A two-dimensional numerical simulation of the dry line environment and its role in the development of mesoscale convective systems

The mesoscale boundary layer model was constructed using a stretched horizontal grid system and a terrain-following vertical coordinate. Different forcing conditions were diagnosed. Vertical turbulent mixing was shown to be responsible for the daytime eastward motion of the dryline. Horizontal advection and horizontal mixing accounted for the nocturnal return of the surface dry line. Kinematic and thermodynamic fields in the simulated dry line environment were also examined. The divergence field and vertical motion were distributed such that there existed a favorable condition for the release of potential instability and hence the possible onset of moist convection in close proximity to the dry line. Limitations of this numerical model are discussed and several suggestions for future research of dry line affected mesoscale convective systems are also given.