Abstract
Abstract. Favored occurrences of Equatorial Counter Electrojets (CEJs) with a quasi 16-day periodicity over Trivandrum (8.5° N, 76.5° E, 0.5° N diplat.) in association with the polar Stratospheric Sudden Warming (SSW) events are presented. It is observed that, the stratospheric temperature at ~30 km over Trivandrum shows a sudden cooling prior to the SSWs and the CEJs of maximum intensity which occurs around this time. In general stronger CEJs are associated with more intense SSW events. The stratospheric zonal mean zonal wind over Trivandrum also exhibits a distinctly different pattern during the SSW period. These circulation changes are proposed to be conducive for the upward propagation of the lower atmospheric waves over the equatorial latitudes. The interaction of such waves with the tidal components at the upper mesosphere and its subsequent modification are suggested to be responsible for the occurrence of CEJs having planetary wave periods.
Highlights
The equatorial electrojet (EEJ) is an intense band of eastward current system that flows, during daylight hours, along the dip equator at an altitude centered at around 105 km
The reversal of the EEJ during the afternoon hours on geomagnetically quiet days called as the “Counter Electrojets (CEJs)” has remained as a challenge warranting an exclusive explanation since it was identified by Gouin and Mayaud (1967)
Another mechanism that has been proposed involves additional currents at 110 km over and above the normal eastward Sq current, which is confined at the geomagnetic equator at 105 km. This additional current could flow either eastward or westward. When it is westward and sufficiently intense it would manifest as CEJ (Rastogi et al, 1992)
Summary
The equatorial electrojet (EEJ) is an intense band of eastward current system that flows, during daylight hours, along the dip equator at an altitude centered at around 105 km. The local effect within the EEJ region such as gravity wave associated vertical winds (Raghavarao and Anandarao, 1980; Aanadarao and Raghavarao, 1987) and the changes in the tidal components (Somayajulu et al, 1993) are some of the earlier suggestions for CEJs. On the other hand, contributions of the global wind and current systems to the occurrence of CEJs have been brought out (Stening et al, 1996; Gurubaran et al, 2002). The occurrence of CEJs of quasi 16-day periodicity has been shown during the winter months of the SSW year 2006 (Vineeth et al, 2007a). This paper aims at reporting some preliminary results pertaining to the above
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
