Interannual Variability Along the Peruvian Cost Using a High Resolution (1/9) ROMS Configuration

Francois Colas
UCLA

A modeling study of the Peru coastal and regional circulation has been performed in order to reproduce main patterns of the mean circulation and their seasonnal variability. A climatological solution of a 1/9 degree Peru ROMS configuration, forced by a general
circulation model at its open boundaries, has been previously validated and shows good agreement with available data (Penven et al. 2005).

In order to assess interannual variability over the 90's we provide the same configuration with boundary conditions from a interannual lower resolution (1/2 degree) model encompassing the Pacific basin. We use a mixture of ERS/Quikscat and NCEP datasets as atmospheric forcing fields.

The solution captures the main interannual SSH anomalies, especially the 97/98 El Nino with its two major peaks. ENSO implications for the near-shore current system are discussed in particular with the help of Lagrangian diagnostics. It is also shown that this regional solution is very sensitive to the information provided at the open boundaries (ie sensitive to the solution over the Pacific basin at lower resolution).