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Land-surface and the key issues

Land-surface and the key issues. Bart van den Hurk co-chair GLASS. Overview of key-issues. Model development (parameterization and model structure) Surface characteristics/parameters Land-atmosphere interaction, feedbacks and climate change attribution Data assimilation.

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Land-surface and the key issues

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  1. Land-surface and the key issues Bart van den Hurk co-chair GLASS Land surface key issues and GLASS progress

  2. Overview of key-issues • Model development (parameterization and model structure) • Surface characteristics/parameters • Land-atmosphere interaction, feedbacks and climate change attribution • Data assimilation Land surface key issues and GLASS progress

  3. General developments in the past decades • Increases in • number of key components • ’80s: surface energy • ’90s: surface hydrology • ’00s: surface biochemistry • ’10s: surface feedbacks (?) • spatial detail • more surface types become relevant (urban, lakes) • more types of land-atm interaction become relevant • contribution to predictability at various time scales Land surface key issues and GLASS progress

  4. Outstanding parameterization issues (1) • Hydrology P-E > 0 Often it’s not! We need: • groundwater redistribution • overland flow (river routing) and wetland formation • dynamic calibration procedures • Snow Okavanga river Botswana: floodplain extent  f(local P) rms of basin discharge old scheme new scheme snow dominated basins Land surface key issues and GLASS progress

  5. Outstanding parameterization issues (2) • Biogeochemistry • Photosynthesis and carbon allocation used to be a “climate application”, but… • phenology (LAI) and dependence on nutrients and droughts • (temperature sensitivity of) soil respiration • releases CH4 from wetlands, BVOC from forest, aerosol from arid or urban areas anomaly fAPAR summer 2003 (obs and modelled); Ciais et al 2005 Land surface key issues and GLASS progress

  6. Outstanding parameterization issues (3) • Human land use and hydrology management • urban “tiles” • lakes • irrigation Siebert et al, 2005 Land surface key issues and GLASS progress

  7. Outstanding issues in land-atmosphere interaction • To what extent is land responsible for land-atm.coupling variability? • Studies with CRM and LES underway • sign of soilm-precip.feedback depends on convective parameterization PCTL positive feedback (Pwet-Pdry) PCTL negative feedback Hohenegger et al, in press Land surface key issues and GLASS progress

  8. Outstanding Land Data Assimilation issues (1) • Multiple systems around (GLDAS, NWP systems) or coming up (Land Flux) • Offline systems rely heavily on precip/rad forcing, coupled (“nudging”) systems on assumed dSM/dRH • Land Flux from GRP maybe should merge concepts Science question: will DA reduce the spread in current ET estimates? Land surface key issues and GLASS progress

  9. Outstanding Land Data Assimilation issues (2) • Data assimilation is also developing into new observational types • (SMOS) soil moisture • LAI from NDVI (requires long assimilation window) • Data assimilation and parameter estimation become increasingly intertwined • parameterization is increasingly relying on calibration rather than model structure • The suite of systems requires a coordinated Land Data Assimilation Intercomparison Project (LDAIP) Land surface key issues and GLASS progress

  10. Outstanding feedback/ attribution issues (1) • Diagnostics for land atmosphere coupling vary widely • (Koster’s , P/sm, LCL/sm, diurnal T/RH) • …but refer to different processes • …and are not always observable • Integrated framework is being developed in GLASS Land surface key issues and GLASS progress

  11. Outstanding feedback/ attribution issues (2) • Experiments address land use in climate signal • Land use 1870 and 1992 provided to 7 GCMs • …but LUCID learns that parameter transfer is far from straightforward • GCMs have different tile structures and model philosophies (e.g. yes/no phenology, yes/no prognostic albedo, …) JJA temp response of land use change Land surface key issues and GLASS progress

  12. Outstanding application/ operation issues (1) • Surface Tile structure • debate on “types of heterogeneity” is not as active anymore, but will increase again when spatial resolution increases (land param. in LES) • some land surface types demand complex tiling structure (e.g. floodplains/wetlands with coupling to groundwater) • tile structure determines interpretation of land use data to a large extent (see LUCID example) • Coupled/offline operation • e.g. routing/groundwater need horizontal network • data assimilation of LAI needs long time window Land surface key issues and GLASS progress

