Effects of Stratification on the Large-Scale Ocean Response to Barometric Pressure

Author: Rui M. Ponte and Sergey Vinogradov
May 22, 2006
Journal Article
Journal of Physical Oceanography

Ponte, R. M., and S. V. Vinogradov, 2007. Effects of stratification on the large-scale ocean response to barometric pressure. J. Phys. Oceanogr., Vol 37, Issue 2 (February 2007), pp. 245--258. doi:10.1175/JPO3010.1.

Single-layer (barotropic) models have been commonly used in studies of the inverted barometer effect
and the oceanic response to atmospheric pressure loading. The potential effects of stratification on this
response are explored here using a general circulation model in a near-global domain with realistic coasts
and bathymetry. Periodic forcing by the diurnal and semidiurnal atmospheric tides and 6-hourly stochastic
forcing from weather center analyses are both examined. A global dynamic response (i.e., departures from
inverted barometer behavior) is clear in the response to atmospheric tides; for stochastic forcing, the largest
dynamic signals occur in shallow and semienclosed regions and at mid- and high latitudes. The influence of
stratification in the dynamics is assessed by comparing surface and bottom pressure signals. Baroclinic
effects are generally weak, particularly in the response to the large-scale atmospheric tides. Under stochastic
forcing, largest differences between surface and bottom pressure signals reach 10%–20% of the surface
signals and tend to occur in regions of enhanced topographic gradients. Bottom-intensified, localized
interactions with topography seem to be involved. Enhanced baroclinicity is also seen at low latitudes,
where stratification effects are also felt in the upper ocean. General implications for modeling the ocean
response to high-frequency atmospheric and tidal forcing are discussed.