scholarly journals Shift of effective lightning areas during pre to post period of solar cycle minimum of 2008-2009 as determined from Schumann resonance studies at Agra, India

2015 ◽  
Vol 57 (6) ◽  
Author(s):  
Birbal Singh ◽  
Devbrat Pundhir
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Seasonal Variations ◽  
Thunderstorm Activity ◽  
Schumann Resonance ◽  
Cycle Minimum ◽  
Source Distance ◽  
Imaging Sensor ◽  
Post Period ◽  
Effective Source

<p>Employing a set of 3-component search coil magnetometer, Schumann resonance studies have been in progress at Agra (Geograph. lat. 27.2°N, long. 78°E), India since 01 April, 2007. We have analysed the data for two periods; first from 01 April, 2007 to 31 March, 2008 (period-I), and then from 01 March, 2011 to 29 February, 2012 (period-II) which correspond to pre and post periods of solar cycle minimum of 2008-2009. From the diurnal variation of first mode intensity and frequency, we study the seasonal variations of global thunderstorm activity, effective source distance and level of lightning during both the periods. We show that world thunderstorm activity shifts to summer in the northern hemisphere as the effective source distance approaches close to the observer, and the level of intense lightning shifts from the month of July, 2007 in period-I to August, 2011 in period-II. This is supported by Lightning Imaging Sensor (LIS) satellite data also. A possible explanation in terms of increasing solar activity is suggested.</p>

scholarly journals Seasonal Variations of the Optimum Reliable Frequencies During Maximum and Minimum Periods of Solar Cycle 24

2020 ◽  
Vol 31 (4) ◽  
pp. 15
Author(s):  
Samar Abdalkaream Thabit ◽  
Loay E. George ◽  
Khalid A. Hadi
Keyword(s):  
Mathematical Model ◽  
Solar Activity ◽  
Solar Cycle ◽  
Seasonal Variations ◽  
Path Length ◽  
Polynomial Equation ◽  
Ionospheric Parameter ◽  
Solar Cycle 24 ◽  
Path Lengths ◽  
Cycle 24

In this research, the seasonal Optimal Reliable Frequency (ORF) variations between different transmitter/receiver stations have been determined. Mosul, Baghdad, and Basra have been chosen as tested transmitting stations that located in the northern, center, and southern of Iraqi zone. In this research, the minimum and maximum years (2009 and 2014) of solar cycle 24 have been chosen to examine the effect of solar activity on the determined seasonal ORF parameter. Mathematical model has been proposed which leads to generate the Optimal Reliable Frequency that can maintain the seasonal connection links for different path lengths and bearings. The suggested ORF parameter represented by a different orders polynomial equation. The polynomial equation has been determined depending on different selected parameters (path length, bearing, time (day), months and BUF values). The suggested seasonal ORF parameter was examined for the three stations of the adopted years. The value of the seasonal ORF ionospheric parameter increased with the increase of path length and varies with the bearing between the transmitting and receiving stations also, the seasonal ORF values were higher at maximum solar cycle (2014) than the minimum solar cycle (2009).

Solar cycle and seasonal variations in F-region vertical drifts over Kodaikanal, India

1995 ◽  
Vol 13 (6) ◽  
pp. 633-640 ◽  
Author(s):  
K. B. Ramesh ◽  
J. H. Sastri
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Seasonal Variations ◽  
Normal Incidence ◽  
Magnetic Activity ◽  
Solar Flux ◽  
Seasonal Trend ◽  
F Region ◽  
Phase Path ◽  
10.7 Cm Solar Flux

Abstract. Measurements of the changes in phase path of F-region reflections at normal incidence at Kodaikanal (77° 28'E, 10° 14'N, dip 3°N) from February 1991 to February 1993 are used to determine the variation of the equatorial evening F-region vertical drifts (V z) with season, solar and magnetic activity. It is found that on average, at Kodaikanal, the post-sunset peak in Vz(Vzp) is higher in equinox and local winter months than in local summer. The day-to-day variability in V zp is highest in summer and lowest in winter. This seasonal trend persists even on magnetically quiet days (Ap \\leq14). Vzp is found to increase with 10.7 cm solar flux in all three seasons but tends to saturate for large flux values (>230 units) during local summer and winter months. Magnetic activity [represented by Ap as well as the time-weighted accumulations of a p and ap (τ)] does not seem to have any statistically significant effect on Vzp , except during equinoctial months of moderate solar activity, when Vzp decreases as magnetic activity increases.

scholarly journals The burst of solar and geomagnetic activity in August–September 2005

2009 ◽  
Vol 27 (3) ◽  
pp. 1019-1026 ◽  
Author(s):  
A. Papaioannou ◽  
H. Mavromichalaki ◽  
E. Eroshenko ◽  
A. Belov ◽  
V. Oleneva
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Geomagnetic Activity ◽  
Neutron Monitor ◽  
Cosmic Ray ◽  
High Energy ◽  
X Ray ◽  
Cycle Minimum ◽  
Short Period ◽  
Ray Density

