Automated Solar Flare Statistics in Soft Xrays over 37 Years of GOES Observations  The Invariance of SelfOrganized Criticality during Three Solar Cycles 

Markus J. Aschwanden Submitted: 20120530 08:52
We analyzed the soft Xray light curves from the {sl Geostationary Operational
Environmental Satellites (GOES)} over the last 37 years (19752011) and
measured with an automated flare detection algorithm over 300,000 solar
flare events (amounting to approx 5 times higher sensitivity than the NOAA
flare catalog). We find a powerlaw slope of α _F=1.98pm0.11 for the
(backgroundsubtracted) soft Xray peak fluxes that is invariant through
three solar cycles and agrees with the theoretical prediction α _F=2.0
of the {sl fractaldiffusive selforganized criticality (FDSOC)} model.
For the soft Xray flare rise times we find a powerlaw slope of α _T
=2.02pm0.04 during solar cycle minima years, which is also consistent
with the prediction α _T=2.0 of the FDSOC model. During solar cycle
maxima years, the powerlaw slope is steeper in the range of α _T approx 2.05.0,
which can be modeled by a solar cycledependent flare pileup bias effect.
These results corroborate the FDSOC model, which predicts a powerlaw slope
of α _E=1.5 for flare energies and thus rules out significant nanoflare
heating. While the FDSOC model predicts the probability distribution functions
of spatiotemporal scaling laws of nonlinear energy dissipation processes,
additional physical models are needed to derive the scaling laws between the
geometric SOC parameters and the observed emissivity in different
wavelength regimes, as we derive here for soft Xray emission. The FDSOC model
yields also statistical probabilities for solar flare forecasting.
Authors: Markus J. Aschwanden and Samuel L. Freeland
Projects: GOES Xrays

Publication Status: (2012) ApJ 754, 112
Last Modified: 20120717 08:26


