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MODELLING CLIMATE VARIABILITY ON INTERANNUAL TIME SCALE

Objective



THE "PRINCIPAL OSCILLATION PATTERN" TECHNIQUE SEEMS WELL-ADAPTED TO THE REPRESENTATION OF MODEL OR OBSERVED CLIMATE VARIABILITY. THE METHOD WILL BE DEVELOPED AND TESTED AT LODYC, WITH PARTICULAR EMPHASIS ON THE FOLLOWING STATISTICAL QUESTIONS :
(1) DATA REDUCTION PRIOR TO POP ANALYSIS; SELECTION CRITERION FOR FURTHER DATA REDUCTION IN THE POP SPACE.
(2) DETECTION OF PROPAGATING STRUCTURES IN PRESENCE OF NOISE AND OTHER MOTIONS : INTERPRETATION OF THE POPS; EFFECT OF LIMITED SAMPLING
(3) INTERCOMPARISON WITH EOF TECHNIQUES
INTERCOMPARISON OF EOFS AND POPS DERIVED FROM DIFFERENT DATA SETS (FOR INTERCOMPARISON PURPOSES)
(4) POPS AND EOFS OF NOISY OR INCOMPLETE DATA SETS (E.G. OBSERVATIONS, SATELLITE DATA).

THESE BASIC STATISTICAL STUDIES WILL BE MADE USING ARTIFICIAL, KNOWN DATA AND MONTE CARLO TECHNIQUES. THE POPS WILL BE APPLIED TO OBSERVED AND MODEL DATA SETS AS SOON AS THEIR PROPERTIES ARE WELL-UNDERSTOOD.
THE POP METHOD WILL BE FIRST APPLIED TO EXISTING SIMULATIONS MADE WITH THE GISS ATMOSPHERIC GCM (MODEL THAT WE HAVE USED FOR SENSIBILITY STUDIES). INTERFERENCES ON THE CLIMATIC INFLUENCES OF THE OCEANIC VARIABILITY WILL BE OBTAINED BY COMPARING RUNS WITH CLIMATOLOGICAL SEA-SURFACE TEMPERATURE (SST) (10 YEARS) TO RUNS WITH AN INTERACTIVE OCEANIC MIXED-LAYER (20 YEARS). SIMILAR RUNS (UNDERWAY) MADE WITH THE HIGH-RESOLUTION LMD ATMOSPHERIC GCM WILL ALSO BE CONSIDERED. IN PARALLEL, OBSERVED ATMOSPHERIC DATA WILL BE ANALYZED AND USED FOR MODEL VALIDATION.

IN A SECOND PHASE, THE POP ANALYSIS WILL BE APPLIED TO THE COUPLED OCEAN-ATMOSPHERE MODEL. A COMPARISON OF THE MODEL RESULTS WITH ENSO, NAC AND OTHER ATMOSPHERIC AND OCEANIC OBSERVATIONS WILL ALLOW EFFICIENT TUNING OF THE COUPLING SCHEME. VARIOUS EXPERIMENTS AIMED AT DETERMINING THE RELATIVE INFLUENCE OF THE DIFFERENT COMPONENTS OF THE MODEL WILL BE INVESTIGATED. THE MODEL WILL THEN BE INTERCOMPARED WITH THE COUPLED MODELS OF THE OTHER PARTICIPATING GROUPS.

IN ADDITION, THE INVESTIGATION OF CLIMATE SENSITIVITY EXPERIMENTS TO CHANGES IN THE BOUNDARY CONDITIONS WILL BE CONTINUED IN A JOINED EFFORT WITH THE OTHER PARTICIPANTS, COMBINING IN PARTICULAR MULTIVARIATE STATISTICAL TECHNIQUES, SIMPLIFIED ATMOSPHERIC MODELS AND DIAGNOSTIC ANALYSIS. THIS SHOULD BRING A BETTER UNDERSTANDING OF THE DYNAMICAL MECHANISMS RESPONSIBLE FOR THE CLIMATE CHANGES DETECTED IN THE COUPLED SYSTEM.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

UNIVERSITE PIERRE ET MARIE CURIE - PARIS VI
Address
Place Jussieu 4
75252 Paris
France

Participants (5)

HOOKE INST F COOPERATIVE ATM RESEARCH
MAX-PLANCK INSTITUT FUER METEOROLOGIE
METEOROLOGISCHE INSTITUT
ROYAL NETHER METEOR INSTITUT
UNIVERSIDAD DE ALCALA DE HENARES