On the Observed Spatial Scale of Northern Hemisphere Transient Motions

Abstract

Blackmon (1976) used spherical harmonics to determine the root-mean-square (rms) 500 mb geo-potential height in various two-dimensional wavenumber regimes. This paper extends his analysis to 1000 mb and presents for both levels the ratio of rms Z in different wavenumber regimes. This ratio shows the relative spatial scale of atmospheric disturbances. Synoptic-scale disturbances dominate the midlatitude oceans, while planetary waves are most important in high and low latitudes. In summer planetary waves are more important at 1000 mb than at 500 mb.