scholarly journals Annual variations in westward auroral electrojet and substorm occurrence rate during solar cycle 23

2014 ◽  
Vol 119 (3) ◽  
pp. 2061-2068 ◽  
Author(s):  
Jianpeng Guo ◽  
T. I. Pulkkinen ◽  
E. I. Tanskanen ◽  
Xueshang Feng ◽  
Barbara A. Emery ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Auroral Electrojet ◽  
Occurrence Rate ◽  
Annual Variations ◽  
Solar Cycle 23

scholarly journals Global characteristics of Pc1 magnetic pulsations during solar cycle 23 deduced from CHAMP data

2013 ◽  
Vol 31 (9) ◽  
pp. 1507-1520 ◽  
Author(s):  
J. Park ◽  
H. Lühr ◽  
J. Rauberg
Keyword(s):  
Solar Cycle ◽  
Major Axis ◽  
Magnetic Activity ◽  
Center Frequency ◽  
Occurrence Rate ◽  
Champ Satellite ◽  
Annual Variations ◽  
Magnetic Pulsations ◽  
Pc1 Pulsations ◽  
Cycle Dependence

Abstract. We present a global climatology of Pc1 pulsations as observed by the CHAMP satellite from 2000 to 2010. The Pc1 center frequency and bandwidth are about 1 and 0.5 Hz, respectively. The ellipticity is mostly linear with the major axis almost aligned with the magnetic zonal direction. The diurnal variation of Pc1 occurrences shows a primary maximum early in the morning and a secondary maximum during pre-midnight hours. The annual variations of the occurrence rates exhibit a clear preference for local summer. The solar cycle dependence of the occurrence rate reveals a maximum at the declining phase (2004–2005). Neither magnetic activity nor solar wind velocity controls the Pc1 occurrence rate significantly. Pc1 occurrence rate peaks at subauroral latitudes, but the steep cutoff towards higher latitudes is due to auroral field-aligned currents masking the Pc1 pulsations. The center frequency of Pc1 pulsations does not show a clear dependence on latitude. The global distribution of Pc1 exhibits highest occurrence rates near the longitude sector of the South Atlantic Anomaly. Pc1 events at auroral latitudes, although they are rarely detected, show a clear occurrence peak around local noon. A majority of the auroral Pc1 events are observed during solar minimum years.

A wavelet analysis of F2 layer critical frequency over solar cycle 23

2018 ◽  
Vol 13 (S340) ◽  
pp. 157-158
Author(s):  
C. S. Seema ◽  
P. R. Prince
Keyword(s):  
Solar Cycle ◽  
Critical Frequency ◽  
Power Spectra ◽  
Quasi Biennial Oscillation ◽  
Equatorial Latitude ◽  
Annual Variations ◽  
Latitudinal Dependence ◽  
Hourly Data ◽  
Solar Cycle 23 ◽  
Direct Outcome

AbstractTemporal oscillations of F2 layer critical frequency are direct outcome of solar EUV variability. The hourly data of F2 layer critical frequency (foF2) during solar cycle 23 over eight ionosonde stations which falls within same longitudinal span are evaluated using Continuous Wavelet Transform (CWT) to estimate the ionospheric variations. The quasi triennial, annual, semiannual, 27 day and diurnal variations of foF2 are clearly evident in the wavelet power spectra of all the stations. Quasi triennial oscillations which show a clear latitudinal dependence is more evident in southern stations. A strong quasi biennial oscillation (QBO) is also noticed in higher latitudes which was not observable in equatorial latitude. The present study reveals that the semiannual variations are more obvious over the annual variation in the equatorial and low latitude stations while the annual variations are prominent in higher latitudes.

scholarly journals Unusual declining phase of solar cycle 23: Weak semi-annual variations of auroral hemispheric power and geomagnetic activity

2009 ◽  
Vol 36 (22) ◽  
Author(s):  
Xiaoli Luan ◽  
Wenbin Wang ◽  
Alan G. Burns ◽  
Stanley C. Solomon ◽  
Yongliang Zhang ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Geomagnetic Activity ◽  
Annual Variations ◽  
Solar Cycle 23

Mid-term Periodicities in Solar Radio Emission Corresponding to Sunspot Number During Solar Cycle 23

Solar Physics ◽  
2021 ◽  
Vol 296 (3) ◽  
Author(s):  
Mahender Aroori ◽  
Panditi Vemareddy ◽  
Partha Chowdhury ◽  
Ganji Yellaiah
Keyword(s):  
Solar Cycle ◽  
Radio Emission ◽  
Sunspot Number ◽  
Solar Radio ◽  
Solar Radio Emission ◽  
Solar Cycle 23

Interpretable Machine Learning to Forecast SEP Events for Solar Cycle 23

2021 ◽  
Author(s):  
Spiridon Kasapis ◽  
Lulu Zhao ◽  
Yang Chen ◽  
Xiantong Wang ◽  
Monica Bobra ◽  
...  
Keyword(s):  
Machine Learning ◽  
Solar Cycle ◽  
Interpretable Machine Learning ◽  
Solar Cycle 23

scholarly journals North–south asymmetry of different solar activity features during solar cycle 23

New Astronomy ◽  
2010 ◽  
Vol 15 (6) ◽  
pp. 561-568 ◽  
Author(s):  
Neeraj Singh Bankoti ◽  
Navin Chandra Joshi ◽  
Seema Pande ◽  
Bimal Pande ◽  
Kavita Pandey
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Solar Cycle 23 ◽  
South Asymmetry
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