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The LoCo theme

The LoCo theme. Bart van den Hurk, Christa Peters-Lidard. What’s the issue?. DeBilt 2002 workshop: “Fixed” atmospheric forcings impose constrain on LSM dynamics -> calibration not carried out in the context of the atmosphere 3-stage experiment plan Stage 1

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The LoCo theme

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  1. The LoCo theme Bart van den Hurk, Christa Peters-Lidard GLASS panel meeting 15 – 17 sep 2004

  2. What’s the issue? • DeBilt 2002 workshop: • “Fixed” atmospheric forcings impose constrain on LSM dynamics -> calibration not carried out in the context of the atmosphere • 3-stage experiment plan • Stage 1 • Inventory of models/cases where LAC is significant • Do coupled/uncoupled runs with “own” LSM-PBL models, analysing the amplification/dampening of perturbation • Stage 2 • Couple suite of LSM’s to common PBL • Stage 3 • Explore data assimilation: repeat exp’s with/without DA GLASS panel meeting 15 – 17 sep 2004

  3. What’s the problem? • Problem of LAC is difficult to conceptualize • Very site/model/climate specific • Complex infrastructure required • Difficult to define clean experiments with well defined BC’s • Communities of LSS’s and PBL’s are rather poorly mixed • Participants need to be familiar with relatively wide range of physics themes and code departments • Related issues have iterated already 20+ years (e.g. stable boundary layer parameterization) GLASS panel meeting 15 – 17 sep 2004

  4. What´s the future? • Criteria: • Address “true” rather than “academical” problems • Follow bottom-up procedure: demonstrate the potential for success by small well defined experiment with modest group size • Don’t plan further than can be overseen from where we are: the issue needs a lot more discussions GLASS panel meeting 15 – 17 sep 2004

  5. What’s the plan? • Define 2 clearcase problems: • (1) The Stable Boundary Layer • Problem: (min) temperature bias in Climate & NWP • Community: both climate change impact & NWP • (2) The hydrological coupling • Problem: evaporation in PILPS exp’s strongly constrained by atm forcing -> are LSM’s overly sensitive? • Community: LSM/Hydrology GLASS panel meeting 15 – 17 sep 2004

  6. What about the stable boundary layer? • Small = beautiful • Don’t reinvent the wheel • The CASES experiment • 3 subsequent diurnal cycles • Studies with SCM’s already carried out (revealed strong sensitivity to Ts = T • LES simulations will be carried out for nighttime conditions (not for daytime) • Plan: particìpate with some LSM groups (KNMI, NASA?) and analyse results in terms of “coupling coefficient”  = f(Ta/z, Ts/z, u/z, …) • KNMI has PhD position which can (partially) be involved GABLS GLASS panel meeting 15 – 17 sep 2004

  7. What about the hydrological coupling? • Look at some areas showing up in the GLACÉ results: • Strongly coupled (HAPEX Sahel) • Weakly coupled (Cabauw) • Carry out both coupled and uncoupled SCM simulations to look at difference in LSM behaviour in coupled and uncoupled modes • Use ELDAS SCM infrastructure developed at ECMWF • Participants: KNMI/ECMWF (depending on funding), ??? • See whether this initiative gan be given more momentum after first published results GLASS panel meeting 15 – 17 sep 2004

  8. What about the LoCo team? • As for everyone: my time is limited, primary research focus is elsewhere • Willing to monitor, not to initialize large scale intercomparison project GLASS panel meeting 15 – 17 sep 2004

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