EFFECTS OF CONVECTION INSTABILITY DUE TO INCOMPATIBILITY BETWEEN OCEAN DYNAMICS AND SURFACE FORCINGS

The study demonstrates that an incompatibility between a surface tempe rature climatology and a given ocean model, into which the climatology is assimilated via Haney restoration, can cause model ocean climate d rift and interdecadal oscillations when the ocean is switched to a wea ker restoration. This is made using an idealized Atlantic Ocean model driven by thermal and wind forcing only. Initially, the temperature cl imatology is forcefully assimilated into the model, and an implied hea t flux held is diagnosed. During this stage any incompatibility is sup pressed. The restoring boundary condition is then switched to a new fo rcing consisting of a part of the diagnosed flux and a part of the res toring forcing in such a way that at the moment of the switching the h eat flux is identical to that prior to the switching. Under this new f orcing condition, the incompatibility becomes manifest, causing change s in convection patterns, and producing drift and interdecadal oscilla tions. The mechanisms are described.