Quasi-Periodic Auroras in the Post-Noon Sector and their Relationship to the High Time Resolution Mode HF Radar

Quasi-Periodic Auroras in the Post-Noon Sector and their Relationship to the High Time Resolution Mode HF Radar

Y. MURATA.¹⁾, N. SATO²⁾, H. YAMAGISHI²⁾, A. S. YUKIMATU²⁾, M. KIKUCHI²⁾, K. MAKITA³⁾T. OGAWA⁴⁾, H. YANG⁵⁾ R. LIU⁵⁾ A. D. M. WALKER⁶⁾ and M. LESTER⁷⁾
¹ Graduate University for Advanced Studies, Japan
²National Institute of Polar Research, Japan
³Takushoku University, Japan
⁴Nagoya University, Japan
⁵Polar Research Institute of China, China.
⁶University of Natal, South Africa.
⁷University of Leicester, UK.

Zhongshan Station in Antarctica is located at 74.49°S in invariant geomagnetic latitude and MLT=UT+1.3hr. All-sky TV camera and meridian-scanning photometer at Zhongshan gives us an opportunity to observe quasi-periodic optical aurora in the vicinity of the cusp/cleft region on the post-noon sector. The field of view of the Syowa East HF radar covers over Zhongshan, so that it is possible to investigate the spatial and temporal signatures of quasi-periodic optical aurora and HF radar aurora. We report here a case study of simultaneous observations of quasi-periodic optical aurora, HF radar backscatter power, Doppler velocity and ground based magnetogram, acquired on August 3, 1997. The Syowa East radar has been operating on a high time resolution mode and all-sky camera and photometers were running at Zhongshan under clear sky. Quasi-periodic optical aurora with period of ~1-min and ~10- min has been identified during ~1200-1400 UT. Fine structure of the aurora showed an east-west aligned band/arc type discrete aurora, and the luminosity position moved poleward quasi-periodically. The HF radar backscatter powers and magnetic variations showed one to one correlations with the 10-min quasi-periodic variations of optical aurora. The magnetic pulsations observed at Zhongshan and Syowa in Antarctica and IMAGE magnetometer array in the northern hemisphere revealed typical field line resonance characteristics; the latitudinal dependence of amplitude and polarization parameters.

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