LEFE type proposal : Impacts of the Andes on the South American (and global?) Climate

1. LEFE type proposal: Impacts of the Andes on the South American (and global?) Climate Systematicerrorson precipitation are important in South America: (manymodels show that, CLIVAR/VAMOS document). Mis-representationof the SALLJ, thattranport the moisturethatfeeds the MCS, diurnal cycle, Etc. have been associated to simulatedprecipitationerrors. Those mis-representationsseem to be in turnrelated to model deficiencies in the physicalparameterizations. Orographic influence on regionalclimateis not wellrepresented by the modelseither. The distinctive features of the Andes are a challenge for numericalmodelling. SALLJ and itsvariability (associatedwith cold surges, MSCs and baroclinicwaves) are largelycontrolled by the presence of the Andes. Also, cut-off lows are a keyfeature in the Andes regionparticularlyduring the cold season. Theyproducesignificantweatherevents. However the physicalprocessesassociatedwiththem are not clearthemand models have deficiences in reproducingthem. But also the Andes impact the global climate: GWs and PWs sources that affect the stratosphericdynamics and in return the tropospheric one via the SAM. This is important for Ozone as well. Theseissues willbeanalysedwith a series of model studiesthatplayswith the representation of orographyand relatedphysicalprocesses in bothGCMs and mesoscale modelswithincreasingresolution. Thesemodel studieswill 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 ArgentinianClimate... » document thatwascommunicated to UMI prior to the Kick-off, these issues will serve as a basis to build-up a LEFE-type projectduring the nextmonths.

2. LEFE type proposal: Impacts of the Andes on the South American (and global?) Climate • Climate change of the orographic influence on regionalclimate (CMIP5) • Systematicerrorassessment in the20th centuryruns • Analysis of dynamicsrelated to orography in present and future climateusing CMIP5: SALLJ, cold surges and cut-off lowsstatistics, etc.

3. Group 2: Physical mechanisms explaining climate variabilty and changes is South America (day 1) 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

4. Group 2: Physicalmechanismsexplainingclimatevariabilty 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.