Tracking down the ENSO delayed oscillator with an adjoint OGCM
Abstract
The adjoint of an ocean general circulation model is used as a tool for investigating the causes of changes in ENSO SST indices. We identify adjoint Kelvin and Rossby waves in the sensitivities to sea level and wind stress at earlier times, which can be traced back for more than a year through western and weak eastern boundary reflections. Depending on the thermocline depth the first and second baroclinic modes are excited. The sensitivities to the heat flux and SST are local and decay in about a month. The sensitivities to the fluxes are converted into the influence of SST using the adjoint of a statistical atmosphere model. Focusing on SST perturbations in the index region itself, we recover, up to a scale factor, the delayed oscillator concept.
Keywords
Cite
@article{arxiv.physics/9708037,
title = {Tracking down the ENSO delayed oscillator with an adjoint OGCM},
author = {Geert Jan van Oldenborgh and Gerrit Burgers and Stephan Venzke and Christian Eckert and Ralf Giering},
journal= {arXiv preprint arXiv:physics/9708037},
year = {2008}
}
Comments
40 pp incl figures; latex with natbib, epsfig; mpegs available at http://www.knmi.nl/~oldenbor, asaccepted by MWR (except abstract)