Lunar‐dependent equatorial ionospheric electrodynamic effects during sudden stratospheric warmings

Abstract

[1] We have used plasma drift and magnetic field measurements during the [2001][2002][2003][2004][2005][2006][2007][2008][2009] December solstices to study, for the first time, the longitudinal dependence of equatorial ionospheric electrodynamic perturbations during sudden stratospheric warmings. Jicamarca radar measurements during these events show large dayside downward drift (westward electric field) perturbations followed by large morning upward and afternoon downward drifts that systematically shift to later local times. Ground-based magnetometer measurements in the American, Indian, and Pacific equatorial regions show strongly enhanced electrojet currents in the morning sector and large reversed currents (i.e., counterelectrojets) in the afternoon sector with onsets near new and full moons during northern winter warming periods. CHAMP satellite and ground-based magnetic field observations indicate that the onset of these equatorial afternoon counterelectrojets is longitude dependent. Our results indicate that these large electrodynamic perturbations during stratospheric warming periods are due to strongly enhanced semidiurnal lunar wave effects. The results of our study can be used for forecasting the occurrence and evolution of these electrodynamic perturbations during arctic winter warmings.Citation: Fejer, B. G., M. E. Olson, J. L. Chau, C. Stolle, H. Lühr, L. P. Goncharenko, K. Yumoto, and T. Nagatsuma (2010), Lunar-dependent equatorial ionospheric electrodynamic effects during sudden stratospheric warmings,

Ionospheric response to the 2009 sudden stratospheric warming over the equatorial, low, and middle latitudes in the South American sector

“…However, the negative phase during geomagnetic storms (decrease in the ionospheric electron density as compared with quiet periods) is related with change in composition of the neutral gas which increases the N 2 /O ratio [de Jesus et al, 2013]. Therefore, a possible physical mechanism to explain the TEC depletion is the change in neutral composition that leads to an increase of the N 2 /O ratio during the SSW since SSW is a large-scale meteorological process and it disturbs background wind, temperature, chemistry, and wave activity of middle atmosphere and vertical thermodynamics coupling in a large range of altitude and latitudes [Fejer et al, 2010]. de Abreu et al [2014] …”

“…In addition, the semidiurnal lunar tides in TEC and wind increase during the SSW event [Xiong et al, 2013]. Fejer et al [2010Fejer et al [ , 2011 showed that lunar semidiurnal tidal wave changes are the most likely source of the unusual ionospheric perturbations.…”

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

“…Observational studies have found that the occurrence of CEJ is dependent on the phase of the moon, suggesting that lunar tides play a role (Bartels and Johnston 1940;Rastogi 1974;Sastri and Arora 1981). Other studies found that a large-amplitude CEJ event during winter is often observed during a stratospheric sudden warming event, suggesting a physical connection between the two phenomena (Stening et al 1996;Fejer et al 2010); see Sect. 4.3.3 for more discussion on the stratospheric sudden warming effect on Sq and EEJ.…”

“…Those big L days are often found at equatorial latitudes during Northern Hemisphere winter, and occasionally during the equinoxes (Bartels and Johnston 1940;Onwumechili 1964). Recent studies pointed out that the big L days during the Northern Hemisphere winter are often associated with the occurrence of stratospheric sudden warming events (Fejer et al 2010;Yamazaki 2014). The effect of stratospheric sudden warming on Sq and L will be detailed in Sect.…”

“…The strong L currents during the northern winter is probably contributed by the big L days in which the amplitude of L is several times larger than other normal days ( (Bartels and Johnston 1940);Onwumechili 1964). Recent studies have shown that the big L days are often associated with the occurrence of stratospheric sudden warmings (Fejer et al 2010;Yamazaki 2014). A stratospheric sudden warming is a large-scale disturbance in the middle and lower atmosphere, which usually occurs during the northern winter.…”