1 / 26

WRF namelist . input

WRF namelist . input. Dr Meral Demirtaş Turkish State Meteorological Service Weather Forecasting Department. WMO, Training Course, 26 - 30 September 201 1 Alanya, Turkey. Outline. Why do we need a namelist? Sections of namelist.input : time_control domains physics dynamics.

kass
Download Presentation

WRF namelist . input

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. WRF namelist.input Dr Meral Demirtaş Turkish State Meteorological Service Weather Forecasting Department WMO, Training Course, 26-30September 2011 Alanya, Turkey

  2. Outline • Why do we need a namelist? • Sections ofnamelist.input: • time_control • domains • physics • dynamics

  3. Why do we need namelist? The namelist.input file helps users to design their model run. A Fortran namelist contains a list of runtime optionsfor the code to read in during its execution. Use of anamelist allows one to change runtimeconfigurationwithout the need to recompile the source code. • Before running real.exe and wrf.exe, edit namelist.input file for runtime options. • The most up-to-dated namelist.inputinstructions are given in the WRF User’s Guide. • Full list of namelists and their default values may be found in Registry files:Registry.EM (ARW),Registry.NMMandregistry.io_boilerplate (IOoptions, shared). Use related documents to guide the modification of thenamelistvalues given in: run/README.namelist test/em_real/examples.namelist

  4. Fortran 90 namelist has very specific format, so editwith care: &namelist-record - start / - end • As a general rule: Multiple columns: domain dependent Single column: value valid for all domains

  5. &time_control • interval_seconds:Time interval between WPS output times, andLBC update frequency • history_interval:Time interval in minutes when a history output iswritten • frame_per_outfile:Number of history times written to one file. • restart_interval:Time interval in minutes when a restart file iswritten.By default, restart file is not written at hour 0.A restart file contains only one time level data, andits valid time is in its file name, • io_form_history/restart/input/boundary:IO format options 1. binary; 2. netCDF (recommended option); 4. PHDF5 5. Grib-1; 10. Grib-2 • debug_level: 0. for standard runs, no debugging. 1. netCDF error messages about missing fields. 50,100,200,300 values give increasing prints. Large values trace the job's progress through physics and time steps.

  6. &domains • time_step:Time step for model integration in seconds. • ARW: 6*dx (dxis the grid distance in km) • NMM: 2.25*dx • time_step_fract_num, time_step_fract_den:Fractional time step specified in separate integers of numerator and denominator. • e_we, e_sn, e_vert: Model grid dimensions (staggered) in x, y and z directions. • num_metgrid_levels: Number of metgrid data levels. • num_metgrid_soil_levels: Number of soil data levels in the input data • dx, dy: grid distances: in meters for ARW; in degrees for NMM.

  7. &domains • p_top_requested:Pressure value at the model top.Constrained by the available data from WPS.Default is 5000 Pa • eta_levels:Specify your own model levels from 1.0 to 0.0.If not specified, program real will calculate a set of levels • ptsgm(NMM only):Pressure level (Pa) at which the WRF-NMM hybridcoordinate transitions from sigma to pressure (default:42000 Pa)

  8. &physics: Physics options • mp_physics:microphysics 0. No microphysics 1. Kessler scheme 2. Lin et al. scheme 3. Single-Moment (WSM) 3-class simple ice scheme 4. Single-Moment (WSM) 5-class scheme 5. Ferrier scheme 6. WSM 6-class graupel scheme 7. Goddard GCE scheme (also use gsfcgce_hail and gsfcgce_2ice) 8. Thompson graupel scheme (2-moment scheme in V3.1) 9. Milbrandt-Yau 2-moment scheme 10. Morrison 2-moment scheme  13. Stonybrook University scheme

  9. Radiation related flags • ra_lw_physics: longwave radiation • 1. RRTM scheme • 3. CAM scheme • 4. rrtmg scheme • 5. New Goddard longwave scheme (Since V3.3) • 99. GFDL scheme (Schwarzkopf and Fels ) • ra_sw_physics: shortwave radiation • 1. Dudhia Scheme • 2. Goddard Shortwave scheme • 3. CAM scheme • 4. rrtmg scheme • 99. GFDL Scheme (Lacis and Hansen).

