Average properties of bipolar magnetic regions during sunspot cycle 21

Solar Physics ◽  
1989 ◽  
Vol 124 (1) ◽  
pp. 81-100 ◽  
Author(s):  
Y. -M. Wang ◽  
N. R. Sheeley
Keyword(s):  
Sunspot Cycle

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.

Cyclic Evolution of Sunspots: Gleaning New Results from Old Data

2000 ◽  
Vol 179 ◽  
pp. 163-165
Author(s):  
S. K. Solanki ◽  
M. Fligge ◽  
P. Pulkkinen ◽  
P. Hoyng
Keyword(s):  
Sunspot Number ◽  
Sunspot Cycle ◽  
Preliminary Results ◽  
Butterfly Diagram

AbstractThe records of sunspot number, sunspot areas and sunspot locations gathered over the centuries by various observatories are reanalysed with the aim of finding as yet undiscovered connections between the different parameters of the sunspot cycle and the butterfly diagram. Preliminary results of such interrelationships are presented.

Neubestimmung der natürlichen irdischen Tritiumzerfallsrate und die Frage der Herkunft des „natürlichen“ Tritium

1959 ◽  
Vol 14 (4) ◽  
pp. 334-342 ◽  
Author(s):  
F. Begemann
Keyword(s):  
Phase Shift ◽  
Decay Rate ◽  
Production Rate ◽  
Residence Time ◽  
Cosmic Radiation ◽  
Sunspot Cycle ◽  
Energy Component ◽  
Tritium Content ◽  
The Earth ◽  
Snow Samples

The terrestrial decay rate of “natural” tritium has been re-determined from measurements of the tritium content of old snow samples from Greenland. The finding by CRAIG and BEGEMANN and LIBBY has been confirmed that the tritium decay rate is about 10 times higher than was anticipated previously.Two mechanisms to explain the discrepancy are discussed,a) production by the low energy component of the cosmic radiation andb) the accretion of solar tritium by the earth, as suggested by FELD and ARNOLD.It is shown that in case all the tritium is produced by cosmic radiation the tropospheric production rate may be expected to vary in antiphase with the sunspot cycle, whereas in case of accretion of solar tritium by the earth the variation should be in phase with the sunspot cycle. In both cases a phase shift between the stratospheric production rate and the amount of tropospheric tritium is to be expected because of the residence time of tritium in the stratosphere. A measurement of the phase shift should allow to determine this residence time.The data obtained on the Greenland samples appear to show such a variation of the production rate. The results can be explained best by assuming that all the tritium is produced by cosmic radiation. This result, however, is only preliminary. More systematic measurements are required to decide between the two possibilities.

SUNSPOT CYCLE CORRELATIONS

1961 ◽  
Vol 95 (1) ◽  
pp. 78-88 ◽  
Author(s):  
David Williams
Keyword(s):  
Sunspot Cycle

Cosmic Ray 11-Year Modulation for Sunspot Cycle 24

Solar Physics ◽  
2014 ◽  
Vol 290 (2) ◽  
pp. 635-643 ◽  
Author(s):  
H. S. Ahluwalia ◽  
R. C. Ygbuhay
Keyword(s):  
Sunspot Cycle ◽  
Cosmic Ray ◽  
Cycle 24

scholarly journals Sunspot Cycle Minima and Pandemics: The Case for Vigilance?

2017 ◽  
Vol 05 (02) ◽  
Author(s):  
Wickramasinghe NC ◽  
Edward J Steele ◽  
Wainwright M ◽  
Gensuke Tokoro ◽  
Manju Fernando ◽  
...  
Keyword(s):  
Sunspot Cycle

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.

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