1. El Niño – Southern Oscillation (ENSO)
Monitoring and Prediction at
NOAA Climate Prediction Center (CPC)
Michelle L’Heureux
ENSO Team Lead
NOAA Climate Prediction Center (CPC)
March 2012

2. Outline
• Monitoring and prediction products at NOAA CPC
• Procedures on how we create and disseminate a forecast
• Current skill of ENSO prediction models
• How ENSO information is used in seasonal prediction

3. Mission of NOAA Climate Prediction Center
We deliver climate prediction, monitoring, and diagnostic
products for timescales from weeks to years to the Nation and
the global community for the protection of life and property
and enhancement of the economy.

4. What are the primary sources of skill in seasonal
climate outlooks for the U.S.?
• The El Niño-Southern Oscillation (ENSO)
• Longer-term trends (use past 10-15 year average of temperature
and precipitation)
• In general, boundary conditions like global sea surface
temperatures (SST) and land surface variables (soil moisture, sea
ice, snow cover) are used

5. What datasets do we rely on to monitor and predict
ENSO?
• In situ observations: ships, TAO moored buoys, and drifting buoys
like Argo
• Geostationary satellites like GOES and polar orbiting satellites like
POES and Suomi
• Various gridded reconstructions of Sea Surface Temperature (SST)
(e.g. ERSST, OISST)
• Gridded Reanalysis products, which combine observations with a
first-guess model forecast to fill gaps (e.g. NCEP/NCAR, CFSR)
• SST and reanalysis are run in “real-time.” For historical comparisons,
homogeneity of the dataset is desired.

6. What products do we use to monitor ENSO?
Weekly and monthly graphics of the
tropical Pacific:
* sea surface temperature (SST)
* subsurface temperature
* sea level pressure (i.e. SOI)
* outgoing longwave radiation (OLR)
* Various levels of winds (850/200-hPa)
* velocity potential + streamfunction

7. What products do we use to predict ENSO?
(1) Dynamical models: large number of observations, mathematical equations that
describe large-scale physical relationships, and parametrizations of smaller sub-grid
features (run on supercomputers)
- NCEP Climate Forecast System (CFS): a tier-one coupled model (ocean and
atmosphere interact freely)
(2) Statistical models: uses a smaller number of observed variables (~1-3) and past
statistical relationships (run on a personal computer)
- CPC Constructed Analog (CA), Canonical Correlation Analysis (CCA), and Markov
(MKV)
(3) Multi-model combinations: uses several dynamical and/or statistical models and
combining them through various statistical methods
- CPC Consolidated Forecast Tool (“CON”): combines models using an ensemble
regression based kernel distribution (see Unger et al., 2009)
- IRI/CPC ENSO Prediction “Plume” which shows ~20+ dynamical and statistical
models and shows the dynamical and statistical model averages

8. What products do we use to predict ENSO?

9. Where are these products located?
• ENSO products are on CPC's website (weekly + monthly updates):
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/enso.shtml
•http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml
http://www.cpc.ncep.noaa.gov/data/indices/
• NCEP Climate Forecast System ENSO prediction (daily update):
http://www.cpc.ncep.noaa.gov/products/CFSv2/CFSv2seasonal.shtml
• CPC “Consolidation (CON)” ENSO prediction (monthly update):
http://www.cpc.ncep.noaa.gov/products/predictions/90day/tools/briefing/unger.pri.php
• Ocean Monitoring products (+ monthly briefing):
http://www.cpc.ncep.noaa.gov/products/GODAS/
• Global Tropics Benefits/Hazards product for Week-1 and Week-2
(weekly briefing):
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/ghazards/index.php
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml

10. NOAA's Official ENSO Index:
Oceanic Niño Index or “ONI”
The ONI is a 3-month running average of SST
anomalies in the Niño-3.4 region of the east-central
equatorial Pacific Ocean.
Retrospectively, we use 5 consecutive 3-month ONI
> 0.5°C as an El Niño episode and ONI < -0.5°C as
La Niña episode.
Dataset: ERSSTv3b, which is a 2°x2° gridded SST
reconstruction (Smith et al., 2008) using in situ data
and statistical relationships to fill in gaps and create a
continuous, homogeneous SST record.
We only compute the ONI back to 1950 because data
coverage is sparse prior to then.

