scholarly journals Kinematics of coronal mass ejections in the LASCO field of view

2020 ◽  
Vol 639 ◽  
pp. A68
Author(s):  
Anitha Ravishankar ◽  
Grzegorz Michałek ◽  
Seiji Yashiro
Keyword(s):  
Coronal Mass Ejections ◽  
Large Angle ◽  
Maximum Velocity ◽  
Solar Cycles ◽  
Heliospheric Observatory ◽  
Average Value ◽  
23Rd Cycle ◽  
24Th Cycle ◽  
Initial Acceleration ◽  
The Individual

In this paper we present a statistical study of the kinematics of 28894 coronal mass ejections (CMEs) recorded by the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory spacecraft from 1996 until mid-2017. The initial acceleration phase is characterized by a rapid increase in CME velocity just after eruption in the inner corona. This phase is followed by a non-significant residual acceleration (deceleration) characterized by an almost constant speed of CMEs. We demonstrate that the initial acceleration is in the range 0.24–2616 m s−2 with median (average) value of 57 m s−2 (34 m s−2) and it takes place up to a distance of about 28 RSUN with median (average) value of 7.8 RSUN (6 RSUN). Additionally, the initial acceleration is significant in the case of fast CMEs (V >  900 km s−1), where the median (average) values are about 295 m s−2 (251 m s−2), respectively, and much weaker in the case of slow CMEs (V <  250 km s−1), where the median (average) values are about 18 m s−2 (17 m s−2), respectively. We note that the significant driving force (Lorentz force) can operate up to a distance of 6 RSUN from the Sun during the first 2 hours of propagation. We found a significant anti-correlation between the initial acceleration magnitude and the acceleration duration, whereas the residual acceleration covers a range from −1224 to 0 m s−2 with a median (average) value of −34 m s−2 (−17 m s−2). One intriguing finding is that the residual acceleration is much smaller during the 24th cycle in comparison to the 23rd cycle of solar activity. Our study has also revealed that the considered parameters, initial acceleration (ACCINI), residual acceleration (ACCRES), maximum velocity (VMAX), and time at maximum velocity (TimeMAX) mostly follow solar cycles and the intensities of the individual cycle.

scholarly journals Estimation of Arrival Time of Coronal Mass Ejections in the Vicinity of the Earth Using SOlar and Heliospheric Observatory and Solar TErrestrial RElations Observatory Observations

Solar Physics ◽  
2019 ◽  
Vol 294 (9) ◽  
Author(s):  
Anitha Ravishankar ◽  
Grzegorz Michałek
Keyword(s):  
Space Weather ◽  
Coronal Mass Ejections ◽  
Arrival Time ◽  
Accurate Determination ◽  
Maximum Velocity ◽  
Maximum Speed ◽  
Estimation Errors ◽  
New Approach ◽  
Heliospheric Observatory ◽  
The Earth

Abstract The arrival time of coronal mass ejections (CMEs) in the vicinity of the Earth is one of the most important parameters in determining space weather. We have used a new approach to predicting this parameter. First, in our study, we have introduced a new definition of the speed of ejection. It can be considered as the maximum speed that the CME achieves during the expansion into the interplanetary medium. Additionally, in our research we have used not only observations from the SOlar and Heliospheric Observatory (SOHO) spacecraft but also from Solar TErrestrial RElations Observatory (STEREO) spacecrafts. We focus on halo and partial-halo CMEs during the ascending phase of Solar Cycle 24. During this period the STEREO spacecraft were in quadrature position in relation to the Earth. We demonstrated that these conditions of the STEREO observations can be crucial for an accurate determination of the transit times (TTs) of CMEs to the Earth. In our research we defined a new initial velocity of the CME, the maximum velocity determined from the velocity profiles obtained from a moving linear fit to five consecutive height–time points. This new approach can be important from the point of view of space weather as the new parameter is highly correlated with the final velocity of ICMEs. It allows one to predict the TTs with the same accuracy as previous models. However, what is more important is the fact that the new approach has radically reduced the maximum TT estimation errors to 29 hours. Previous studies determined the TT with a maximum error equal to 50 hours.

