Time series of baroclinic potential energy in the upper 500 meters of the North Pacific (20-50N, 145E-130W) prepared by White (1977a) are analyzed by spectral and cross-spectral methods in the period range from 2 to 10 years. Maximum energy occurs in the 7 to 10 year range over the entire data field. In the 20-30N zone we find first order baroclinic Rossby waves with wave lengths of about 1000 to 3000 km to be the dominating phenomenon in the 7 to 10 year range....