Following is a chart comparing the 2011-12 La Nina to other cold ENSO episodes that have occurred since 1949. With the exception of 1961-62 and 2008-09 the cold episodes are based on the Oceanic Niño Index (ONI) and are those specified in the CPC's tabulation of Cold & Warm Episodes by Season. A description of the parameters follows the chart. A GWO phase space plot is included for those cold episodes for which AAM data is available. Data for 2011-12 will be updated periodically.
|
Year
|
Nov-Mar
AAM
|
Peak MEI4
|
Peak MEI Season
|
Peak
ONI
|
Peak ONI Season
|
L.A. Rain
|
GWO
Phase Plot
|
| 1949-501,2 |
-- |
-1.423 |
APRMAY |
-1.7 |
DJF |
9.94 |
-- |
| 1950-511 |
-- |
-1.247 |
NOVDEC |
-1.0 |
NDJ, DJF |
8.21 |
-- |
| 1954-551 |
-- |
-1.578 |
MAYJUN (54) |
-1.2 |
ASO |
11.94 |
-- |
| 1955-561 |
-- |
-2.276 |
MAYJUN (55) |
-2.0 |
OND |
16.00 |
-- |
| 1956-571 |
-- |
-1.516 |
MAYJUN (56) |
-0.9 |
SON, OND |
9.54 |
-- |
| 1961-623 |
-0.513 |
-1.093 |
DECJAN |
-0.6 |
ASO, SON |
18.79 |
|
| 1962-63 |
-1.259 |
-0.843 |
JANFEB |
-0.7 |
OND, NDJ |
8.38 |
|
| 1964-65 |
-1.145 |
-1.496 |
JULAUG |
-1.2 |
SON, OND |
13.69 |
|
| 1967-68 |
-0.770 |
-1.060 |
APRMAY |
-0.9 |
JFM |
16.58 |
|
| 1970-71 |
-0.976 |
-1.898 |
MARAPR |
-1.3 |
DJF, JFM |
12.32 |
|
| 1971-72 |
-0.173 |
-1.463 |
AUGSEP |
-1.0 |
OND |
7.17 |
|
| 1973-74 |
-1.331 |
-1.942 |
DECJAN |
-2.1 |
NDJ |
14.92 |
|
| 1974-75 |
-0.842 |
-1.255 |
OCTNOV |
-0.9 |
OND |
14.35 |
|
| 1975-76 |
-0.713 |
-2.000 |
SEPOCT |
-1.7 |
OND, NDJ |
7.22 |
|
| 1984-85 |
-0.597 |
-0.743 |
APRMAY |
-1.1 |
NDJ |
12.82 |
|
| 1988-89 |
-1.139 |
-1.591 |
AUGSEP |
-1.9 |
OND, NDJ |
8.08 |
|
| 1995-96 |
-0.227 |
-0.644 |
DECJAN |
-0.7 |
OND to JFM |
12.46 |
|
| 1998-99 |
-0.541 |
-1.233 |
JANFEB |
-1.4 |
NDJ, DJF |
9.09 |
|
| 1999-00 |
-0.781 |
-1.242 |
JANFEB |
-1.6 |
NDJ, DJF |
11.57 |
|
| 2000-01 |
-0.795 |
-.755 |
OCTNOV |
-0.7 |
NDJ |
17.94 |
|
| 2007-08 |
-1.010 |
-1.631 |
FEBMAR |
-1.4 |
DJF, JFM |
13.53 |
|
| 2008-093 |
-0.596 |
-.783 |
SEPOCT |
-0.8 |
DJF |
9.08 |
|
| 2010-11 |
-0.596 |
-2.037 |
AUGSEP |
-1.4 |
SON, OND, NDJ |
20.20 |
|
| 2011-125 |
-0.370 |
-1.046 |
DECJAN |
-1.0 |
OND, NDJ |
8.19 |
|
1. AAM and AAM tendency anomaly data not available.
2. Based on ONI values beginning with DJF 1949-50.
3. ONI did not meet threshold of 5 consecutive overlapping seasons.
4. MEI values are normalized and may change as new data is added. Specified values were current as of April 24, 2012.
5. Data as of April 24, 2012.
|
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. Data is from the GWO phase space data file linked on 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). Reference Wolter and Timlin, 1993, 1998. MEI values are normalized and may change as new data is added.
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.
Peak ONI Season: The peak tri-monthly season(s) for which the ONI is computed.
L.A. Rain: The water year precipitation total in inches for Downtown Los Angeles (USC). Reference NWS Los Angeles/Oxnard Downtown Los Angeles Climate Page, 1921-2006 Water Year Rainfall.
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 from the GWO phase space data file linked on the Global Synoptic Dynamic Model page of the PSD Map Room Climate Products. Reference Weickmann and Berry, 2008.