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Detection of an ENSO signal in seasonal length‐of‐day variations
Author(s) -
Gross Richard S.,
Marcus Steven L.,
Eubanks T. Marshall,
Dickey Jean O.,
Keppenne Christian L.
Publication year - 1996
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/96gl03260
Subject(s) - amplitude , seasonality , el niño southern oscillation , climatology , oscillation (cell signaling) , southern oscillation , day length , atmospheric sciences , magnitude (astronomy) , environmental science , momentum (technical analysis) , physics , geology , astrophysics , biology , ecology , photoperiodism , genetics , finance , quantum mechanics , horticulture , economics
Conservation of angular momentum dictates that as the wind‐driven axial atmospheric angular momentum changes, so will the length‐of‐day (LOD). In particular, as the strength of the seasonal zonal winds change, so should the strength of the seasonal LOD signals. Here, observed changes in the strengths of the annual and semiannual LOD signals during 1963–1991 are analyzed and shown to be both significantly correlated (at the 99% significance level) with the Southern Oscillation Index (SOI), and to exhibit trends of comparable magnitude but opposite signs. This reported correlation between the SOI and changes in the amplitude of the seasonal LOD signals demonstrates a linkage between seasonal LOD (and hence seasonal zonal wind) variability and the El Niño/Southern Oscillation (ENSO) phenomenon. Furthermore, this study suggests that observed variations in the amplitudes of the seasonal LOD signals can be used to study changes in the strengths of the seasonal atmospheric zonal winds on interannual to decadal and longer time scales.