Research supported by NOAA CPO’s Climate Variability and Predictability (CVP) program and the Modeling, Analysis, Predictions and Projections (MAPP) program has been accepted for publication in the Journal of Climate.
While the ENSO response is traditionally linked to a single deep baroclinic mode throughout the tropical Pacific, the paper by Ji et al., “El Niño–Southern Oscillation Sea Level Pressure Anomalies in the Western Pacific: Why Are They There?”, explores the contribution of both barotropic and baroclinic modes, as well as interactions between the two, to Sea Level Pressure (SLP).
The authors determined that the barotropic mode is the primary driver behind SLP anomalies in the western Pacific, while the baroclinic mode remains important throughout the central and eastern Pacific. Subsequent QTCM diagnostic experiments further elucidated the dynamical pathway linking these regions of the Pacific by selectively suppressing baroclinic-barotropic interactions in progressively larger bands.
These experiments showed that baroclinic-barotropic interactions are key to creating the barotropic signal that sustains the characteristic ENSO SLP anomalies observed in the western Pacific.
To access an early online release of the paper, visit: http://dx.doi.org/10.1175/JCLI-D-14-00716.1