GEOGRAPHICAL VARIABILITY OF THE FIRST BAROCLINIC ROSSBY RADIUS OF DEFORMATION

Global 1 degrees x 1 degrees climatologies of the first baroclinic gra vity-wave phase speed c(1) and the Rossby radius of deformation lambda (1) are computed from climatological average temperature and salinity profiles. These new atlases are compared with previously published 5 d egrees x 5 degrees coarse resolution maps of lambda(1) for the Norther n Hemisphere and the South Atlantic and with a 1 degrees x 1 degrees f ine-resolution map of c(1) for the tropical Pacific. It is concluded t hat the methods used in these earlier estimates yield values that are biased systematically low by 5%-15% owing to seemingly minor computati onal errors. Geographical variations in the new high-resolution maps o f c(1) and lambda(1) are discussed in terms of a WKB approximation tha t elucidates the effects of earth rotation, stratification, and water depth on these quantities. It is shown that the effects of temporal va riations of the stratification can be neglected in the estimation of c (1) and lambda(1) at any particular location in the World Ocean. This is rationalized from consideration of the WKB approximation.