Premium
Width and structure of mesoscale optical auroral arcs
Author(s) -
Knudsen D. J.,
Donovan E. F.,
Cogger L. L.,
Jackel B.,
Shaw W. D.
Publication year - 2001
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2000gl011969
Subject(s) - zenith , mesoscale meteorology , arc (geometry) , amplitude , physics , standard deviation , cutoff , gaussian , sky , optics , geology , astrophysics , geometry , meteorology , mathematics , statistics , quantum mechanics
Arc widths were calculated for 3126 stable auroral arcs observed by an all‐sky camera located in Gillam, Manitoba. The camera is filtered to accept 5577‐Å emissions and has a single‐pixel spatial resolution of 1.7 km at zenith. The measured mean width of stable mesoscale arcs located within ±5° of magnetic zenith is 18 km with a standard deviation of 9 km. The width distribution exhibits a steep cutoff below 8 km; when combined with studies of small‐scale auroral structure this cutoff suggests a gap in the occurrence of arcs with widths of order 1 km. This feature of the arc width spectrum argues against the notion of a turbulent cascade of energy from larger to small scales. Residuals from the Gaussian fits are only about 3% of the arc amplitude on average, indicating little sub‐structure within arcs at scales down to the measurement resolution.