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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 33, issue 5 | Copyright
Ann. Geophys., 33, 525-530, 2015
https://doi.org/10.5194/angeo-33-525-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

ANGEO Communicates 06 May 2015

ANGEO Communicates | 06 May 2015

Direct observations of blob deformation during a substorm

T. Ishida2,1, Y. Ogawa2,1, A. Kadokura2,1, K. Hosokawa3, and Y. Otsuka4 T. Ishida et al.
  • 1National Institute of Polar Research, Tokyo 190-8518, Japan
  • 2Department of Polar Science, SOKENDAI (The Graduate University for Advanced Studies),Tokyo 190-8518, Japan
  • 3Department of Communication Engineering and Informatics, University of Electro-Communications,Tokyo 182-8585, Japan
  • 4Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-8601, Japan

Abstract. Ionospheric blobs are localized plasma density enhancements, which are mainly produced by the transportation process of plasma. To understand the deformation process of a blob, observations of plasma parameters with good spatial–temporal resolution are desirable. Thus, we conducted the European Incoherent Scatter radar observations with high-speed meridional scans (60–80 s) during October and December 2013, and observed the temporal evolution of a blob during a substorm on 4 December 2013. This paper is the first report of direct observations of blob deformation during a substorm. The blob deformation arose from an enhanced plasma flow shear during the substorm expansion phase, and then the blob split into two smaller-scale blobs, whose scale sizes were more than ~100 km in latitude. Our analysis indicates that the Kelvin–Helmholtz instability and dissociative recombination could have deformed the blob structure.

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We studied the localized plasma density enhancements called blobs, which are often produced in the high-latitude ionosphere by the transportation process of plasma or particle precipitations. This subject is important because such structures affect radio wave propagation and can cause scintillation of GNSS signals in the deformation process. This paper is the first report of direct observations of blob deformation during a substorm.
We studied the localized plasma density enhancements called blobs, which are often produced in...
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