  10. sf_sfclay_physics:surface layer • 0. No surface-layer scheme • 1. Monin-Obukhov Similarity scheme • 2. Monin-Obukhov-Janjic Similarity Scheme • 3. Global Forecasting System (GFS) scheme (NMM only) •  4. QNSE  • 5. MYNN  • 7. Pleim-Xiu (ARW only), only tested with Pleim-Xiu surface and ACM2 PBL • 10. TEMF surface layer • sf_surface_physics:land surface • 0. No surface temperature prediction • 1. Thermal Diffusion scheme • 2. Unified NOAH Land-Surface Model • 3. RUC Land-Surface Model • 7. Pleim-Xiu scheme (ARW only)

  11. sf_urban_physics • 1. Urban Canopy Model • 2. Building Environment Parameterization • 3. Building Energy Model

  12. num_soil_layers: number of soil layers in land surface model 2. Pleim-Xu land-surface model 4. Noah land-surface model 5. Thermal diffusion scheme 6. RUC Land Surface Model • bl_pbl_physics: planetary boundary layer 0. no boundary-layer 1. Yonsei University scheme (use with sf_sfclay_physics=1) 2. Mellor-Yamada-Janjic TKE Scheme (use with sf_sfclay_physics=2) 3. NCEP Global Forecast System scheme (use with sf_sfclay_physics=3) 4. QNSE(use with sf_sfclay_physics=4) 5. MYNN 2.5 level TKE (use with sf_sfclay_physics=1,2 and 5) 6. MYNN 3rd level TKE (use with sf_sfclay_physics=5) 7. ACM2 (Pleim) scheme(use with sf_sfclay_physics=1, 7) 8. Bougeault and Lacarrere (BouLac) TKE (use with sf_sfclay_physics=1,2) 9. CAM UW PBL 10. Total Energy - Mass Flux (TEMF) 99. MRF scheme(to be removed)

  13. Flags related with cloud parameterization • cu_physics: cumulus parameterization • 0. No cumulus parameterization. • 1. Kain-Fritsch scheme • 2. Betts-Miller-Janjic scheme • 3. Grell-Devenyi ensemble scheme • 4. Simplified Arakawa-Schubert scheme(NMM only)  •  5. New Grell 3D scheme (G3)  • 6. Tiedtke scheme • 7. CAM Zhang-McFarlane scheme • 14. New Simpified Arakawa-Schubert

  14. &dynamicsDiffusion, damping,advection options rk_ord: time-integration scheme option:  2. Runge-Kutta 2nd order  3. Runge-Kutta 3rd order (recommended) diff_opt:  turbulence and mixing option:  0. no turbulence or explicit spatial numerical filters (km_opt IS IGNORED).  1. evaluates 2nd order diffusion term on coordinate surfaces. uses kvdif for vertical diff unless PBL option is used. may be used with km_opt = 1 and 4. (Note that option 1 is recommended for real-data cases.)  2. evaluates mixing terms in physical space (stress form) (x,y,z). turbulence parameterization is chosen by specifying km_opt. km_opt: eddy coefficient option  1. constant (use khdif and kvdif)  2. 1.5 order TKE closure (3D)  3. Smagorinsky first order closure (3D) (Note: option 2 and 3 are not recommended for dx > 2 km) 4. horizontal Smagorinsky first order closure (recommended for real-data case)

  15. &bc_control: Boundary control spec_bdy_width: Total number of rows for specified boundary value nudging. & namelist_quilt:Specifies asynchronized I/O for MPI applications. nio_tasks_per_group: Default value is 0, means no quilting; value > 0 quilting I/O nio_groups: Default is 1, do NOT change.

