On the variability of the semidiurnal solar and lunar tides of the
equatorial electrojetduring sudden stratospheric warmings
Abstract
The variabilities of the semidiurnal solar and lunar tide of the
equatorial electrojet (EEJ) are investigated during the 2003, 2006, 2009
and 2013 major sudden stratospheric warming (SSW) events in this study.
For this purpose, the ground-magnetometer recordings at the equatorial
observatories in Huancayo and Fuquene are utilized. Results show a major
enhancement in the amplitude of the EEJ semidiurnal lunar tide in each
of the four warming events. The EEJ semidiurnal solar tidal amplitude
shows an amplification prior to the onset of warmings, a reduction
during the deceleration of the zonal mean zonal wind at 60°N and 10hPa
and a second enhancement a few days after the peak reversal of the zonal
mean zonal wind during all the four SSWs. Results also reveal that the
amplitude of the EEJ semidiurnal lunar tide becomes comparable or even
greater than the amplitude of the EEJ semidiurnal solar tide during all
these warming events. The present study also compares the EEJ
semidiurnal solar and lunar tidal changes with numerical simulations of
the variability of the migrating semidiurnal solar (SW2) and lunar (M2)
tide in neutral temperature at ~120km altitude. A better
agreement between the enhancements of the EEJ semidiurnal lunar tide and
the M2 tide in neutral temperature is observed in comparison with the
enhancements of the EEJ semidiurnal solar tide and the SW2 tide in
neutral temperature.