I am working on El Nino since January 1993. I have realized coupled GCM simulations: global atmospheric model ARPEGE from CNRM with either Pacific ocean model OPA6 or global ocean model OPA7 from LODYC. I have especially focused my analysis on ENSO events. I have used the "Zebiak and Cane" model. I have developed a theoretical approach to El Nino. This work have allowed to exhibit full analytical expressions of coupled processes which could be involved in the El Nino onsets. The originality of my work is to study the results of coupled GCM from the theoretical coupled processes point of view.
I am now in charge of the coupled-GCM CoPIVEP (Coupled Processes and Interannual Variability in the Equatorial Pacific) intercomparison. The following laboratories participate in CoPIVEP:
The second topic of my work is about the role of the westerly wind bursts in the onsets of El Nino. This work is co-superintended by Jean-Luc Redelsperger (CNRM, TOGA-COARE) and me, with the collaboration of Pascale Delecluse (LODYC).
I propose 2 levels of diagnosis:
Level 1: "Documentation of the Interannual Varibility" (DIV)
I propose to perform EOF (and Complex EOF) with the interannual
monthly mean atmospheric surface temperature.
I will perform also the time spectrum analysis for the whole data
and for each EOF. [Some other analysis can be possible as the
time-space analysis (wavelets - ondelettes in French).]
Depending on the available data, the characteristic zonal structure
of the interannual signals will be precised (phase lag between SST,
oceanic currents, wind stresses).
Level 2: "COupled Processes" (COP)
With the available data (annual and seasonal mean state), it is
possible to compute the theoritical efficiencies of some coupled
processes for the whole Pacific basin. The objectives will be:
For the level 1: we have on our computers a scientific library which provides the necessary statistical functions.
For the level 2: the programs have been already developped for CoPIVEP but they will be adapted to the CMIP data.
Validation: For CoPIVEP, I already use the SST of COLA-CAC [and Levitus for the 3D temperature: annual mean and seasonal mean]. I will need of measurenments of vertical velocity in the 0-100m layer (TAO-array ?). All informations about other observation data sets will be wellcome.
For level 1: monthly mean of SST or atmospheric surface temperature (AST). If possible, also wind stresses, oceanic surface currents.
For level 2: total-simulation mean and seasonal (at least DJF,MAM, JJA,SON) mean of the SST (or AST), and the latitude- vertical cross section of the oceanic temperature and vertical velocity. (The best would be the 3D data in the Pacific bassin).
David Stephenson (sub-project North Atlantic Oscillation) is now working in the CNRM (200 meters from my location) and we have working together for 2 years at CERFACS (in the Climate Modelling and Global Change team). We can interact to use the CMIP data.
Pontaud and Thual (1995): Some effects of the mean zonal thermocline gradient on planetary equatorial waves, Annales Geophysicae,13, 1223-1228.
Pontaud, Terray, Guilyardi, Sevault, Stephenson and Thual (1995): Coupled ocean-atmosphere modelling - computing and scientific aspects, 2nd UNAM-CRAY supercomputing conference, Numerical simulations in the environmental and earth sciences, Mexico, Cambridge University Press.
Pontaud, Terray, Guilyardi, Thual, Stephenson, Delecluse, Madec and Deque (1995): Coupled ocean-atmosphere simulations, in TOGA95,2-7 april 1995, Melbourne, Australia, WMO-TD n. 717, December 1995, 605-609.
Pontaud and Thual (1997): Coupled processes for equatorial Pacific interannual variability, Q.J.R.M.S., accepted.
Guilyardy, Madec, Terray, Deque, Pontaud, Imbard, Stephenson, Filiberti, Cariolle, Delecluse and Thual (1995): Simulation couplee ocean-atmosphere de la variabilite du climat, C.R. Acad. Sci, Paris,t320, serie IIa, 683-690.