A. Henderson-Sellers, M. Fischer, K. McGuffie and D. Noone Australian Nuclear Science & Technology Organisation, University of Technology, Sydney and University of Colorado PILPS is a key component of the Global Land Atmosphere System Study (GLASS) which aims to foster an evaluation of the next generation of land- surface schemes and to coordinate the evaluation of land-surface schemes in their different applications. GLASS is a GEWEX project which serves as an interface between the land-surface community and international modelling. PILPS’ GEWEX research is also affiliated with IGBP, particularly ILEAPS. It is co-chaired by Professor Ann Henderson-Sellers of ANSTO and Professor Andrew Pitman of Macquarie University. Created in 1992, PILPS has offered the land-surface simulation community a frame of reference for intercomparison and high quality data sets against which to evaluate their modelling of land- atmosphere exchanges for almost 13 years. It is the World Climate Research Programme’s (WCRP) longest MIP – Model Intercomparison Project. Matt Fischer Ann Henderson-Sellers Contacts iPILPS: Community Modelling of Stable Water Isotopes The goals of iPILPS are to (i) offer a framework for inter-comparison of isotope-enabled land surface schemes (ILSS) and (ii) encourage improvement of these schemes by evaluation against high quality (isotope) observations. When iPILPS was approved by GLASS in September 2004, it was agreed that its first stage (Phase 1) would focus on the stable water isotopes H 2 18 O and 1 H 2 H 16 O with carbon isotopic simulations to be combined in from The three locations selected for iPILPS Phase 1 lie in GEWEX CSE basins and offer a broad range of ecological and climatic conditions: Mid-latitude (deciduous) grass/wood, Munich 48°N 11°E Tropical (evergreen) rainforest, Manaus 3°S 60°W Mid-latitude eucalypt (evergreen) forest, Tumbarumba 35°S 148°E A field campaign has been launched at Tumbarumba in Australia as part of the IAEA Moisture Isotopes in the Biosphere and Atmosphere (MIBA) project which will also provide additional new diurnal isotope data. Introduction to PILPS Isotopes in PILPS: iPILPS iPILPS Phase 1 Experiment Phase 1 of iPILPS tests the hypothesis that: observation and analysis of the diurnal fluxes of 1 H 2 18 O and 1 H 2 H 16 O between the soil, plants and atmosphere can accurately determine the partitioning of precipitation into transpiration, evaporation and total runoff. iPILPS will contribute (i) to improving the accuracy with which land-surface schemes partition net available surface energy into latent and sensible heat fluxes and thus (ii) to decreasing the uncertainty in hydro-climate modelling and water resource vulnerability predictions. Phase 1 of iPILPS exploits novel stable water isotope (SWI) data and analysis techniques in the development and evaluation of numerical models of ILSSs. To achieve the project aims, it is necessary to: 1.identify and validate hydro-climate models’ ILSSs which already (or plan soon to) incorporate SWIs; 2.appraise SWI data applicable to hydro-climatic and water resource aspects of ILSSs; 3.identify ILSS model and observational data gaps and resolve them; and 4.apply SWI data to specific predictions of well understood locations simulated by available ILSSs. Forcing and Locations for Phase 1 For iPILPS Phase 1, it was determined that the only way of supplying adequately good forcing was to use an isotope-enabled atmospheric model. The REMO (REgionales MOdel, developed by the Max Planck Institute for Meteorology, Hamburg) had been shown to generate high quality simulations for two of the three selected locations (Sturm et al., 2004a,b). The spatial resolution of REMO is ½ degree (~ 54km) with a model timestep of 5 minutes. REMO is nested into ECHAM and the iPILPS Phase 1 forcings were derived from nesting into the ‘climatological’ version of ECHAM which had a constant annual cycle in sea-surface temperatures (Fischer and Sturm, 2005). iPILPS Simulations and Data Needs  18 O in ‰ Annual precipitation BALTEX GAME Murray-Darling CATCH Amazon Mackenzie Mississippi Phase 1 began in late 2004 with distribution of its plan and call for participants. Simulations started in February 2005 with a First Workshop in Sydney in April. Preliminary analysis shows interesting dispersion of simulated 2 H in diurnally transpired flux (above for Tumbarumba January hourly average over all days). To date 5 ILSSs have submitted results to the interactive web page and these results can be viewed on the web. iPILPS ILSS’ evaluation is being undertaken in two stages each with two components: (i) conservation check and spin-up analysis; and (ii) comparison and evaluation against observations. However, there is a dearth of diurnal scale observations of the stable water isotopes H 2 18 O and 1 H 2 H 16 O.  2 H in ‰ Transpiration All ILSS owner are welcome to join iPILPS and anyone with quality observational data at diurnal resolutions is encouraged to contact the iPILPS convenors (below).