The observation and simulation of ionospheric response to CIR/high-speed streams-induced geomagnetic activity on 4 April 2005

Radio Science ◽  
2016 ◽  
Vol 51 (8) ◽  
pp. 1297-1311 ◽  
Author(s):  
Yanhong Chen ◽  
Wenbin Wang ◽  
Na Qiu ◽  
Siqing Liu ◽  
Jiancun Gong ◽  
...  
Keyword(s):  
Geomagnetic Activity ◽  
High Speed ◽  
Ionospheric Response

scholarly journals Spectral analysis of auroral geomagnetic activity during various solar cycles between 1960 and 2014

2016 ◽  
Vol 34 (12) ◽  
pp. 1159-1164 ◽  
Author(s):  
Pieter Benjamin Kotzé
Keyword(s):  
Spectral Analysis ◽  
Geomagnetic Activity ◽  
Solar Minimum ◽  
High Speed ◽  
Solar Rotation ◽  
Pearson Correlation ◽  
Coronal Holes ◽  
Rotation Period ◽  
Period Change ◽  
Solar Cycles

Abstract. In this paper we use wavelets and Lomb–Scargle spectral analysis techniques to investigate the changing pattern of the different harmonics of the 27-day solar rotation period of the AE (auroral electrojet) index during various phases of different solar cycles between 1960 and 2014. Previous investigations have revealed that the solar minimum of cycles 23–24 exhibited strong 13.5- and 9.0-day recurrence in geomagnetic data in comparison to the usual dominant 27.0-day synodic solar rotation period. Daily mean AE indices are utilized to show how several harmonics of the 27-day recurrent period change during every solar cycle subject to a 95 % confidence rule by performing a wavelet analysis of each individual year's AE indices. Results show that particularly during the solar minimum of 23–24 during 2008 the 27-day period is no longer detectable above the 95 % confidence level. During this interval geomagnetic activity is now dominated by the second (13.5-day) and third (9.0-day) harmonics. A Pearson correlation analysis between AE and various spherical harmonic coefficients describing the solar magnetic field during each Carrington rotation period confirms that the solar dynamo has been dominated by an unusual combination of sectorial harmonic structure during 23–24, which can be responsible for the observed anomalously low solar activity. These findings clearly show that, during the unusual low-activity interval of 2008, auroral geomagnetic activity was predominantly driven by high-speed solar wind streams originating from multiple low-latitude coronal holes distributed at regular solar longitude intervals.

scholarly journals Spatial and seasonal effects on the delayed ionospheric response to solar EUV changes

2019 ◽  
Author(s):  
Erik Schmölter ◽  
Jens Berdermann ◽  
Norbert Jakowski ◽  
Christoph Jacobi
Keyword(s):  
Southern Hemisphere ◽  
Geomagnetic Activity ◽  
Correlation Coefficients ◽  
Seasonal Effects ◽  
Constant Delay ◽  
Average Delay ◽  
Ionospheric Response ◽  
The Difference ◽  
Longitudinal Variability ◽  
The Impact

Abstract. This study correlates different ionospheric parameters with the integrated solar EUV radiation for an analysis of the delayed ionospheric response in order to confirm previous studies on the delay and to further specify variations of the delay. Several time series for correlation coefficients and delays are presented to characterize the trend of the delay from 2011 to 2013. The impact of the diurnal variations of ionospheric parameters in the analysis on hourly resolution for fixed locations are discussed and specified with calculations in different time scales and with comparison to solar and geomagnetic activity. An average delay for TEC of ≈ 18.7 hours and for foF2 of ≈ 18.6 hours is calculated at four European stations. Through comparison with the Australian region the difference between northern and southern hemisphere is analyzed and a seasonal variation of the delay between northern and southern hemisphere is calculated for TEC with ≈ 5 ± 0.7 hours and foF2 with ≈ 8 ± 0.8 hours. The latitudinal and longitudinal variability of the delay is analyzed for the European region and a decrease of the delay from ≈ 21.5 hours at 30° N to ≈ 19.0 hours at 70° N has been found. For winter months a roughly constant delay of ≈ 19.5 hours is calculated. In this study a North-South trend of the ionospheric delay during summer month has been observed with ≈ 0.06 hours per degree in latitude. The results based on solar and ionospheric data in hourly resolution and the analysis of the delayed ionospheric response to solar EUV show the seasonal and latitudinal variations. Results also indicate the dependence on the geomagnetic activity as well as on the 11-year solar cycle.

scholarly journals An alternative way to identify local geomagnetically quiet days: a case study using wavelet analysis

2016 ◽  
Vol 34 (4) ◽  
pp. 451-462 ◽  
Author(s):  
Virginia Klausner ◽  
Andrés Reinaldo Rodriguez Papa ◽  
Cláudia Maria Nicole Cândido ◽  
Margarete Oliveira Domingues ◽  
Odim Mendes
Keyword(s):  
Wavelet Analysis ◽  
Geomagnetic Activity ◽  
Solar Minimum ◽  
High Speed ◽  
Wavelet Coefficient ◽  
Magnetic Activity ◽  
New Method ◽  
Storm Events ◽  
High Speed Stream

