Das Projekt "Interannual and decadal climate variability: Scale interaction experiments" wird vom Umweltbundesamt gefördert und von Max-Planck-Institut für Meteorologie durchgeführt. General Information/Objectives: To identify the patterns of the decadal variability in the atmosphere and in the oceans and to identify the nature of the variability. To identify the nature of tele connections in the tropical and midlatitudes regions, especially with a link to the tropical biennial cycle. To investigate the nature of the contribution of intraseasonal processes (MJO, Blocking) to the inter annual variability. To investigate possible mechanisms for influences of the inter annual variability by the decadal variability (subduction, gyre dynamics, etc...). To investigate the links between the ENSO, the Asian Summer Monsoon, and the Tropical Atlantic Brief Description of the Research Project: Several research projects, either under way or about to be completed, have shown the rich character of climate variability at several time scales. It has been exposed how several major time scales of variability are often superposed and strongly interacting with each other. The inter annual time scale seems to play a pivotal role, interacting strongly at the lower end of the spectrum with intraseasonal variability, i.e. intraseasonal oscillations of various kinds, among which the Madden-Julian Oscillation (MJO) is prominent. At the other end, the inter annual variability is affected by interactions with longer time scales, as for instance, the Southern Oscillation (SO) system. Evidence is starting to emerge of a biennial cycle connected with the ENSO-monsoon relation ship that has not been sufficiently investigated. There are also clues that ocean and atmosphere are coupled at the intraseasonal time-scale and that this scale can interact with the large scale variability of the system. For instance, westerly wind bursts in the Western Pacific are very important for extracting heat from the ocean and for initiating eastward motion of surface water. Whether these events can act as a preconditioning of ENSO, or what other function they have within the ENSO- Monsoon system, needs clarification. The overall target of SINTEX is to assess the possible mechanisms of modulation by the decadal variability of the inter annual variations, and rather long simulations (longer than 100 years) with coupled models with realistic equatorial dynamics are needed. The core numerical simulations will be performed by three main coupled atmosphere/ocean model combinations, each of them including state-of-the-art, advanced, global models: A finite difference model both in the atmosphere and ocean with high horizontal resolution in the ocean (UKMO), a finite difference model with an original coupling approach that allows evaluation of the model physics on the ocean grid (LMD-OPA), a state-of-the-art spectral model coupled to an advanced ocean model via a coupler that guarantees energetic consistency in the exchange (ECHAM4-OPA). ... Prime Contractor: Consiglio Nazionale delle Richerche, Instituto per lo Studio delle Metodologie Geofisiche Ambientali; Bologna; Italy.