Due to the current gap in continued funding from the U.S. National Science Foundation (NSF), the NSF Unidata Program Center has temporarily paused most operations. See NSF Unidata Pause in Most Operations for details.
Due to the current gap in continued funding from the U.S. National Science Foundation (NSF), the NSF Unidata Program Center has temporarily paused most operations. See NSF Unidata Pause in Most Operations for details.
Response to Eric Pepke's mail: We use an I/O library layered on top of the netCDF library. With this library we can read and write netCDF files with time axes with several conventions, but internally, our EPS I/O library always returns to the calling routines a two-integer array in which the first integer is the "true Julian Day Number" with units of days, and the second integer is the number of milliseconds since midnight of the true Julian Day. This two-integer time word represents time periods spanning centuries with millisecond accuracy. Some other oceanographic institutions are also using this representation of time in netCDF files. Our EPS I/O library includes a complete set of routines for manipulation, calculation, and character string representation of our standard two-integer representation of time. The representation of the time axis within the netCDF file can be of several types, for both read and write, including the UDUNITS standard, the double integer array which is used internally by the EPS routines, and some other time representations which are supported for compatibility with other in-house software packages. Time axes can be written or read in either real or integer format. However, regardless of the format of the time axis in the netCDF data file itself, the values used internally by the EPS library will be the double integer array. NOTE: We are using the astronomer's True Julian Day (eg, May 23, 1968 is 2,400,000), which should not be confused with the "year-day" (eg, Feb 2 is year-day 33). The "year-day" is frequently called julian day (incorrectly) by oceanographers and meteorologists. Our two-integer time word (word1=True Julian Day, word2=milliseconds since midnight of the True Julian Day) allows millisecond accuracy for time periods extending over centuries. ------------------------------------------------------------- Nancy N. Soreide Phone: 206-526-6728 NOAA/PMEL/OCRD FAX: 206-526-6744 7600 Sand Point Way NE OMNET: TAO.PMEL Seattle, WA 98115 Internet: nns@xxxxxxxxxxxxx
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