Rainfall in Western South America:

1

• 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

2

• 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.

3

4
ENSO, El Niño and Climo

5

• 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

6
All Nino3 ,3.4, 12

Thanks to Vern Kousky
7
Event-to-Event Variability of SST Anomalies (El
Niño)
8

• SST Anomalies (1983-2003)

(Source CPC/NOAA)
9

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

10

• Sea surface temperature
• correlations
• with FMA precipitation
• in Peru

11
Correlations Nino12

Thanks to Yamina Silva, Instituto Geofisico Del
Peru
12

Precip Vs NINO12
Thanks to Yamina Silva, Instituto Geofisico Del
Peru
13
Correlations Nino 3.4

Thanks to Yamina Silva, Instituto Geofisico Del
Peru
14

• Composite precipitation
• in
• tercile classes
• for western South America
• tropics

15
Occurrence Nino34

16
Occurrence Nino12

17
FMA Circ Comps
Meridional and Vertical Winds Mean (1971-2000)
10N
EQ
10S
Composite Anomaly Nino12 10 warmest
18

NINO12 4 Cases
NINO3.4 4 Cases
Both 6 Cases
19

20

21

22

NINO12 4 Cases
NINO3.4 4 Cases
Both 6 Cases
23

NINO12 WARM MARCH
1953
1957
1965
1972
24

NINO3.4 Only March
1966
1969
1973
1995
25

1958
1992
1993
1983
1998
1987
March of years with both warm NINOP12 and NINO3.4
26

• Summary
• Rainfall in near equatorial regions of Ecuador
  and Peru are sensitive to the local sst
  anomalies (NINO12 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.

27

28
Nino 3.4
Thanks to Vern Kousky
29
Nino 12
Thanks to Vern Kousky
30
Correlations Nino 4.0

Thanks to Yamina Silva, Instituto Geofisico Del
Peru
31
Correlations Nino 3

32
January N12
Precip Vs NINO12
Thanks to Yamina Silva, Instituto Geofisico Del
Peru
33
March N12
Precip Vs NINO12
Thanks to Yamina Silva, Instituto Geofisico Del
Peru
34

35

36
February N12
Precip Vs NINO12
Thanks to Yamina Silva, Instituto Geofisico Del
Peru