Nathaniel Johnson


Recent advances and challenges in understanding ENSO diversity

When Sep 18, 2019
from 03:30 pm to 04:30 pm
Where 112 Walker Building, John J. Cahir Auditorium
Contact Name Steven Feldstein
Contact email
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Nathaniel Johnson NOAA

Recent studies on the El Niño-Southern Oscillation (ENSO) have revealed its rich spatial and temporal diversity, underscoring that the phenomenon cannot be captured by a single spatial pattern or index.  Here I discuss some recent efforts in understanding this ENSO diversity.  The application of self-organizing map analysis to tropical Pacific sea surface temperature (SST) patterns yields nine statistically distinguishable “ENSO flavors,” providing a visual representation of the continuum of ENSO SST patterns.  Some ENSO flavors can have distinct wintertime impacts over North America, as the nonlinear relationship between SST and deep convection in the eastern tropical Pacific induces nonlinearities in the El Niño teleconnection patterns.  SST pattern variations also can induce deviations from the canonical El Niño atmospheric response in the central tropical Pacific, as a zonal SST gradient pattern potentially can amplify or offset the canonical response.  Overall, the identification of these distinct flavors of ENSO provide hope to seasonal forecasters that there are sources of skill beyond the canonical ENSO pattern.