Annual baroclinic Rossby waves in the central North Pacific.

Abstract

XBT data, collected in the central North Pacific under the NORPAX program (TRANSPAC) is analyzed , by means of inverse methods (cross-spectral fit). The data are separated into two parts: a fluctuation with length scales in the order of the dimensions of the North Pacific basin and a wavelike fluctation with much shorter scales of a few hundred kilometers. At the annual frequency the wavelike fluctuation is found to consist of a random field of first-order baroclinic Rossby waves travelling basically northwest with wave-lengths of 300 km and phase speeds of 1 cm sSUB- SUB1 . The group velocity is directed mainly southwest and is of the order of 1 cm sSUB-SUB1. The fields of temperature, pressure, velocity, sea level elevation, and horizontal and vertical particle displacement associated with the annual baroclinic Rossby waves are described. (A)