Numerical simulations of the life cycle of a baroclinic wave

Abstract

A new conceptual visualization of cyclone-frontal evolution is presented by Shapiro and Keyser (1990). The primary differences between this model and the classical Norwegian frontal cyclone model are the absence of an occlusion, the presence of a warm-core seclusion, and the “bent back” warm front or westward extension of the warm front. In the present study, a mesoscale numerical model is used to investigate the kinematics and structural features of the bent back warm front. Simulations are performed using a 2nd-order closure turbulence parameterization with a sophisticated surface layer similarity scheme. The adiabatic and inviscid case is also examined. Results show that the seclusion and bent back warm front are present in both the adiabatic and inviscid case and using the 2nd-order closure parameterization. An occlusion also forms in later stages in both cases, indicating that the absence of an occlusion in the original publication of the Shapiro and Keyser model is a shortcoming. The results also show that, while the adiabatic components of the flow are responsible for creating the important features of cyclogenesis and frontogenesis, diabatic physical processes exert a strong influence on the ultimate cyclone/frontal structure. Sensitivity studies are performed in order to further investigate this issue.