Back

11 March, 2002

The set of dynamical and statistical model forecasts issued during February and early March show a somewhat wide range of possible ENSO conditions for the coming 3 to 8 months (April-May-June through November-December-January). More models are indicating a warming tendency than a cool or purely neutral outlook. However, only a moderate proportion of them forecast significant warming (e.g., warming to 0.6 degrees C or more above average in the Niño 3.4 region for the June-July-August seasonal average). A sizeable fraction are forecasting ENSO conditions in the upper half of the neutral category-between 0.0 and 0.5 degrees C above normal. The warmest forecast comes from the dynamical model of the Japanese Meteorological Agency (1.2 degrees C above normal), and the coldest one is from the NOAA/CDC linear inverse model, calling for SST anomalies of -0.4 degrees C in the Niño 3.4 region for summer of 2002. For later in the year, such as August-September-October or later, six of the twelve models that forecast to that long a lead time suggest El Niño development: the NCEP coupled, Scripps Hybrid Coupled, Lamont-Doherty, JMA, CPC Markov, CPC canonical correlation analysis, and the UBC nonlinear CCA.

FORECAST SST ANOMALIES (deg C) IN NINO 3.4 REGION

Model	AMJ	MJJ	JJA	JAS	ASO	SON	OND	NDJ
==Dynamical models==
NASA/NSIPP model	0.8	0.8	0.8	0.6	0.4	0.3	0.4	0.4
NCEP Coupled model	0.3	0.4	0.5	0.6	0.7	0.7	0.8
Japanese Met. Agcy. model	1	1.2	1.2	1.1
Scripps Inst. model	0.3	0.4	0.5	0.6	0.7	0.8	0.9	0.9
Lamont-Doherty model	0.4	0.4	0.5	0.7	1	1.2
BMRC intermed. model	0.4	0.6	0.6	0.6	0.5	0.6	0.6
CSIRO model	0	0	0.1	-0.1	-0.2	-0.3	-0.3
ECMWF model	0.7	0.7
KMA SNU (Korea) model	0.3	0.3	0.3	0.3	0.4	0.4	0.4
Average, dynam. models	0.4	0.5	0.6	0.6	0.5	0.5	0.5
==Statistical models==
NCEP/CPC Markov model	0.4	0.5	0.6	0.7	0.8	1	1.1	1.2
NOCC/CDC Linear Inverse	-0.4	-0.4	-0.4	-0.4	-0.3	-0.3	-0.2	-0.2
Dool Constructed Analog	-0.3	-0.3	-0.3	-0.3	-0.4	-0.4	-0.4	-0.3
NCEP/CPC Can Cor Anal	0.5	0.7	0.8	0.9	1	1.2	1.3
Landsea/Knaff CLIPER	0.3	0.3	0.4	0.4	0.4	0.4	0.4	0.5
Mason 6-method combo
Univ. BC nonlinear Can Cor	0.5	0.6	0.7	0.7	0.8	0.9	0.9
Average, statistical models	0.2	0.2	0.3	0.3	0.4	0.5	0.5
AVERAGE, ALL MODELS	0.3	0.4	0.5	0.5	0.4	0.5	0.5

Some notes about the formulation of the entries in the table above:
 
 

=>Only models producing forecasts on a monthly basis are included. This means that some models whose forecasts appear in the Experimental Long-Lead Forecast Bulletin (produced by COLA) do not appear in the table (e.g. the COLA forecasts).

=>The SST anomaly forecasts are for the 3-month periods shown, and are for the Niño 3.4 region (120-170W, 5N-5S). Often, the anomalies are provided directly in a graph or a table by the respective forecasting centers for the Niño 3.4 region. In some cases, however, they are given for 1-month periods, for 3-month periods that skip some of the periods in the above table, and/or only for a region (or regions) other than Niño 3.4. In these cases, the following means are used to obtain the needed anomalies for the table:

o temporal averaging,

o linear temporal interpolation,

o visual averaging of values on a contoured map, and

o regional SST anomaly adjustment using the climatological variances of one region versus that of another.
 
 

As an example of the last case, suppose only the Niño 3 anomaly is provided. The Niño 3.4 anomaly is then obtained by decreasing the Niño 3 anomaly by the factor defined by the ratio of the year-to-year variance of Niño 3.4 to the year-to-year variance of Niño 3 SST, for the 3-month season in question.

Back