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ENSO and tropical Pacific metrics for coupled GCMs. Goals : Document the performance of ENSO and tropical simulation in CMIP coupled models. Help better understanding of processes in models and identify new mechanisms
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ENSO and tropical Pacific metrics for coupled GCMs • 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.) Eric Guilyardi on behalf of the ad hoc WG of the CLIVAR Pacific Panel • Audience: • Model developers • Non ENSO specialists, producers/users of climate change projections
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.
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, ...)
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
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.
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? or • Individual reanalyses to compute indices and Pacific Panel members to compile/summarize.
Views and suggestions to: • Eric.Guilyardi@locean-ipsl.upmc.fr • Magdalena.Balmaseda@ecmwf.int • axel@hawaii.edu