NetCDF

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NetCDF

• NetCDF (Network Common Data Form) is a
  machine-independent, self-describing, binary data
  format standard for exchanging scientific data.
• It is commonly used in climatology applications
  (e.g., weather forecasting, climate change) and
  GIS applications.
• NetCDF data is
• Self-Describing. A netCDF file includes
  information about the data it contains.
• Portable. A netCDF file can be accessed by
  computers with different ways of storing
  integers, characters, and floating-point numbers.
• Direct-access. A small subset of a large dataset
  may be accessed efficiently, without first
  reading through all the preceding data.
• Appendable. Data may be appended to a properly
  structured netCDF file without copying the
  dataset or redefining its structure.
• Sharable. One writer and multiple readers may
  simultaneously access the same netCDF file.

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NCDUMP

• ncdump generates an ASCII representation of a
  specified netCDF file on standard output. The
  ASCII representation is in a form called CDL
  (network Common Data form Language)
• ncdump -c-h -v ... -b-f cf -l
  len -n name -p n,n file
• -c Coordinate variable data
  and header information
• -h Header information only,
  no data
• -v var1,... Data for variable(s)
  ltvar1gt,... only
• -b cf Brief annotations for C or
  Fortran indices in data
• -f cf Full annotations for C or
  Fortran indices in data
• -l len Line length maximum in data
  section (default 80)
• -n name Name for netCDF
• -p n,n Display floating-point
  values with less precision
• file File name of input
  netCDF file

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NCVIEW VCDAT

• Ncview is a visual browser for netCDF format
  files. Typically you would use ncview to get a
  quick and easy, push-button look at your netCDF
  files. You can view simple movies of the data,
  view along various dimensions, take a look at the
  actual data values, change color maps, invert the
  data, etc. It runs on UNIX platforms under X11
• Climate Data Analysis Tools (CDAT) is a freely
  available software infrastructure used for
  analysis, manipulation and plotting of
  atmospheric science (and other) data. It is
  designed for gridded datasets but can also cope
  with other types. Below are some key features of
  CDAT
• the software is open-source, consisting of a
  collection of Python modules.
• available for multiple platforms (but not
  Windows).
• a choice of interfaces command-line, scripting
  or graphical user-interface (Visual CDAT
  (VCDAT)).
• an XML-based format and tools for aggregating
  large datasets.
• manipulation of large data arrays possible due to
  use of Python Numeric package.

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NCL NCAR Command Language

• The NCAR Command Language (NCL) is an interpreted
  programming language, specifically designed for
  the access, analysis, and visualization of data.
  NCL has many features common to modern
  programming languages, including types,
  variables, operators, expressions, conditional
  statements, loops, and functions and procedures.
  Binaries are free and are available for most
  common Linux/Unix, Mac OS and Windows.
• NCL is a powerful software tool that allows
  researchers to easily and effectively access,
  process and visualize geoscientific data.
• Although NCL was designed primarily for weather
  and climate research, it is used today in fields
  as diverse as forestry, space monitoring,
  disaster prevention, applied insurance, genetic
  studies, aircraft data analysis, renewable
  energy, wildfires, animal disease modeling
  studies.
• NCL also comes with many useful built-in
  functions for processing and manipulating data.
  Researchers can compute statistics and
  correlations, perform re-gridding and
  interpolation, use constructs to support simple
  array operations, or employ advanced mathematical
  functions such as spherical harmonics.

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NCL NCAR Command Language

• Another NCL strength is its ability to deliver
  superior 2D visualizations in PDF, Postscript,
  X11, and NCGM formats. These images are suitable
  for publication in journals or for presentations
  at scientific conferences.
• One thing that sets NCL apart from other
  visualization software is its extensive
  geoscientific data ingest capabilities. NCL makes
  it easy to access and browse data in multiple
  file formats, including netCDF, GRIB-1, HDF4,
  HDF-EOS, GRIB-2, and HDF5 ASCII, and binary.
  "Data formats that contain metadata are converted
  to a uniform-variable interface similar to
  netCDF, which is quite convenient for
  scientists," says Haley. "Likewise, you can write
  NCL output to various data formats."
• A brief NCL_Manual and NCL_Graphics at
• http//climate.eas.gatech.edu/6132/

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An Example of NCL Script

• load "NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_cod
  e.ncl
• change sst by 2C over southern pacific region
• SST_cpl dimensions (12,64,128)
• system ("cp -f sst_64x128_clim_c020411.nc
  sstp2.nc")
• f addfile("sstp2.nc","w")
• f-gtSST_cpl(,-60.20,140.290.)f-gtSST_cpl(,
  -60.20,140.290.)2

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CAM-CLM Subroutine Call Tree

• GT HTML Version of CAM3.1-CLM3 code see at
• http//climate.eas.gatech.edu/cam3/