  13. Outstanding application/ operation issues (2) • Land Information System (LIS) • LIS is increasingly suited for complex modelling/data assimilation experiments • multiple LSMs coupled to WRF or using offline forcings data • data assimilation capabilities • but its portability can probably be improved • Also ECMWF is integrating offline surface driver into Integrated Forecasting System Land surface key issues and GLASS progress

  14. Conclusions on outstanding issues • Parameterization • new components (groundwater, lakes, urban, …) • new diagnostics and/or experimental set-up: • Data assimilation • combination of scheme structures desired • trade-off data assimilation/parameter calibration revisited • Infrastructure • need for flexible LIS-type systems will increase “What is the true contribution of the land component to the climate system?” “Does my land surface model describe this contribution sufficiently well?” Land surface key issues and GLASS progress

  15. Progress report of GLASS LoCo GSWP • The current structure Land surface key issues and GLASS progress

  16. Some issues concerning GLASS structure • PILPS-type studies are still quite active (Urban, Snow, Radiation) but does not answer the question: how good should a model be? What benchmark should be considered? • Data-assimilation is not well visible in structure • Difference between local and global coupling is artificial Land surface key issues and GLASS progress

  17. Proposal for new structure (under discussion) Coordinated LDAIP LUCID land-atmosphere coupling model data fusion LoCo metrics GLACE2 LandFlux PILPS-Urban benchmarking SnowMIP RAMI4PILPS PILPS-Carbon 2 current projects new projects Land surface key issues and GLASS progress

  18. Proposal for new structure (under discussion) LUCID land-atmosphere coupling model data fusion LoCo metrics GLACE2 PILPS-Urban benchmarking SnowMIP Land surface key issues and GLASS progress

  19. Global Land Atmosphere Coupling Exp 2: GLACE2 • Adressing potential seasonal predictability from land surface state • Integration into WCRP/TFSP project { Land surface key issues and GLASS progress

  20. Experiment overview Step 1: Initialize land states with “observations”, using GSWP approach Perform ensembles of retrospective seasonal forecasts Evaluate forecasts against observations Initialize atmosphere with “observations”, via reanalysis Prescribed SSTs or the use of a coupled ocean model Land surface key issues and GLASS progress

  21. Experiment overview Step 2: “Randomize” land initialization! Initialize land states with “observations”, using GSWP approach Perform ensembles of retrospective seasonal forecasts Evaluate forecasts against observations Initialize atmosphere with “observations”, via reanalysis Prescribed SSTs or the use of a coupled ocean model Land surface key issues and GLASS progress

  22. Experiment overview Step 3:Compare skill; isolate contribution of realistic land initialization. Forecast skill obtained in identical experiment, except that land is not initialized to realistic values Forecast skill obtain in experiment using realistic land initialization Forecast skill due to land initialization Land surface key issues and GLASS progress

  23. Confirmed participant list Group/Model # models Points of Contact 1. NASA/GSFC (USA): GMAO seasonal forecast system (old and new) 2. COLA (USA): COLA GCM, NCAR/CAM GCM 3. Princeton (USA): NCEP GCM 4. IACS (Switzerland): ECHAM GCM 5. KNMI (Netherlands): ECMWF 6. GFDL (USA): GFDL system 7. U. Gothenburg (Sweden): NCAR 8. CCSR/NIES/FRCGC (Japan): CCSR GCM 2 R. Koster, T. Yamada 2 P. Dirmeyer, Z. Guo E. Wood, L. Luo 1 1 S. Seneviratne, R. Andreas 2 B. van den Hurk, H. Camargo, G. Balsamo 1 T. Gordon 1 J.-H. Jeong 1 T. Yamada 11 models Land surface key issues and GLASS progress

  24. Generation of SST Boundary Conditions • Needed: SST conditions for forecasts that do not include measurements of SSTs during the forecast period. • Approach: Determine persistence timescales from observational record (with data exclusion) and reduce initial (measured) SST anomalies with time into the forecast, using those timescales. Land surface key issues and GLASS progress

  25. “Persisted” SST boundary conditions have been constructed and are now available online. (T. Yamada) Land surface key issues and GLASS progress

