Derivation of aurora scaling parameters from ground-based imaging observations: Numerical tests

摘要

In the study of scaling properties of auroral luminosity variations by ground-basedimaging observations, a problem arises that the actual scaling characteristics are distortedbecause of contributions to images from extension of auroral structures along thegeomagnetic field. The field-aligned trends come into play for whatever small deviationsfrom the magnetic zenith, making questionable the appropriateness of ground imagingdata for investigation of turbulence signatures in aurora. In order to clear up how to correctfor this effect, we have modeled the distortions, stemming from aspect angle broadening,for synthesized self-similar fluctuations with known scaling characteristics in the planeperpendicular to the magnetic field. Both narrow and wide field-aligned profiles ofluminosity were considered. Three estimators for deriving scaling parameters wereapplied, including the wavelet estimator, dyadic filter estimator, and standard deviationstatistical estimator, of which the wavelet estimator is shown to be most robust. Theformulas are presented that relate the observed scaling characteristics with the true ones forthe case of aurora being observed near magnetic zenith.