scholarly journals Coronal Field Opens at Lower Height During the Solar Cycles 22 and 23 Minimum Periods: IMF Comparison Suggests the Source Surface Should Be Lowered

Solar Physics ◽  
2011 ◽  
Vol 269 (2) ◽  
pp. 367-388 ◽  
Author(s):  
C. O. Lee ◽  
J. G. Luhmann ◽  
J. T. Hoeksema ◽  
X. Sun ◽  
C. N. Arge ◽  
...  
Keyword(s):  
Source Surface ◽  
Solar Cycles ◽  
Lower Height ◽  
Coronal Field

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

scholarly journals Modelling short-term Solar Spectral Irradiance (SSI) using coronal electron density and temperature profiles based on solar magnetic field observations

2016 ◽  
Vol 12 (S327) ◽  
pp. 82-85 ◽  
Author(s):  
J. M. Rodríguez Gómez ◽  
L. E. Antunes Vieira ◽  
A. Dal Lago ◽  
J. Palacios ◽  
L. A. Balmaceda ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Magnetic Field ◽  
Transport Model ◽  
Spectral Irradiance ◽  
Source Surface ◽  
Solar Cycles ◽  
Short Term ◽  
Flux Transport ◽  
Field Source ◽  
Solar Spectral Irradiance

AbstractSome key physical processes that impact the evolution of Earth's atmosphere on time-scale from days to millennia, such as the EUV emissions, are determined by the solar magnetic field. However, observations of the solar spectral irradiance are restricted to the last few solar cycles and are subject to large uncertainties. We present a physics-based model to reconstruct short-term solar spectral irradiance (SSI) variability. The coronal magnetic field is estimated to employ the Potential Field Source Surface extrapolation (PFSS) based on observational synoptic charts and magnetic flux transport model. The emission is estimated to employ the CHIANTI atomic database 8.0. The performance of the model is compared to the emission observed by TIMED/SORCE.

Large-Scale Coronal Magnetic Structure and Its Variations during an 11-year Solar Cycle

1994 ◽  
Vol 144 ◽  
pp. 35-39
Author(s):  
E. V. Ivanov
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Large Scale ◽  
Heliospheric Current Sheet ◽  
Reference Points ◽  
Source Surface ◽  
Solar Cycles ◽  
Dipole Component ◽  
Global Magnetic Field ◽  
Main Components

AbstractMaps of coronal magnetic fields at different heights calculated under potential approximation, have been used to reconstruct the corona shape in different phases of solar cycles 21 and 22. The shape of the solar corona depends on the maximum heliolatitudes and the structure of the heliospheric current sheet (HCS) that, in turn, are determined by space-time variations of the 3 main components of the global magnetic field of the Sun: 1) the axial dipole component; 2) the inclined dipole component; and 3) the quadrupole component. Variations of theHCSmaximum heliolatitudes and the width of the corona at 2.5R⊙during a solar cycle are compared with variations of the global magnetic field indices in the photosphere and at the source surface. The role of the solar cycle reference points and the global magnetic field indices in the corona shape variations over a solar cycle are discussed.

The LDE-Type Flare Occurrence (1969-1993)

1994 ◽  
Vol 144 ◽  
pp. 279-282
Author(s):  
A. Antalová
Keyword(s):  
Time Series ◽  
Fourier Analysis ◽  
Sunspot Cycle ◽  
List Type ◽  
Type Number ◽  
Solar Cycles ◽  
Type Iv ◽  
Long Duration ◽  
Cycle Maximum ◽  
Flare Index

AbstractThe occurrence of LDE-type flares in the last three cycles has been investigated. The Fourier analysis spectrum was calculated for the time series of the LDE-type flare occurrence during the 20-th, the 21-st and the rising part of the 22-nd cycle. LDE-type flares (Long Duration Events in SXR) are associated with the interplanetary protons (SEP and STIP as well), energized coronal archs and radio type IV emission. Generally, in all the cycles considered, LDE-type flares mainly originated during a 6-year interval of the respective cycle (2 years before and 4 years after the sunspot cycle maximum). The following significant periodicities were found:• in the 20-th cycle: 1.4, 2.1, 2.9, 4.0, 10.7 and 54.2 of month,• in the 21-st cycle: 1.2, 1.6, 2.8, 4.9, 7.8 and 44.5 of month,• in the 22-nd cycle, till March 1992: 1.4, 1.8, 2.4, 7.2, 8.7, 11.8 and 29.1 of month,• in all interval (1969-1992):a)the longer periodicities: 232.1, 121.1 (the dominant at 10.1 of year), 80.7, 61.9 and 25.6 of month,b)the shorter periodicities: 4.7, 5.0, 6.8, 7.9, 9.1, 15.8 and 20.4 of month.Fourier analysis of the LDE-type flare index (FI) yields significant peaks at 2.3 - 2.9 months and 4.2 - 4.9 months. These short periodicities correspond remarkably in the all three last solar cycles. The larger periodicities are different in respective cycles.

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.

