TY - JOUR
T1 - Excitation Mechanism of Ionospheric 6-Day Oscillation During the 2019 September Sudden Stratospheric Warming Event
AU - Miyoshi, Yasunobu
AU - Yamazaki, Yosuke
N1 - Funding Information:
The numerical simulation was mainly performed using the computer systems at Research Institute for Information Technology of Kyushu University and at National Institute of Information and Communications Technology, Japan. This project was supported by JSPS and DFG under the Joint Research Projects-LEAD with DFG (JRPs-LEAD with DFG). This work was also supported in part by ESA through contract 4000126709/19/NL/IS “VERA”. The GFD/DENNOU library was used to produce the figures. The JRA-55 meteorological reanalysis data sets are provided by the Japan Meteorological Agency (JMA).
Funding Information:
The numerical simulation was mainly performed using the computer systems at Research Institute for Information Technology of Kyushu University and at National Institute of Information and Communications Technology, Japan. This project was supported by JSPS and DFG under the Joint Research Projects‐LEAD with DFG (JRPs‐LEAD with DFG). This work was also supported in part by ESA through contract 4000126709/19/NL/IS “VERA”. The GFD/DENNOU library was used to produce the figures. The JRA‐55 meteorological reanalysis data sets are provided by the Japan Meteorological Agency (JMA).
Publisher Copyright:
©2020. The Authors.
PY - 2020/9/1
Y1 - 2020/9/1
N2 - A sudden stratospheric warming (SSW) event in the Antarctic region occurred in September 2019. During the SSW event, the quasi 6-day wave (Q6DW) was enhanced in the mesosphere, and strong 6-day oscillations are observed in ionospheric parameters, such as the equatorial electrojet (EEJ) and electron density. The 6-day variation in the EEJ has a westward moving structure with the zonal wave number 1, indicating the influence of the Q6DW. In this study, we investigate the excitation mechanism of the 6-day variations in the EEJ and electron density using numerical simulations. The main results are as follows. The 6-day variations in the ionosphere are not generated by the Q6DW but generated by the waves with periods from 10 to 14 hr. The amplitude of the 10–14 hr waves is modulated with a period of 6 days, due to the nonlinear interaction between the Q6DW and migrating semidiurnal tide. This leads to the 6-day variations in the EEJ and electron density through the E region dynamo process. At a fixed local time, the secondary waves generated by the Q6DW-tidal interaction produce westward moving ionospheric 6-day variations with zonal wave number 1, which cannot be distinguished from the ionospheric variations by the Q6DW itself. The interference of secondary waves leads to a longitudinal asymmetry in the magnitude of the ionospheric 6-day oscillation.
AB - A sudden stratospheric warming (SSW) event in the Antarctic region occurred in September 2019. During the SSW event, the quasi 6-day wave (Q6DW) was enhanced in the mesosphere, and strong 6-day oscillations are observed in ionospheric parameters, such as the equatorial electrojet (EEJ) and electron density. The 6-day variation in the EEJ has a westward moving structure with the zonal wave number 1, indicating the influence of the Q6DW. In this study, we investigate the excitation mechanism of the 6-day variations in the EEJ and electron density using numerical simulations. The main results are as follows. The 6-day variations in the ionosphere are not generated by the Q6DW but generated by the waves with periods from 10 to 14 hr. The amplitude of the 10–14 hr waves is modulated with a period of 6 days, due to the nonlinear interaction between the Q6DW and migrating semidiurnal tide. This leads to the 6-day variations in the EEJ and electron density through the E region dynamo process. At a fixed local time, the secondary waves generated by the Q6DW-tidal interaction produce westward moving ionospheric 6-day variations with zonal wave number 1, which cannot be distinguished from the ionospheric variations by the Q6DW itself. The interference of secondary waves leads to a longitudinal asymmetry in the magnitude of the ionospheric 6-day oscillation.
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U2 - 10.1029/2020JA028283
DO - 10.1029/2020JA028283
M3 - Article
AN - SCOPUS:85092566175
SN - 2169-9380
VL - 125
JO - Journal of Geophysical Research: Space Physics
JF - Journal of Geophysical Research: Space Physics
IS - 9
M1 - e2020JA028283
ER -