WIND ENERGY METEOROLOGY                          UNIT 6                          ATMOSPHERIC FLOW MODELING II:            ...
ATMOSPHERIC FLOW MODELING II                          SCALES OF ATMOSPHERIC MOTION                          ‣ The atmosphe...
ATMOSPHERIC FLOW MODELING II                          SCALES OF ATMOSPHERIC MOTION                           Scale Categor...
ATMOSPHERIC FLOW MODELING II                          SCALES OF ATMOSPHERIC MOTION                          EXAMPLE: MICRO...
ATMOSPHERIC FLOW MODELING II                          SCALES OF ATMOSPHERIC MOTION                          EXAMPLE: MESOS...
ATMOSPHERIC FLOW MODELING II                          SCALES OF ATMOSPHERIC MOTION                          EXAMPLE: MESOS...
ATMOSPHERIC FLOW MODELING II                          SCALES OF ATMOSPHERIC MOTION                          EXAMPLE: MESOS...
ATMOSPHERIC FLOW MODELING II                          SCALES OF ATMOSPHERIC MOTION                          EXAMPLE: SYNOP...
ATMOSPHERIC FLOW MODELING II                          SCALES OF ATMOSPHERIC MOTION                          EXAMPLE: GLOBA...
ATMOSPHERIC FLOW MODELING II                          MESOSCALE MODELING                          EXAMPLE: WEATHER RESEARC...
ATMOSPHERIC FLOW MODELING II                          WHAT IS WRF...?                          ‣   Weather Research and Fo...
ATMOSPHERIC FLOW MODELING II                          WHAT IS WRF...?                          WRF system components      ...
ATMOSPHERIC FLOW MODELING II                          WHAT IS WRF...?                          ‣   Non-hydrostatic model  ...
ATMOSPHERIC FLOW MODELING II                          WHAT IS WRF...?                          ‣ Advanced Research WRF (AR...
ATMOSPHERIC FLOW MODELING II                          ARW OR NMM...?                          ‣ ARW and NMM               ...
ATMOSPHERIC FLOW MODELING II                          ARW DYNAMICS: KEY FEATURES                          ‣ Equations     ...
ATMOSPHERIC FLOW MODELING II                          GOVERNING EQUATIONS                          compressible,          ...
ATMOSPHERIC FLOW MODELING II                          VERTICAL COORDINATE                          The ARW equations are f...
ATMOSPHERIC FLOW MODELING II                          ARW DYNAMICS: KEY FEATURES                          Horizontal grid ...
ATMOSPHERIC FLOW MODELING II                          ARW DYNAMICS: KEY FEATURES                          ‣ Prognostic Var...
ATMOSPHERIC FLOW MODELING II                          ARW DYNAMICS: KEY FEATURES                          ‣ Spatial Discre...
ATMOSPHERIC FLOW MODELING II                          ARW DYNAMICS: KEY FEATURES                          ‣ Lateral Bounda...
ATMOSPHERIC FLOW MODELING II                          ARW DYNAMICS: KEY FEATURES                          ‣ Earths rotatio...
ATMOSPHERIC FLOW MODELING II                          WRF MODEL PHYSICS                          ‣ Microphysics: Bulk sche...
ATMOSPHERIC FLOW MODELING II                          WRF MODELING SYSTEM                                                 ...
ATMOSPHERIC FLOW MODELING II                          WRF PRE-PROCESSING SYSTEM                          ‣ The purpose of ...
ATMOSPHERIC FLOW MODELING II                          WRF PRE-PROCESSING SYSTEM                                           ...
ATMOSPHERIC FLOW MODELING II                          THE GEOGRID PROGRAM                          ‣ Geogrid defines      ...
ATMOSPHERIC FLOW MODELING II                          THE GEOGRID PROGRAM                          ‣ First, choose a map p...
ATMOSPHERIC FLOW MODELING II                          ARW PROJECTIONS                                                     ...
ATMOSPHERIC FLOW MODELING II                          ARW DYNAMICS: NESTING                          ‣ A nested domain is ...
ATMOSPHERIC FLOW MODELING II                          ARW DYNAMICS: NESTING                                               ...
ATMOSPHERIC FLOW MODELING II                          GEOGRID: INTERPOLATING STATIC FIELDS                          ‣ Geog...
ATMOSPHERIC FLOW MODELING II                          GEOGRID: INTERPOLATING STATIC FIELDS                          Normal...
ATMOSPHERIC FLOW MODELING II                          GEOGRID: INTERPOLATING STATIC FIELDS                          ‣ Inte...
