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II: Progress of EDMF, III: comparison/validation of convection schemes I: some other stuff

Sander Tijm (HIRLAM) Contributions of: Siebesma, De Rooy, Lenderink, De Roode, Sass, Calvo, Ivarsson, Bengtsson, Malardel, Rontu. II: Progress of EDMF, III: comparison/validation of convection schemes I: some other stuff. Hirlam fog problem (2006). Fog improvement. Fog problem over the sea

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II: Progress of EDMF, III: comparison/validation of convection schemes I: some other stuff

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  1. Sander Tijm (HIRLAM) Contributions of: Siebesma, De Rooy, Lenderink, De Roode, Sass, Calvo, Ivarsson, Bengtsson, Malardel, Rontu II: Progress of EDMF,III: comparison/validation of convection schemesI: some other stuff

  2. Hirlam fog problem (2006)

  3. Fog improvement • Fog problem over the sea • Too much fog and too low temperature • Especially in spring and summer • Runaway effect of cloud top cooling -> more cloud water -> larger emissivity -> stronger cloud top cooling • Until in equilibrium with surface flux

  4. Fog improvement

  5. Fog improvement • Improvement of behaviour through (Bent Hansen Sass): • Reduction of cloud water due to raining out of fog layer (fall speed of cloud droplets) • Reduction of cooling through adjustment of thin cloud layer emissivity • Less cloud top cooling and cloud water formation • Less fog and not so cold

  6. Fog improvement

  7. LW-radiation problem • With new surface scheme (quicker reaction to radiation) LW-radiation very important for winter conditions • Clear sky, cold and dry LW-down too low • Surface LW-up too large • Too rapid cooling of surface

  8. LW-radiation problem

  9. De Roode, De Rooy, Lenderink, Siebesma EDMF (TKE)

  10. Use LES to derive updraft model in clear boundary layer. 0 h (km) 1 0 5 x(km) Updraft at height z composed of those grid points that contain the highest p% of the vertical velocities: p=1%,3%,5%:

  11. Development • EDMF (ECMWF) (Massflux + K-profile) • Moist TKE (KNMI) • Merge EDMF + TKE

  12. Problems (RICO case) • mean state not too bad, but …. • Lots of noise • results extremely dependent on parameters • Unpredictable

  13. Adjustment of EC-EDMF • Strip ECMWF EDMF to basics • Some recoding + clean-up • Get rid off ECMWF tricks (prescribed entrainment, turn off diffusivity in cloud, etc) • Use other closure of MF

  14. Modifications in massflux • Dry parcel: • Reduce initial updraft velocity (reduces mass flux contribution at surface) • Moist parcel: • Replace massflux profile, by linear profile subcloud + Rooy/Siebesma in cloud • Moist parcel entrains 10-20% less than dry one (reduces intermittency)

  15. TKE modifications • Add dissipation massflux as source of TKE • Do correction of length scale formulation TKE for transport massflux dry parcel. • Do correction of length scale formulation in case of no shear. • Add small backgroud diffussion to avoid instability in solver. • Apply simple cloud fraction formulation

  16. Results • Stable results ! Almost no intermittency. Good results at least for RICO, Dry CBL + FIRE. More cases to test

  17. RICO

  18. RICO

  19. Dry CBL: ED

  20. Dry CBL: MF

  21. Dry CBL

  22. Dry CBL: T-prof

  23. FIRE

  24. FIRE: ED

  25. FIRE: MF

  26. Developments • Test more cases + including transition cases. • Put more ECMWF stuff back ? • Make cloud mass flux profile more flexible ?

  27. Validation and intercomparison of convection schemes

  28. HIRLAM: intercomparison • Two convection schemes in HIRLAM • Been developed next to each other • Development resources necessary for other tasks (mesoscale) • Release of Hirlam reference system 7.2 • Intercomparison during summer 2007 to choose between schemes

  29. Intercomparison: setup • 8 months in 4 different seasons • Two meteorologically different months per season (e.g. July and August 2006) • Special setups (0.05 degrees, 4D-Var, new surface scheme) • Initial conditions from ECMWF analysis • Surface analysis

  30. Objective verification • Precipitation (30%), Clouds (20%), Synoptic (20%), Upper air (10%), Special features (10%), Daily Cycle (10%) • 8 months: 60% • Special cases: 40% • Other features (sophistication physics, documentation, coding standards, future improvements: independent experts)

  31. Objective verification • Use contingency tables for precipitation (threshold) and cloud cover (correct bin) • Calculate BIAS, PC, FAR, POFD, ETS, HKS, ORSS • Translate scores to 0-100 scale, e.g.: • 100*1/BIAS if BIAS > 1; • 100*BIAS if BIAS < 1

  32. Objective verification • Use RMS and bias for synoptic scores • Best scheme gets 100 for certain score • Second scheme gets 100*RMS(best)/RMS(worst) • Bias: 100*(1-bias/RMS(worst))

  33. Validation of convection schemes • Developments in EDMF important for pbl state, transition to deep convection • Compiling dataset to validate shallow convection in mesoscale model output • Some deep convection cases included also • Observations include: Cabauw tower, Radiosonde, MSG, GPS IWV, 10-min syn obs NL, Radar, PBL from ceilometers

  34. Validation archive • Archive stored at ECMWF • Open for anyone to use • Description at: http://www.knmi.nl/~tijm/HARMONIE_cases.html

  35. Fair weather cumulus

  36. Example: convection dying inland

  37. Daily cycle of convection

  38. Daily cycle of convection

  39. Convection PBL development

  40. Outlook • In addition to shallow convection validation of deep convection: • Strength and depth • Physics dynamics interaction • Impact of parameterisation on resolved deep convection • Impact of initial and boundary conditions • Convection over sea (subtle) • Combination of standard observations over NL ideal for validation work

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