1

CF Unleashed:Introduction to Cf/Radial

Joe VanAndel

National Center for Atmospheric Research

vanandel@ucar.edu

2013/1/8

The National Center for Atmospheric Research is sponsored by the National Science Foundation

2

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

3

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

4

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

4

5

What Kind of Instruments?

• Scanning• Staring• Vertically Pointing• Mobile or Fixed

5

6

Stationary Scanning

6

7

Mobile/Scanning

7

8

Airborne Scanning Radar

8

9

Airborne Vertically Pointing

9

10

Fixed, Staring Profilers

10

11

Advantages• Readable on Linux, OS X, Windows• Supported by multiple languages:

– C/C++– Fortran– Python– IDL– Matlab

11

12

Advantages (2)

• Byte order independent• Efficient storage:

– supports variable gates/beam– native compression

12

13

Staggered 2-D Storage

13

14

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)

14

15

Sample Surveillance Data

15

16

Range Height Radar Data

16

17

Lidar Data

17

18

Data Content Overview

• data fields (moments)• each moment is a collection of “Rays”• each ray has range gates

18

19

Metadata

• each ray has metadata:– range– elevation– latitude– longitude– altitude– time

19

20

Metadata(2)

• Moving platforms:– heading– roll– pitch– rotation– tilt

20

21

Coordinate Conventions

• Fixed location• Mobile ground-based (truck mounted

radars)• Airborne radars/lidars

21

22

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)

22

Future work (1)

• Incorporating metadata from NODC netCDF templates

• Incorporating metadata from NetCdf Attribute Convention for Data Discovery

23

24

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.

24

25

Who is using CfRadial?

• NCAR• UNIDATA• DOE/ARM• NOAA/NSSL• EEC (commercial radar vendor)• Pro Sensing (commercial radar vendor)• Various university users

25

26

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.

27

Acknowledgements

27

Co-Authors:

Mike Dixon Wen-Chau LeeBob RillingChris Burghart

28

Questions?

28

??

?