The following chart compares various climate parameters for cold ENSO episodes that have occurred since 1949. Except where noted, the cold episodes listed are those specified in the CPC's tabulation of Cold & Warm Episodes by Season. The cold and warm episodes are based on the Oceanic Niño Index (ONI), which is calculated using the three month running mean of ERSST.v5 SST anomalies in the Niño 3.4 region with multiple-centered 30 year base periods. A description of the parameters follows the chart. With the exception of years prior to 1957, a Nov-Mar GWO phase space plot is included for each episode.
|
Year
|
ERSST
Version
|
Nov-Mar
AAM
|
Peak MEI
|
Peak MEI Season
|
Peak
ONI
|
Peak ONI Season
|
L.A. Rain
|
GWO
Phase Plot
|
| 1949-501,2 |
v5 |
-- |
-1.445 |
APRMAY |
-1.5 |
DJF |
9.94 |
-- |
| 1950-511,3 |
v4 |
-- |
-1.235 |
NOVDEC |
-0.8 |
NDJ, DJF |
8.21 |
-- |
| 1954-551 |
v5 |
-- |
-1.528 |
MAYJUN (54) |
-0.9 |
ASO |
11.94 |
-- |
| 1955-561 |
v5 |
-- |
-2.209 |
MAYJUN (55) |
-1.7 |
OND |
16.00 |
-- |
| 1956-571,3 |
v3b |
-- |
-1.490 |
MAYJUN (56) |
-0.6 |
JJA, JAS |
9.54 |
-- |
| 1961-623 |
v2 |
-0.514 |
-1.065 |
DECJAN |
-0.3 |
ASO, SON |
18.79 |
|
| 1962-633 |
v3b |
-1.260 |
-0.837 |
JANFEB |
-0.4 |
OND, NDJ |
8.38 |
|
| 1964-65 |
v5 |
-1.146 |
-1.476 |
JULAUG |
-0.8 |
ASO - DJF |
13.69 |
|
| 1967-683 |
v4 |
-0.770 |
-1.106 |
APRMAY |
-0.7 |
JFM |
16.58 |
|
| 1970-71 |
v5 |
-0.977 |
-1.870 |
MARAPR |
-1.4 |
DJF, JFM |
12.32 |
|
| 1971-72 |
v5 |
-0.173 |
-1.439 |
AUGSEP |
-1.0 |
OND |
7.17 |
|
| 1973-74 |
v5 |
-1.332 |
-1.912 |
DECJAN |
-2.0 |
NDJ |
14.92 |
|
| 1974-75 |
v5 |
-0.843 |
-1.230 |
OCTNOV |
-0.8 |
OND |
14.35 |
|
| 1975-76 |
v5 |
-0.714 |
-1.968 |
SEPOCT |
-1.7 |
NDJ |
7.22 |
|
| 1983-844 |
v5 |
-1.095 |
-0.7 |
MJ |
-1.0 |
OND |
10.43 |
|
| 1984-85 |
v5 |
-0.597 |
-1.2 |
AM |
-1.1 |
NDJ |
12.82 |
|
| 1988-89 |
v5 |
-1.140 |
-1.8 |
JJ, JA, AS |
-1.8 |
OND, NDJ |
8.08 |
|
| 1995-96 |
v5 |
-0.227 |
-0.9 |
AS, MJ |
-1.0 |
SON - NDJ |
12.46 |
|
| 1998-99 |
v5 |
-0.541 |
-1.7 |
JA |
-1.6 |
NDJ, DJF |
9.09 |
|
| 1999-00 |
v5 |
-0.781 |
-1.4 |
ND, FM |
-1.7 |
NDJ, DJF |
11.57 |
|
| 2000-01 |
v5 |
-0.798 |
-0.9 |
ON, JF |
-0.7 |
OND - DJF |
17.94 |
|
| 2005-06 |
v5 |
-0.613 |
-0.8 |
MA |
-0.9 |
DJF |
13.19 |
|
| 2007-08 |
v5 |
-1.012 |
-1.5 |
FM |
-1.6 |
NDJ, DJF |
13.53 |
|
| 2008-09 |
v5 |
-0.597 |
-1.1 |
JA, AS, SO |
-0.8 |
DJF, JFM |
9.08 |
|
| 2010-11 |
v5 |
-0.596 |
-2.4 |
JJ, JA |
-1.6 |
ASO-NDJ |
20.20 |
|
| 2011-12 |
v5 |
-0.370 |
-1.4 |
SO |
-1.1 |
SON, OND |
8.69 |
|
| 2016-17 |
v5 |
0.088 |
-0.6 |
SO, FM |
-0.7 |
SON, OND |
19.00 |
|
| 2017-18 |
v5 |
-0.549 |
-1.3 |
MA |
-1.0 |
NDJ |
4.68 |
|
| 2020-215 |
v5 |
-0.105 |
-1.2 |
AS, SO, ND, DJ |
-1.3 |
OND |
5.82 |
|
1. AAM and AAM tendency anomaly data not available.
2. Based on ONI values
beginning with DJF 1949-50.
3. Not a Cold Episode using ERSST v5.
4. MEI values are v2 starting with 1983-84.
5. Data as of August 16, 2021.
|
ERSST
Version: The most recent ERSST version for which the episode was designated a cold episode. (See Peak ONI below.)
Nov-Mar AAM: The mean of the global relative atmospheric angular momentum anomaly for the period November 1 to March 31 of the following year. GWO phase space data is calculated using code from the Global Synoptic Dynamic Model page of the PSD Map Room Climate Products. Reference Weickmann and Berry, 2008.
Peak MEI:The peak seasonal value of the Multivariate ENSO Index (MEI). MEI values are v2 starting with 1983-84. MEI v1 values were last updated in March 2018.
Peak MEI Season: The peak bi-monthly season(s) for which the MEI is computed.
Peak ONI: The peak Oceanic Niño Index (ONI) based on SST anomalies in the Niño 3.4 region. Reference Climate Prediction Center Cold & Warm Episodes by Season (Multiple centered 30-year base periods.)
Peak ONI Season: The peak tri-monthly season(s) for which the ONI is computed.
L.A. Rain: The July-June rainfall year precipitation total in inches for Downtown Los Angeles (USC). Reference WRCC LOS ANGELES DWTN USC CAMPUS, CA. See Precipitation>Quantity>Monthly Precipitation Listings>Monthly Totals.
GWO Phase Space Plot: Plot of global relative atmospheric angular momentum anomaly vs. global relative atmospheric angular momentum tendency anomaly for the period November 1 to March 31 of the following year. Data is calculated using code from the Global Synoptic Dynamic Model page of the PSD Map Room Climate Products. Reference Weickmann and Berry, 2008.