Collaborative VLA and LASCO Observations of Nonthermal Energy Release in the Corona

2001 ◽  
Vol 203 ◽  
pp. 520-522
Author(s):  
R. F. Willson
Keyword(s):  
Coronal Mass Ejections ◽  
Large Angle ◽  
Large Array ◽  
Related Activity ◽  
Heliospheric Observatory ◽  
Very Large Array ◽  
X Ray ◽  
Abrupt Changes ◽  
Coronal Magnetic Fields ◽  
Burst Emission

We discuss recent collaborative observations of coronal mass ejections and related activity using the Very Large Array (VLA) and the Solar and Heliospheric Observatory (SOHO). VLA observations show the onset of intense 400 cm burst emission during an X1 GOES soft X-ray burst observed by the Yohkoh spacecraft and prior to a CME observed by the Large Angle Spectroscometric C2 Coronagraph (LASCO) on board SOHO. VLA snapshot maps show that the 400 cm burst site varied discontinuously throughout the course of the flare, possibly reflecting abrupt changes in the structure of the coronal magnetic fields along which the energetic particles traveled.

scholarly journals Statistical relationship between solar flares and coronal mass ejections

2008 ◽  
Vol 4 (S257) ◽  
pp. 233-243 ◽  
Author(s):  
Seiji Yashiro ◽  
Nat Gopalswamy
Keyword(s):  
Coronal Mass Ejections ◽  
Solar Flares ◽  
Large Angle ◽  
Outer Edge ◽  
Heliospheric Observatory ◽  
X Ray ◽  
The Difference ◽  
Statistical Relationships ◽  
Flare Site ◽  
Spectrometric Coronagraph

AbstractWe report on the statistical relationships between solar flares and coronal mass ejections (CMEs) observed during 1996-2007 inclusively. We used soft X-ray flares observed by the Geostationary Operational Environmental Satellite (GOES) and CMEs observed by the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) mission. Main results are (1) the CME association rate increases with flare's peak flux, fluence, and duration, (2) the difference between flare and CME onsets shows a Gaussian distribution with the standard deviation σ = 17 min (σ = 15 min) for the first (second) order extrapolated CME onset, (3) the most frequent flare site is under the center of the CME span, not near one leg (outer edge) of the CMEs, (4) a good correlation was found between the flare fluence versus the CME kinetic energy. Implications for flare-CME models are discussed.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

scholarly journals Glacier Flow Dynamics of the Severnaya Zemlya Archipelago in Russian High Arctic Using the Differential SAR Interferometry (DInSAR) Technique

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2466 ◽  
Author(s):  
Nela ◽  
Bandyopadhyay ◽  
Singh ◽  
Glazovsky ◽  
Lavrentiev ◽  
...  
Keyword(s):  
Maximum Velocity ◽  
Lower Surface ◽  
Sar Interferometry ◽  
Surface Velocity ◽  
Ice Caps ◽  
Average Value ◽  
Glacier Velocity ◽  
Severnaya Zemlya ◽  
Academy Of Sciences ◽  
Severnaya Zemlya Archipelago

Glacier velocity is one of the most important parameters to understand glacier dynamics. The Severnaya Zemlya archipelago is host to many glaciers of which four major ice caps encompassing these glaciers are studied, namely, Academy of Sciences, Rusanov, Karpinsky, and University. In this study, we adopted the differential interferometric synthetic aperture radar (DInSAR) method utilizing ALOS-2/PALSAR-2 datasets, with a temporal resolution of 14 days. The observed maximum velocity for one of the marine-terminating glaciers in the Academy of Sciences Ice Cap was 72.24 cm/day (≈263 m/a). For the same glacier, an increment of 3.75 times the flow rate was observed in 23 years, compared to a previous study. This has been attributed to deformation in the bed topography of the glacier. Glaciers in other ice caps showed a comparatively lower surface velocity, ranging from 7.43 to 32.12 cm/day. For estimating the error value in velocity, we selected three ice-free regions and calculated the average value of their observed movement rates by considering the fact that there is zero movement for ice-free areas. The average value observed for the ice-free area was 0.09 cm/day, and we added this value in our uncertainty analysis. Further, it was observed that marine-terminating glaciers have a higher velocity than land-terminating glaciers. Such important observations were identified in this research, which are expected to facilitate future glacier velocity studies.

