The crossover to the”1/ f ” region of solar wind fluctuations.

The crossover to the”1/ f ” region of solar wind fluctuations. https://scientific-publications.ukaea.uk/wp-content/themes/blade/images/empty/thumbnail.jpg 150 150 UKAEA Opendata UKAEA Opendata https://secure.gravatar.com/avatar/679db0b751d3e5fa797cd4b46afe6f58?s=96&d=mm&r=g 1st January 2010 5th September 2018

The crossover to the”1/ f ” region of solar wind fluctuations.

R.M.Nicol S.C.Chapman R.O.Dendy

Published

Wepresentgeneralizedstructurefunction(GSF)analysisof magneticandvelocityfieldfluctuationsmeasured insituinthesolarwindat ~ 1 AUwiththeACEspacecraft.Wedecomposethefluctuationsintodirectionsparalleland perpendiculartothemeanlocalbackgroundmagneticfield.GSFplotsbasedonthesequantitiesareshowntoprovideaclear indicatorofthespectralbreakbetweentheinertialrangeand"1 / f " rangeofscaling.InGSFplots,theprojectedvelocityand magneticfieldfluctuationstrackeachothercloselyintheinertialrangeinbothfastandslowsolarwindandatsolarmaximum andminimum.Atlongertimescalesthe“1 / f ” rangeiseasilyidentified,becausethemagneticfieldfluctuationsdisplaya flatteningoftheGSFs(exponentsbecomezero)consistentwitha ~ 1 / f PSD.Thevelocityfluctuationsontheotherhand haveGSFswhichsteepen,consistentwithaPSDof ~ 1 / f a where a asdeterminedbyGSFvarieswithsolarwindspeedand solarcyclebutisclosertotwo.Theextentoftheinertialrangedeterminedinthismannerdiffersbetweenfastandslowsolar windstreams,andbetweenperiodsofmaximumandminimumsolaractivity.