On the Occurrence of Afternoon Counter Electrojet Over Indian Longitudes During June Solstice in Solar Minimum. Issue 3 (12th March 2018)

• Record Type: Journal Article
• Authors: Pandey, Kuldeep; Sekar, R.; Anandarao, B. G.; Gupta, S. P.; Chakrabarty, D.
• Is Part Of: Journal of geophysical research. Volume 123:Issue 3(2018)
• Page Start: 2204
• Page End: 2214
• Publication Date: 2018-03-12
• Subjects: equatorial ionosphere -- electrojet model -- counter electrojet -- Sq electric field; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2017JA024725
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: Studies made earlier using ground‐based observations of geomagnetic field over the Indian longitudes revealed that the occurrence of equatorial counter electrojet (CEJ) events in afternoon hours is more frequent during June solstice (May‐June‐July‐August) in solar minimum than in other periods. In general, the June solstice solar minimum CEJ events occur between 1500 local time (LT) and 1800 LT with peak strength of about −10 nT at around 1600 LT. In order to understand the frequent occurrence of these CEJ events, an investigation is carried out using an equatorial electrojet model (Anandarao, 1976, https://doi.org/10.1029/GL003i009p00545 ) and the empirical vertical drift model by Fejer et al. (2008, https://doi.org/10.1029/2007JA012801 ). The strength, duration, peak value, and the occurrence time of CEJ obtained using electrojet model match remarkably well with the corresponding observation of average geomagnetic field variations. The occurrence of CEJ is found to be due to solar quiet (Sq) electric field in the westward direction which is manifested as downward drift in Fejer et al. (2008, https://doi.org/10.1029/2007JA012801 ) model output during 1500–1800 LT. Further, the occurrence of afternoon reversal of Sq electric field in this season is shown to be consistent with earlier studies from Indian sector. Therefore, this investigation provides explicit evidence for the role of westward Sq electric field on the generation of afternoon CEJ during June solstice in solar minimum periods over the Indian sector indicating the global nature of these CEJ events. Key Points: Westward Sq electric field causes afternoon CEJ over India during June solstice in solar minimum The consequences of Fejer et al. (2008) empirical model drifts are brought out CEJ characteristics obtained from the electrojet model match well with observations