scholarly journals Solar activities and geomagnetism: Long-term statistical study of magnetics clouds activity days occurrence as a function of the phases of solar cycles 11 to 24

2021 ◽  
Vol 16 (4) ◽  
pp. 180-187
Author(s):  
Salfo Kaboré ◽  
Karim Guibula ◽  
Jean Louis Zerbo ◽  
Frédéric Ouattara
Keyword(s):  
Statistical Study ◽  
Solar Cycles

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.

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.

scholarly journals Large-Scale Patterns of Prominences in the Global Solar Cycles During 1880–1995

1998 ◽  
Vol 167 ◽  
pp. 442-445
Author(s):  
Dirk K. Callebaut ◽  
Valentine I. Makarov ◽  
Ksenia S. Tavastsherna
Keyword(s):  
Large Scale ◽  
Wolf Number ◽  
Solar Cycles ◽  
Zonal Distribution ◽  
Periodic Oscillations ◽  
Period 1880 ◽  
Latitude Distribution ◽  
The Mean ◽  
Long Term Variations

AbstractThe zonal distribution of prominences, their poleward migration from the sunspot zone to the poles, the polar magnetic field reversals and a correlation of the mean latitude of filament bands at minimum activity with the maximum of Wolf number in the next cycle are briefly discussed for the period 1880–1995. The need for research on the longterm latitude distribution of the prominences is emphasized. New results concerning long-term variations of the torsional oscillations of the Sun and quasi-periodic oscillations of the latitude zonal boundaries from an analysis of Hα charts (1915–1990) are given.

A long-term statistical study of treated Class II, Division 1 malocclusions

1975 ◽  
Vol 67 (6) ◽  
pp. 697-698
Author(s):  
Peter E. Paulos ◽  
Robert S. Portenga ◽  
Richard D. Seabold
Keyword(s):  
Statistical Study ◽  
Class Ii ◽  
Division 1 ◽  
Class Ii Division 1

scholarly journals Large scale magnetic helicity fluxes estimated from MDI magnetic synoptic charts

2012 ◽  
Vol 8 (S294) ◽  
pp. 157-158
Author(s):  
Shangbin Yang ◽  
Hongqi Zhang
Keyword(s):  
Solar Cycle ◽  
Magnetic Flux ◽  
Solar Disk ◽  
Large Scale ◽  
Magnetic Helicity ◽  
Local Correlation ◽  
Solar Cycles ◽  
23Rd Solar Cycle ◽  
Term Evolution

AbstractTo investigate the characteristics of large scale and long term evolution of magnetic helicity with solar cycles, we use the method of Local Correlation Tracking (LCT) to estimate the magnetic helicity evolution over the 23rd solar cycle from 1996 to 2009 by using 795 MDI magnetic synoptic charts. The main results are: the hemispheric helicity rule still holds in general, i.e. the large-scale negative (positive) magnetic helicity dominates the northern (southern) hemisphere. However, the large scale magnetic helicity fluxes show the same sign in both hemispheres around 2001 and 2005. The global, large scale magnetic helicity flux over the solar disk changes from negative value at the beginning of the 23rd solar cycle to positive value at the end of the cycle, which also shows the similar trend from the normalized magnetic flux by using the magnetic flux. The net accumulated magnetic helicity is negative in the period between 1996 and 2009.

scholarly journals Grand minima of solar activity during the last millennia

2011 ◽  
Vol 7 (S286) ◽  
pp. 372-382 ◽  
Author(s):  
Ilya G. Usoskin ◽  
Sami K. Solanki ◽  
Gennady A. Kovaltsov
Keyword(s):  
Solar Activity ◽  
Historical Record ◽  
Moderate Activity ◽  
Solar Cycles ◽  
Cosmogenic Isotope ◽  
Cyclic Variations ◽  
Grand Maximum ◽  
Grand Minima ◽  
Stellar Dynamo

