A Baroclinic Model of the Atmosphere Applicable to the Problem of Numerical Forecasting in Three Dimensions. II

A theory for the application to numerical forecasting of a 3-parameter model of the troposphere is developed and then tested on one synoptic case. The model itself has been described in an earlier paper. An essential feature of this model, beyond other models so far introduced, is that the static stability may vary arbitrarily in a horizontal direction and with time as well. This implies a thermal wind which may change direction with height, and it is shown that this non-parallelism of the isotherms in the vertical is important from the standpoint of thermodynamics. Furthermore, it is shown that the rotation of the thermal wind with height is closely connected with cyclogenesis and the deepening and filling of existing cyclones.

The case selected for numerical computation was the synoptic situation of November 24, 1951, at 03z over Western Europe and the easternmost part of the Atlantic. Tendencies for sea level pressure and for the two parameters defining the tropospheric temperature distribution with height were computed; they compared fairly well with observed changes.