scholarly journals Profiling of Individual Desulfo-Glucosinolate Content in Cabbage Head (Brassica oleracea var. capitata) Germplasm

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1860 ◽  
Author(s):  
Shiva Ram Bhandari ◽  
Juhee Rhee ◽  
Chang Sun Choi ◽  
Jung Su Jo ◽  
Yu Kyeong Shin ◽  
...  
Keyword(s):  
Significant Variation ◽  
The Other ◽  
Glucosinolate Content ◽  
Breeding Programs ◽  
Average Value ◽  
Hydrolysis Products ◽  
Coefficients Of Variation ◽  
Anti Cancer ◽  
The Individual ◽  
Different Origins

Individual glucosinolates (GSLs) were assessed to select cabbage genotypes for a potential breeding program. One hundred forty-six cabbage genotypes from different origins were grown in an open field from March to June 2019; the cabbage heads were used for GSL analyses. Seven aliphatics [glucoiberin (GIB), progoitrin (PRO), epi-progoitrin (EPI), sinigrin (SIN), glucoraphanin (GRA), glucoerucin (GER) and gluconapin (GNA)], one aromatic [gluconasturtiin (GNS)] and four indolyl GSLs [glucobrassicin (GBS), 4-hydroxyglucobrassicin (4HGBS), 4-methoxyglucobrassicin (4MGBS), neoglucobrassicin (NGBS)] were found this study. Significant variation was observed in the individual GSL content and in each class of GSLs among the cabbage genotypes. Aliphatic GSLs were predominant (58.5%) among the total GSLs, followed by indolyl GSL (40.7%) and aromatic GSLs (0.8%), showing 46.4, 51.2 and 137.8% coefficients of variation, respectively. GIB, GBS and NGBS were the most common GSLs found in all genotypes. GBS was the most dominant GSL, with an average value of 3.91 µmol g−1 (0.79 to 13.14 µmol g−1). SIN, GIB, PRO and GRA were the other major GSLs, showing average values of 3.45, 1.50, 0.77 and 0.62 µmol g−1, respectively. The genotypes with relatively high contents of GBS, SIN, GIB and GRA warrant detailed studies for future breeding programs since the hydrolysis products of these GSLs have several anti-cancer properties.

scholarly journals The tracks of α -particles and protons in photographic emulsions

1935 ◽  
Vol 150 (870) ◽  
pp. 382-394 ◽  
Keyword(s):  
Large Angle ◽  
Silver Bromide ◽  
Photographic Emulsion ◽  
High Magnification ◽  
Straight Line ◽  
The Subject ◽  
The Individual ◽  
Photographic Emulsions ◽  
Α Particles

1—It has been known for some twenty-five years that when an α -particle passes through a photographic emulsion, the silver bromide grains which it encounters are rendered developable. Kinoshita examined the question in some detail in 1910, and came to the conclusion that, for the emulsions tested, every grain struck by an α -particle can be developed. During the following years Reinganum, Michl, Mayer and others worked on the subject, and showed that after development the track of each separate α -particle is visible, under a high magnification, as a row of developed grains in a straight line. If a spot of radioactive matter, such as radium C, be placed on the surface of a plate, α -particles are emitted in all directions, and produce a halo consisting of a number of tracks radiating from a centre. Photographs of these haloes, and of the individual tracks, were published inter alia by Kinoshita and Ikeuti, and Walmsley and Makower. Some of the large-angle deflections reported by the latter are probably tracks of two separate α -particles arising from the same spot of contamination in the emulsion. In 1925 it was observed by Blau that tracks could also be produced by natural protons ejected from a layer of paraffin by α -particles. It was found, however, that not every grain encountered necessarily becomes developable; owing, doubtless, to the feebler ionization along the path of a proton. This is true at least for the less sensitive emulsions. The protons which result from the disintegration of aluminium when bombarded by α -particles have also been recorded in this way by Blau, and Blau and Wambacher. Furthermore Blau and Wambacher have published results obtained with protons ejected by the passage of neutrons through paraffin, and through the gelatine of the emulsion.

