1 / 35

numerical short range fog forecast and low clouds with COSMO-FOG

numerical short range fog forecast and low clouds with COSMO-FOG. Matthieu Masbou & Andreas Bott. Meteorologisches Institut – Universität Bonn- mmasbou@uni-bonn.de. DACH2010-Meteorologentagung- Bonn. Fog: A visibility reduction. 1.4km. 1km. 0.5 km. 100 m. 50 m. FOG Visibility < 1000 m

ora
Télécharger la présentation

numerical short range fog forecast and low clouds with COSMO-FOG

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. numerical short range fog forecast and low clouds with COSMO-FOG Matthieu Masbou & Andreas Bott Meteorologisches Institut – Universität Bonn- mmasbou@uni-bonn.de DACH2010-Meteorologentagung- Bonn

  2. Fog: A visibility reduction 1.4km 1km 0.5 km 100 m 50 m FOG Visibility < 1000 m 0.01 g/kg < LWC < 0.3 g/kg

  3. Fog Formation 1D 1D • Cooling • Moistening • Turbulent Mixing • Reach saturation Radiation fog Precipitation fog 3D 3D 3D Upslope fog Valley fog Advection fog

  4. 3D FOG Model = COSMO + PAFOG 20 000 m Water/Ice Cloud Precipitation qc Nc 2000 m Nc Fog/Stratus Nc qc Soil Model Droplet number concentration Liquid Water Content LM-Dynamics PAFOG-Microphysics Boundary

  5. PAFOG Microphysics Supersaturation S Assumption for droplet spectra :Log-normal 200 0.2 0.25 0.3 D droplet diameter CCN conc. in c/m3 0.35 Dc,0 mean value of D σc standard deviation of size distribution (σc=0.2) 0 10 20 Diameter in μm

  6. PAFOG Microphysics 1- Activation[Twomey (1954)] : k and Na depend on their environment (maritime, rural, urban) 2a-Detailed Condensation/Evaporation : parametrised Köhler relation [Chaumerliac et al. (1987) and Sakakibara (1979)] 2b-Time dependent relation between supersaturation S and diameter D 3-Droplet size dependent sedimentation [Berry and Pranger 1974] Positive Definite Advection Scheme [Bott (1989)]

  7. STANDARD-PAFOG Microphysics g/kg LWC-PAFOG microphysics LWC-Standard microphysics 500 0.5 g/kg Altitude 0.25 0 0.01 51.5 53.5 1/cm3 CCN-PAFOG microphysics Latitude 500 70 1/cm3 Lindenberg Observatory 2005 September 27th 03 UTC 27 hours forecast Altitude 40 10 0 51.5 53.5 Latitude

  8. Vertical resolution 14 layers below 2000 m 25 layers below 2000 m 94 m COSMOoperational COSMO-FOG Atmosphere 51 m 40 m 10 layers Δz=4m 20 m Soil 8 levels: 0.005; 0.02; 0.08; 0.24; 0.78 cm…

  9. Vertical resolution 14 layers below 2000 m 32 layers below 2000 m 94 m Tatm Tatm COSMO-operational COSMO-FOG Atmosphere 51 m 40 m 10 layers Δz=4m 20 m Soil Tsoil Tsoil 8 levels: 0.005; 0.02; 0.08; 0.24; 0.78 cm…

  10. Vertical resolution 14 layers below 2000 m 25 layers below 2000 m 94 m Tatm Tatm COSMOoperational COSMO-FOG Atmosphere 51 m 40 m 10 layers Δz=4m 20 m Soil Tsoil Tsoil 8 levels: 0.005; 0.02; 0.08; 0.24; 0.78 cm…

  11. Vertical resolution 14 layers below 2000 m 25 layers below 2000 m 94 m Tatm Tatm COSMOoperational COSMO-FOG Atmosphere 51 m 40 m 10 layers Δz=4m 20 m FOG Soil Tsoil Tsoil 8 levels: 0.005; 0.02; 0.08; 0.24; 0.78 cm…

  12. Turbulence Scheme Turbulent mixing terms are given by a flux gradient relation Parametrized following Mellor and Yamada(1982) 2.5th-Order (Raschendorfer, 2001)

  13. Instability in Turbulence Scheme Kh 10 time steps

  14. Instability in Turbulence Scheme Kh 20 time steps

  15. Instability in Turbulence Scheme Kh 30 time steps

  16. Instability in Turbulence Scheme Kh 40 time steps

  17. Modification of Turbulence Scheme Collaboration with Olivier Fuhrer, Meteoswiss Step 1: replace semi- implicit calculation of the TKE diffusion term by a implicit calculation

  18. Modification of Turbulence Scheme Collaboration with Olivier Fuhrer, Meteoswiss Step 1: replace semi- implicit calculation of the TKE diffusion term by a implicit calculation After 30 minute integration

  19. Modification of Turbulence Scheme Collaboration with Olivier Fuhrer, Meteoswiss Step 1: replace semi- implicit calculation of the TKE diffusion term by a implicit calculation After 1 hour integration

  20. Modification of Turbulence Scheme Collaboration with Olivier Fuhrer, Meteoswiss Step 1: replace semi- implicit calculation of the TKE diffusion term by a implicit calculation After 2 hour integration First development of numerical Instabilities !!

