Open AccessSpatially growing Rossby lee waves: Implications for a coupled ocean‐atmosphere global circulation model
Author(s) -
Hughes Roger L.,
O'Farrell Siobhan P.
Publication year - 1999
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/1998jc900129
Subject(s) - rossby wave , potential vorticity , zonal and meridional , geology , ocean general circulation model , ocean current , climatology , amplitude , atmosphere (unit) , atmospheric sciences , atmospheric circulation , vorticity , general circulation model , physics , oceanography , vortex , mechanics , meteorology , climate change , quantum mechanics
Large‐amplitude Rossby lee waves are observed in the Southern Ocean of an ocean general circulation model. These waves result in a reduced ability of an associated coupled ocean‐atmosphere general circulation model to model the observed sea ice distribution around Antarctica. To understand this behavior, Rossby lee waves within a meridionally sheared eastward directed ocean current are investigated theoretically. It is found that shearing the current results in a significant asymmetry in the lee wave field, the amplitude of which increases linearly downstream. In the regions where the meridional gradient of the shear exceeds β but is of opposite sign, there are no Rossby lee waves. Waves are trapped to the region where β dominates. Investigation of the ocean general circulation model shows that the meridional shear does not exceed β. However, the meridional gradient of Ertel's potential vorticity, a more appropriate quantity in a continuously stratified ocean general circulation model, is negative as required.