Low-frequency sea level variability estimated from a data-constrained general circulation model

Author: Sergey Vinogradov, Rui M. Ponte, P. Heimbach and C. Wunsch
Date: 
December 11, 2006 - December 15, 2006
Type: 
Presentation
Venue: 
American Geophysical Union, Fall Meeting 2006
Citation: 

Vinogradov, S. V., R. M. Ponte, P. Heimbach, C. Wunsch, 2006, Low-frequency sea level variability estimated from a data-constrained general circulation model. Amer. Geophys. Union Fall Meeting 2006, San Francisco, CA, December 11-15 2006.

The US ECCO-GODAE product combines numerous types of oceanographic observations, including both in- situ and remotely sensed data, with the MIT general circulation model in an optimization procedure that minimizes model-data misfits in a least-squares sense. The result is an estimate of the global ocean state (temperature, salinity, currents and sea level) and the surface atmospheric forcing fields (wind stress, heat flux and freshwater flux) since 1992 that are in the best consistence with the observations. In this work, we use the ECCO-GODAE solution as a tool to study sea level variability on seasonal to inter-annual scales with a focus on annual and semi-annual periods. Preliminary analysis indicates the importance of wind stress and heat flux forcing to the long-period sea level oscillations. A substantial part of the sea level variability can be assigned to changes in steric height, but bottom pressure changes are not completely negligible in several areas. Steric height contributions come mostly from the upper ocean, but significant variability is found throughout the water column. The difference between sea level variability in coastal areas and the open ocean is also highlighted in comparisons among the ECCO-GODAE estimate, altimetry observations and tide gauges.