Wavelet Analysis on Solar Wind Parameters and Geomagnetic Indices

Katsavrias, Christos; Preka‐Papadema, P.; Moussas, X.

doi:10.1007/s11207-012-0078-6

Cited by 71 publications

(47 citation statements)

References 37 publications

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“…This is possibly due to magnetic storms that result from the sporadic occurrence of coronal-mass ejections, and the fact that fast streams from coronal holes during solar cycle minima are more dominant. This finding is in line with results obtained by Katsavrias et al (2012) who found that the 27.0-day period could not be detected at a confidence level of 99 % during the minimum of cycle 23 in the case of the interplanetary magnetic field components. It has been proposed in previous investigations of periodicities in solar wind parameters (e.g.…”

Section: Resultssupporting

confidence: 93%

Spectrum analysis of short-period <i>K</i> index behaviour at high and mid-latitudes

Kotzé

2015

Ann. Geophys.

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Abstract. Geomagnetic activity levels during the declining phase and solar minimum period of the solar cycle are considerably different from those during the solar maximum phase. Previous studies revealed variations in the pattern of recurrent activity from cycle to cycle as well as variations in the average geomagnetic activity levels during a solar cycle. During the declining phase of a solar cycle (and solar minimum), the solar and interplanetary causes of geomagnetic activity are substantially different from those during the solar maximum phase. Co-rotating fast solar wind streams originating from large polar coronal holes, extending towards the Sun's equator, interact with the Earth's magnetosphere, resulting in recurrent geomagnetic activity particularly during solar cycle minimum periods. This is a wellknown phenomenon with respect to 27.0-and 13.5-day recurrence geomagnetic activity, and it is well-known to be related to sectorial (non-axial) poloidal magnetic field structure in the Sun. Published results of the recent solar-cycle-23 minimum showed that the presence of 9.0-and 6.7-day recurrent geomagnetic activities can be attributed to the sectorial spherical harmonic structure present in the solar magnetic field. In this study we performed a wavelet and LombScargle analysis of the geomagnetic activity K index at Lerwick (LER), Hermanus (HER) and Canberra (CNB) for the period between 1960 and 2010, overlapping with solar cycles 20 to 23. Daily mean K indices are used to identify how several harmonics of the 27.0-day recurrent period change during each solar cycle when comparing high and mid-latitude geomagnetic activity, applying a 95 % confidence level. In particular the behaviour of the second (13.5-day), third (9.0-day) and fourth (6.7-day) harmonics are investigated by doing a wavelet analysis of each individual year's K indices at each location. Results obtained show that particularly during solar minima the 27.0-day period is no longer detectable above the 95 % confidence level, and that geomagnetic activity is in fact dominated by higher harmonics like 13.5-, 9.0-and 6.7-day periods. These findings in fact are in line with previous investigations and confirm the results obtained by researchers using other geomagnetic activity indices like aa and C9. The wavelet-spectrum analysis also reveals that during the downward phase of cycle 23 and the very long minimum of 23-24 between 2002 and 2008, the 27.0-day activity period drops below the 95 % confidence level. This is confirmed by Lomb-Scargle analyses of every year's K index activity. Results obtained in this study support evidence by other investigations that this can be attributed to the lack of coronal-mass ejection (CME)-dominated solar activity during solar minima, periods characterized by strong solar dipolar magnetic fields, less sunspot numbers than at solar maxima, and multiple prominent co-rotating solar wind streams present. This analysis further confirms previous studies by other authors that the pattern of recurrent activity is dictat...

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Section: Resultssupporting

confidence: 93%

Spectrum analysis of short-period <i>K</i> index behaviour at high and mid-latitudes

Kotzé

2015

Ann. Geophys.

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“…130 days 129.9; 137; 133 days Solar flare occurrence rate (Bai 2003); periodicity of solar flare index for cycle 23 (Kilcik et al 2010); solar electron flux (Chowdhury et al 2009) 7. 181 days 176; 175; 182; 187 days Occurrence of solar type III radio burst during minimum phase of cycle 23 (Lobzin et al 2012); solar electron flare occurrence during cycle 23 (Chowdhury & Ray 2006); solar wind velocity and DST index (Katsavrias et al 2012); sunspot area of whole sphere for cycle 23 (Chowdhury et al 2009) 8. 227 days 209-222; 226 days Variation of the photospheric magnetic flux (Knaack et al 2005); X-ray flares of B & C classes for cycle 23 (Dimitropoulou et al 2008) 9.…”

Section: Resultsmentioning

confidence: 99%

“…227 days 209-222; 226 days Variation of the photospheric magnetic flux (Knaack et al 2005); X-ray flares of B & C classes for cycle 23 (Dimitropoulou et al 2008) 9. 303 days 310; 313 days Occurrence rate of solar proton flares; IMF (B y component) (Katsavrias et al 2012) 10.…”

