Combining acoustic tomography with space-borne and in situ observations of an open ocean region
Abstract
A 4-dimensional variational data assimilation algorithm is presented for monitoring open ocean eddies in the regions, where open boundaries are the major sources of model forecast uncertainties on time scales larger than one week. A quasigeostrophic numerical model is employed as a strong constraint for evolution of the ocean state. Initial and open lateral boundary conditions are used as control variables. The problem is regularized by enforcing smoothness in the fields of vorticity, buoyancy and vertical velocity. Performance of the algorithm is tested by twin-data experiments and then applied to the real observations in the region of the Kuroshio Extension. It is shown that mesoscale variability in an open ocean 1000×1000 km region can be effectively reconstructed by combining data from five acoustic transducers, satellite altimeter, and relatively sparse in situ measurements. We study the impact of various data types on the quality of assimilation, and compare performance of the algorithm with the standard statistical inversion of the acoustic travel time data. Analysis of the energy and potential enstrophy balances of the optimized model solution provides an observational evidence of the properties of free geostrophic turbulence predicted by theory and observed in numerical experiments.
- Publication:
-
35th COSPAR Scientific Assembly
- Pub Date:
- 2004
- Bibcode:
- 2004cosp...35.3107Y