On the variability of the semidiurnal solar and lunar tides of the equatorial electrojet (EEJ)

Share this story:
Friday, November 9, 2018

The variabilities of the semidiurnal solar and lunar tides 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, ground-magnetometer recordings at the equatorial observatories in Huancayo and Fuquene are utilized.

Plot showing EEJ obtained from Huancayo and Fuquene observatories
(a) The day-to-day variations of the EEJ obtained from Huancayo and Fuquene observatories between December 1, 2008 and March 1, 2009 are presented in this plot. The white and black dots at the bottom represent the days of full moon and new moon, respectively. (b) The amplitude of the semidiurnal solar (red) and lunar (blue) tides of the EEJ during the same period. (c) Daily time series of the zonal mean zonal wind (U) at 60 deg N and 10 hPa (red) and the North Pole temperature at 10 hPa (black) during the same period. (d) The phase of the semidiurnal tide of the EEJ. (e) Daily solar flux values during this time interval. (f) The phase of the semidiurnal lunar tide of the EEJ.

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 deg N and 10 hPa and a second enhancement a few days after the peak reversal of the zonal mean zonal wind during all 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 the variability of the migrating semidiurnal solar (SW2) and lunar (M2) tides in neutral temperature and zonal wind obtained from numerical simulations at E-region heights. A better agreement between the enhancements of the EEJ semidiurnal lunar tide and the M2 tide is found in comparison with the enhancements of the EEJ semidiurnal solar tide and the SW2 tide in both the neutral temperature and zonal wind at the E-region altitudes.

Publication Name: Annales Geophysicae

First HAO Author's Name: Tarique Adnan Siddiqui

 

Organizations:

Topics: