An Attempt of Representing the Features of Height Field in Polar Area by Using Experimental Orthogonal Function

By using monthly mean values of geopotential height field in 12 months in the polar region and the empirical orthogonal function we obtained a set of eigenvectors having a clear synoptic significance, every eigenvector represents a typical distribution of height field. We define the projections of monthly mean height fields for individual years on these eigenvectors as polar vortex coefficients. The polar vortex coefficients represent the degree of resemblance of real height fields to the corresponding tropical fields. It is found that the polar vortex coefficients have a close relation to the weather of out country.