Rainfall in Western South America: The “traditional El Niño” versus “Global ENSO” C F Ropelewski and L Goddard IRI The Earth Institute, Columbia University (With thanks to Yamina Silva, Instituto Geofisico Del Peru) The 28th Climate Diagnostics and Prediction Workshop Reno NV, October 2003

Traditional El Niño versus Global ENSO El Niño – The maximum in mean annual cycle of sea surface temperature along the west coast of South America i.e. anomalies with respect to the annual mean ENSO – Defined here as the positive displacement of the mean annual cycle of sea surface temperature in the equatorial Pacific i.e. anomalies wrt the mean annual cycle.

ENSO, El Niño and Climo

ENSO Composite Years 57 –58 (e.g. Jan 57 to Dec 58) – – – – – – – 98

All Nino3,3.4, 1+2 Thanks to Vern Kousky

Event-to-Event Variability of SST Anomalies (El Niño)

SST Anomalies ( ) (Source CPC/NOAA)

Annual Cycle-Precipitation and Temperature (80.75S, 5.25W, New et al 1999)

Sea surface temperature correlations with FMA precipitation in Peru

Correlations Nino – – – – – 1.0 Thanks to Yamina Silva, Instituto Geofisico Del Peru

Thanks to Yamina Silva, Instituto Geofisico Del Peru Precip Vs NINO12

Correlations Nino – – – – – 1.0 Thanks to Yamina Silva, Instituto Geofisico Del Peru

Composite precipitation in tercile classes for western South America tropics

Occurrence Nino34

Occurrence Nino1+2

FMA Circ Comps Meridional and Vertical Winds Mean ( ) 10S EQ 10N Composite Anomaly Nino1&2 10 warmest

NINO1&2 – 4 Cases NINO3.4 – 4 Cases Both – 6 Cases

NINO1&2 – 4 Cases NINO3.4 – 4 Cases Both – 6 Cases

NINO1&2 WARM MARCH

NINO3.4 Only March

March of years with both warm NINOP1&2 and NINO3.4

Summary Rainfall in near equatorial regions of Ecuador and Peru are sensitive to the “local” sst anomalies (NINO1&2 here) in FMA. Correlations i.e. teleconnections with central and western Pacific sst anomalies are weaker during the same season. Most large “local” FMA sst anomalies occur in conjunction with the larger scale ENSO phenomenon. There are some notable exceptions including: 1953, 1957, 1965, 1972 and most recently 2001 and 2002.

Nino 3.4 Thanks to Vern Kousky

Nino 1+2 Thanks to Vern Kousky

Correlations Nino – – – – – 1.0 Thanks to Yamina Silva, Instituto Geofisico Del Peru

Correlations Nino – – – – – 1.0

Thanks to Yamina Silva, Instituto Geofisico Del Peru January N12 Precip Vs NINO12

March N12 Precip Vs NINO12 Thanks to Yamina Silva, Instituto Geofisico Del Peru

February N12 Thanks to Yamina Silva, Instituto Geofisico Del Peru Precip Vs NINO12