ATMOSPHERIC FLOW MODELING II                          WRF PRE-PROCESSING SYSTEM                                           ...
ATMOSPHERIC FLOW MODELING II                          THE UNGRIB PROGRAM                          ‣ What is a GRIB file?  ...
ATMOSPHERIC FLOW MODELING II                          THE UNGRIB PROGRAM                          ‣ What does it do?      ...
ATMOSPHERIC FLOW MODELING II                          THE UNGRIB PROGRAM: VTABLES                                         ...
ATMOSPHERIC FLOW MODELING II                          WRF PRE-PROCESSING SYSTEM                                           ...
ATMOSPHERIC FLOW MODELING II                          THE METGRID PROGRAM                          ‣ Horizontally interpol...
ATMOSPHERIC FLOW MODELING II                          WPS SUMMARY                                                         ...
ATMOSPHERIC FLOW MODELING II                          INITIALIZATION                          ‣ ideal.exe                 ...
ATMOSPHERIC FLOW MODELING II                          RUNNING WRF                          ‣ ideal.exe                    ...
ATMOSPHERIC FLOW MODELING II                          POST-PROCESSING: GRAPHICS                          ‣ Several graphic...
ATMOSPHERIC FLOW MODELING II                          POST-PROCESSING: GRAPHICS                          NCL graphis      ...
ATMOSPHERIC FLOW MODELING II                          POST-PROCESSING: VERIFICATION                          MET verificat...
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Atmospheric flow modeling II

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Atmospheric flow modeling II

  1. 1. WIND ENERGY METEOROLOGY UNIT 6 ATMOSPHERIC FLOW MODELING II: MESO-SCALE MODELING Detlev Heinemann ENERGY METEOROLOGY GROUP INSTITUTE OF PHYSICS OLDENBURG UNIVERSITY FORWIND – CENTER FOR WIND ENERGY RESEARCHMittwoch, 15. Juni 2011
  2. 2. ATMOSPHERIC FLOW MODELING II SCALES OF ATMOSPHERIC MOTION ‣ The atmosphere features a wide range of circulation types, with a wide variety of different behaviors. ‣ Typically, these circulations are classified according to their size (spatial scale) and/or their oscillation period or duration (time scale) 2Mittwoch, 15. Juni 2011
  3. 3. ATMOSPHERIC FLOW MODELING II SCALES OF ATMOSPHERIC MOTION Scale Category Time Scale Spatial Scale Examples seconds to turbulence, small microscale meters to 1 km minutes cumulus clouds thunderstorms, sea minutes to hours kilometers to mesoscale breezes, mountain to 1 day hundreds of km circulations fronts, cyclones, synoptic scale days to weeks thousands of km anticyclones planetary waves, planetary scale weeks to months global el niño 3Mittwoch, 15. Juni 2011
  4. 4. ATMOSPHERIC FLOW MODELING II SCALES OF ATMOSPHERIC MOTION EXAMPLE: MICROSCALE boundary layer turbulence small cumulus clouds / turbulent eddies 4Mittwoch, 15. Juni 2011
  5. 5. ATMOSPHERIC FLOW MODELING II SCALES OF ATMOSPHERIC MOTION EXAMPLE: MESOSCALE thunderstorms/collections of individual storms and their thunderstorms component parts 5Mittwoch, 15. Juni 2011
  6. 6. ATMOSPHERIC FLOW MODELING II SCALES OF ATMOSPHERIC MOTION EXAMPLE: MESOSCALE mountain circulations (lee vortices in this case) 6Mittwoch, 15. Juni 2011
  7. 7. ATMOSPHERIC FLOW MODELING II SCALES OF ATMOSPHERIC MOTION EXAMPLE: MESOSCALE sea breeze circulations 7Mittwoch, 15. Juni 2011
  8. 8. ATMOSPHERIC FLOW MODELING II SCALES OF ATMOSPHERIC MOTION EXAMPLE: SYNOPTIC SCALE high and low pressure most of what we consider day-to- systems, warm and cold fronts day weather 8Mittwoch, 15. Juni 2011
  9. 9. ATMOSPHERIC FLOW MODELING II SCALES OF ATMOSPHERIC MOTION EXAMPLE: GLOBAL SCALE planetary-scale waves climate patterns (e.g., el niño / la niña) 9Mittwoch, 15. Juni 2011
