2011 SuperDARN Workshop
Medium-scale traveling ionospheric disturbances simultaneously observed with the SuperDARN Hokkaido radar and FORMOSAT/ISUAL
T. Ogawa (1), T. Adachi (2), and N. Nishitani (3)
(1) National Institute of Information and Communications Technology, Koganei, Tokyo, Japan
(2) Department of Electrical Engineering, Stanford University, Stanford, California, USA
(3) Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan
abstract. Medium-scale traveling ionospheric disturbances (MSTID) have been observed with various instruments like radar, airglow imager, GPS satellite, etc. SuperDARN HF radars having a wide field-of-view (FOV) in the horizontal plane have also contributed to MSTID observations at high- and mid-latitudes, though these radars cannot clarify vertical MSTID structures. MSTID observations with a SuperDARN radar combined with an optical instrument capable of imaging MSTID in the vertical plane are required to know three-dimensional MSTID structures.
We present some results from simultaneous observations of nighttime MSTID with the Hokkaido SuperDARN HF radar and a limb imager, called ISUAL (Imager for Sprites and Upper Atmospheric Lightning), on the FORMOSAT-2 satellite. The radar observed MSTID propagating southwestward in the horizontal plane, and ISUAL did two-dimensional OI 630-nm airglow structures in the vertical plane along the N-S satellite track. The observations were made during the night on 20 and 21 December 2006 and 29 December 2008. On 20 and 21 December, the radar FOV was separated by a few hundred kilometers or more from the ISUAL observation area, while on 29 December, the ISUAL observation area was inside the radar FOV. Analyses of data from both instruments and simultaneous total electron content data from a dense GPS network in Japan suggest that spatial MSTID structures observed with the HF radar are well identified as airglow intensity enhancements at altitudes of 200-300 km observed with ISUAL.