WRF - Developmental Testbed Center

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Configuring a run with multiple domainsWRF-NMM V2.2 supports stationary one-way (Gopalakrishnan et al. 2006) and two-waynesting. By setting the feedback switch in the namelist.input file to 0 or 1, the domainsbehave as one-way or two-way nests, respectively. The model can handle multipledomains at the same nest level (no overlapping nest), and/or multiple nest levels(telescoping). Make sure that you compile the code with nest options turned on asdescribed in Chapter 2.The nest(s) can be located anywhere inside the parent domain as long as they are at least5 parent grid points away from the boundaries of the parent grid. Similar to the coarsestdomain, nests use an E-staggered grid with a rotated latitude-longitude projection. Thehorizontal grid spacing ratio between the parent and the nest is 1:3, and every third pointof the nest coincides with a point in the parent domain. The time step used in the nestmust be 1/3 that of the parent time step.No nesting is applied in the vertical, that is, the nest has the same number of verticallevels as its parent. Note that, while the hybrid levels of the nest and parent in sigmaspace coincide, the nest and the parent do not have the same levels in pressure or heightspace. This is due to the differing topography, and consequently different surfacepressure between the nest and the parent.Nests can be introduced in the beginning of the model forecast or later into the run.Similarly, nests can run until the end of the forecast or can be turned off earlier in the run.Namelist variables start_* and end_* control the starting and ending time for nests.When a nest is initialized, its topography is obtained from the static file created for thatnest level by the WPS (see Chapter 3). Topography is the only field used from the staticfile. All other information for the nest is obtained from the lower-resolution parentdomain. Land variables, such as land-sea mask, SST, soil temperature and moisture areobtained through a nearest-neighbor approach.To obtain the temperature, geopotential, and moisture fields for the nest initialization, thefirst step is to use cubic splines to vertically interpolate those fields from hybrid levels toconstant pressure levels in each horizontal grid point of the parent grid. The second stepis to bilinearly interpolate those fields in the horizontal from the parent grid to the nest.The third step is to use the high-resolution terrain and the geopotential to determine thesurface pressure on the nest. Next, the pressure values in the nest hybrid surfaces arecalculated. The final step is to compute the geopotential, temperature and moisture fieldsover the nest hybrid surface using a cubic spline interpolation in the vertical.The zonal and meridional components of the wind are obtained by first performing ahorizontal interpolation from the parent to the nest grid points using a bi-linear algorithm.The wind components are then interpolated in the vertical from the parent hybrid surfacesonto the nest hybrid surfaces using cubic splines.WRF-NMM V3: User’s Guide 5-23
The boundary conditions for the nest are updated at every time step of the parent domain.The outermost rows/columns of the nest are forced to be identical to the parent domaininterpolated to the nest grid points. The third rows/columns are not directly altered by theparent domain, that is, their values are obtained from internal computations within thenest. The second rows/columns are a blend of the first and third rows/columns. Thisprocedure is analogous to what is used to update the boundaries of the coarsest domainwith the external data source. To obtain the values of the mass and momentum fields inthe outermost row/column of the nest, interpolations from the parent grid to the nest arecarried in the same manner as for nest initialization.Most of options to start a nest run are handled through the namelist. Note: All variablesin the namelist.input file that have multiple columns of entries need to be edited withcaution.The following are the key namelist variables to modify:• start_ and end_year/month/day/minute/second: These control the nest startand end times• history_interval: History output file in minutes (integer only)• frames_per_outfile: Number of output times per history output file, used tosplit output files into smaller pieces• max_dom: Setting this to a number greater than 1 will invoke nesting. Forexample, if you want to have one coarse domain and one nest, set this variableto 2.• e_we/e_sn: Number of grid points in the east-west and north-south directionof the nest. In WPS, e_sw. e_sn for the nest are specified to cover the entiredomain of the coarse grid while, in file namelist.input, e_we and e_sn for thenest are specified to cover the domain of the nest.• e_vert: Number of grid points in the vertical. No nesting is done in thevertical, therefore the nest must have the same number of levels as its parent.• dx/dy: grid spacing in degrees. The nest grid spacing must be 1/3 of its parent.• grid_id: The domain identifier will be used in the wrfout naming convention.The coarser grid must have grid_id = 1.• parent_id: Specifies the parent grid of each nest. The parents should beidentified by their grid_id.• i_parent_start/j_parent_start: Lower-left corner starting indices of the nestdomain in its parent domain. The coarser grid should have parent_id = 1.• parent_grid_ratio: Integer parent-to-nest domain grid size ratio. Note: Mustbe 3 for the NMM.• parent_time_step_ratio: Integer parent-to-nest domain timestep ratio. Note:Must be 3 for the NMM. Since the timestep for the nest is determined usingthis variable, namelist variable time_step only assumes a value for the coarsestgrid.• feedback: If feedback = 1, values of prognostic variables in the nest arefedback and overwrite the values in the coarse domain at the coincidentpoints. 0 = no feedback.WRF-NMM V3: User’s Guide 5-24
