TY - JOUR
T1 - Investigation on the Variability of the Geomagnetic Daily Current During Sudden Stratospheric Warmings
AU - Owolabi, Charles
AU - Lei, Jiuhou
AU - Bolaji, O. S.
AU - Jimoh, Oluwaseyi
AU - Ruan, Haibing
AU - Li, Na
AU - Niu, Xiaojuan
AU - Yoshikawa, Akimasa
N1 - Funding Information:
This work was supported by the National Natural Science Foundation of China (41831070 and 41325017), and the Open Research Project of Large Research Infrastructures of CAS??Study on the Interaction Between Low/Mid-Latitude Atmosphere and Ionosphere Based on the Chinese Meridian Project.? C. Owolabi is grateful to the Chinese Scholarship Council (CSC) for making the CSC scholarship possible for his doctoral studies. The authors are very grateful to the INTERMAGNET (http://www.intermagnet.org), WDC (http://www.wdc.bgs.ac.uk/data.html), MAGDAS/CPMN (http://data.icswse.kyushu-u.ac.jp), OHP (http://ohpdmc.eri.u-tokyo.ac.jp), and JMA ((https://www.jma.go.jp/jma/indexe.html) teams for providing records of geomagnetic data used in this study. We are very thankful to IAGA (http://www.geomag.bgs.ac.uk/cgi-bin/coordcalc) for providing a quasi-dipole geomagnetic coordinate calculator. We are very grateful to the NCEP/NCAR reanalysis team for providing access to the zonal mean zonal wind and stratospheric temperature data set used in this study. Thanks are due to the Atmospheric Chemistry and Dynamics Laboratory at National Aeronautics and Space Administration (NASA)/GSFC for providing the zonal wave numbers data in geopotential height used in this study. We thank the SPDF/GSFC for providing record of Kp index and daily F10.7 solar radio flux data used in the present study (https://omniweb.gsfc.nasa.gov/form/dx1.html).
Publisher Copyright:
©2019. American Geophysical Union. All Rights Reserved.
PY - 2019
Y1 - 2019
N2 - The magnetic field records of the magnetometer networks in the American, East Asian-Australian, and European-African sectors were employed in this present work. We used them to investigate equatorial electrojet (EEJ), counter electrojet (CEJ), tidal variability in EEJ strength and ionospheric current during the 2005/2006 and 2008/2009 sudden stratospheric warming (SSW) events. In addition to the well-investigated tidal variability in EEJ strength over the American and East Asian sectors, we investigated that of the African sector for the first time. Interestingly, the tidal components in EEJ strength during both SSW events clearly exhibit marked longitudinal differences with high, moderate, and low amplitudes in the American, East Asian, and African sectors, respectively. An exception found around day 71 in the African sector after the 2008/2009 SSW event had higher solar diurnal tidal component as compared to that of the Asian sector. Over the American sector, solar and lunar semidiurnal tides were strongly associated with CEJ current during both SSW events, whereas at the African and East Asian sectors such variabilities are not evident. A solar diurnal tidal component was strongly related to a reduction in the EEJ strength over the East Asian sector. In addition, a prolonged period of CEJ occurrence that begins during the SSW precondition and ends when the SSW was evolving characterized the African sector during both SSW events. There is a steady shift in phase at later hours when both SSW events are evolving.
AB - The magnetic field records of the magnetometer networks in the American, East Asian-Australian, and European-African sectors were employed in this present work. We used them to investigate equatorial electrojet (EEJ), counter electrojet (CEJ), tidal variability in EEJ strength and ionospheric current during the 2005/2006 and 2008/2009 sudden stratospheric warming (SSW) events. In addition to the well-investigated tidal variability in EEJ strength over the American and East Asian sectors, we investigated that of the African sector for the first time. Interestingly, the tidal components in EEJ strength during both SSW events clearly exhibit marked longitudinal differences with high, moderate, and low amplitudes in the American, East Asian, and African sectors, respectively. An exception found around day 71 in the African sector after the 2008/2009 SSW event had higher solar diurnal tidal component as compared to that of the Asian sector. Over the American sector, solar and lunar semidiurnal tides were strongly associated with CEJ current during both SSW events, whereas at the African and East Asian sectors such variabilities are not evident. A solar diurnal tidal component was strongly related to a reduction in the EEJ strength over the East Asian sector. In addition, a prolonged period of CEJ occurrence that begins during the SSW precondition and ends when the SSW was evolving characterized the African sector during both SSW events. There is a steady shift in phase at later hours when both SSW events are evolving.
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U2 - 10.1029/2019JA026667
DO - 10.1029/2019JA026667
M3 - Article
AN - SCOPUS:85069926674
VL - 124
SP - 6156
EP - 6172
JO - Journal of Geophysical Research: Space Physics
JF - Journal of Geophysical Research: Space Physics
SN - 2169-9380
IS - 7
ER -