On a method for the representation of the normal state of the lower atmosphere in the extratropics, and its applications

Abstract

Theoretical reasons for considering the temporal, zonal and time-and-zone root mean square values of meteorological parameters as their normal values in the extratropics are given. Using geostrophic relative vorticity (ζ g ) data for the Northern Hemisphere Extratropics for four months typical of the four seasons it is shown that the time averages of the zonal root mean square values of ζ g — calledK — are useful in determining the normal locations and other properties of extratropical jet streams.