Page 1 and 2: ForewordUser's Guide for the NMM Co
Page 3 and 4: • WPP Directory Structure 7-3•
Page 5 and 6: The WRF modeling system software is
Page 7 and 8: WRF-NMM FLOW CHARTTerrestrialDataMo
Page 9 and 10: Vendor Hardware OS CompilerCray X1
Page 11 and 12: If all of these executables are def
Page 13 and 14: Once the tar file is obtained, gunz
Page 15 and 16: HWRF is set, then (3) will be autom
Page 17 and 18: In addition to these three links, a
Page 19 and 20: • Real-data simulations• Non-hy
Page 21 and 22: k. Morrison double-moment scheme (1
Page 23 and 24: g. GFDL surface layer (88): (This s
Page 25 and 26: Other physics optionsa. gwd_opt: Gr
Page 27 and 28: to the convergence of meridians app
Page 29 and 30: Variable NamesValue(Example)Descrip
Page 39: mpirun.lsf wrf.exeand for interacti
Page 43 and 44: Examples:1. One nest and one level
Page 45 and 46: ottom_top_stag = 28 ;soil_layers_st
Page 47 and 48: float HLENSW(Time, south_north, wes
Page 49 and 50: float HBOTS(Time, south_north, west
Page 51 and 52: operational mesoscale Eta model. J.
Page 53 and 54: Mlawer, E. J., S. J. Taubman, P. D.
Page 55 and 56: NCEP WRF Postprocessor (WPP)WPP Int
Page 57 and 58: ./configureYou will be given a list
Page 59 and 60: equested output field. If the pre-r
Page 61 and 62: RAINCV SNOW HBOTRAINNCVSNOWCNote: F
Page 63 and 64: Running WPPFour scripts for running
Page 65 and 66: i. As the grid id of a pre-defined
Page 67 and 68: The GrADS package is available from
Page 69 and 70: Height on pressure surface HEIGHT O
Page 71 and 72: MELTPrecipitation type (4 types) -
Page 73 and 74: Press at tropopause PRESS AT TROPOP
Page 75 and 76: RIP4RIP IntroductionRIP (which stan
Page 77 and 78: A successful compilation will resul
Page 79 and 80: iinterp = 0v v v v vH V H V h h h h
Page 81 and 82: espectively, of the centered domain
Page 83 and 84: This can be either 'h' (for hours),
Page 85: eal variable expect values that are
Page 88 and 89: of all the requested trajectories a
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Creating Vis5D Dataset with RIPVis5
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User’s Guide for the NMM Core of
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Configuration: The configure script
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This program reads the contents of
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Period - Describes communications f
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fine grid), f (forcing, how the lat
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# halo HALO_NMM_K dyn_nmm8:q2;24:t
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(http://www.mmm.ucar.edu/wrf/WG2/Ti
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User's Guide for the NMM Core of th
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2. Make sure the files listed below
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User's Guide for the NMM Core of th
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Program geogridThe purpose of geogr
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1. Define a model coarse domain and
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to GEOGRID.TBL in the geogrid direc
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the GRIB data were downloaded to th
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By this point, there is generally n
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two nests are defined to have the s
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Note: For the WRF-NMM the variables
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simulations may use a constant SST
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entire simulation domain, and data
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that lists the variables and attrib
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http://www.ecmwf.int/products/data/
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intermediate formats (metgrid/src/r
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GRIB1| Level| From | To |Param| Typ
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corresponding source grid point. Gi
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tile_x = 1200tile_y = 1200tile_z =
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1. PARENT_ID : A list of MAX_DOM in
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V -DX- H| / |DY dx DY| / |H - DX- V
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intermediate files if ungrib is to
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the index and data tiles for the da
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1. PROJECTION : A character string
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25. SCALE_FACTOR : A real value tha
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10. INTERP_MASK : The name of the f
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1. four_pt : Four-point bi-linear i
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8. search : Breadth-first search in
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19 Mixed Tundra20 Barren TundraTabl
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LU_INDEX:units = "category" ;LU_IND
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netcdf met_em.d01.2009-01-05_12:00:
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}:ISOILWATER = 14 ;:grid_id = 1 ;:p
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WRF - Developmental Testbed Center

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