  16. More options • More are introduced here: • IO options • Vertical interpolation options • SST update and other options for long simulations • Adaptive-time step • Digital filter • Global runs • Moving nest • TC options • IO quilting

  17. Vertical interpolation options (1) Program real for ARW only, optional, &domains: use_surface: whether to use surface observations use_levels_below_ground: whether to use data below the ground lowest_lev_from_sfc:logical, whether surface data is used to fill the lowest model level values force_sfc_in_vinterp: number of levels to use surface data, default is 1 extrap_type: how to do extrapolation: 1 - use 2 lowest levels; 2 - constant t_extrap_type: extrapolation option for temperature: 1 - isothermal; 2 - 6.5 K/km; 3 - adiabatic

  18. Vertical interpolation options (2) Program real for ARW only, optional: • interp_type:in pressure or log pressure • lagrange_order:linear or quadratic • zap_close_levels:delta p where a non-surface pressure level is removed in vertical interpolationrelated namelists: examples.namelist constant pressure surfaces model surfaces ground

  19. SST update for long simulations (1) Lower boundary update control: allow SST, seaicemonthlyvegetation fraction and albedo to beupdated during a model run: sst_update: 0 – no SST update 1 – update SST Set before running real, and this will create additionaloutput files: wrflowinp_d01, wrflowinp_d02, .. To use these files in wrf, in &time_control, add auxinput4_inname = “wrflowinp_d<domain>” auxinput4_interval = 360 sst_skin: diurnal water temp update tmn_update: deep soil temp update, usedwith lagday Lagday: averaging time bucket_mm: bucket reset value for rainfall bucket_j: bucket reset value for radiationfluxes spec_exp: exponential multiplier forboundary zoneramping

  20. Adaptive time steps • Adaptive-time-step is a way to maximize themodel time step while keeping themodelnumerically stable • New since V3. (Very efficient to use for real-time runs.) Namelist control: &domains use_adaptive_time_step: logical switch step_to_output_time: whether to write at exact historyoutput times target_cfl: maximum cfl allowed (1.2) max_step_increase_pct: percentage of time step increaseeach time; set to 5, 51, (largervalues for nests) starting_time_step: in seconds; e.g. set to 4*dx max_time_step: in seconds; e.g. set to 8*dx min_time_step: in seconds; e.g. set to 4*dx

  21. Digital filter initialization (1) • Digital filter initialization is a simple way toremove initial model imbalance: – May be introduced by simple interpolation,different topography, or by objective analysis, ordata assimilation – It may generate spurious gravity waves in theearly simulation hours, which could causeerroneous precipitation, numerical instability anddegrade subsequent data assimilation • Using DFI – can construct consistent model fields which do notexist in the initial conditions, e.g. vertical motion,cloud variables – may reduce the spin-up problem in early simulationhours DFI is done after real, or data-assimilation step, just before model integration.

  22. Digital filter initialization (2)

  23. Digital filter initialization (3) DFI is done after real, or data-assimilation step, just before model integration. Namelist control: &dfi dfi_opt: dfi options: 0: no DFI; 1: DFL; 2: DDFI; 3: TDFI (recommended) dfi_nfilter: filter options 0 - 8, recommended: 7 dfi_cutoff_seconds : cutoff period dfi_write_filtered_input : whether to writefiltered IC dfi_bckstop_* : stop time for backward integration dfi_fwdstop_* : stop time for forward integration

  24. Global applications Setup is mostly done in WPS: map_proj = ‘lat-lon’ e_we, e_sn: geogrid will compute dx, dy See template ‘namelist.wps.global’ for details. In the model stage: fft_filter_lat: default value is 45 degrees Caution: some options do not work, or have been tested with global domain. Start with template ‘namelist.input.global’

  25. Acknowledgements: Thanks to earlier presentations of NCAR/MMM Division (Wei Wang), for providing excellent starting point for this talk!

  26. Thanks for attending….

More Related