Re: [cf-satellite] [CF-metadata] MSG CPP standard name for time_offset_of_observation / pixel_delta_time

• To: cf-metadata@xxxxxxxxxxxx
• Subject: Re: [cf-satellite] [CF-metadata] MSG CPP standard name for time_offset_of_observation / pixel_delta_time
• From: Steve Hankin <Steven.C.Hankin@xxxxxxxx>
• Date: Thu, 03 Feb 2011 16:26:46 -0800

[cross-posting this email to the cf-satellite list]

=====================================

On 2/3/2011 1:11 PM, Janine Goldstein Aquino wrote:

Hi all,

At NCAR/RAF we have netCDF files with multiple time frequencies in the same file:

   dimensions:
      Time = 18421;
      Sps1 = 1;        // samples per second
      Sps25 = 25;    // samples per second
      ...
   variables:
      int Time(Time);
      float var1(Time, sps1);
      float var2(Time, sps25);
      ...

This is not CF compliant and we are concerned that users will not know to look

for the subsecond dimension and recognize it as time.

Reading your suggestion below, I can see us implementing another use for the attribute "coordinate_offset". I took a stab at the udunits compatible "units" value.

Not quite sure how that would work...

  dimensions:
    Time = 18421;
    Sps25 = 25;
  variables:
    int time(Time) ;
      :standard_name = "time"
      :units = "seconds since 2010-08-15 10:09:00 +0000" ;
      ...
    int sps25(Sps25) ;
      :standard_name = "coordinate_offset" ;
      :ref_coordinate = "time" ;
      :units = "1/25 seconds since time" ;
      ...
    float var2(Time,sps25);

All of Tim's comments about how to implement the :coordinates attribute
apply here as well.

Regards,
Janine