Influence of the definition of dissipative events on their statistics
Abstract
A convenient and widely used method to study the turbulent plasma in the solar corona is to examine statistics of properties of events (or structures) associated to flares either in observations or in numerical simulations. Numerous papers have followed such a methodology, using different definitions of an event, but the reasons behind the choice of a particular definition is very rarely discussed. We give here a comprehensive set of possible event definitions starting from a onedimensional data set such as a timeseries of energy dissipation. Each definition is then applied to a timeseries of energy dissipation obtained from simulations of a shellmodel of magnetohydrodynamic turbulence, or from a new model of coupled shellmodels designed to represent a magnetic loop in the solar corona. We obtain distributions of the peak dissipation power, total energy, duration and waitingtime associated with each definition. These distributions are then investigated and compared, and the influence of the definition of an event on the statistics is discussed. In particular, powerlaw distributions are more likely to appear when using a threshold. The sensitivity of the distributions to the definition of an event seems also to be weaker for events found in a highly intermittent time series. Some implications for statistical results obtained from observations are discussed.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 June 2005
 DOI:
 10.1051/00046361:20042360
 arXiv:
 arXiv:astroph/0411592
 Bibcode:
 2005A&A...436..355B
 Keywords:

 Sun: corona;
 Sun: flares;
 magnetohydrodynamics (MHD);
 methods: data analysis;
 Astrophysics
 EPrint:
 8 pages, 13 figures. Submitted to Astronomy&