  26. Many groups started simulations Land surface key issues and GLASS progress

  27. Original timeline • Summer 2007: • Finish identifying interested modeling groups • Summer 2007 • Provide data to participants (meteorological forcing data, atmospheric initialization, SST conditions) • Summer/Fall 2008 • Simulations due • Fall/Winter 2008 • First analyses performed Land surface key issues and GLASS progress

  28. New timeline • Summer 2007: • Finish identifying interested modeling groups • Summer 2007 • Provide data to participants (meteorological forcing data, atmospheric initialization, SST conditions) • Summer/Fall 2008 • Simulations due • Fall/Winter 2008 • First analyses performed Spring 2008 Fall/Winter 2008 First Spring 2009 Land surface key issues and GLASS progress

  29. http://gmao.gsfc.nasa.gov/research/GLACE-2/ Land surface key issues and GLASS progress

  30. Proposal for new structure (under discussion) LUCID land-atmosphere coupling model data fusion LoCo metrics GLACE2 PILPS-Urban benchmarking SnowMIP Land surface key issues and GLASS progress

  31. Land Use and Climate – IDentification of robust impacts (LUCID) • Designed to separate land use change and GHG signal • Multiple phases (prescribed SST  coupled models) • Phase 1: • Fixed SSTs • 4 ensembles (30 yrs, 5 members) • pre-industrial/present-day vegetation • pre-industrial/present-day GHG & SST • 7 GCMs • First results presented during sep 2008 Paris w/s Land surface key issues and GLASS progress

  32. Major outcome • Transfer of common landuse maps to model parameters quite variable • tiling structure • assignment of PFTs • parameter treatment (fixed/prognostic albedo, z0) • phenology (prescribed/prognostic LAI) • Result • Response between models not very uniform • No reason to suspect significant teleconnection patterns from land use • GRL paper (Pitman et al) being drafted Land surface key issues and GLASS progress

  33. LUCID JJA LHF Small difference between forest/crop LAI phenology of LAI Land surface key issues and GLASS progress

  34. Proposal for new structure (under discussion) LUCID land-atmosphere coupling model data fusion LoCo metrics GLACE2 PILPS-Urban benchmarking SnowMIP Land surface key issues and GLASS progress

  35. LoCo Fueling convection • Multiple processes • Multiple diagnostics being explored • Proposal for hierarchy of land-atm coupling maps (see GEWEX News November’08) • Proof of concept to be applied to SGP with LIS PBL cloud formation Triggering of convection direct PBL feedback on surface fluxes remembering anomalies Land surface key issues and GLASS progress

  36. Proposal for new structure (under discussion) LUCID land-atmosphere coupling model data fusion LoCo metrics GLACE2 PILPS-Urban benchmarking SnowMIP Land surface key issues and GLASS progress

  37. PILPS-Urban (Sue Grimmond, KCL) http://geography.kcl.ac.uk/micromet/ModelComparison • Aimed at evaluation of urban models • range in structure (simple plane parallel canopies  complex multicomponent canyon models) • Big group (22 models!) • Initial data-set (Vancouver) released for testing • Presently: models are running an anonymous city • hierarchy of data releases (characteristics, calibration, validation) Land surface key issues and GLASS progress

  38. Proposal for new structure (under discussion) LUCID land-atmosphere coupling model data fusion LoCo metrics GLACE2 PILPS-Urban benchmarking SnowMIP Land surface key issues and GLASS progress

  39. SnowMIP (Richard Essery) • BAMS overview paper submitted • Main results: • focus on forest • 33 models, 11 countries • sites Canada, US, Switzerland • results: • accumulation and ablation ~ ok • albedo ~ ok • mass and difference forest/open land vary widely • soil temperatures too low Land surface key issues and GLASS progress

  40. SWE accumulation at open sites Land surface key issues and GLASS progress

  41. Soil Temperature Land surface key issues and GLASS progress

  42. Final remarks • Parameterization focuses on new components • Systematic benchmarking of both models and data is not well embedded but needs attention • Data assimilation will benefit from LDAIC • New infrastructure inspired on LIS should combine offline modelling, data fusion and benchmarking • GLASS panel will get new membership Land surface key issues and GLASS progress

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