Post-processing WRF-ARW data with the NCAR Command Language 13th Annual WRF Users’ Workshop, June 25-29, 2012 Mary Haley  NCAR CISL VETS The National Center for Atmospheric Research is sponsored by the National Science Foundation. Goals •  Introduce you to NCL and WRF-NCL •  Get you familiar with WRF-NCL scripts •  Opening and examining a data file •  Reading and querying variables •  Plotting variables •  Sneak in tips and information for existing users (like what’s new) NCL & WRF-NCL WRF Users’ Workshop June 25-29, 2012 l l Topics •  Overview •  NCL language basics •  File input/output •  Data Analysis •  Visualization •  Calling Fortran code from NCL •  Debugging, common mistakes •  Installation, setup, URLs •  What’s new NCL & WRF-NCL WRF Users’ Workshop June 25-29, 2012 l l A scripting (interpreted) language tailored for the analysis and visualization of geoscientific data •  Developed in NCAR/CISL in close collaboration with CGD & MMM scientists •  UNIX binaries and source available, free •  Extensive NCL website, hundreds of examples •  Hands-on workshops •  Email lists for consulting http://www.ncl.ucar.edu / What is NCL? •  A scripting language similar to Python or IDL •  Tailored to climate and atmospheric sciences •  Has variable types, “if-then-endif”, “do” loops, arithmetic operators •  F90-like array arithmetic that automatically ignores missing values (where it makes sense) •  Can call your own Fortran 77/90 or C routines 1.  Simple, robust file input/output 2.  Hundreds of data analysis routines 3.  Publication-quality graphics that are highly customizable NCL & WRF-NCL WRF Users’ Workshop June 25-29, 2012 l l NCL: File input and output •  Data model based on netCDF model (metadata describes data) •  One function reads all supported data formats: −  NetCDF, GRIB 1 and 2, HDF4, HDF-EOS2, HDF- EOS5, shapefiles, (new: NetCDF4, HDF5) −  Writes NetCDF-3 and HDF4 (compressed NetCDF too) •  OPeNDAP-enabled client available •  ASCII, binary (read and write) http://www.ncl.ucar.edu/Applications/list_io.shtm l NCL & WRF-NCL WRF Users’ Workshop June 25-29, 2012 l l NCL: Data analysis •  Array-based math •  Hundreds of functions -  WRF-ARW specific functions -  Spherical harmonics -  Scalar and vector regridding -  Vertical interpolation -  EOFs •  Many tailored to geosciences •  Most automatically handle missing data •  Can call C and Fortran routines - WRAPIT http://www.ncl.ucar.edu/Applications/list_dataP.shtm l NCL & WRF-NCL WRF Users’ Workshop June 25-29, 2012 l l NCL: Visualization •  High-quality and customizable visualizations •  Contours, XY, vectors, wind barbs, streamlines •  Maps with common map projections •  Handles data on regular and irregular grids, triangular meshes •  Specialized scripts for meteograms, skew-T, wind roses, histograms, cross section, panels •  wrf_xxxx functions: simplifies visualization for WRF-ARW data •  Over 1,400 visualization “options” http://www.ncl.ucar.edu/gallery.shtm l NCL & WRF-NCL WRF Users’ Workshop June 25-29, 2012 l l NCL Training Workshops -  First training workshop in 2000, 60 so far, 898 attendees -  3-4 local workshops a year -  1-2 free annual workshops at a UCAR member university -  One invited international workshop -  Lectures taught by a scientist and a software engineer -  Includes special lecture on various data formats used in geosciences – lots of students working with WRF! -  Four hands-on labs sessions; students encouraged to bring their own datasets NCL & WRF-NCL WRF Users’ Workshop June 25-29, 2012 l l WRF-NCL A suite of analysis and visualization functions tailored for WRF-ARW model data •  Included with NCL since 2006 •  Developed by scientists in MMM •  Maintained by Cindy Bruyère/MMM and myself •  Functions for calculating basic diagnostics (wrf_user_getvar) •  Functions for customized visualizations •  Website with lots of analysis and visualization examples •  Workshops and tutorials http://www.mmm.ucar.edu/wrf/OnLineTutorial/ Graphics/NCL/ NCL & WRF-NCL WRF Users’ Workshop June 25-29, 2012 l l