Abstract

An unseasonal development of Equatorial Plasma Bubble (EPB)/Equatorial Spread-F (ESF) activity in a wide longitudinal sector over India and Southeast Asia during the post-sunset hours of 28 July 2014 has been investigated in detail using the multiple independent observations in this paper and a companion paper by (Prog Earth Planet Sci 5:10, 2018). This post-sunset ESF/EPB event was preceded by a substantial elevation of the equatorial F-layer due to strong pre-reversal enhancement (PRE) during the season which is climatologically unfavorable for strong PRE and post-sunset EPBs. In this paper, it is found that a strong equatorward meridional neutral wind at off-equatorial E-region and enhanced longitudinal gradient of equatorial electrojet appear to be the responsible candidates for the enhanced PRE and EPB development on 28 July 2014. These changes in the local wind system and PRE are found to have an apparent connection with the planetary wave forces of lower atmospheric origin. Both the post-sunset height rise (PSSR) and lower thermospheric meridional neutral wind consistently exhibit quasi-2-day planetary wave-like oscillations during 20–31 July 2014 with maximum amplitudes on 28 July 2014. This study emphasizes the role of planetary wave forces from the lower atmosphere that can alter the local neutral wind system and E-region conductivities that may lead to the development of strong PRE and EPB activity which were otherwise climatologically unfavorable for post-sunset EPB/ESF development.

Details

Title
Unseasonal development of post-sunset F-region irregularities over Southeast Asia on 28 July 2014: 2. Forcing from below?
Author
Ajith, K K 1 ; Ram, S Tulasi 1   VIAFID ORCID Logo  ; Carter, B A 2 ; S Sathish Kumar 3 ; Yamamoto, M 4 ; Yokoyama, T 5 ; Gurubaran, S 1 ; Sripathi, S 1 ; Hozumi, K 5 ; Groves, K 6 ; Caton, R G 7 

1  Indian Institute of Geomagnetism, Navi Mumbai, India 
2  RMIT University, Melbourne, Australia 
3  Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Tirunelveli, India 
4  Research Institute for Sustainable Humanosphere (RISH), Kyoto University, Uji, Japan 
5  National institute of Information and Communications Technology, Tokyo, Japan 
6  Boston College, Boston, USA 
7  Space Vehicles Directorate, Air Force Research Laboratory, Kirtland AFB, Albuquerque, NM, USA 
Pages
1-15
Publication year
2018
Publication date
Oct 2018
Publisher
Springer Nature B.V.
e-ISSN
21974284
Source type
Scholarly Journal
Language of publication
English
DOI
https://doi.org/10.1186/s40645-018-0218-1
ProQuest document ID
2115976483
Copyright
Progress in Earth and Planetary Science is a copyright of Springer, (2018). All Rights Reserved., © 2018. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.