Question about ship data

[huaracheguarache]

Hi! I have a netCDF file with NWP model data from the MOSAiC Expedition. The file contains data for many surface level variables, and I'm struggling to figure out how it fits into the CF convention. The model data has coordinates reftime (reference time of the forecast), and leadtime (lead time of the forecast). The reference time coordinates are associated with lat/lon coordinates of the trajectory of the ship through the ice, and for each reference time coordinate you have a set of lead time coordinates. The drawing below illustrates the what this looks like:

The reftime coordinate makes me think that this could fall under a trajectory featureType since the coordinate is associated with the ship's drift through the ice, but the leadtime coordinate could be considered as a time series. What kind of featureType is this data?

[JonathanGregory]

Dear Michael @huaracheguarache

I think you are right that your data is a trajectory with the reftime as the time coordinate. I assume the leadtime is a forecast period (could have the standard name of forecast_period) - right? If so, this is another dimension of the data variables, which isn't part of the trajectory description. Chapter 9 prescribes that features must have certain dimensions, according to featureType, but they are not prevented from having other dimensions as well e.g. example H14 could have a data variable NO3(leadtime,obs) , where obs is the sample dimension that spans all the times of all the trajectories.

Best wishes

Jonathan