11. The ENSO Alert System
The ENSO Alert System provides the public with a succinct
summary of the status of ENSO.
An El Niño or La Niña Watch:
Issued when the environment in the equatorial Pacific basin is favorable for
the development of El Niño or La Niña conditions within the next six (6)
months.
An El Niño or La Niña Advisory:
Issued when El Niño or La Niña conditions in the equatorial Pacific basin are
observed and expected to continue.
Final El Niño or La Niña Advisory: Issued
after El Niño or La Niña conditions have ended.
NA:
The ENSO Alert System will not be active when El Niño or La Niña
conditions are not observed or expected to develop in the equatorial Pacific
basin.

12. What is the criteria for an ENSO Advisory?
The ENSO Alert System is based on El Niño and La Niña “conditions” that allows the
NOAA to be able to issue watches/ advisories in real-time.
The value of the ONI is to define episodes retrospectively.
El Niño conditions: one-month positive SST anomaly of +0.5 or greater in the Niño-3.4
region and an expectation that the 3-month ONI threshold will be met.
La Niña conditions: one-month negative SST anomaly of −0.5 or less in the Niño-3.4 region
and an expectation that the 3-month ONI threshold will be met.
AND
An atmospheric response typically associated with El Niño/ La Niña over the equatorial
Pacific Ocean.

13. ENSO Alert System is updated with the
“ENSO Diagnostic Discussion”
NOAA's monthly ENSO Diagnostic
Discussion is used to update the
ENSO Alert System status.
Also gives a short ~3 paragraph
summary of the current observations
and prediction of ENSO.
Can click on status to get detailed
information on Alert System
definitions
http://www.cpc.noaa.gov/products/
analysis_monitoring/enso_advisory
/ensodisc.html

14. How is the monthly ENSO Diagnostic Discussion
put together?
Step #1: Send out forecaster spreadsheets to the ENSO team (9
people). They are given ~2.5 days to consider analysis and then give
their individual forecast.
Step #2: All team member forecasts are combined. We show the
probability of each ENSO category out to ~8 leads.
Step #3: Lead author writes the initial draft and it is iterated on by the
internal ENSO team. Eventually the draft is sent for comments by
external NOAA employees outside of CPC.
– If a change in status, NOAA leadership and public affairs are
notified.
Step #4: The discussion is finalized and translated into Spanish by
weather forecast office in San Juan.

15. What do the ENSO forecasters examine?
Each forecaster has expertise in different areas and tends to weight different
aspects of ENSO. In general, the forecasters rely on:
(1) Various ENSO-related monitoring products
(2) Dynamical and statistical models and multi-model combinations
(3) Their knowledge and experience of previous ENSO episodes

16. How is the forecasters input synthesized?
Each forecaster fills out a spreadsheet with probabilities of three categories (El
Niño – Neutral – La Niña). All forecasts are averaged to create the
probabilities. See example below:

17. How is the monthly ENSO Diagnostics Discussion distributed to
the Public?
• Discussion is posted to CPC website. There is also an email listserv which has
10,000+ subscribers (includes technical experts, media, general public, etc.).
• Within hours, NOAA posts a press release (if a noteworthy change in ENSO) and
articles will appear on media outlets (Reuters, Bloomberg, AP, etc.)
• NOAA/NWS has several public affairs officials who are available to arrange
interviews radio, TV, newspapers, blogs….

18. How well do models predict ENSO?
• Recently, dynamical models have slightly edged statistical models
in forecast skill (Barnston et al. BAMS, in press)
• Models have trouble with transition timing and predicting
amplitude of ENSO events.
• Stronger ENSO events tend to be better predicted than weaker
ones.
• From decade-to-decade, ENSO prediction skill can vary widely due
to natural internal variability (can overwhelm forecast model
improvements).
• “Spring prediction barrier:” historically, forecasts before the
Northern Hemisphere Spring have low skill.
• Intraseasonal variability (i.e. MJO) is not captured in most of these
models and these phenomenon can have considerable impact on
ENSO evolution.

