High resolution auroral absorption measurement with scanning-beam riometer at L=6.1

• Main Authors: Hisao Yamagishi, Takashi Kikuchi, Syuichi Ikeda, Takeo Yoshino
• Format: Report
• Language: English
• Published: National Institute of Polar Research/Hiraiso Solar-Terrestrial Research Center, Communications Research Laboratory/University of Electro-Communications/University of Electro-Communications 1989
• Subjects: Syowa Station; Antarc*; Antarctica
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=4069; http://id.nii.ac.jp/1291/00004069/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=4069&item_no=1&attribute_id=18&file_no=1

A multi-narrow-beam riometer system is in operation at Syowa Station, Antarctica since February 1985,to observe the cosmic radio noise absorption (CNA) with a spatial resolution of 10km at 90km altitude. This system, together with optical auroral observation at Syowa Station, enabled us to study the spatial relationship between visible aurora and auroral radio wave absorption with much better temporal and spatial resolution than previous studies.The relationship was studied for different types of auroras, i.e., (1) Poleward expanding arc in the evening hours, (2) Equatorward drifting arc embedded in homogeneous background aurora at midnight hours, and (3) Pulsating aurora in the post break-up phase. For case (1), a region of strong absorption was found to propagate poleward with a poleward expanding arc. However, the absorption area extended to the lower latitude side of a poleward-moving arc due to a longer remaining of the absorption even after the disappearance of visible aurora. For case (2), little absorption accompanied with discrete auroras. However, a better coincidence was found between absorption and homogeneous background aurora. For case (3), temporal variation of the both phenomena showed one-to-one correspondence, although the luminosity of auroras was much weaker than in the other cases.