Linear momentum approximation and frontogenesis caused by baroclinic ekman momentum flow

A method of linear momentum approximation is proposed that deals with weak nonlinear problems in an ap-proximate manner. A motion of nonlinear nature is obtained in the system by assuming the motion to be in the form of linear momentum flow in the corresponding space introduced, followed by the transformation from the specified into a physical space. Significant results have been thereby derived in examining the effects of baroclinic Ekman mo-mentum flow upon Eady-type baroclinic waves and frontogenesis. Also, this technique can be applied to investigate the dynamic characteristics of the weak nonlinear boundary layer including topography, stratification and non-Ekmantype friction for gaining further insight into the influence on the boundary layer inner parameters of ter-rain, baroclinicity and inhomogeneous process so that the classic theory is revised.