Automated identification
of current sheets in the solar wind

Welcome to the website of the IKI-IZMIRAN inter-institutional project on current sheets!

METHOD

The current sheet list comes from an automated method of current sheet identification that suggests a formalization of the long-time experience of observers in the visual finding of CSs based on the analysis of the IMF and plasma parameters that vary sharply at CSs of different origins in the solar wind (Behannon et al. 1981; Blanco et al. 2006; Zhang et al. 2008; Suess et al. 2009; Simunac et al. 2012; Zharkova and Khabarova, 2012, 2015; Khabarova et al. 2015, 2016; Khabarova and Zank 2017; Malova at al. 2017; Adhikari et al. 2019).

The main features seen with a resolution not worse than one minute that may characterize a CS crossing are as follows: (i) a decrease in the IMF magnitude B, (ii) a decrease in VA/V (VA is the Alfvén speed, and V is the solar wind speed), and (iii) an increase in the plasma β (the ratio of the plasma pressure to the magnetic pressure). Since automatization of the CS recognition process requires setting the same rules for CSs occurring in different plasmas under different conditions, normalization should be performed. After obtaining B, VA/V, and β with a one second cadence, we calculate their one-second derivatives. Spikes of the derivatives occurring out of the noise level indicate the CS location.

The noise cutoff: A threshold of β=3 for a one second resolution data has been imposed. The next important point is that the signatures of a CS crossing should be observed in different key parameters altogether. In statistical terms this means finding a maximum correlation between different datasets to restrict final results by those complying with necessary signatures observed in all key parameters. Applying the maximum correlation condition, we finally obtain the following thresholds: values above dB/dt= -0.14, below dβ/dt=0.11, and above d(VA/V)/dt= -0.003 are considered as noise; here t= 1 s (see Figure below). Note that the thresholds will be different if one considers a lower data resolution or averaged data. Only the spikes that appear simultaneously in dB/dt and any of two other parameters are considered as pointing out the CS location.

Important! If you employ the method and/or the database, please refer to the website and cite the following article: O. Khabarova, T. Sagitov, R. Kislov, and G. Li, Automated identification of current sheets - a new tool to study turbulence and intermittency in the solar windarXiv:2101.02804 (JGR, under review)

 

   

 

   





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