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Are the results of PILPS or GSWP affected by the lack of land surface-atmosphere feedback?

TOA Radiation. S ingle C olumn M odel. Horizontal Flux Divergences. L and S urface M odel. (www.arm.gov). A Single Column Model. Report of the GLASS workshop on land – atmosphere interaction Bart van den Hurk, Paul Houser and Jan Polcher 19-20 April, 2002.

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Are the results of PILPS or GSWP affected by the lack of land surface-atmosphere feedback?

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  1. TOA Radiation Single Column Model Horizontal Flux Divergences Land Surface Model (www.arm.gov) A Single Column Model Report of the GLASS workshop on land – atmosphere interaction Bart van den Hurk, Paul Houser and Jan Polcher 19-20 April, 2002 Are the results of PILPS or GSWP affected by the lack of land surface-atmosphere feedback? Is the use of offline land surface models in LDAS making optimal use of the assimilated data? We need experiments designed to quantify land – atmosphere feedback in land surface modelling and data assimilation. This will take the next step in the complexity chain from offline land surface models to fully coupled GCM’s. Focus on land – atmosphere coupling by means of turbulent exchange, but discarding the processes related to radiation and precipitation.

  2. The main scientific questions: When and where does land – atmosphere interaction play a significant role in the evolution of land-atmosphere fluxes and state variables? Does the absence of this coupling in PILPS-like calibration/evaluation experiments put a strong constraint on the general applicability of the results of these experiments? Is the solution of a land data assimilation experiment using an offline land surface model configuration different from a system that includes land – atmosphere feedback?

  3. PHASE 1: GOAL: Inventory conditions (climate, land cover and –heterogeneity, synoptic situation) where modelled fluxes and state variables are sensitive to the land-atmosphere coupling. ACTION: For a number of locations and time periods, the behaviour of land surface models in an offline and a coupled mode (using a SAM – Simplified Atmospheric Model) will be compared. The SAM should be able to calculate the vertical exchange processes due to turbulence, thermodynamics and radiation, but does not necessarily supply the precipitation and radiation forcing to the land surface. PHASE 2: GOAL: Identify the nature of the land – atmosphere coupling by varying the combinations land model – boundary layer model in a systematic way. ACTION: Use a common land – atmosphere coupler (which is being established within the ALMA action of GLASS), and start with providing a single boundary layer model, to which a range of land surface models can be connected. PHASE 3: GOAL: The relation between data assimilation and land – atmosphere feedback will be addressed. ACTION: In this phase, a combination of an offline model and SCM should be allowed to assimilate additional data that are not present in the forcings already provided. These additional data could consist of surface state variables (soil moisture, snow), atmospheric quantities (screen level parameters, surface heating rates), surface fluxes or combinations of these obtained from co-located field experiments or remote sensing.

  4. Known Actions • ELDAS: Coupling TESSEL, the surface scheme in the DWD Lokal Modell, and the ISBA models to a common SCM and assimilation procedure. • Individual Efforts • Hoshin and Luis? • Christa and Paul: NASA-AIST coupling of LIS 1km global LSM to PBL model • Others?

  5. The First International Local-Coupled Action Field Experiment (FILCAFE) • GOAL: Collect a specifically targeted dataset to meet the objectives of the GLASS local-coupled action. • A well-defined mesoscale hydrologic catchment (for surface water balance observations) • Observations from groundwater table through PBL • Include heterogeneity in elevation, vegetation, soils, climate (inc. snow), etc. • Observation platforms: • In-situ: weather, fluxes, snow, soil moisture, groundwater, vegetation • Aircraft: fluxes, temperature, moisture, microwave, etc. • Soundings: tethered • Satellite: various Questions: What should the spatial scale and heterogeneity be? When, where, and how long? Is this experiment of interest? • States • Soil Moisture • Groundwater • Surface Water • Temperature • (soil, veg, air) • Humidity • Wind • Pressure • Snow • Carbon • Nitrogen • Biomass • Fluxes • Evapotranspiration • Sensible Heat Flux • PBL fluxes • Radiation • Runoff • Drainage • Isotopes/carbon • Parameters • Soil Properties • Vegetation Properties • Elevation & Topography • Subgrid Variation • Catchment Delineation • River Connectivity • Forcing • Precipitation • Wind profiles • Humidity profiles • Radiation • Air Temperature profiles

  6. How do we get action on theGLASS local-coupled action?Bart van den Hurk, Hoshin Gupta, Luis Bastidas, Jan Polcher, Christa Peters-Lidard, Paul HouserDevelop a Phase 1 experimental planPut in place tools (SCM) and datasetsEngage the community

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