Dynamics of Absolute Vorticity in the Boussinesq Fluid

The dynamics of absolute vorticity in the Boussinesq fluid is examined. It is shown that the Boussinesq approximation only captures one of the horizontal components of the solenoidal term. Based on scaling ana-lysis of typical midlatitude synoptic systems, the horizontal component of the solenoidal term neglected by the Boussinesq approximation is at least of the same order of magnitude as the one captured by the Boussinesq approximation. This leads to severe underestimation of absolute vorticity and circulation.