocks and pressure pulses internal to magnetic clouds

2007 ◽  
Vol 112 (A6) ◽  
pp. n/a-n/a ◽  
Author(s):  
Michael R. Collier ◽  
Ronald P. Lepping ◽  
Daniel B. Berdichevsky
Keyword(s):  
Statistical Study ◽  
Magnetic Clouds ◽  
Interplanetary Shocks ◽  
Pressure Pulses

Response of the mid-latitude ionosphere to solar magnetic sector crossing

1979 ◽  
Vol 57 (2) ◽  
pp. 218-221 ◽  
Author(s):  
G. F. Lyon ◽  
V. P. Bhatnagar
Keyword(s):  
Total Electron Content ◽  
Seasonal Effects ◽  
Electron Content ◽  
Sector Boundary ◽  
Total Electron ◽  
Magnetic Sector ◽  
Boundary Crossings ◽  
The Earth ◽  
Epoch Analysis ◽  
Solar Magnetic Sector

Using sector boundary passages past the earth as key days, a superimposed epoch analysis has been carried out of Total Electron Content, foF2 and hpF2. It is found that there is an enhancement of Total Electron Content on the key day for toward-to-away (−, +) sector boundary crossings only, and that this effect is greater in winter (~ 15%) than in summer (~ 10%). The correlation with (−, +) solar magnetic sector crossings (SMSC) seems to derive from the Svalgaard–Mansurov effect but the reason for seasonal effects remains in doubt.

scholarly journals On the solar origin of interplanetary disturbances observed in the vicinity of the Earth

2003 ◽  
Vol 21 (4) ◽  
pp. 847-862 ◽  
Author(s):  
N. Vilmer ◽  
M. Pick ◽  
R. Schwenn ◽  
P. Ballatore ◽  
J. P. Villain
Keyword(s):  
Interplanetary Medium ◽  
Solar Physics ◽  
Magnetic Clouds ◽  
Careful Examination ◽  
Large Set ◽  
Interplanetary Shocks ◽  
Solar Source ◽  
Solar Origin ◽  
The Earth ◽  
Interplanetary Physics

Abstract. The solar origin of 40 interplanetary disturbances observed in the vicinity of the Earth between January 1997 and June 1998 is investigated in this paper. Analysis starts with the establishment of a list of Interplanetary Mass Ejections or ICMEs (magnetic clouds, flux ropes and ejecta) and of Interplanetary Shocks measured at WIND for the period for which we had previously investigated the coupling of the interplanetary medium with the terrestrial ionospheric response. A search for associated coronal mass ejections (CMEs) observed by LASCO/SOHO is then performed, starting from an estimation of the transit time of the inter-planetary perturbation from the Sun to the Earth, assumed to be achieved at a constant speed (i.e. the speed measured at 1 AU). EIT/SOHO and Nançay Radioheliograph (NRH) observations are also used as proxies in this identification for the cases when LASCO observations do not allow one to firmly establish the association. The last part of the analysis concerns the identification of the solar source of the CMEs, performed using a large set of solar observations from X-ray to radio wavelengths. In the present study, this association is based on a careful examination of many data sets (EIT, NRH and H images and not on the use of catalogs and of Solar Geophysical Data reports). An association between inter-planetary disturbances and LASCO/CMEs or proxies on the disk is found for 36 interplanetary events. For 32 events, the solar source of activity can also be identified. A large proportion of cases is found to be associated with a flare signature in an active region, not excluding of course the involvement of a filament. Conclusions are finally drawn on the propagation of the disturbances in the interplanetary medium, the preferential association of disturbances detected close to the Earth’s orbit with halos or wide CMEs and the location on the solar disk of solar sources of the interplanetary disturbances during that period.Key words. Interplanetary physics (interplanetary shocks); solar physics, astrophysics and astronomy (flares and mass ejections)

Response of the equatorial ionosphere to solar magnetic sector crossing

1985 ◽  
Vol 63 (4) ◽  
pp. 472-474 ◽  
Author(s):  
J. Hanumath Sastri
Keyword(s):  
Boundary Crossing ◽  
Sunspot Activity ◽  
Sector Boundary ◽  
Superposed Epoch Analysis ◽  
Boundary Crossings ◽  
F Region ◽  
The Earth ◽  
Epoch Analysis ◽  
Solar Magnetic Sector ◽  
East West

A superposed epoch analysis has been carried out of h′F values at Kodaikanal (10°14′N, 77°28′E, dip 3.0°N) pertaining to years of high sunspot activity using solar wind sector boundary passages past the earth as key days. It is found that there is a reduction in h′F values at 2000 LT 1 or 2 days after the sector boundary crossing. The amplitude of this effect which is noticed with both (+, −) and (−, +) sector boundary crossings is higher in equinoxes than in solstices. The response of the equatorial F region to sector boundary crossing seems to originate from perturbations of the equatorial east–west electric field in the post-sunset period associated with the enhancement in geomagnetic activity in the wake of sector boundary crossing.

scholarly journals Correction to “A statistical study of interplanetary shocks and pressure pulses internal to magnetic clouds”

2007 ◽  
Vol 112 (A9) ◽  
pp. n/a-n/a
Author(s):  
Michael R. Collier ◽  
Ronald P. Lepping ◽  
Daniel B. Berdichevsky
Keyword(s):  
Statistical Study ◽  
Magnetic Clouds ◽  
Interplanetary Shocks ◽  
Pressure Pulses
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