Premium
A thermal oscillation under a restorative forcing
Author(s) -
Cai Wenju,
Chu Peter C.
Publication year - 1998
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 - 10.1002/qj.49712454707
Subject(s) - advection , rossby wave , oscillation (cell signaling) , ocean general circulation model , climatology , forcing (mathematics) , geology , convection , thermal , meteorology , physics , general circulation model , oceanography , thermodynamics , climate change , biology , genetics
The authors report an interdecadal oscillation in a wind‐ and thermally‐driven ocean general circulation model (OGCM). The oscillation is tantalizing in that it occurs under a relatively strong thermal damping (26.3 W m −2 K −1 ). Examinations involving a two‐dimensional OGCM, a simple thermal ‘flip–flop’ model, and a three‐dimensional OGCM with and without the nonlinear effect of temperature in the state equation of sea water demonstrate that the oscillation is not driven by mechanisms such as the so‐called convective oscillator, or the advective overshooting oscillator. Instead, the oscillation is associated with the propagation of modelled long Rossby‐waves with westward phase velocity. It is found that the north–south basin extent of the OGCM is an important factor; a larger north–south basin extent is conducive to the generation of thermal wind flows crucial for initiating the propagation of disturbances. The geophysical relevance of these results is discussed.