ON THE THREE-DIMENSIONAL MOTIONS IN AN OUTBREAK OF POLAR AIR

E. Palmén University of Chicago

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C. W. Newton University of Chicago

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Abstract

An attempt is made to study, by means of a detailed synoptic analysis, the three-dimensional air-motion in a typical outbreak of a polar air-mass. The mean vertical velocities at different levels over the entire cold-air region south of latitude 45°N are computed by use of the principle of continuity of mass. The maximum mean subsidence is found to be nearly 2 km per day at about the 600-mb level. In addition, the distribution of vertical velocity in different parts of the cold tongue is computed by means of trajectories on isentropic surfaces, and some examples of characteristic three-dimensional air trajectories are given. The results show that a typical outbreak of cold air can be regarded as an effective cell for meridional exchange of mass, heat and angular momentum.

Abstract

An attempt is made to study, by means of a detailed synoptic analysis, the three-dimensional air-motion in a typical outbreak of a polar air-mass. The mean vertical velocities at different levels over the entire cold-air region south of latitude 45°N are computed by use of the principle of continuity of mass. The maximum mean subsidence is found to be nearly 2 km per day at about the 600-mb level. In addition, the distribution of vertical velocity in different parts of the cold tongue is computed by means of trajectories on isentropic surfaces, and some examples of characteristic three-dimensional air trajectories are given. The results show that a typical outbreak of cold air can be regarded as an effective cell for meridional exchange of mass, heat and angular momentum.

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