  10. 10. ATMOSPHERIC FLOW MODELING II MESOSCALE MODELING EXAMPLE: WEATHER RESEARCH & FORECASTING MODEL (WRF) http://www.wrf-model.org 10Mittwoch, 15. Juni 2011
  11. 11. ATMOSPHERIC FLOW MODELING II WHAT IS WRF...? ‣ Weather Research and Forecasting Model ‣ Operational forecasting and atmospheric research ‣ Community Model ‣ Developed by NCAR and NOAA ‣ New Version – 3.3: released April 2011 11Mittwoch, 15. Juni 2011
  12. 12. ATMOSPHERIC FLOW MODELING II WHAT IS WRF...? WRF system components 12Mittwoch, 15. Juni 2011
  13. 13. ATMOSPHERIC FLOW MODELING II WHAT IS WRF...? ‣ Non-hydrostatic model ‣ Terrain-following hydrostatic pressure coordinate ‣ Arakawa C-grid staggering ‣ Runge-Kutta 2nd and 3rd order time integration schemes ‣ 2nd to 6th order advection schemes ‣ Semi-implicit acoustic step off-centering ‣ ARW and NMM dynamical cores. 13Mittwoch, 15. Juni 2011
  14. 14. ATMOSPHERIC FLOW MODELING II WHAT IS WRF...? ‣ Advanced Research WRF (ARW) and Nonhydrostatic Mesoscale Model (NMM) are both dynamical cores ‣ Dynamical core includes advection, pressure- gradients, Coriolis, buoyancy, filters, diffusion and time-stepping. ‣ Both use Eulerian mass dynamical cores with terrain-following vertical coordinates ‣ Both share physics, software framework, and parts of the pre- and post-processing systems. 14Mittwoch, 15. Juni 2011
  15. 15. ATMOSPHERIC FLOW MODELING II ARW OR NMM...? ‣ ARW and NMM ‣ Atmospheric physics research ‣ Case-study research ‣ Real-time NWP and forecast system research ‣ Data assimilation research ‣ Teaching dynamics and NWP ‣ ARW only ‣ Regional climate and seasonal time-scale research ‣ Coupled-chemistry applications ‣ Global simulations ‣ Idealized simulations at many scales (e.g. convection, baroclinic waves, large eddy simulations) 15Mittwoch, 15. Juni 2011
  16. 16. ATMOSPHERIC FLOW MODELING II ARW DYNAMICS: KEY FEATURES ‣ Equations ‣ Fully compressible ‣ Non-hydrostatic ‣ Scalar conservative ‣ Vertical Coordinate ‣ Mass-based terrain following coordinate ‣ Top of model is a constant pressure surface 16Mittwoch, 15. Juni 2011
  17. 17. ATMOSPHERIC FLOW MODELING II GOVERNING EQUATIONS compressible, nonhydrostatic, flux-form Euler equations (using a terrain-following mass vertical coordinate) plus diagnostic relation for the inverse density equation of state (plus inclusion of moisture...) 17Mittwoch, 15. Juni 2011
  18. 18. ATMOSPHERIC FLOW MODELING II VERTICAL COORDINATE The ARW equations are formulated using a terrain-following hydrostatic-pressure vertical co- ordinate denoted by η and defined as where where ph: hydrostatic component of the pressure phs and pht: values along the surface and top boundaries, respectively. η varies from a value of 1 at the surface to 0 at the upper boundary of the model domain. This vertical coordinate is also called a mass vertical coordinate. 18Mittwoch, 15. Juni 2011
  19. 19. ATMOSPHERIC FLOW MODELING II ARW DYNAMICS: KEY FEATURES Horizontal grid Arakawa C-grid staggering 19Mittwoch, 15. Juni 2011
  20. 20. ATMOSPHERIC FLOW MODELING II ARW DYNAMICS: KEY FEATURES ‣ Prognostic Variables ‣ Velocity componets u, v ‣ Vertical velocity w, potential temp, geopotential, surface pressure ‣ Time Integration ‣ 3rd order Runge-Kutta scheme (Wicker and Skamarock, 2002) Defining the prognostic variables in the ARW solver as Φ = (U, V, W, Θ, φ′, µ′, Qm) and the model equations as Φt = R(Φ), the RK3 integration takes the form of 3 steps to advance a solution Φ(t) to Φ(t + ∆t): 20Mittwoch, 15. Juni 2011
  21. 21. ATMOSPHERIC FLOW MODELING II ARW DYNAMICS: KEY FEATURES ‣ Spatial Discretization ‣ 2nd to 6th order advection options in horizontal and vertical ‣ Turbulent Mixing and Model Filters ‣ Divergence damping, sub-grid scale turbulence formulation ‣ Initial Conditions ‣ 3 dimensional for real cases ‣ Digital filtering initialization (DFI) 21Mittwoch, 15. Juni 2011
