Abstract
An observational analysis is made of the magnitudes of individual terms in the potential vorticity equation applied to the normal January and July maps for the Northern Hemisphere. From the measurements along 45N an estimate is made of the total “forcing function” for the asymmetric disturbances. Cross sections along 30, 45, and 6ON of the mean meridional velocity and mean temperature and hemispheric distributions of a measure of the normal static stability are also shown.