文档介绍：Dynamics of Atmospheres and Oceans, 18 (1993) 209-234 209
Elsevier Science Publishers ., Amsterdam
Variability in a homogeneous global ocean forced
by barometric pressure
Rui M. Ponte
Atmospheric and Environmental Research, Inc., 840 Memorial Drive, Cambridge, MA 02139, USA
(Received 8 April 1992; revised 22 October 1992; accepted 30 December 1992)
ABSTRACT
The nature of the oceanic response to pressure loading is explored using a constant-density,
shallow-water numerical model driven by atmospheric pressure fields from the European Centre for
Medium Range Weather Forecasts. The model has realistic bottom topography and coastlines and is
run for 1 year (1986) on a global domain. Meridional gradients in mean sea-level are generally large
(10-20 cm over 20-30*), particularly in high southern latitudes. Sea-level variability is strong in mid-
and high latitudes (typical standard deviations of 10-15 cm), but weakens towards the equator. Results
indicate a significant contribution of pressure-driven fluctuations to the observed large-scale sea-level
variability in mid- and high latitudes, away from western boundary regions. Pressure-induced velocity
signals are, in contrast, generally small compared with other types of variability.
The validity of the inverted barometer approximation is found to be strongly dependent on
frequency and geographical location. Globally, the approximation is not reliable for periods shorter
than approximately 2 days, but failure at longer periods occurs over extensive regions (. the tropical
Atlantic and Pacific, and the Southern Ocean). Nonisostatic contributions to the sea-level variability are
substantial in many areas, including the tropics, the high-latitude North Atlantic, the Gulf of Mexico,
and several other boundary regions.