Long-term Cyclic Variations of Prominences, Green and Red Coronae over Solar Cycles

2000 ◽  
Vol 179 ◽  
pp. 201-204
Author(s):  
Vojtech Rušin ◽  
Milan Minarovjech ◽  
Milan Rybanský
Keyword(s):  
Emission Lines ◽  
High Latitudes ◽  
Green Line ◽  
Solar Cycles ◽  
The South ◽  
Coronal Emission ◽  
Local Maxima ◽  
The North ◽  
Cyclic Variations

AbstractLong-term cyclic variations in the distribution of prominences and intensities of green (530.3 nm) and red (637.4 nm) coronal emission lines over solar cycles 18–23 are presented. Polar prominence branches will reach the poles at different epochs in cycle 23: the north branch at the beginning in 2002 and the south branch a year later (2003), respectively. The local maxima of intensities in the green line show both poleward- and equatorward-migrating branches. The poleward branches will reach the poles around cycle maxima like prominences, while the equatorward branches show a duration of 18 years and will end in cycle minima (2007). The red corona shows mostly equatorward branches. The possibility that these branches begin to develop at high latitudes in the preceding cycles cannot be excluded.

Comparison of Interstorey Drift in General RC Buildings in Pounding and No Pounding Case

2020 ◽  
Vol 2 (1) ◽  
pp. 40-47
Author(s):  
Anand Dev Bhatt
Keyword(s):  
Seismic Analysis ◽  
Linear Time ◽  
Time History ◽  
Case Analysis ◽  
Rc Buildings ◽  
Adjacent Buildings ◽  
Sufficient Distance ◽  
Earthquake Load ◽  
Interstorey Drift ◽  
Lower Height

 Inter-storey drift is an important parameter of structural behavior in seismic analysis of buildings. Pounding effect in building simply means collision between adjacent buildings due to earthquake load caused by out of phase vibration of adjacent buildings. There is variation in inter-storey drift of adjacent buildings during pounding case and no pounding case. The main objective of this research was to compare the inter-storey drift of general adjacent RC buildings in pounding and no pounding case. For this study two adjacent RC buildings having same number of stories have been considered. For pounding case analysis there is no gap in between adjacent buildings and for no pounding case analysis there is sufficient distance between adjacent buildings. The model consists of adjacent buildings having 4 and 4 stories but unequal storey height. Both the buildings have same material & sectional properties. Fast non-linear time history analysis was performed by using El-centro earthquake data as ground motion. Adjacent buildings having different overall height were modelled in SAP 2000 v 15 using gap element for pounding case. Finally, analysis was done and inter-storey drift was compared. It was found that in higher building inter-storey drift is greater in no pounding case than in pounding case but in adjacent lower height building the result was reversed. Additionally, it was found that in general residential RC buildings maximum inter-storey drift occurs in 2nd floor.

Energetics of X-Class Flares at the Minima of 22, 23, and 24 Solar Cycles

2020 ◽  
Vol 60 (7) ◽  
pp. 929-935
Author(s):  
G. G. Motorina ◽  
A. L. Lysenko ◽  
S. A. Anfinogentov ◽  
G. D. Fleishman
Keyword(s):  
Solar Cycles

scholarly journals The earliest example of sexual dimorphism in bivalves—evidence from the astartid Nicaniella (Lower Jurassic, southern Germany)

2021 ◽  
pp. 1-10
Author(s):  
Baran Karapunar ◽  
Winfried Werner ◽  
Franz T. Fürsich ◽  
Alexander Nützel
Keyword(s):  
Principal Component Analysis ◽  
Life History ◽  
Shape Analysis ◽  
Principal Component ◽  
Sex Change ◽  
Lower Jurassic ◽  
Allocation Of Resources ◽  
Fourier Shape Analysis ◽  
Lower Height ◽  
Male To Female

Abstract Protandrous sex change (sex change from male to female) is one of the diverse sexual expressions exhibited by bivalves, but its expression in the shell is quite rare. Previous studies on living and fossil astartids suggest a relationship between protandrous sex change and the formation of crenulations on the ventral shell margin at later ontogenetic stages. Here we report the formation of such crenulations in the Early Jurassic astartid Nicaniella rakoveci (Kuhn, 1935) from the Amaltheenton Formation at Buttenheim, Franconia. This is the earliest known record of protandrous hermaphroditism in fossil bivalves, predating previous reports by at least 13 Myr. A principal component analysis of linear size measurements and Fourier shape analysis of the shell outlines revealed that the outline of Nicaniella rakoveci specimens varies from subquadrate to subcircular, but this variation is independent of the presence or absence of crenulations and therefore not associated with sex. Crenulated specimens exhibit a lower height/inflation ratio than non-crenulated ones, suggesting that the protandrous females have more inflated valves than the males. The formation of crenulations was probably related to allocation of resources for reproduction. The most likely function of the crenulations was to increase the internal shell volume in the female stage to accommodate more eggs rather than being an adaptation against predation as often assumed for other bivalves. The formation of crenulations is part of the protandrous life history and probably is controlled by a genetic mechanism that is also responsible for sex change.

Statistical analysis of soft X-ray solar flares during solar cycles 22, 23, and 24

2021 ◽  
Vol 366 (1) ◽  
Author(s):  
Bo Xiong ◽  
Ting Wang ◽  
Xiaolin Li ◽  
Yunxing Yin
Keyword(s):  
Statistical Analysis ◽  
Solar Flares ◽  
Solar Cycles ◽  
X Ray
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