Abstract. This paper proposes a new method to evaluate geomagnetic activity based on wavelet analysis during the solar minimum activity (2007). In order to accomplish this task, a newly developed algorithm called effectiveness wavelet coefficient (EWC) was applied. Furthermore, a comparison between the 5 geomagnetically quiet days determined by the Kp-based method and by wavelet-based method was performed. This paper provides a new insight since the geomagnetic activity indexes are mostly designed to quantify the extent of disturbance rather than the quietness. The results suggest that the EWC can be used as an alternative tool to accurately detect quiet days, and consequently, it can also be used as an alternative to determine the Sq baseline to the current Kp-based 5 quietest days method. Another important aspect of this paper is that most of the quietest local wavelet candidate days occurred in an interval 2 days prior to the high-speed-stream-driven storm events. In other words, the EWC algorithm may potentially be used to detect the quietest magnetic activity that tends to occur just before the arrival of high-speed-stream-driven storms.

scholarly journals Dayside ionospheric response to recurrent geomagnetic activity during the extreme solar minimum of 2008

2010 ◽  
Vol 37 (2) ◽  
pp. n/a-n/a ◽  
Author(s):  
S. Tulasi Ram ◽  
J. Lei ◽  
S.-Y. Su ◽  
C. H. Liu ◽  
C. H. Lin ◽  
...  
Keyword(s):  
Geomagnetic Activity ◽  
Solar Minimum ◽  
Ionospheric Response

scholarly journals GEOMAGNETIC ACTIVITY AND AURORAS CAUSED BY HIGH-SPEED STREAMS: A REVIEW

2007 ◽  
pp. 91-102 ◽  
Author(s):  
FERNANDO L. GUARNIERI ◽  
BRUCE T. TSURUTANI ◽  
EZEQUIEL ECHER ◽  
WALTER D. GONZALEZ
Keyword(s):  
Geomagnetic Activity ◽  
High Speed

scholarly journals Solar and geomagnetic activity effects on mid-latitude F-region electric fields

2008 ◽  
Vol 26 (9) ◽  
pp. 2911-2921 ◽  
Author(s):  
V. V. Kumar ◽  
M. L. Parkinson ◽  
P. L. Dyson ◽  
R. Polglase
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Geomagnetic Activity ◽  
High Speed ◽  
Theoretical Models ◽  
Solar Flux ◽  
Quiet Time ◽  
F Region ◽  
Diurnal Patterns ◽  
Ae Index

Abstract. Diurnal patterns of average F-region ionospheric drift (electric field) and their dependence on solar and geomagnetic activity have been defined using digital ionosonde Doppler measurements recorded at a southern mid-latitude station (Bundoora 145.1° E, 37.7° S geographic, 49° S magnetic). A unique database consisting of 300 907 drift velocities was compiled, mostly using one specific mode of operation throughout 1632 days of a 5-year interval (1999–2003). The velocity magnitudes were generally larger during the night than day, except during the winter months (June–August), when daytime velocities were enhanced. Of all years, the largest drifts tended to occur during the high speed solar wind streams of 2003. Diurnal patterns in the average quiet time (AE<75 nT) meridional drifts (zonal electric field) peaked at up to ~6 m s−1 poleward (0.3 mV m−1 eastward) at 03:30 LST, reversing in direction at ~08:30 LST, and gradually reaching ~10 m s−1 equatorward at ~13:30 LST. The quiet time zonal drifts (meridional electric fields) displayed a clear diurnal pattern with peak eastward flows of ~10 m s−1 (0.52 mV m−1 equatorward) at 09:30 LST and peak westward flows around midnight of ~18 m s−1 (0.95 mV m−1 poleward). As the AE index increased, the westward drifts increased in amplitude and they extended over a greater fraction of the day. The perturbation drifts changed in a similar way with decreasing Dst except the daytime equatorward flows strengthened with increasing AE index, whereas they became weak for Dst<−60 nT. The responses in all velocity components to changing solar flux values were small, but net poleward perturbations during the day were associated with large solar flux values (>192×10−22 W m−2 Hz−1). These results help to more fully quantify the response of the mid-latitude ionosphere to changing solar and geomagnetic conditions, as required to refine empirical and theoretical models of mid-latitude electric fields.

scholarly journals Ionospheric response to CIR-induced recurrent geomagnetic activity during the declining phase of solar cycle 23

2015 ◽  
Vol 120 (2) ◽  
pp. 1394-1418 ◽  
Author(s):  
Yanhong Chen ◽  
Wenbin Wang ◽  
Alan G. Burns ◽  
Siqing Liu ◽  
Jiancun Gong ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Geomagnetic Activity ◽  
Ionospheric Response ◽  
Solar Cycle 23

scholarly journals Solar wind high-speed streams and related geomagnetic activity in the declining phase of solar cycle 23

2011 ◽  
Vol 533 ◽  
pp. A49 ◽  
Author(s):  
G. Verbanac ◽  
B. Vršnak ◽  
S. Živković ◽  
T. Hojsak ◽  
A. M. Veronig ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Geomagnetic Activity ◽  
High Speed ◽  
Solar Cycle 23
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