Equatorial counter electrojets and polar stratospheric sudden warmings – a classical example of high latitude-low latitude coupling?

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.

Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

“…In particular, Stening (1977d) and Stening et al (1996) found that winter-time counter electrojet events tend to occur during stratospheric sudden warmings. Vineeth et al (2009) confirmed this correlation, and also pointed out that the counter electrojet during stratospheric sudden warmings is prone to a quasi 16-day modulation. demonstrated that there is an enhancement in the amplitude of the semidiurnal tide in the mesosphere during counter electrojet events associated with stratospheric sudden warmings.…”

Occurrence of blanketing E<sub>s</sub> layer (E<sub>sb</sub>) over the equatorial region during the peculiar minimum of solar cycle 24

“…However, frequent presence of strong CEEJ is observed mainly during January and February of 2009, which coincides with a period of strong sudden stratospheric warming (SSW) (Upadhayaya and Mahajan, 2013). The occurrence of CEEJ during SSWs was reported in earlier studies (Stening et al, 1996;Rastogi, 1999;Vineeth et al, 2009;Yamazaki et al, 2012 SSWs were observed from 16 January to 16 February 2009, which are reported to be the strongest and most long-lived of the past 50 years (Manney et al, 2009). This SSW period is shown by vertical dotted lines in Fig.…”

Lunar tidal effects in the electrodynamics of the low latitude ionosphere

“…The low-latitude ionospheric response to sudden stratospheric warmings (SSWs) has been an area of extreme interest in recent years [e.g., Vineeth et al, 2009;Chau et al, 2009Chau et al, , 2010Sridharan et al, 2009;Goncharenko et al, 2010a, b;Fejer et al, 2010Fejer et al, , 2011Yue et al, 2010;Rodrigues et al, 2011;Liu et al, 2011;Park et al, 2012;Yamazaki et al, 2012a, b]. These events are characterized by large-scale metereological changes in the winter polar atmosphere, driven by the rapid growth of upward propagating quasi-stationary planetary (Rossby) waves, rapid growth of waves from the polar troposphere, and their interaction with the mean circulation, that last for several days or even a few weeks [e.g., Matsuno, 1971;Andrews et al, 1987;Liu and Roble, 2002;Holton, 2004].…”