Documentation.
Name:
alpha_exp_cwt.pro
Purpose:
Calculate Calculate the power spectral index (alpha) by linear fit of the power spectral density (PSD) as a function of wavelength value, k. PSD is obtained by means of the Continuos Wavelet Transform using a "Mexican hat" wavelet of scale a (=1/k).
Calling sequence:
ALPHA_EXP_CWT, img, ind, binnscales, range, linfit_params
Input parameters:
img = Br, Blos, or Btot HARP cutout magnetogram corrected for limb presence.
ind = structure containing magnetogram's metada (resolution).
binnscales = Number of binslinear valuesscales into k-spacebe forconsidered calculatingin the 1Dwavelet PSDtransform. fromThese thevalues 2Dcreate PSD (angle integration). Optimal value for computation time/goo fit is 900a non-uniformed grid of k values. Default value is 120.
range = definition of the Inertial range for linear fit in units of Mm^-1 . Default values are 0.05 to 0.5 (or 2 - 20 Mm in linear size)Optional input parameters:
None
Output parameters:
linfit_params - 3 elements 1D array containing the resulting parameters from the linear fit of PSD(k).
linfit_params[0] = slope of the linear fit (alpha exponent)
linfit_params[1] = 1-sigma error associated to the slope
linfit_params[2] = goodness-of-fit parameter value.
Property name in DB:
alpha_exp_fftcwt_blos, alpha_exp_fftcwt_br, alpha_exp_fftcwt_btot
alpha_exp_fftcwt_blos.alpha, alpha_exp_fftcwt_blos.sigma, alpha_exp_fftcwt_blos.fit_r
Repository:
https://dev.flarecast.eu/stash/projects/FE/repos/alpha_exp_cwt-idl/browse
References
- http://dx.doi.org/10.1086/431732http://adsabs.harvard.edu/abs/2015SoPh2008SoPh..290248..335G311H