Performance strategies for 3D metrics/coordinates

[JeremyCollin]

Hi there,

I am a developer in CROCO team and we are about to redisign the proprocessing toolbox based on XGCM and xarray. Actually we had a version called xcroco that looks really similar to your project which is really cool by the way :) .

I have a question with regards to vertical metrics and coordinate, I am afraid that it could impact preformances with 4D datasets. For instance, someone taking a full simulation using mf_datasets() and then only computing a snapshot of a derived variable.

• Are xgrid metrics computed on all time serie or only sliced time range ?
• Same question for coordinates actually

I see that you thought about this (include_3D_metrics and include_Z0 parameters from xroms.roms_dataset(). What are your conclusions on the matter ?

Thanks for you time.