The EOF analysis is a useful technique In meteorology and oceanography for descriptive multivariate statistics. It is based on a representation of the large data sets in terms of a limited number of orthogonal basis functions while retaining as much as possible of the variation in the data.
In the EOF technique the data are first arranged into a matrix Z , where z is the rainfall amount collected at the time t (t=1,2,3,to n)and station x (x=1,2,3 to p)Before the analysis the anomaly data matrix is prepared as equation 1 where