Spatial distribution of rolled up Kelvin-Helmholtz vortices at Earth's dayside and flank magnetopause

• Main Authors: M. G. G. T. Taylor, H. Hasegawa, B. Lavraud, T. Phan, C. P. Escoubet, M. W. Dunlop, Y. V. Bogdanova, A. L. Borg, M. Volwerk, J. Berchem, O. D. Constantinescu, J. P. Eastwood, A. Masson, H. Laakso, J. Soucek, A. N. Fazakerley, H. U. Frey, E. V. Panov, C. Shen, J. K. Shi, D. G. Sibeck, Z. Y. Pu, J. Wang, J. A. Wild
• Format: Article
• Language: English
• Published: Copernicus Publications 2012-06-01
• Series: Annales Geophysicae
• Online Access: https://www.ann-geophys.net/30/1025/2012/angeo-30-1025-2012.pdf
• ISSN: 0992-7689; 1432-0576

The Kelvin-Helmholtz Instability (KHI) can drive waves at the magnetopause. These waves can grow to form rolled-up vortices and facilitate transfer of plasma into the magnetosphere. To investigate the persistence and frequency of such waves at the magnetopause we have carried out a survey of all Double Star 1 magnetopause crossings, using a combination of ion and magnetic field measurements. Using criteria originally used in a Geotail study made by Hasegawa et al. (2006) (forthwith referred to as H2006), 17 candidate events were identified from the entire TC-1 mission (covering ~623 orbits where the magnetopause was sampled), a majority of which were on the dayside of the terminator. The relationship between density and shear velocity was then investigated, to identify the predicted signature of a rolled up vortex from H2006 and all 17 events exhibited some level of rolled up behavior. The location of the events had a clear dawn-dusk asymmetry, with 12 (71%) on the post noon, dusk flank suggesting preferential growth in this region.