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  • Kiranmayi, L., and G.S.Bhat, 2008: Quasi-periodic, global oscillations in sea level pressure. Climate Dynamics, 31, DOI 10.1007/s00382-008-0413-7.

The sea level pressure (SLP) variability in
3060 day intraseasonal timescales is investigated using
25 years of reanalysis data addressing two issues. The first
concerns the non-zero zonal mean component of SLP near
the equator and its meridional connections, and the second
concerns the fast eastward propagation (EP) speed of SLP
compared to that of zonal wind. It is shown that the entire
globe resonates with high amplitude wave activity during
some periods which may last for few to several months,
followed by lull periods of varying duration. SLP variations
in the tropical belt are highly coherent from 25S to
25N, uncorrelated with variations in mid latitudes and
again significantly correlated but with opposite phase
around 60S and 65N. Near the equator (8S8N), the
zonal mean contributes significantly to the total variance in
SLP, and after its removal, SLP shows a dominant zonal
wavenumber one structure having a periodicity of 40 days
and EP speeds comparable to that of zonal winds in the
Indian Ocean. SLP from many of the atmospheric and
coupled general circulation models show similar behaviour
in the meridional direction although their propagation
characteristics in the tropical belt differ widely.

Last Updated: 2008-08-21

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