  The stochastics two-layer quasi-geostrophic flow model is an intermediate
system between the single-layer two dimensional barotropic flow model and the
continuously stratified three dimensional baroclinic flow model. This model is
widely used to investigate basic mechanisms in geophysical flows, such as
baroclinic effects, the Gulf Stream and subtropical gyres.
  A large deviation principle for the two-layer quasi-geostrophic flow model
under uncertainty is proved. The proof is based on the Laplace principle and a
variational approach. This approach does not require the exponential tightness
estimates which are needed in other methods for establishing large deviation
principles.
