DocumentCode :
2666827
Title :
The Hurst exponents of the geomagnetic horizontal component during quiet and active periods
Author :
Hamid, Nurul Shazana Abdul ; Gopir, Geri ; Ismail, Mahamod ; Misran, Norbahiah ; Hasbi, Alina Marie ; Usang, Mark Dennis ; Yumoto, Kiyohumi
Author_Institution :
Sch. of Appl. Phys., Univ. Kebangsaan Malaysia, Bangi, Malaysia
fYear :
2009
fDate :
26-27 Oct. 2009
Firstpage :
186
Lastpage :
190
Abstract :
The focus in this paper is mainly to characterize the fractal properties denoted by the Hurst exponent of geomagnetic field during quiet and active periods of geomagnetism activity. Analysis is made on the time series of the geomagnetic horizontal component data, H, which were acquired by the Magnetic Data Acquisition System (MAGDAS) developed by the Space Environment Research Center (SERC) of Kyushu University in Japan. The data set covers the quiet and active periods in August 2005 at the equatorial stations of Cebu and Davao in the Philippines. This month had very intense geomagnetic storm with the Dstmin, Kp and Ap indices for the quietest and active days of the month are -20 nT, 2, 6 and -216 nT, 9, 110 respectively. For both stations, the data sampling interval is 1 second for each time periods or one day giving a sample size of 86,400. Using the fast Fourier transform, the power law of the data time series was obtained in the shorter time periods of 10 minutes to 6 hours. This observed power spectrum law exhibit scaling with corresponding Hurst exponents of 0.3-0.5 for quiet periods and 0.5-0.7 for active periods for both stations. For comparison, other fractal techniques were performed which are rescaled range analysis (RS) and detrended fluctuation analysis (DFA) on the data set, and the same ranges of the Hurst exponents were obtained. The work also includes simulation of the similar sized data sets by generating the fractional Brownian motions (FBM) with the Hurst exponents of 0.3-0.7. Our results show that the H component at these equatorial stations is a fractal in nature and become more persistent during active periods of geomagnetism activity. Thus, the Hurst exponent could be used to characterize the geomagnetic time series during quiet and active periods.
Keywords :
Brownian motion; fast Fourier transforms; magnetic storms; solar wind; solar-terrestrial relationships; time series; AD 2005 08; Cebu; Davao; FBM; Hurst exponent; Japan; Kyushu University; MAGDAS; Magnetic Data Acquisition System; Philippines; SERC; Space Environment Research Center; active period; detrended fluctuation analysis; equatorial station; fast Fourier transform; fractional Brownian motion; geomagnetic horizontal component; geomagnetic storm; geomagnetism activity; power spectrum law; quiet period; rescaled range analysis; solar wind; time series; Data acquisition; Fast Fourier transforms; Fluctuations; Fractals; Geomagnetism; Magnetic analysis; Performance analysis; Sampling methods; Storms; Time series analysis; fractal and Hurst exponent; geomagnetic field; scaling; time series;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Space Science and Communication, 2009. IconSpace 2009. International Conference on
Conference_Location :
Negeri Sembilan
Print_ISBN :
978-1-4244-4956-9
Electronic_ISBN :
978-1-4244-4956-9
Type :
conf
DOI :
10.1109/ICONSPACE.2009.5352642
Filename :
5352642
Link To Document :
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