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Angular momentum exchange among the solid Earth, atmosphere, and oceans: A case study of the 1982-1983 El Nino eventThe 1982-1983 El Nino/Southern Oscillation (ENSO) event was accompanied by the largest interannual variation in the Earth's rotation rate on record. In this study we demonstrate that atmospheric forcing was the dominant cause for this rotational anomaly, with atmospheric angular momentum (AAM) integrated from 1000 to 1 mbar (troposphere plus stratosphere) accounting for up to 92% of the interannual variance in the length of day (LOD). Winds between 100 and 1 mbar contributed nearly 20% of the variance explained, indicating that the stratosphere can play a significant role in the Earth's angular momentum budget on interannual time scales. Examination of LOD, AAM, and Southern Oscillation Index (SOI) data for a 15-year span surrounding the 1982-1983 event suggests that the strong rotational response resulted from constructive interference between the low-frequency (approximately 4-6 year) and quasi-biennial (approximately 2-3 year) components of the ENSO phenomenon, as well as the stratospheric Quasi-Biennial Oscillation (QBO). Sources of the remaining LOD discrepancy (approximately 55 and 64 microseconds rms residual for the European Centre for Medium-Range Forecasting (EC) and U.S. National Meteorological Center (NMC) analyses) are explored; noise and systematic errors in the AAM data are estimated to contribute 18 and 33 microseconds, respectively, leaving a residual (rms) of 40 (52) microseconds unaccounted for by the EC (NMC) analysis. Oceanic angular momentum contributions (both moment of inertia changes associated with baroclinic waves and motion terms) are shown to be candidates in closing the interannual axial angular momentum budget.
Document ID
19950048339
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Dickey, J. O.
(Jet Propulsion Laboratory, Pasadena, CA United States)
Marcus, S. L.
(Jet Propulsion Laboratory, Pasadena, CA United States)
Hide, R.
(Jet Propulsion Laboratory, Pasadena, CA United States)
Eubanks, T. M.
(U.S. Naval Observatory, Washington, DC United States)
Boggs, D. H.
(Jet Propulsion Laboratory, Pasadena, CA United States)
Date Acquired
August 16, 2013
Publication Date
December 10, 1994
Publication Information
Publication: Journal of Geophysical Research
Volume: 99
Issue: B12
ISSN: 0148-0227
Subject Category
Geosciences (General)
Accession Number
95A79938
Distribution Limits
Public
Copyright
Other

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