el niño and the southern oscillationeaps.mit.edu/~rap/courses/12810_notes/enso.pdf ·...
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El Niño and the
Southern Oscillation
(“ENSO”)
“Normal” SST
Walker circulation
ps(hPa)
Correlations (×10) of fluctuations in annual mean
sea level pressure with those at Darwin. The
magnitude of the correlation exceeds 0.4 in the
shaded regions. (After Trenberth and Shea, 1987.)
Cx0 ,x p x 0,tp x,t
p 2x 0,t p 2x,t
1880 1890 1900 1910 1920-40
-30
-20
-10
0
10
20
30
40
so
i
1920 1930 1940 1950 1960-40
-30
-20
-10
0
10
20
30
40
so
i
1960 1970 1980 1990 2000-40
-30
-20
-10
0
10
20
30
so
i
soi
Southern Oscillation Index 1880-2000
SOI 10 SLPTahitiSLPDarwin
1880 1890 1900 1910 1920-40
-30
-20
-10
0
10
20
30
40
so
i
1920 1930 1940 1950 1960-40
-30
-20
-10
0
10
20
30
40
so
i
1960 1970 1980 1990 2000-40
-30
-20
-10
0
10
20
30
so
i
soi
Southern Oscillation Index 1880-2000
SOI 10 SLPTahitiSLPDarwin
“Normal” SST
Walker circulation
“Normal” SST
Sea surface temperature anomalies (C)
0 – 10S, 80 – 90W
1950 1955 1960 1965 1970 1975-4
-3
-2
-1
0
1
2
3
4
SO
I, S
ST
an
om
aly
(K
)
1975 1980 1985 1990 1995 2000-4
-3
-2
-1
0
1
2
3
4S
OI,
SS
T a
no
mal
y (
K)
SST anomalies (Nino 1+2)
vs SOI
SOI
SST
Annual rainfall (in percentiles) in a selection of
regions. Black bars coincide with "El Niño" years.
cold
warm
cold
warm
Correlations (×10) of fluctuations in annual mean
sea level pressure with those at Darwin. The
magnitude of the correlation exceeds 0.4 in the
shaded regions. (After Trenberth and Shea, 1987.)
Cx0 ,x p x 0,tp x,t
p 2x 0,t p 2x,t
El Nino impacts in U.S. winter
2015 El Nino
SST, OLR now
Niño Region SST Departures
(oC) Recent Evolution
The latest weekly SST
departures are:
Niño 4 1.4ºC
Niño 3.4 1.0ºC
Niño 3 1.0ºC
Niño 1+2 1.9ºC
Sub-Surface Temperature Departures in the Equatorial
Pacific
Most recent pentad analysis
Recently, negative anomalies in the eastern Pacific
have dissipated, while they have increased at depth
in the western Pacific.
During the last two months, positive subsurface
temperature anomalies increased at depth in the
eastern Pacific.
Outgoing Longwave
Radiation (OLR) Anomalies
Drier-than-average Conditions (orange/red shading)
Wetter-than-average Conditions (blue shading)
During November- mid January, positive
OLR anomalies were observed near the
Date Line.
During early March, negative OLR
anomalies shifted from Indonesia to the
Date Line.
Since mid March, positive anomalies
have been evident near Indonesia, while
negative anomalies have persisted near
the Date Line.
Tropical OLR and Wind
Anomalies During the Last
30 Days Negative OLR anomalies (enhanced convection
and precipitation) were evident near the Date
Line. Positive OLR anomalies (suppressed
convection and precipitation) were located over
the far western Pacific.
Weak, anomalous low-level (850-hPa) westerly
winds were located in the central and east-
central Pacific.
Anomalous upper-level (200-hPa)
easterlies were observed over the central
and east-central Pacific. An anomalous
anti-cyclonic couplet straddled the
equator over the central tropical Pacific.
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