  22. 22. ATMOSPHERIC FLOW MODELING II ARW DYNAMICS: KEY FEATURES ‣ Lateral Boundary Conditions ‣ Periodic, open, symmetric ‣ Top Boundary Conditions ‣ Gravity wave absorbing ‣ Constant pressure level ‣ Rigid lid option ‣ Bottom Boundary Conditions ‣ Physical or free-slip 22Mittwoch, 15. Juni 2011
  23. 23. ATMOSPHERIC FLOW MODELING II ARW DYNAMICS: KEY FEATURES ‣ Earths rotation ‣ Full Coriolis terms included ‣ Mapping to Sphere ‣ Four supported map projections ‣ Nesting ‣ One-way and two-way nesting ‣ Static or moving grids ‣ Nudging ‣ Grid analysis and observation nudging capabilities 23Mittwoch, 15. Juni 2011
  24. 24. ATMOSPHERIC FLOW MODELING II WRF MODEL PHYSICS ‣ Microphysics: Bulk schemes ranging from simplified physics suitable for mesoscale modeling to sophisticated mixed-phase physics suitable for cloud-resolving modeling. ‣ Cumulus parameterizations: Adjustment and mass-flux schemes for mesoscale modeling in- cluding NWP. ‣ Surface physics: Multi-layer land surface models ranging from a simple thermal model to full vegetation and soil moisture models, including snow cover and sea ice. ‣ Planetary boundary layer physics: Turbulent kinetic energy prediction or non-local K schemes. ‣ Atmospheric radiation physics: Longwave and shortwave schemes with multiple spectral bands and a simple shortwave scheme. Cloud effects and surface fluxes are included. 24Mittwoch, 15. Juni 2011
  25. 25. ATMOSPHERIC FLOW MODELING II WRF MODELING SYSTEM 25Mittwoch, 15. Juni 2011
  26. 26. ATMOSPHERIC FLOW MODELING II WRF PRE-PROCESSING SYSTEM ‣ The purpose of the WPS is to prepare input to WRF for real- data simulations. It: ‣ defines simulation domain and ARW nested domains ‣ computes latitude, longitude, map scale factor and Coriolis parameters at every grid point ‣ interpolates time invariant terrestrial data to simulation grids (e.g. terrain height and soil type) ‣ interpolates time-varying meteorological fields from another model onto simulation domains 26Mittwoch, 15. Juni 2011
  27. 27. ATMOSPHERIC FLOW MODELING II WRF PRE-PROCESSING SYSTEM 27Mittwoch, 15. Juni 2011
  28. 28. ATMOSPHERIC FLOW MODELING II THE GEOGRID PROGRAM ‣ Geogrid defines ‣ Map projection ‣ Geographic location of domains ‣ Dimensions of domain ‣ Geogrid provides ‣ Values for static fields at each model grid point ‣ Computes latitude, longitude, map scale factor and Coriolis parameters at each grid point ‣ Horizontally interpolates static terrestrial data (e.g. topography, height, land use category, soil type, vegetation fraction, monthly surface albedo) 28Mittwoch, 15. Juni 2011
  29. 29. ATMOSPHERIC FLOW MODELING II THE GEOGRID PROGRAM ‣ First, choose a map projection ‣ Why? - The Earth is roughly ellipsoidal, but WRF computational domains are defined by rectangles on a plane ‣ ARW can use the following projections ‣ Lambert conformal ‣ Mercator ‣ Polar stereographic ‣ Latitude-longitude 29Mittwoch, 15. Juni 2011
  30. 30. ATMOSPHERIC FLOW MODELING II ARW PROJECTIONS 30Mittwoch, 15. Juni 2011
  31. 31. ATMOSPHERIC FLOW MODELING II ARW DYNAMICS: NESTING ‣ A nested domain is wholly contained within its parent domain and receives information from its parent. ‣ It may also feed information back to its parent [2-way nesting] ‣ A nested domain has exactly one parent ‣ A domain may have one or more children ‣ 2-way nests on the same nesting level must not overlap in coverage 31Mittwoch, 15. Juni 2011
  32. 32. ATMOSPHERIC FLOW MODELING II ARW DYNAMICS: NESTING Nesting structure as a tree for the domains at left Example configuration: 4 domains Each domain is assigned a domain ID # 32Mittwoch, 15. Juni 2011
  33. 33. ATMOSPHERIC FLOW MODELING II GEOGRID: INTERPOLATING STATIC FIELDS ‣ Geogrid interpolates terrestrial, time-invariant fields ‣ Topography height ‣ Land use categories ‣ Soil type (top layer and bottom layer) ‣ Annual mean soil temperature ‣ Monthly vegetation fraction ‣ Monthly surface albedo 33Mittwoch, 15. Juni 2011