19. Anomaly Correlations of ENSO models from 2002-2011
Orange/Red Shading: Higher correlations (more skill)
White/Blue: Lower correlations ( 0 < r < 0.5)
Light Grey: Negative correlations (very poor skill!)
Lead Time (0-8 months) is on Y-axis and Target Season is on the X-axis
The orange box designates the statistical models (the rest are dynamical)
From Barnston et al. (BAMS, in press) “Skill of Real-Time Seasonal ENSO Model Predictions during
2002-2011– Is our Capability Increasing?”

20. Anomaly Correlations and Root Mean Squared Error
(RMSE) of ENSO models (all months from 2002-2011)
Correlation by Lead Time RMSE (standardized units) by Lead Time
1 1.2
0
0 8 0
Lead (months) 0 Lead (months)
8
• At 0-month lead, ENSO model • For lead times greater than 2 months, RMSE of
skill ranges from 0.75 to 0.95. “persistence” is greater than all models.
• At 6-month lead, ENSO model • In general, models with high correlation tend to
skill ranges from 0.1 to 0.7. have low RMSE.

21. Anomaly Correlations by Lead Time
1
Top Panel:
May-Sept At 6-month lead:
Target
ENSO model skill
ranges from below
zero to 0.55 during
0 boreal summer
0 8
1 ENSO model skill
ranges from 0.45 to
0.9 during boreal
winter
Bottom Panel:
Nov-Mar
Target
0
0 Lead (months) 8

22. Top Panel: 3-year sliding Correlation based on Hindcasts (1981-2010)
Bottom Panel: 3-year sliding standard deviation of Niño-3.4
ENSO model skill
decreased during
2002-10 (and in early-
mid 1990s) in part due
to the observed ENSO
variability (lower
amplitude ENSO events
and more transitions
between phases)

23. Input from ENSO updates are incorporated into other CPC
products and services: Seasonal and Monthly Outlooks, Drought
Outlook, Fire Potential conference call, U.S. and Global Hazards,
etc.

24. Who benefits from these climate outlooks?
A few examples:
1. NOAA climate outlooks provide big picture context for the weather events.
This gives local TV weather forecasters and the private sector increased
opportunity to add value to their forecasts, and to tell a better story.
2. Electric power companies have used climate forecasts for decades to make
decisions relevant to energy trading.
3. U.S. federal government agencies, including FEMA, Department of Interior,
Department of State, Military use them for planning purposes and resource
allocation.
4. Local and State governments use them to allocate resources, e.g., California has
used prediction of El Nino to maintain drainage canals.

25. How is ENSO used in seasonal temperature and
precipitation outlooks?
First, some quick background on our
seasonal outlooks:
Seasonal outlooks are probabilistic (given in %
chance) reflecting the fact that confidence is
lower than a deterministic weather forecast.
Precipitation and Temperature (P&T) outlooks
are given for three (“tercile”) categories: above
average/median – near average/median – below
average/median
Probabilities either reflect a “tilt in the odds” or
“favoring” of a certain category or “Equal
Chances (EC)” which means no category is
favored (33.3% – 33.3% – 33.3%).

26. Some desired quantities of a seasonal outlook (or
a probabilistic climate forecast, in general)
“Reliable”: Over a long enough time period, the forecast probability reflects how often that
category actually occurred. – given a forecast for a 60% chance of above-average
temperatures, one would expect above average temperatures to occur 60% of the time.
“Sharpness:” a high probability issued for the correct observed category
“Discrimination:” If outcomes are different, are the forecasts different? The probability of
a forecasted category should increase when that observed category occurs (probability
should decrease when the category occurs less)
– If forecast is always the same regardless of actual observation, then no discrimination
“Resolution:” If forecasts are different, are the outcomes different? The probability of a
forecasted category should be different when the observed outcome is different.
– If the outcome is always the same regardless of the forecasts, then there is no resolution.
– Even if the forecast is always wrong, it has high resolution if it can distinguish between
outcomes.
Great verification reference: http://www.cawcr.gov.au/projects/verification/

