ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-31-2077-2013 Zonal velocity of the equatorial plasma bubbles over Kolhapur, India Nade D. P. 1 Sharma A. K. 1 Nikte S. S. 1 Patil P. T. 2 Ghodpage R. N. https://orcid.org/0000-0003-3052-2873 2 Rokade M. V. 5 Gurubaran S. 3 Taori A. https://orcid.org/0000-0002-0460-0471 4 Sahai Y. 6 Earth and Space Science Laboratory, Department of Physics, Shivaji University, Kolhapur, India Medium Frequency Radar, Indian Institute of Geomagnetism, Shivaji University Campus, Kolhapur, India Indian Institute of Geomagnetism, New Panvel, Navi Mumbai, India National Atmospheric Research Laboratory, Gadanki, India Centre for Materials for Electronics Technology (C-MET) Hyderabad, 500051, India Universidade do Vale do Paraiba (UNIVAP), São José dos Campos, São Paulo, Brazil 22 11 2013 31 11 2077 2084 Copyright: © 2013 D. P. Nade et al. 2013 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://angeo.copernicus.org/articles/31/2077/2013/angeo-31-2077-2013.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/31/2077/2013/angeo-31-2077-2013.pdf

This paper presents the observations of zonal drift velocities of equatorial ionospheric plasma bubbles and their comparison with model values. These velocities are determined by nightglow OI 630.0 nm images. The nightglow observations have been carried out from the low latitude station Kolhapur (16.8° N, 74.2° E; 10.6° N dip lat.) during clear moonless nights. Herein we have presented the drift velocities of equatorial plasma bubbles for the period of February–April 2011. Out of 80 nights, 39 showed the occurrence of equatorial plasma bubbles (49%). These 39 nights correspond to magnetically quiet days (ΣKp < 26). The average eastward zonal velocities (112 ± 10 m s<sup>−1</sup>) of equatorial plasma bubbles increased from evening sector to 21:00 IST (Indian Standard Time = Universal Time + 05:30:00 h), reach maximum about 165 ± 30 m s<sup>−1</sup> and then decreases with time. The calculated velocities are in good agreement with that of recently reported values obtained with models with occasional differences; possible mechanisms of which are discussed.

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