Statistical characteristics of Doppler spectral width as observed by the conjugate SuperDARN radars

• Published in: Annales Geophysicae
• Main Authors: Hosokawa, K., Woodfield, E. E., Lester, M., Milan, S. E., Sato, N., Yukimatu, A. S., Iyemori, T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: European Geosciences Union (EGU), Copernicus Publications, Springer Verlag (Germany) 2017
• Subjects: Science & Technology; Physical Sciences; Astronomy & Astrophysics; Geosciences; Multidisciplinary; Meteorology & Atmospheric Sciences; Geology; ionosphere; ionosphere-magnetosphere interactions; plasma convection; magnetospheric physics; magnetopause; cusp; and boundary layers; BOUNDARY-LAYER CAMPAIGN; COHERENT HF RADAR; AURORAL ACTIVITY; F-REGION; IDENTIFICATION; IRREGULARITIES; BACKSCATTER; FIELD; DMSP; Iceland
• Online Access: http://www.ann-geophys.net/20/1213/2002/; http://hdl.handle.net/2381/39284; https://doi.org/10.5194/angeo-20-1213-2002

We performed a statistical analysis of the occurrence distribution of Doppler spectral width around the day-side high-latitude ionosphere using data from the conjugate radar pair composed of the CUTLASS Iceland-East radar in the Northern Hemisphere and the SENSU Syowa-East radar in the Southern Hemisphere. Three types of spectral width distribution were identified: (1) an exponential-like distribution in the lower magnetic latitudes (below 72°), (2) a Gaussian-like distribution around a few degrees magnetic latitude, centered on 78°, and (3) another type of distribution in the higher magnetic latitudes (above 80°). The first two are considered to represent the geophysical regimes such as the LLBL and the cusp, respectively, because they are similar to the spectral width distributions within the LLBL and the cusp, as classified by Baker et al. (1995). The distribution found above 80° magnetic latitude has been clarified for the first time in this study. This distribution has similarities to the exponential-like distribution in the lower latitude part, although clear differences also exist in their characteristics. These three spectral width distributions are commonly identified in conjugate hemispheres. The latitudinal transition from one distribution to another exhibits basically the same trend between two hemispheres. There is, however, an interhemispheric difference in the form of the distribution around the cusp latitudes, such that spectral width values obtained from Syowa-East are larger than those from Iceland-East. On the basis of the spectral width characteristics, the average locations of the cusp and the open/closed field line boundary are estimated statistically. The Iceland East-Finland radar pair (the Cooperative UK Twin Located Auroral Sounding System : CUTLASS) is funded by the Particle Physics and Astronomy Research Council (PPARC), U.K., under grant PPA/R/R/1997/00256, the Finnish Meteorological Institute, Helsinki, and the Swedish Institute for Space Research, Uppsala. The Ministry of Education, Culture, Sports, Science and Technology supports the Syowa HF radar systems. The 39th, 40th and 41th JAREs have carried out the HF radar operation at Syowa. This research is supported by the Grantin Aid for Scientific Research (A:11304029) from Japan Society for the Promotion of Science (JSPS). This study is funded by a part of ‘Ground Research for Space Utilization’ promoted by NASDA and Japan Space Forum. EEW is indebted to PPARC for a research studentship. Peer-reviewed Publisher Version