Earth Planets Space, Vol. 55 (No. 12), pp. e25-e28, 2003E-LETTER
Yuichi Aoyama1, Isao Naito2, Tetsuya Iwabuchi3, and Nobuo Yamazaki3
1Radio Science Center for Space and Atmosphere, Kyoto University, Uji, Japan
2National Astronomical Observatory/Graduate University for Advanced Studies, Tokyo, Japan
3Meteorological Research Institute, Tsukuba, Japan
(Received November 18, 2003; Revised December 26, 2003; Accepted December 26, 2003)
A quasi-14 month fluctuation in the atmospheric excitation function for the Earth's wobble is discussed by using the re-analysis data of the European Center for Medium-range Weather Forecast for the 14 years between 1980 and 1993. The spectrum of the atmospheric wind excitation function shows a striking peak near the 14-month period. As a result, the atmospheric (wind plus pressure) excitation function shows exactly the same power as that of the geodetic excitation function inferred from the observed wobble at the Chandler wobble frequency (about 14 months), suggesting that the atmosphere excited the Chandler wobble between 1980 and 1993. The wind fluctuation comes mostly from the tropospheric wind.
Key words: ECMWF wind, quasi-14-month fluctuation, atmospheric excitation, Chandler wobble.