  34. 34. ATMOSPHERIC FLOW MODELING II GEOGRID: INTERPOLATING STATIC FIELDS Normally, source data are given on a different projection from the model grid 34Mittwoch, 15. Juni 2011
  35. 35. ATMOSPHERIC FLOW MODELING II GEOGRID: INTERPOLATING STATIC FIELDS ‣ Interpolation options ‣ 4-point bilinear ‣ 16-point overlapping parabolic ‣ 4-point average (simple or weighted) ‣ 16-point average (simple or weighted) ‣ Grid cell average ‣ Nearest neighbour ‣ Breadth-first search 35Mittwoch, 15. Juni 2011
  36. 36. ATMOSPHERIC FLOW MODELING II WRF PRE-PROCESSING SYSTEM 36Mittwoch, 15. Juni 2011
  37. 37. ATMOSPHERIC FLOW MODELING II THE UNGRIB PROGRAM ‣ What is a GRIB file? ‣ WMO standard file format for storing regulary distributed fields ‣ General Regularly-distributed Information in Binary ‣ Fields are compressed with a lossy compression [Think of truncating numbers to a fixed number of digits] ‣ Fields in file are identified by code number ‣ These numbers are referenced against an external table to determing the corresponding field 37Mittwoch, 15. Juni 2011
  38. 38. ATMOSPHERIC FLOW MODELING II THE UNGRIB PROGRAM ‣ What does it do? ‣ reads in GRIB data ‣ extracts meteorological fields ‣ derives required fields if necessary ‣ e.g. Computes RH from T, P and Q ‣ writes requested fields to an intermediate file format ‣ How does ungrib know which fields to extract? ‣ from vtables ... 38Mittwoch, 15. Juni 2011
  39. 39. ATMOSPHERIC FLOW MODELING II THE UNGRIB PROGRAM: VTABLES 39Mittwoch, 15. Juni 2011
  40. 40. ATMOSPHERIC FLOW MODELING II WRF PRE-PROCESSING SYSTEM 40Mittwoch, 15. Juni 2011
  41. 41. ATMOSPHERIC FLOW MODELING II THE METGRID PROGRAM ‣ Horizontally interpolates meteorological data, extracted by ungrib, to simulation domains, defined by geogrid ‣ Rotates winds to WRF grid ‣ i.e. rotates so that U-component is parallel to x-axis, V- component parallel to y-axis 41Mittwoch, 15. Juni 2011
  42. 42. ATMOSPHERIC FLOW MODELING II WPS SUMMARY 42Mittwoch, 15. Juni 2011
  43. 43. ATMOSPHERIC FLOW MODELING II INITIALIZATION ‣ ideal.exe ‣ Program for controlled (idealized) scenarios ‣ Examples include 2-D and 3-D idealized cases, with or without topography, with or without an initial thermal perturbation. ‣ real.exe ‣ Program for real data cases ‣ Interpolates the intermediate files generated by metgrid.exe in the vertical, creates boundary and initial condition files and does some consistency checks. 43Mittwoch, 15. Juni 2011
  44. 44. ATMOSPHERIC FLOW MODELING II RUNNING WRF ‣ ideal.exe ‣ Program for controlled (idealized) scenarios ‣ Examples include 2-D and 3-D idealized cases, with or without topography, with or without an initial thermal perturbation. ‣ real.exe ‣ Program for real data cases ‣ Interpolates the intermediate files generated by metgrid.exe in the vertical, creates boundary and initial condition files and does some consistency checks. 44Mittwoch, 15. Juni 2011
  45. 45. ATMOSPHERIC FLOW MODELING II POST-PROCESSING: GRAPHICS ‣ Several graphical packages available ‣ NCL ‣ ARWpost ‣ RIP4 ‣ VAPOR ‣ IDV 45Mittwoch, 15. Juni 2011
  46. 46. ATMOSPHERIC FLOW MODELING II POST-PROCESSING: GRAPHICS NCL graphis ‣ NCAR Command Language ‣ reads in WRF-ARW data directly ‣ generates a number of graphical plots using scripts ‣ e.g. Horizontal, cross- section, skewT, meteogram, panel 46Mittwoch, 15. Juni 2011
  47. 47. ATMOSPHERIC FLOW MODELING II POST-PROCESSING: VERIFICATION MET verification software ‣ Model Evaluation Tools ‣ All the basics – RMSE, bias, skill scores ‣ Advanced spatial methods (wavelets, objects) ‣ Confidence intervals 47Mittwoch, 15. Juni 2011

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