LEFE type proposal: Impacts of the Andes on the South American (and global?) Climate Systematic errors on precipitation are important in South America: (many models show that, CLIVAR/VAMOS document). Mis-representation of the SALLJ, that tranport the moisture that feeds the MCS, diurnal cycle, Etc. have been associated to simulated precipitation errors. Those mis-representations seem to be in turn related to model deficiencies in the physical parameterizations. Orographic influence on regional climate is not well represented by the models either. The distinctive features of the Andes are a challenge for numerical modelling. SALLJ and its variability (associated with cold surges, MSCs and baroclinic waves) are largely controlled by the presence of the Andes. Also, cut-off lows are a key feature in the Andes region particularly during the cold season. They produce significant weather events. However the physical processes associated with them are not clear them and models have deficiences in reproducing them. But also the Andes impact the global climate: GWs and PWs sources that affect the stratospheric dynamics and in return the tropospheric one via the SAM. This is important for Ozone as well. These issues will be analysed with a series of model studies that plays with the representation of orography and related physical processes in both GCMs and mesoscale models with increasing resolution. These model studies will serve as a basis for a re-assesment of currents SSO schemes, convection and PBL parameterizations. Building-up on the « Dynamical impact of the Andes on the Argentinian Climate... » document that was communicated to UMI prior to the Kick-off, these issues will serve as a basis to build-up a LEFE-type project during the next months.

LEFE type proposal: Impacts of the Andes on the South American (and global?) Climate ● Climate change of the orographic influence on regional climate (CMIP5) ● Systematic error assessment in the20th century runs ● Analysis of dynamics related to orography in present and future climate using CMIP5: SALLJ, cold surges and cut-off lows statistics, etc.

Topics disccussed relating to Physical processes at mesoscale associated to climate variability contributing to precipitation forecast quality, Brief survey of used models in France and in Argentina:MesoNH BRAMS and WRF Relevant physical processes: Nocturnal Boundary layer (vertical resolution) Deep convective parameterization and its relevance at small scales Importance of evolutive aerosols for clouds modelling Validation of results from satellites Direct calculation of synthetic satellite images from model results (IR, microwave, visible) Radiative properties of clouds in radiative transfer codes Initial conditions and surface properties Consensus for relevant but out of collaboration Intercomparison of different models Interest to identify an experimental existing project over South America which gives a good framework or model intercomparison Group 2: Physical mechanisms explaining climate variabilty and changes is South America (day 1)

Analysis of the large-scale processes affecting the Southern American Climate at the inter-annual time-scales. Were discussed, the analysis of the CMIP5 runs, their representation of the ENSO variability, and of the SAM associated variability. Was also discussed the analysis of the teleconnections from the indian monsoon regions and from the ENSO region. This is left for memory at the present stage and in the context of the UMI, but emphasis is given to the need to enlarge the number of people from IPSL that could interact with UMI, in particular on these topics. The same remark applies to the polution studies over urban areas, a very active topic at UMI as well as at IPSL. Group 2: Physical mechanisms explaining climate variabilty and changes is South America (day 1)