An ocean model for de-aliasing high-frequency barotropic sea level variations

Author: N. Hirose, I. Fukumori, V. Zlotnicki and Rui M. Ponte
May 10, 2000
AGU Spring Meeting, Washington, DC

Hirose, N., I. Fukumori, V. Zlotnicki, and R.M. Ponte, 2000. An ocean model for de-aliasing high-frequency barotropic sea level variations. AGU Spring Meeting, Washington, DC, May 2000.

Recent studies reveal the significance of high frequency (T < 20days) sea level fluctuations associated with a barotropic response of the ocean to wind and atmospheric pressure variations. These sea level variations pose an aliasing problem for altimetry
(e.g., TOPEWPOSEIDON, Jason-1) and gravity missions (e.g., GRACE). This study aims to establish an operational model to estimate the wind- and pressure-driven high frequency signals and to remove them from satellite measurements, similar to the
treatment of tidal aliasing. A shallow-water, barotropic model, forced by wind and pressure estimates from NCEP, is tuned with respect to TOPEWPOSEIDON data and ocean bottom pressure observations by way of adjustments to model friction and bottom
topography. Globally averaged, the wind- and pressure-driven models explain dynamic signals of 2.7 and 0.2 cm2 in the sea level and 2.0 and 0.5 mba? in the bottom pressure variations, respectively. The nature of the ocean's response is investigated by
analyses of the model and data. In particular, a global non-inverted barometer response is revealed due to a 5-day Rossby-Haunvitz wave in atmospheric pressure.