Numerical Simulation of the Development of the Intermediate-Scale Cyclone in a Moist Model Atmosphere

Abstract

Abstract The genesis and development of an intermediate-scale cyclone in middle latitudes was simulated numerically and its three-dimensional structure analysed. A six-level moist primitive equation model was run for a channel flow with an initial weak baroclinicity. The motion was initiated in the flow by introducing wave motion with wavelength of 6000 km. As the initial disturbance was intensified, an extended front developed and, after several days in real time, an intermediate-scale disturbance was formed on the extended front. The analysis indicates that this secondary cyclone has a longitudinal wavelength of about 1500 km and a latitudinal half-wavelength of about 600 km. The depression is observed most strongly below 700 mb with a vertical or slightly eastward tilted trough axis. A sharp concentration of isotherms is situated in the northern part of the cyclone. In the lower troposphere, the warm air is observed on the cast side of the low center and the cold air on the west side. This thermal cont...