27. How is ENSO used in seasonal temperature and
precipitation outlooks?
ENSO impacts are already captured in dynamical climate model forecasts,
like the NCEP Climate Forecast System (CFS) and the new National Multi-
Model Ensemble (NMME).
However, several statistical tools (that are not conditioned on ENSO phase)
do not resolve ENSO impacts over the U.S.
Some tools like Optimal Climate Normal (OCN), which captures the
longer-term trends, do not incorporate ENSO impacts at all.
Thus, the seasonal forecaster will often weight the dynamical models more
(over the statistical models) in the outlook during ENSO periods.
During ENSO periods, the forecaster often uses historical ENSO
composites and boxplots in association with the model guidance.

28. ENSO Composites and Boxplots for the U.S.
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/enso.shtml#composite
Central Florida
Precipitation (DJF)

29. Global ENSO Regression and Correlation Maps
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/enso.shtml#composite
• Gridded temperature anomalies (CPC GHCN) and precipitation anomalies (CPC Unified
Precipitation) associated with the standardized Niño-3.4 index from 1948-2010.
• Assuming linearity so regression anomalies showing sign of El Niño (reverse for La Niña)

30. The IRI provides global seasonal climate outlooks
outside of the United States
http://portal.iri.
columbia.edu/
Recently, the IRI has become a close partner on NOAA's ENSO prediction team,
assisting in the creation and dissemination of the ENSO outlooks.
http://iri.columbia.edu/climate/ENSO/currentinfo/QuickLook.html

31. Summary
• NOAA CPC provides routine monitoring and prediction products
for ENSO, which are available on our website.
• Once a month, the ENSO team determines the probabilities for each
ENSO category, which provides the ENSO prediction for the
upcoming ~8 seasons.
• A variety of ENSO models (statistical and dynamical) are
considered to create the forecast. Over the past 10 years, dynamical
models are slightly more skillful than statistical models.
• The ENSO outlook is incorporated (implicitly and explicitly) into
CPC’ s monthly/seasonal temperature and precipitation outlooks
and other products.

32. Miscellaneous Slides

33. Since 1995, what has been the performance of U.S.
Seasonal Temperature and Precipitation Outlooks?
Temperature HSS Precipitation HSS
Mean = 22.3, Coverage = 50.9% Mean = 10.9, Coverage = 31.4%
Hedike Skill Score (HSS) is the percent improvement over random chance.
No skill forecast = 0
Perfect forecast = 100
Worse than random chance < 0

34. Other climate phenomenon impacting Peru?
• On a shorter, “subseasonal” timescale (i.e. weekly forecasts out to ~1
month): the Madden Julian Oscillation (MJO)
Nov-Mar Precipitation Anomalies May- Sept Precipitation Anomalies

35. Timeline for Weekly ENSO Update
Updated each Monday (Tuesday if holiday):
6:30am: Many graphics are produced using NCEP data via an
automated “cron” job
7 – 8:30am: Put together ENSO powerpoint (edit text, reformat
some figures)
8:30 – 10am: Reviewed by ~3 other CPC employees
10 – 11am: Incorporate feedback
By 11am EST: Finalize and upload to the CPC web (Powerpoint
and PDF)

36. Timeline for Monthly ENSO Diagnostics
Discussion
Released on the Thursday between the 4th-10th of the
month at 9am EST/EDT.
Mon. Tues. Wed. Thurs. Fri.
Email Forecaster Initial Draft is Draft is
Week forecaster spreadsheets completed reviewed by
before the spreadsheets due ENSO team
Release
Draft is Feedback Discussion is ENSO Discussion is
emailed to from Outside finalized. released
Outside Collaborators Spanish Email listserv
Week of the Collaborators translation is
Release (Press Release if
Spanish finalized by applicable)
translation WFO San
begins Juan