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Atmospheric Effects on Earth Rotation and Polar Motion

Published online by Cambridge University Press:  03 August 2017

David A. Salstein
David A. Salstein*
Affiliation:
Atmospheric and Environmental Research, Inc., 840 Memorial Drive, Cambridge, MA 02139 USA

Abstract

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The variability in the earth's rotation rate not due to known solid body tides is dominated on time scales of about four years and less by variations in global atmospheric angular momentum (M), as derived from the zonal wind distribution. Among features seen in the length of day (Δl.o.d.) record produced by atmospheric forcing are the strong seasonal cycle, quasi-periodic fluctuations around 40–50 days, and an interannual signal forced by a strong Pacific warming event, known as the El Niño. Momentum variations associated with these time scales arise in different latitudinal regions. Furthermore, winds in the stratosphere make a particularly important contribution to seasonal variability.

Other related topics discussed here are (i) comparisons of the M series from wind fields produced at different weather centers, (ii) the torques that dynamically link the atmosphere and earth, and (iii) longer-term non-atmospheric effects that can be seen upon removal of the atmospheric signal. An interesting application for climatological purposes is the use of historical earth rotation series as a proxy for atmospheric wind variability prior to the era of upper-air data. Lastly, results pertaining to the role of atmospheric pressure systems in exciting rapid polar motion are presented.

Type
Geophysics
Information
Symposium - International Astronomical Union , Volume 129: The Impact of VLBI on Astrophysics and Geophysics , 1988 , pp. 401 - 410
Copyright
Copyright © Reidel 1988 

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