Section: Resultsmentioning

confidence: 99%

“…They found significant power with a 1.28 yr period, however, it was observed to vary strongly with time. A 1.3 yr periodicity has also been detected in variations of the interplanetary magnetic field and geomagnetic activity (Paularena et al 1995;Szabo et al 1995;Lockwood 2001;Mursula et al 2003;Katsavrias et al 2012) as well as in the variation of the photospheric magnetic flux (Knaack et al 2005) and in the solar wind speed (Richardson et al 1994;Prabhakaran Nayar et al 2002). Based on an analysis of the same data, however, Antia & Basu (2000) drew conclusions that contradict those of Howe et al (2000).…”

Section: Introductionmentioning

confidence: 95%

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Periodicities in the X-Ray Emission From the Solar Corona

Chowdhury

Jain

Awasthi

2013

ApJ

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We have studied the time series of full disk integrated soft and hard X-ray emission from the solar corona during 2004 January to 2008 December, covering the entire descending phase of solar cycle 23 from a global point of view. We employ the daily X-ray index derived from 1 s cadence X-ray observations from the Si and CZT detectors of the "Solar X-ray Spectrometer" mission in seven different energy bands ranging between 6 and 56 keV. X-ray data in the energy bands 6-7, 7-10, 10-20, and 4-25 keV from the Si detector are considered, while 10-20, 20-30, and 30-56 keV high energy observations are taken from the CZT detector. The daily time series is subjected to power spectrum analysis after appropriate correction for noise. The Lomb-Scargle periodogram technique has shown prominent periods of ∼13.5 days, ∼27 days, and a near-Rieger period of ∼181 days and ∼1.24 yr in all energy bands. In addition to this, other periods like ∼31, ∼48, ∼57, ∼76, ∼96, ∼130, ∼227, and ∼303 days are also detected in different energy bands. We discuss our results in light of previous observations and existing numerical models.

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“…The major periods of IMF2 was 5-7 years, and it may be associated with an atmospheric oscillation closely connected to the El Niño Southern Oscillation (ENSO). IMF3 exhibited runoff variations on a scale of 10-13 years, which was similar to the 11-year cycle of sunspots (Katsavrias et al, 2012). IMF4 represented multi-decadal variations in runoff.…”

Section: Eemd Analysis For Future Average Annual Runoffmentioning

confidence: 68%

Runoff of arid and semi-arid regions simulated and projected by CLM-DTVGM and its multi-scale fluctuations as revealed by EEMD analysis

et al. 2016

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Runoff is a major component of the water cycle, and its multi-scale fluctuations are important to water resources management across arid and semi-arid regions. This paper coupled the Distributed Time Variant Gain Model (DTVGM) into the Community Land Model (CLM 3.5), replacing the TOPMODEL-based method to simulate runoff in the arid and semi-arid regions of China. The coupled model was calibrated at five gauging stations for the period 1980-2005 and validated for the period 2006-2010. Then, future runoff (2010-2100) was simulated for different Representative Concentration Pathways (RCP) emission scenarios. After that, the spatial distributions of the future runoff for these scenarios were discussed, and the multi-scale fluctuation characteristics of the future annual runoff for the RCP scenarios were explored using the Ensemble Empirical Mode Decomposition (EEMD) analysis method. Finally, the decadal variabilities of the future annual runoff for the entire study area and the five catchments in it were investigated. The results showed that the future annual runoff had slowly decreasing trends for scenarios RCP 2.6 and RCP 8.5 during the period 2010-2100, whereas it had a non-monotonic trend for the RCP 4.5 scenario, with a slow increase after the 2050s. Additionally, the future annual runoff clearly varied over a decadal time scale, indicating that it had clear divisions between dry and wet periods. The longest dry period was approximately 15 years (2040)(2041)(2042)(2043)(2044)(2045)(2046)(2047)(2048)(2049)(2050)(2051)(2052)(2053)(2054)(2055) for the RCP 2.6 scenario and 25 years for the RCP 4.5 scenario. However, the RCP 8.5 scenario was predicted to have a long dry period starting from 2045. Under these scenarios, the water resources situation of the study area will be extremely severe. Therefore, adaptive water management measures addressing climate change should be adopted to proactively confront the risks of water resources.

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Wavelet Analysis on Solar Wind Parameters and Geomagnetic Indices

Cited by 71 publications

References 37 publications

Spectrum analysis of short-period <i>K</i> index behaviour at high and mid-latitudes

Spectrum analysis of short-period <i>K</i> index behaviour at high and mid-latitudes

Periodicities in the X-Ray Emission From the Solar Corona

Runoff of arid and semi-arid regions simulated and projected by CLM-DTVGM and its multi-scale fluctuations as revealed by EEMD analysis

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Wavelet Analysis on Solar Wind Parameters and Geomagnetic Indices

Cited by 71 publications

References 37 publications

Spectrum analysis of short-period &lt;i&gt;K&lt;/i&gt; index behaviour at high and mid-latitudes

Spectrum analysis of short-period &lt;i&gt;K&lt;/i&gt; index behaviour at high and mid-latitudes

Periodicities in the X-Ray Emission From the Solar Corona

Runoff of arid and semi-arid regions simulated and projected by CLM-DTVGM and its multi-scale fluctuations as revealed by EEMD analysis

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Spectrum analysis of short-period <i>K</i> index behaviour at high and mid-latitudes

Spectrum analysis of short-period <i>K</i> index behaviour at high and mid-latitudes