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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, 20-23 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 Composite Years
57 –58 (e.g. Jan 57 to Dec 58)
65 - 66
68 – 69
72 – 73
82 – 83
86 – 87
90 – 91
94 – 95
97 – 98
Correlations Nino1+2
-0.5 – -0.3-0.3 – 0.3 0.3 – 0.5 0.5 – 0.7 0.7 – 1.0
Thanks to YaminaSilva, InstitutoGeofisico Del Peru
Correlations Nino 3.4
-0.5 – -0.3-0.3 – 0.3 0.3 – 0.5 0.5 – 0.7 0.7 – 1.0
Thanks to YaminaSilva, InstitutoGeofisico Del Peru
FMA Circ CompsMeridional
andVertical WindsMean
(1971-2000)
10S EQ10N
CompositeAnomalyNino1&210 warmest
Ranked Sea Surface Temperature for February-April NINO Areas
YEAR NINO1&2 NINO3.4 1950
53 8 57 5 58 9 3 1960
65 10 66 6 69 5 1970
72 6 73 8 1980
83 2 1 87 3 4 1990
92 4 2 93 7 10 95 7 98 1 (1) 2000
01 (n) 02 (n) Yellow – NINO1&2 only, RED – NINO3.4 Only
NINO1&2 – 4 Cases
NINO3.4 – 4 Cases
Both – 6 Cases
Ranked Sea Surface Temperature for February-April NINO Areas
YEAR NINO1&2 NINO3.4 1950
53 8 57 5 58 9 3 1960
65 10 66 6 69 5 1970
72 6 73 8 1980
83 2 1 87 3 4 1990
92 4 2 93 7 10 95 7 98 1 (1) 2000
01 (n) 02 (n) Yellow – NINO1&2 only, RED – NINO3.4 Only
NINO1&2 – 4 Cases
NINO3.4 – 4 Cases
Both – 6 Cases
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.
Correlations Nino 4.0
-0.5 – -0.3-0.3 – 0.3 0.3 – 0.5 0.5 – 0.7 0.7 – 1.0
Thanks to YaminaSilva, InstitutoGeofisico Del Peru