Recipe: File naming conventions

Problem

We want to understand the file naming conventions of G5NR products

Solution

The standard generic complete name for G5NR products appear as

c1440_NR.collection.timestamp.nc4

where

c1440_NR

the c1440 token indicates the resolution of the cubed-sphere grid. 1440² is the number of grid points in each face of the cubed-sphere. NR stands for Nature Run.

collection

The operational GEOS-5 data are organized into file collections that contain fields with common characteristics. However, computational considerations required that 3D collections have a single variable in them. Collection names are of the form

freq_dims_group_HV

where the four attributes (freq,dims,group,HV) are:

freq: time-independent (const), instantaneous (instF ), time-average (tavgF ), diurnally time-averaged (tdavF ) where F indicates the frequency or averaging interval and can be one of the following:

30mn = every 30 minutes

01hr = hourly

01mo = monthly

The tdavF files typically contain monthly diurnal files, meaning, monthly means for each hour of the day: 0 UTC, 1 UTC, …, 23UTC.

dims: 2d for collections with only 2-dimensional fields or 3d for collections with a mix of 2- and 3-dimensional fields.

group: A short mnemonic for the type of fields in the collection, or the variable name for single-variable collections.

HV: Horizontal and Vertical grid, where

H can be:

N: Nominal (full) horizontal resolution of lat/lon grid.

C: Coarse (reduced) horizontal resolution of lat/lon grid

V can be:

x: horizontal-only data (surface, single level, etc.); dims must be 2D

p: pressure-level data (see Appendix B of spec file for levels TODO); dims must be 3D

v: model layer centers (see Appendix B of spec file TODO); dims must be 3D

e: model layer edges (see Appendix B of spec file); dims must be 3D

timestamp

This token defines the date and time associated with the data in the file. It has the form yyyymmdd_hhmmz, where

yyyy - year string (e.g. "2006")

mm - month string (e.g. "09" for September)

dd - day of the month string

hh - hour (UTC)

mm - minute

nc4: All files are in the NetCDF-4 format, hence the suffix ".nc4".