INFLUENCE OF MIDOCEAN RIDGES ON ROSSBY WAVES

Influence of mid-ocean ridges on Rossby wave activity is discussed in simple models. Ridges can influence Rossby waves in two ways, topograp hic scattering and mid-ocean local generation. It is found that both p rocesses are rather sensitive to model parameters such as frequency, r idge height, and ridge width in both barotropic and baroclinic models. In the barotropic model, for certain model parameters there is perfec t transmission of Rossby waves, while for some other model parameters the transmission is rather weak. In a two-layer model, if the frequenc y is not low enough, trapping of baroclinic signals around topography will occur. The mid-ocean ridge is generally not as efficient as the e astern boundary in generating barotropic waves except at high frequenc ies in a barotropic model. It is much more efficient than the eastern boundary in generating baroclinic waves when wind forcing has a very l arge zonal scale, while less efficient when wind forcing has a short z onal scale.