Barotropic motions and the exchange of angular momentum between the oceans and solid earth

Author: Rui M. Ponte
Date: 
April 1, 1990
Type: 
Journal Article
Venue: 
Journal of Geophysical Research
Citation: 

Ponte, R.M., 1990. Barotropic motions and the exchange of angular momentum between the oceans and solid earth. Journal of Geophysical Research, 95, 11369-11374.

The role of the ocean in transferring angular momentum between the atmosphere and the solid Earth is examined for periods longer than a day. Changes in the total angular momentum of the ocean can occur through the action of external torques such as surface wind stresses and continental torques (i.e., body forces acting on lateral boundaries), which represent momentum exchange with the atmosphere and the solid earth respectively. Analysis of these external torques suggests that in general, the related angular momentum exchanges are mostly associated with barotropic variability in the ocean. Solutions for a mid‐latitude basin, obtained with a shallow water numerical model forced by simple periodic zonal winds, illustrate how the momentum exchanged with the atmosphere is quickly transmitted to the solid Earth through the continental torque, with the bottom friction torque being negligible. For wind forcing confined to the middle of the ocean basin, both free waves and forced variability with large horizontal decay scales can participate in the interaction with the boundaries. The fast time scales involved in oceanic barotropic adjustment permit a rapid equilibration between the forcing regions and the coastal boundaries. The angular momentum transfer mechanism between the ocean and the solid Earth is consistent with the observed coherence at no discernible time lag between atmospheric and solid Earth angular momentum variations.

 

The research of this article was presented at the Chapman Conference on Geodetic VLBI: Monitoring Global Change, Washington, DC in April 1991.

Ponte, R.M., 1991. Angular momentum in the ocean and mechanisms of exchange with the atmosphere and solid Earth. Chapman Conference on Geodetic VLBI: Monitoring Global Change, Washington DC, April 1991.