AbstractIn this review we discuss the occurrence and statistical properties of Grand minima based on the available data covering the last millennia. In particular, we consider the historical record of sunspot numbers covering the last 400 years as well as records of cosmogenic isotopes in natural terrestrial archives, used to reconstruct solar activity for up to the last 11.5 millennia, i.e. throughout the Holocene. Using a reconstruction of solar activity from cosmogenic isotope data, we analyze statistics of the occurrence of Grand minima. We find that: the Sun spends about most of the time at moderate activity, 1/6 in a Grand minimum and some time also in a Grand maximum state; Occurrence of Grand minima is not a result of long-term cyclic variations but is defined by stochastic/chaotic processes; There is a tendency for Grand minima to cluster with the recurrence rate of roughly 2000-3000 years, with a weak ≈210-yr periodicity existing within the clusters. Grand minima occur of two different types: shorter than 100 years (Maunder-type) and long ≈150 years (Spörer-type). It is also discussed that solar cycles (most possibly not sunspots cycle) could exist during the Grand minima, perhaps with stretched length and asymmetric sunspot latitudinal distribution.These results set new observational constraints on long-term solar and stellar dynamo models.

scholarly journals The long-term effects of space weather on satellite operations

2010 ◽  
Vol 28 (6) ◽  
pp. 1361-1367 ◽  
Author(s):  
D. T. Welling
Keyword(s):  
Background Radiation ◽  
High Energy ◽  
High Energy Particle ◽  
Solar Cycles ◽  
Long Term Effects ◽  
Radiation Background ◽  
Particle Exposure ◽  
Total Lifetime ◽  
The Impact

Abstract. Integrated lifetime radiation damage may cause spacecraft to become more susceptible to operational anomalies by changing material characteristics of electronic components. This study demonstrates and quantifies the impact of these effects by examining the National Oceanic and Atmospheric Administration (NOAA) National Geophysical Data Center (NGDC) satellite anomaly database. Energetic particle data from the Geostationary Operational Environmental Satellites (GOES) is used to construct the total lifetime particle exposure a satellite has received at the epoch of an anomaly. These values are compared to the satellite's chronological age and the average exposure per year (calculated over two solar cycles.) The results show that many anomalies occur on satellites that have received a total lifetime high-energy particle exposure that is disproportionate to their age. In particular, 10.8% of all events occurred on satellites that received over two times more 20 to 40 MeV proton lifetime particle exposure than predicted using an average annual mean. This number inflates to 35.2% for 40 to 80 MeV protons and 33.7% for ≥2 MeV electrons. Overall, 73.5% of all anomalies occurred on a spacecraft that had experienced greater than two times the expected particle exposure for one of the eight particle populations used in this study. Simplistically, this means that the long term radiation background exposure matters, and that if the background radiation is elevated during the satellite's lifetime, the satellite is likely to experience more anomalies than satellites that have not been exposed to the elevated environment.

scholarly journals Large- and small-scale periodicities in the mesosphere as obtained from variations in O<sub>2</sub> and OH nightglow emissions

2017 ◽  
Vol 35 (2) ◽  
pp. 227-237 ◽  
Author(s):  
Ravindra P. Singh ◽  
Duggirala Pallamraju
Keyword(s):  
Gravity Wave ◽  
Statistical Study ◽  
Small Scale ◽  
Radio Flux ◽  
Low Latitude ◽  
Atmospheric Processes ◽  
Solar Influence ◽  
Seasonal Dependence

Abstract. Using 3 years (2013–2015) of O2(0–1) and OH(6–2) band nightglow emission intensities and corresponding rotational temperatures as tracers of mesospheric dynamics, we have investigated large- and small-timescale variations in the mesosphere over a low-latitude location, Gurushikhar, Mount Abu (24.6° N, 72.8° E), in India. Both O2 and OH intensities show variations similar to those of the number of sunspots and F10.7 cm radio flux with coherent periodicities of 150 ± 2.1, 195 ± 3.6, 270 ± 6.4, and 420 ± 14.8 days, indicating a strong solar influence on mesospheric dynamics. In addition, both mesospheric airglow intensities also showed periodicities of 84 ± 0.6, 95 ± 0.9, and 122 ± 1.3 days which are of atmospheric origin. With regard to the variability of the order of a few days, O2 and OH intensities were found to be correlated, in general, except when altitude-dependent atmospheric processes were operative. To understand mesospheric gravity wave behavior over the long term, we have carried out a statistical study using the periodicities derived from the nocturnal variations in all four parameters (O2 and OH intensities and their respective temperatures). It was found that the major wave periodicity of around 2 h duration is present in all the four parameters. Our analyses also reveal that the range of periods in O2 and OH intensities and temperatures is 11 to 24 and 20 to 60 min, respectively. Periods less than 15 min were not present in the temperatures but were prevalent in both emission intensities. No seasonal dependence was found in either the wave periodicities or the number of their occurrence.

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