Open AccessOn the equatorward motion and fading of proton aurora during substorm growth phase
Author(s) -
Liu W. W.,
Donovan E. F.,
Liang Jun,
Voronkov Igor,
Spanswick Emma,
Jayachandran P. T.,
Jackel Brian,
Meurant Mathieu
Publication year - 2007
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2007ja012495
Subject(s) - substorm , brightness , magnetosphere , proton , fading , fade , physics , polar , plasma sheet , photometer , geophysics , magnetic field , atmospheric sciences , astronomy , telecommunications , decoding methods , quantum mechanics , computer science , acoustics
Using 50 high‐quality events from the Canadian Auroral Network for the OPEN Program Unified Study (CANOPUS) Gillam Meridian Scanning Photometer over 10 a (1989–1998), we show that proton aurora in the substorm growth phase exhibits a systematic tendency to fade. The average pattern of fading consists of a period of relatively stable proton aurora brightness and then a period of 15–20 min before onset during which the brightness decreases by an average of 15%. We interpret the observed proton aurora brightness variation in terms of the magnetic field stretching in the near‐Earth magnetosphere; in particular, the fading is interpreted as a result of the central plasma sheet magnetic field lines having stretched to such a degree that the loss cone closing effect dominates precipitation due to nonadiabatic proton motions.