  21. Modification of Turbulence Scheme Collaboration with Olivier Fuhrer, Meteoswiss Step 1: replace semi- implicit calculation of the TKE diffusion term by a implicit calculation Step 2: Based on the work of M. Buzzy, 2008 Instability due to wind Shear term : Filtering the wind gradient before evaluating the stability function More details about problem of the instability in stable turbulence regime. See Buchard and Deleersnijder 2001, Mellor 2003, Buzzi 2008

  22. Modification of Turbulence Scheme Kh Min Kh=1.0 1 UTC 2 UTC 3 UTC 4 UTC 5 UTC Min Kh=0.001

  23. Modification of Turbulence Scheme Kh Min Kh=1.0 7 UTC 8 UTC 9 UTC 10UTC 11UTC Min Kh=0.001

  24. Sensitivity of soil temperature No significant influence on fog spatial extension October, 6th 2005 init 00 UTC Measurements original initialization TKVH min = 0.001 T_SO + 2 C T_SO - 2 C

  25. Sensitivity of soil moisture No significant influence on fog spatial extension October, 6th 2005 init 00 UTC Measurements original initialization TKVH min = 0.001 W_SO = ADP W_SO = Pore Vol.

  26. 06 October 2005 01 UTC MSG-product for fog and low stratus Specifiy water content in kg/kg (COSMO-FOG) TKVH min = 1.0 TKVH min = 0.001

  27. 06 October 2005 02 UTC MSG-product for fog and low stratus Specifiy water content in kg/kg (COSMO-FOG) TKVH min = 1.0 TKVH min = 0.001

  28. 06 October 2005 03 UTC MSG-product for fog and low stratus Specifiy water content in kg/kg (COSMO-FOG) TKVH min = 1.0 TKVH min = 0.001

  29. 06 October 2005 04 UTC MSG-product for fog and low stratus Specifiy water content in kg/kg (COSMO-FOG) TKVH min = 1.0 TKVH min = 0.001

  30. 06 October 2005 05 UTC MSG-product for fog and low stratus Specifiy water content in kg/kg (COSMO-FOG) TKVH min = 1.0 TKVH min = 0.001

  31. 06 October 2005 06 UTC MSG-product for fog and low stratus Specifiy water content in kg/kg (COSMO-FOG) TKVH min = 1.0 TKVH min = 0.001

  32. 06 October 2005 07 UTC MSG-product for fog and low stratus Specifiy water content in kg/kg (COSMO-FOG) TKVH min = 1.0 TKVH min = 0.001

  33. 06 October 2005 08 UTC MSG-product for fog and low stratus Specifiy water content in kg/kg (COSMO-FOG) TKVH min = 1.0 TKVH min = 0.001

  34. CONCLUSION - Implementation of new turbulent diffusion scheme - Solve numerical instability in the vertical mixing - Turbulent Scheme very sensitive of TKVH min value Outlook - Sensitivity study of TKVH and TKVM min values • influence of initialization time

  35. Bibliography Burchard, H. and E. Deleersnijder, 2001: Stability of algebraic non-equilibrium second order closure models. Ocean Modelling, 3, 33-50. Buzzi, M., 2008: Challenges in Operational Numerical Weather Prediction at High Resolution in Complex Terrain, PhD‘s thesis, Swiss federal institute of technology (ETH). Deleersnijder, E. and H. Burchard, 2003: Reply to Mellor‘s comments on „ Stability of algebraic non-equilibrium second order closure models“. Ocean Modelling, 5, 291-293. Galperkin, B., L. K. Kantha, S. Hassid and A. Rosati, 1988: A quasi-equilibrium turbulent energy model for geophysical flows. J. Atmos. Sci., 45, 55-62. Kantha, L.H. and C.A. Clayson, 1994: An improved mixed layer model for geophysical applications. J. Geophys. Res., 99, 235-266. Mellor, G.L. and T. Yamada, 1982: Development of a turbulence closure model for geophysical fluid problems. Reviews of Geophysics and Space Physics, 20, 851-875. Mellor, G.L., 2003: Comments on „ Stability of algebraic non-equilibrium second order closure models“ by H. Burchard and E. Deleersnijder. Ocean Modelling, 5, 193-194.

More Related