Abstract. During the August–September 2005 burst of solar activity, close to the current solar cycle minimum, a significant number of powerful X-ray flares were recorded, among which was the outstanding X17.0 flare of 7 September 2005. Within a relatively short period (from 22 August to 17 September) two severe magnetic storms were also recorded as well as several Forbush effects. These events are studied in this work, using hourly mean variations of cosmic ray density and anisotropy, derived from data of the neutron monitor network. During these Forbush effects the behavior of high energy cosmic ray characteristics (density and anisotropy) is analyzed together with interplanetary disturbances and their solar sources, and is compared to the variations observed in geomagnetic activity. A big and long lasting (~6 h) cosmic ray pre-decrease (~2%) is defined before the shock arrival on 15 September 2005. The calculated cosmic ray gradients for September 2005 are also discussed.

scholarly journals A significant decrease of the fundamental Schumann resonance frequency during the solar cycle minimum of 2008-9 as observed at Modra Observatory

2009 ◽  
Vol 39 (4) ◽  
pp. 345-354 ◽  
Author(s):  
Adriena Ondrášková ◽  
Sebastián Ševčík ◽  
Pavel Kostecký
Keyword(s):  
Solar Cycle ◽  
Resonance Frequency ◽  
Fundamental Mode ◽  
Lower Ionosphere ◽  
Mode Frequency ◽  
Schumann Resonance ◽  
Schumann Resonances ◽  
Cycle Minimum ◽  
The North ◽  
Cycle Maximum

A significant decrease of the fundamental Schumann resonance frequency during the solar cycle minimum of 2008-9 as observed at Modra ObservatoryThe Schumann resonances (SR) are electromagnetic eigenmodes of the resonator bounded by the Earth's surface and the lower ionosphere. The SR frequency variability has been studied for more than 4 decades. Using data from the period 1988 to 2002,Sátori et al. (2005)showed that the SR fundamental mode frequency decreased on the 11-year time scale by 0.07 - 0.2 Hz, depending on which component of the field was used for estimation and likely also on the location of the observer. A decrease by 0.30 Hz from the latest solar cycle maximum to the minimum of 2009 is found in data from Modra Observatory. This extraordinary fall of the fundamental mode frequency can be attributed to the unprecedented drop in the ionizing radiation in X-ray frequency band. Although the patterns of the daily and seasonal variations remain the same in the solar cycle minimum as in the solar cycle maximum, they are significantly shifted to lower frequencies during the minimum. Analysis of the daily frequency range suggests that the main thunderstorm regions during the north hemisphere summer are smaller in the solar cycle minimum than in the maximum.

Prominences and Solar Activity

1979 ◽  
Vol 44 ◽  
pp. 357-372
Author(s):  
Z. Švestka
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
List Type ◽  
Type Number ◽  
Flare Loops ◽  
Filament Activation

The following subjects were discussed:(1)Filament activation(2)Post-flare loops.(3)Surges and sprays.(4)Coronal transients.(5)Disk vs. limb observations.(6)Solar cycle variations of prominence occurrence.(7)Active prominences patrol service.Of all these items, (1) and (2) were discussed in most detail and we also pay most attention to them in this report. Items (3) and (4) did not bring anything new when compared with the earlier invited presentations given by RUST and ZIRIN and therefore, we omit them.

scholarly journals On the Prediction of Solar Cycles

Solar Physics ◽  
2021 ◽  
Vol 296 (1) ◽  
Author(s):  
V. Courtillot ◽  
F. Lopes ◽  
J. L. Le Mouël
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Transfer Function ◽  
Singular Spectrum Analysis ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Planetary Motion ◽  
Data Sets ◽  
Solar Cycles ◽  
Jovian Planets

AbstractThis article deals with the prediction of the upcoming solar activity cycle, Solar Cycle 25. We propose that astronomical ephemeris, specifically taken from the catalogs of aphelia of the four Jovian planets, could be drivers of variations in solar activity, represented by the series of sunspot numbers (SSN) from 1749 to 2020. We use singular spectrum analysis (SSA) to associate components with similar periods in the ephemeris and SSN. We determine the transfer function between the two data sets. We improve the match in successive steps: first with Jupiter only, then with the four Jovian planets and finally including commensurable periods of pairs and pairs of pairs of the Jovian planets (following Mörth and Schlamminger in Planetary Motion, Sunspots and Climate, Solar-Terrestrial Influences on Weather and Climate, 193, 1979). The transfer function can be applied to the ephemeris to predict future cycles. We test this with success using the “hindcast prediction” of Solar Cycles 21 to 24, using only data preceding these cycles, and by analyzing separately two 130 and 140 year-long halves of the original series. We conclude with a prediction of Solar Cycle 25 that can be compared to a dozen predictions by other authors: the maximum would occur in 2026.2 (± 1 yr) and reach an amplitude of 97.6 (± 7.8), similar to that of Solar Cycle 24, therefore sketching a new “Modern minimum”, following the Dalton and Gleissberg minima.

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