Distribution Characteristics and Risk Evaluation of Cd and Hg in Sediments on the Zhenjiang Ancient Canal River

2013 ◽  
Vol 726-731 ◽  
pp. 296-300
Author(s):  
Zhi Gang Chen ◽  
An Ping Wei ◽  
Xiao Hong Zhou
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Heavy Metal Contamination ◽  
Risk Index ◽  
Potential Ecological Risk ◽  
Middle Part ◽  
Average Value ◽  
Heavy Metal Element ◽  
Individual Potential ◽  
The Individual

The purpose of this paper is to study the speciation and contents of two types of heavy metals (Cd and Hg) in the sediments in Power Bridge (D1) and Nanshui Bridge (N2) in the middle part of the Ancient Canal in Zhenjiang. The relationship between the speciation of these heavy metals and their environmental factors were described. Morerover, the ecological hazard and trace to the source of these two types of heavy metals was also determined preliminarily. The results showed that (1) the main heavy metal contamination in the sediments of Power Bridge and Nanshui Bridge is Cd, and the average value is 20 mg/Kg, 17 mg/Kg, respectively, which were higher than environmental background value;(2) The peak value of Hg and Cd were near equilibrium in the 0.1-0.2m depth of Sediments; (3) Calculate the individual potential ecological risk index in the sediments of heavy metal element of two sample points both quantity of contents are Cd>Hg. And visible ecological threat of heavy metals were from Cd. After removing the Cd value, the RI value showed that ecological harm index basically below mild ecological harm degree.

scholarly journals On the flow of air behind an inclined flat plate of infinite span

1927 ◽  
Vol 116 (773) ◽  
pp. 170-197 ◽  
Keyword(s):  
Flat Plate ◽  
Unit Length ◽  
Large Angle ◽  
Vortex System ◽  
Water Region ◽  
Infinite Extent ◽  
Freely Moving ◽  
The Individual ◽  
Moving Fluid ◽  
Dead Water

The general form of the flow behind an infinitely long thin flat plate inclined at a large angle to a fluid stream of infinite extent has been known for many years past. The essential features of the motion are illustrated in the smoke photograph given in fig. 1, Plate 6. At the edges, thin bands of vorticity are generated, which separate the freely-moving fluid from the “dead-water” region at the back of the plate; and at some distance behind, these vortex bands on account of their lack of stability roll up and form what is now commonly known as a vortex street (see fig. 2). Various theories for calculating the resistance of the plate have also been advanced from time to time. One of the earliest is the theory of “discontinuous” motion due to Kirchhoff and Rayleigh, who obtained the expression π sin α/4 + π sin α ρV 0 2 b (see symbols) for the normal force per unit length of the plate. More recently Kármán has obtained a formula for the resistance of a plate normal to the general flow, in terms of the dimensions of the vortex system at some distance behind the plate. In spite, however, of these and other important investigations, much more remains to be discovered before it can be said that the phenomenon of the flow is completely understood. No attempt has hitherto been made, as far as the writers are aware, to determine experimentally, at incidences below 90°, the frequency and speed with which the vortices pass downstream; the dimensions of the vortex system; the average strength of the individual vortices; or the rate at which vorticity is leaving the edges of the plate. The present investigation has been undertaken to furnish information on these features of the flow.

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