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Metadata • Metadata is information about a variable or a file. • In NetCDF-land, metadata consists of: – Attributes (units, history, grid type, long name) – Named dimensions – Coordinate arrays (must be one-dimensional) • WRF-ARW data doesn’t normally have traditional 1D coordinate arrays, WRF coordinates are generally 2D (XLAT, XLONG) • The “_FillValue” attribute is a special one indicating a variable’s missing value. “missing_value” not recognized • When you do an “ncdump -h” on a NetCDF file, you see all the metadata • NCL variables are based on this metadata model.
Missing values (_FillValue attribute) • “_FillValue” is a NetCDF and NCL reserved attribute • Most NCL functions ignore _FillValue: x = (/1,2,3,-999,5/) ; no msg val yet xavg = avg(x) ; = -197.6 x@_FillValue = -999 ; now has a msg val xavg = avg(x) ;(1+2+3+5)/4 = 2.75 • Must be same as type of variable Use ‘@’ to reference attributes • “missing_value” attribute has no special status to NCL. If “T” has “missing_value” attribute and no “_FillValue”: T@_FillValue = T@missing_value • Best not to use zero as a _FillValue • Sample NCL (netCDF) default missing values: integer -999 float -999. double -9999. string “missing” short -99 byte 0xff character 0x00 logical Missing “print” / “printVarSummary” will print _FillValue value. “print” is very verbose
Page 1 and 2: Post-processing WRF-ARW Data with t
Page 3 and 4: • Overview • NCL basics • Fil
Page 5 and 6: WRF-NCL A suite of analysis and vis
Page 7 and 8: NCL: File input and output • Data
Page 9: NCL: Visualization • High-quality
Page 22 and 23: A T-S diagram is a graph showing th
Page 24 and 25: Based on a visualization of Adam Ph
Page 26 and 27: John Fasullo, NCAR/CGD
Page 29 and 30: CCMVal Workshop 2009 � June 1-5,
Page 33 and 34: load “$NCARG_ROOT/lib/ncarg/nclsc
Page 35 and 36: Mixing types ; Mixing types, “lar
Page 37 and 38: Arrays • Row major. . . like C/C+
Page 39: Special functions for arrays ; Very
Page 43 and 44: File and variable attributes ; Use
Page 45 and 46: Array reorder, reshape, reverse ; R
Page 47 and 48: Array index subscripting, : and ::
Page 51 and 52: KHDIF : 0 KVDIF : 0 MP_PHYSICS : 3
Page 53 and 54: float V ( Time, bottom_top, south_n
Page 55 and 56: Back to NCL scripts: Two ways to re
Page 57 and 58: Reading (and examining) a variable
Page 59 and 60: Creating a new variable & adding at
Page 62 and 63: WRF-NCL built-in functions Can use
Page 64 and 65: Other WRF-NCL “WRFUserARW.ncl”
Page 66 and 67: Other WRF-NCL “WRFUserARW.ncl”
Page 68 and 69: Modifying wrf_user_getvar function
Page 70 and 71: Step-by-step WRF-ARW visualizations
Page 72 and 73: NCL & WRF-NCL � WRF User’s User
Page 75 and 76: wrf_contour/wrf_vector Create line/
Page 77 and 78: wrf_map_overlays/wrf_overlays Overl
Page 79 and 80: http://www.mmm.ucar.edu/wrf/OnLineT
Page 83 and 84: Example F77 code: myTK.f C NCLFORTS
Page 85 and 86: Calling Fortran 90 codes from NCL
Page 87 and 88: Example F90 code: myTK.f90 + stub m
Page 91 and 92:
Debugging tips • Start with an ex
Page 93 and 94:
• Overview • NCL basics • Fil
Page 95 and 96:
Customizing your NCL graphics envir
Page 97 and 98:
With and without a “.hluresfile
Page 99 and 100:
Useful URLS • Online WRF-NCL Grap
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