Vörös, Z. and Leitner, M. and Narita, Y. and Consolini, G. and Kovács, P. and Lichtenberger, János (2015) Probability density functions for the variable solar wind near the solar cycle minimum. JOURNAL OF GEOPHYSICAL RESEARCH A: SPACE PHYSICS, 120 (8). pp. 61526166. ISSN 21699380

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Abstract
Unconditional and conditional statistics are used for studying the histograms of magnetic field multiscale fluctuations in the solar wind near the solar cycle minimum in 2008. The unconditional statistics involves the magnetic data during the whole year in 2008. The conditional statistics involves the magnetic field time series split into concatenated subsets of data according to a threshold in dynamic pressure. The threshold separates faststream leading edge compressional and trailing edge uncompressional fluctuations. The histograms obtained from these data sets are associated with both multiscale (B) and smallscale (δB) magnetic fluctuations, the latter corresponding to timedelayed differences. It is shown here that, by keeping flexibility but avoiding the unnecessary redundancy in modeling, the histograms can be effectively described by a limited set of theoretical probability distribution functions (PDFs), such as the normal, lognormal, kappa, and logkappa functions. In a statistical sense the model PDFs correspond to additive and multiplicative processes exhibiting correlations. It is demonstrated here that the skewed smallscale histograms inherent in turbulent cascades are better described by the skewed logkappa than by the symmetric kappa model. Nevertheless, the observed skewness is rather small, resulting in potential difficulties of estimation of the thirdorder moments. This paper also investigates the dependence of the statistical convergence of PDF model parameters, goodness of fit, and skewness on the data sample size. It is shown that the minimum lengths of data intervals required for the robust estimation of parameters is scale, process, and model dependent. ©2015. American Geophysical Union. All Rights Reserved.
Item Type:  Article 

Uncontrolled Keywords:  turbulence; Solar wind; Probability density function 
Subjects:  Q Science / természettudomány > QE Geology / földtudományok > QE01 Geophysics / geofizika 
SWORD Depositor:  MTMT SWORD 
Depositing User:  MTMT SWORD 
Date Deposited:  29 Dec 2015 06:20 
Last Modified:  29 Dec 2015 06:20 
URI:  http://real.mtak.hu/id/eprint/31557 
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