TY - JOUR
T1 - Quasi-biennial oscillation of the ionospheric wind dynamo
AU - Yamazaki, Yosuke
AU - Liu, Huixin
AU - Sun, Yang Yi
AU - Miyoshi, Yasunobu
AU - Kosch, Michael J.
AU - Mlynczak, Martin G.
N1 - Funding Information:
Geomagnetic data for Memambetsu, Kakioka, and Kanoya were provided by the Japan Meteorological Agency and available at the website of the Kakioka Magnetic Observatory at http://www.kakioka-jma.go.jp/en/. The other geomagnetic data were provided by the Geospatial Information Authority of Japan and available at http://www.gsi.go.jp/buturisokuchi/geomag_index.html (Japanese). We thank both the institutions for their commitment to the long-term operation. The disturbance storm time index Dst was provided by the World Data Center for geomagnetism, Kyoto (http://wdc.kugi.kyoto-u.ac.jp/dstdir/). The list of geomagnetically quietest days of each month and the geomagnetic activity index Ap were provided by the GFZ German Research Centre for Geosciences, available at http://www.gfz-potsdam.de/kp-index. The SABER temperature data were downloaded from http://saber.gats-inc.com/index.php. We thank the SABER science team and Gats Inc. for processing and distributing the SABER data. GAIA simulation was performed using the computer systems at National Institute of Information and Communications Technology, Japan. The meteorological reanalysis data used in the GAIA simulation were provided from the cooperative research project of the JRA-25 long-term reanalysis by the Japan Meteorological Agency and the Central Research Institute of Electric Power Industry. The GAIA model data presented in this paper will be made available upon request. The radiosonde data for the monthly mean zonal wind at Singapore were downloaded from the website of Freie Universität Berlin (FUB) at http://www.geo.fu-berlin.de/en/met/ag/strat/produkte/qbo/. The ENSO activity index NINO.3 was provided by the Japan Meteorological Agency, available at http://www.data.jma.go.jp/gmd/cpd/db/elnino/index/dattab.html (Japanese). The SOHO/SEM EUV data were obtained from the website of Space Science Center, University of Southern California at http://www.usc.edu/dept/space_science/sem_data/sem_data.html. Y.Y. and M.J.K. were supported by Natural Environment Research Council grant NE/K01207X/1. H.L. aknowledges support by JSPS KAKENHI grants 15K05301 and 15H02135. Y.-Y.S. was supported by the NICT International Exchange Program. Y.M. acknowledges support by JSPS KAKENHI grant (B)15H03733.
Publisher Copyright:
©2017. The Authors.
PY - 2017/3/1
Y1 - 2017/3/1
N2 - The interannual variation of the ionospheric solar quiet (Sq) current system is examined. A dense magnetometer network over Japan enables the accurate determination of the central position of the northern Sq current loop or the Sq current focus, during 1999–2015. It is found that the Sq focus latitude undergoes an interannual variation of ±2° with a period of approximately 28 months, similar to the quasi-biennial oscillation (QBO) in the tropical lower stratosphere. The QBO-like variation of Sq is particularly evident during 2005–2013. No corresponding interannual variability is found in solar extreme ultraviolet radiation. Comparisons with tidal winds, derived from a whole-atmosphere model, reveal that the QBO-like variation of the Sq current focus is highly correlated with the amplitude variations of migrating and nonmigrating diurnal tides in the lower thermosphere. The results suggest that the stratospheric QBO can influence the ionospheric wind dynamo through the QBO modulation of tides.
AB - The interannual variation of the ionospheric solar quiet (Sq) current system is examined. A dense magnetometer network over Japan enables the accurate determination of the central position of the northern Sq current loop or the Sq current focus, during 1999–2015. It is found that the Sq focus latitude undergoes an interannual variation of ±2° with a period of approximately 28 months, similar to the quasi-biennial oscillation (QBO) in the tropical lower stratosphere. The QBO-like variation of Sq is particularly evident during 2005–2013. No corresponding interannual variability is found in solar extreme ultraviolet radiation. Comparisons with tidal winds, derived from a whole-atmosphere model, reveal that the QBO-like variation of the Sq current focus is highly correlated with the amplitude variations of migrating and nonmigrating diurnal tides in the lower thermosphere. The results suggest that the stratospheric QBO can influence the ionospheric wind dynamo through the QBO modulation of tides.
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U2 - 10.1002/2016JA023684
DO - 10.1002/2016JA023684
M3 - Article
AN - SCOPUS:85014681886
SN - 2169-9380
VL - 122
SP - 3553
EP - 3569
JO - Journal of Geophysical Research: Space Physics
JF - Journal of Geophysical Research: Space Physics
IS - 3
ER -