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Equatorial waves in the lower stratosphere. I: A novel detection method
Author(s) -
Tindall J. C.,
Thuburn J.,
Highwood E. J.
Publication year - 2006
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1256/qj.04.152
Subject(s) - rossby wave , stratosphere , wavenumber , equator , kelvin wave , zonal and meridional , equatorial waves , gravity wave , latitude , longitude , rossby radius of deformation , geology , atmospheric sciences , quasi biennial oscillation , forcing (mathematics) , geophysics , climatology , physics , geodesy , gravitational wave , optics , astrophysics
Wavenumber–frequency spectral analysis and linear wave theory are combined in a novel method to quantitatively estimate equatorial wave activity in the tropical lower stratosphere. The method requires temperature and velocity observations that are regularly spaced in latitude, longitude and time; it is therefore applied to the ECMWF 15‐year re‐analysis dataset (ERA‐15). Signals consistent with idealized Kelvin and Rossby‐gravity waves are found at wavenumbers and frequencies in agreement with previous studies. When averaged over 1981–93, the Kelvin wave explains approximately 1 K 2 of temperature variance on the equator at 100 hPa, while the Rossby‐gravity wave explains approximately 1 m 2 s −2 of meridional wind variance. Some inertio‐gravity wave and equatorial Rossby wave signals are also found; however the resolution of ERA‐15 is not sufficient for the method to provide an accurate climatology of waves with high meridional structure. Copyright © 2006 Royal Meteorological Society