Difference between revisions of "CF"
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::Pre-define band names | ::Pre-define band names | ||
::Pre-define by wavelength/frequency range | ::Pre-define by wavelength/frequency range | ||
− | Proposal by Tom Whittaker | + | |
+ | :2. Data quality | ||
+ | ::Modifiers such as "percent_cloud_free" | ||
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+ | :3. Swath geometry | ||
+ | ::Orbital parameters | ||
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+ | :4. Engineering parameters | ||
+ | ::Calibration tables | ||
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+ | ==Spectral Band Proposal by Tom Whittaker== | ||
Create standard_names that can be recognized by applications as | Create standard_names that can be recognized by applications as | ||
being the special "band dimension" variable (similar to "time"). | being the special "band dimension" variable (similar to "time"). | ||
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::<attribute name="units" value="cm" /> | ::<attribute name="units" value="cm" /> | ||
:</variable> | :</variable> | ||
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== Join the Cluster e-mail list == | == Join the Cluster e-mail list == |
Revision as of 00:02, July 21, 2011
The CF Standards Cluster of the ESIP Federation
Objectives
- Propose relevant extensions to the CF naming conventions that are relevant to observational data
- Provide tutorials on the use of the CF conventions at Federation meetings
- Create use cases that demonstrate the value of CF usage in remote sensing
Get Involved: Monthly Telecons
- Next telecon: to be announced
- Minutes of past telecons/meetings:
Possible CF Extensions
- 1. Spectral bands
- Define as dimension rather than coordinate variable
- Pre-define band names
- Pre-define by wavelength/frequency range
- 2. Data quality
- Modifiers such as "percent_cloud_free"
- 3. Swath geometry
- Orbital parameters
- 4. Engineering parameters
- Calibration tables
Spectral Band Proposal by Tom Whittaker
Create standard_names that can be recognized by applications as being the special "band dimension" variable (similar to "time"). The name of this dimension variable would not, however, be specified, but inferred from its attributes.
Create two coordinate axis types ("wavelength" and "wavenumber") that can be recognized by the NetCDF library as defining a "spectral coordinate".
Thus, the band dimension might be declared:
- <variable name="band" shape="band" type="float" >
- <attribute name="standard_name" value="wavelength" />
- <attribute name="units" value = "cm" />
- <attribute name="_CoordinateAxisType" value = "wavelength" />
- </variable>
The dimension variable can then be used to dimension arrays associated with the spectral channels, e.g., wavelength boundaries for each band (channel), units, scaling, etc. The use of these (dimensioned) variables, however, would be up to the application developers rather than made part of the conventions, per se.
This would necessitate creating perhaps two new standard_names:
wavelength (there is already a "radiation_wavelength" with "electromagnetic_wavelength" as an alias, but I don't see an issue for making just "wavelength" a standard name, either. I also recognize that in most cases this refers to the center wavelength of the band/channel, and perhaps should be so designated...?).
wavenumber (There is no equivalent standard_name. Again, I imagine this would actually refer to a center wavenumber).
We would also then need to define two new coordinate axis types: wavelength and wavenumber.
For the case where people don't or can't use the dimension variable as a coordinate variable, we recommend that they use the convention name "band" as the dimension variable so that applications can at least recognize this for what it is.
In all cases, new (dimensioned) variables could then be used to specify band-specific attributes. For example:
- <variable name="minimum_wavelength" shape="band" type="double">
- <attribute name="units" value="cm" />
- </variable>
Join the Cluster e-mail list
External Links
Join the CF-satellite e-mail list (UCAR): http://mailman.unidata.ucar.edu/mailman/listinfo/cf-satellite
Governance
Interim Chair: Rob Raskin raskin at jpl.nasa.gov