An extensive survey of dayside diffuse aurora based on optical observations at Yellow River Station
Abstract
By using 7 years optical auroral observations obtained at Yellow River Station (magnetic latitude N) at Ny-Alesund, Svalbard, we performed the first extensive survey for the dayside diffuse auroras (DDAs) and acquired observational results as follows. (1) The DDAs can be classified into two broad categories, i.e., unstructured and structured DDAs. The unstructured DDAs are mainly distributed in the morning and afternoon, but the structured DDAs predominantly occurred around the magnetic local noon (MLN). (2) The unstructured DDAs observed in morning and afternoon present obviously different properties. The afternoon ones are much stable and seldom show pulsating property. (3) The DDAs are more easily observed under geomagnetically quiet times. (4) The structured DDAsmainly show patchy, stripy, and irregular forms and are often pulsating and drifting. The drifting directions are mostly westward (with speed 5km/s), but there are cases showing eastward or poleward drifting. (5) The stripy DDAs are exclusively observed near theMLN and,most importantly, their alignments are confirmed to be consistent with the direction of ionospheric convection near the MLN. (6) A new auroral form, called throat aurora, is found to be developed from the stripy DDAs. Based on the observational results and previous studies, we proposed our explanations to the DDAs. We suggest that the unstructured DDAs observed in the morning are extensions of the nightside diffuse aurora to the dayside, but that observed in the afternoon are predominantly caused by proton precipitations.
Keywords
Cite
@article{arxiv.1606.02653,
title = {An extensive survey of dayside diffuse aurora based on optical observations at Yellow River Station},
author = {De-Sheng Han and Xiang-Cai Chen and Jian-Jun Liu and Qi Qiu and K. Keika and Ze-Jun Hu and Jun-Ming Liu and Hong-Qiao Hu and Hui-Gen Yang},
journal= {arXiv preprint arXiv:1606.02653},
year = {2016}
}