1. ENSO and tropical Pacific metrics for coupled GCMs
Eric Guilyardi
on behalf of the ad hoc WG of the CLIVAR Pacific Panel
Goals:
Document the performance of ENSO and tropical simulation in CMIP coupled models.
Help better understanding of processes in models and identify new mechanisms
Establish guidance for multi-model ensembles means (rejection of inadequate models, weighting, etc.)
Audience:
Model developers
Non ENSO specialists, producers/users of climate change projections

2. ENSO metrics guidelines
Definition. A metric is defined as a single scalar which measures the model performance, i.e. some “distance” of the model result to the reference observation/reanalysis. Any other analysis is referred to as a diagnostic.
Priority: identify the “magic” 5 to 7 ENSO metrics that are essential among the many identified.
Also key to document the background systematic errors in the tropical Pacific.

3. ENSO metrics categories
Base ENSO metrics
Ocean subsurface (e.g. warm water volume, thermocline sharpnes, etc...)
Surface (e.g. Niño 3,4,... SSTA stddev indices, seasonal phase lock, ENSO period, Trans-Niño index,...)
Atmosphere (e.g. SOI, ISO variability, ...)
Background systematic errors (e.g. cold tongue, trade winds strength, eastern edge of the warm pool,...)
ENSO Feedbacks (Bjerknes, heat flux, ...)
ENSO teleconnections (with Asian monsoon, PNA, ...)

4. Collaboration with GSOP ?
Help identify ocean references:
Re-analysis (ORA-S3, SODA, ECCO,NCEP, Ishii,...)
Ocean heat content or other subsurface proxy
Velocity (TAO, OSCAR, ARGO,...)
Temperature and salinity (TAO, XBTs, ARGO,...)
Help test some ideas of ocean-related metrics

5. Collaboration with GSOP ?
For example:
Time series of Upper 300m of Equatorial heat content: to identify the trends
Thermocline depth and slope: time series in East and West Pacific. Suggestions:
East:130W- 90W, 5N - 5S
West:150E-170W, 5N - 5S
Slope=West-East
Goal: to have an idea of existing uncertainty, and whether the ocean reanalysis from GSOP can be used to validate coupled models.

6. Collaboration with GSOP ?
QUESTION: which is the more practical approach?
GSOP to compute/compile and summarize indices recommended by the Pacific Panel or
Pacific Panel to access GSOP reanalyses via OPenDap servers?
Individual reanalyses to compute indices and Pacific Panel members to compile/summarize.

7. Views and suggestions to: