[en] Several transpolar auroras have been observed with the IMAGE-Far Ultraviolet (FUV) imagers. The unique capability of the IMAGE-FUV experiment to image the proton and electron aurora simultaneously on a global scale is used to study this phenomenon. A set of 12 transpolar aurora observed with IMAGE-FUV is studied. We find that the dynamics of the transpolar aurora in relation with the IMF is consistent with previously published studies. The proton energy flux in the transpolar structure is determined and compared with the electron contribution. The contribution of the proton aurora inside the transpolar arc is also considered at the global scale. On the average, transpolar structure contributes similar to10% of the total precipitation. We find that the proton precipitation carries similar to5% of the energy flux of the transpolar arc. In 11 of the 12 cases of transpolar events studied, a local brightening of the auroral Lyman-alpha emission is detected concurrently with the appearance of the transpolar structure. The intensification takes place at the nightside base of the transpolar arc, in the auroral oval. The duration of the intensification is variable but shorter than the lifetime of the transpolar arc. This study also suggests that the localized intensification is mainly due to an increase of the proton precipitation.
Disciplines :
Earth sciences & physical geography
Author, co-author :
Hubert, Benoît ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
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