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CF Unleashed:Introduction to Cf/Radial
Joe VanAndel
National Center for Atmospheric Research
2013/1/8
The National Center for Atmospheric Research is sponsored by the National Science Foundation
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CF -What is it?
• Climate and Forecast Metadata Convention• Locate data in space–time and as a function
of other independent variables, to facilitate processing and graphics
• for– model-generated data– observational datasets
• originally no support for radial data2
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Motivation
• Support radar/lidar community• Provide better interoperability for data
providers and tool creators• provide libraries and tools to
– read/write datasets – convert from legacy formats– display radial data
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What is Cf/Radial?
• CF extensions for radial radar/lidar data• CF compliant netCDF
– netCDF is familiar to many scientists– CF allows assimilating data into forecast
models
• Details: http://www.ral.ucar.edu/projects/titan/docs/radial_formats
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What Kind of Instruments?
• Scanning• Staring• Vertically Pointing• Mobile or Fixed
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Stationary Scanning
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Mobile/Scanning
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Airborne Scanning Radar
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Airborne Vertically Pointing
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Fixed, Staring Profilers
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Advantages• Readable on Linux, OS X, Windows• Supported by multiple languages:
– C/C++– Fortran– Python– IDL– Matlab
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Advantages (2)
• Byte order independent• Efficient storage:
– supports variable gates/beam– native compression
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Staggered 2-D Storage
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Transparent Compression
• NetCDF4 uses HDF5 as storage layer • NetCDF4/HDF5 supports transparent
compression• compressed files can be as small as 20% of
the original size (data dependent)
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Sample Surveillance Data
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Range Height Radar Data
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Lidar Data
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Data Content Overview
• data fields (moments)• each moment is a collection of “Rays”• each ray has range gates
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Metadata
• each ray has metadata:– range– elevation– latitude– longitude– altitude– time
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Metadata(2)
• Moving platforms:– heading– roll– pitch– rotation– tilt
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Coordinate Conventions
• Fixed location• Mobile ground-based (truck mounted
radars)• Airborne radars/lidars
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Current tools
• Radx C++ library• Conversions: Read/Write
• CfRadial• DORADE (legacy binary radar format)• Universal Format (UF) - very old binary format• NEXRAD level 2 archive• Foray1 (EOL netCDF)• SIGMET (writing is not supported)
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Future work (1)
• Incorporating metadata from NODC netCDF templates
• Incorporating metadata from NetCdf Attribute Convention for Data Discovery
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Future work (2)
• convert SOLO (display/editing tool) to read/write CfRadial
• Python libraries and tools• Matlab libraries• IDL libraries• Community archive of user contributed
libraries and tools.
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Who is using CfRadial?
• NCAR• UNIDATA• DOE/ARM• NOAA/NSSL• EEC (commercial radar vendor)• Pro Sensing (commercial radar vendor)• Various university users
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Conclusion
• Want to encourage more users to adopt CfRadial
• We welcome your ideas on how to publicize this format
NCAR is supported by the National Science Foundation.
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Acknowledgements
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Co-Authors:
Mike Dixon Wen-Chau LeeBob RillingChris Burghart
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Questions?
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