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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Geomagnetic lunar and solar daily variations during the last 100 years
AU - Yamazaki , Yosuke
AU - Kosch, Michael
N1 - ©2014. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
PY - 2014/8
Y1 - 2014/8
N2 - This paper describes long-term changes in the geomagnetic lunar (L) and solar (S) daily variations. We analyze the eastward component of the geomagnetic field observed at eight midlatitude stations during 1903–2012. The amplitude and phase for the semidiurnal component of the L and S variations are examined. Both L and S amplitudes correlate with the solar activity index F10.7, revealing a prominent 11 year solar cycle. In both cases, the correlation is slightly better with inline image than F10.7. The sensitivity of the L variation to solar activity is comparable with that of the S variation. The solar cycle effect is also found in the phase of the S variation but not apparent in the phase of the L variation. The ratio in the amplitude of the L to S variation shows a long-term decrease (approximately 10% per century), which may be due to a reduction in lunar tidal waves from the lower atmosphere to the upper atmosphere in association with climate change.
AB - This paper describes long-term changes in the geomagnetic lunar (L) and solar (S) daily variations. We analyze the eastward component of the geomagnetic field observed at eight midlatitude stations during 1903–2012. The amplitude and phase for the semidiurnal component of the L and S variations are examined. Both L and S amplitudes correlate with the solar activity index F10.7, revealing a prominent 11 year solar cycle. In both cases, the correlation is slightly better with inline image than F10.7. The sensitivity of the L variation to solar activity is comparable with that of the S variation. The solar cycle effect is also found in the phase of the S variation but not apparent in the phase of the L variation. The ratio in the amplitude of the L to S variation shows a long-term decrease (approximately 10% per century), which may be due to a reduction in lunar tidal waves from the lower atmosphere to the upper atmosphere in association with climate change.
KW - geomagnetic daily variations
KW - ionospheric currents
KW - solar activity
KW - upper atmosphere
KW - long-term variations
KW - climate change
U2 - 10.1002/2014JA020203
DO - 10.1002/2014JA020203
M3 - Journal article
VL - 119
SP - 6732
EP - 6744
JO - Journal of Geophysical Research
JF - Journal of Geophysical Research
SN - 0148-0227
IS - 8
ER -