Numerical modelling of balanced atmospheric flow

AbstractAtmospheric flows of importance for weather forecasting are mostly characterized by a requirement of “balance” in which the three-dimensional wind field can be determined implicitly from the pressure and moisture distribution. A mathematical definition of balance is described based on a Hamiltonian formulation which requires that sufficiently large fluid parcels remain close to a minimum energy configuration. The resulting evolution equations are an approximate form of the equations of motion. Numerical solutions of the equations describing balanced flow are presented and compared with those where the balance approximation is not enforced. There are large differences in cases where the balanced equations have singular solutions. The implications for modelling real atmospheric flows are discussed