f_nczarr_enhanced.f90 File Reference

Demonstrate NcZarr with the NetCDF-4 enhanced data model (Fortran). More...

Functions/Subroutines
program	f_nczarr_enhanced
subroutine	handle_err (status)

Detailed Description

Demonstrate NcZarr with the NetCDF-4 enhanced data model (Fortran).

Creates a local NcZarr store with: Root group: time (unlimited) and x dimensions, temperature(time,x) and pressure(time,x) variables. Child group obs/: station (unlimited), obs_value(station) and obs_time(station) variables.

Note: NcZarr supports groups and unlimited dims from the enhanced model; user-defined types (enum, compound) require HDF5 storage.

Reopens the store and validates all metadata and data values.

Learning Objectives:

• Use NcZarr with the NetCDF-4 enhanced data model features from Fortran
• Create groups in a Zarr store with nf90_def_grp()
• Use unlimited dimensions in NcZarr datasets
• Combine root-level and child-group variables in one store
• Verify round-trip correctness for multi-group NcZarr datasets

Key Concepts:

• Enhanced Data Model: NcZarr supports groups and unlimited dimensions from the NetCDF-4 enhanced model (but not user-defined types)
• Groups in Zarr: nf90_def_grp() creates sub-groups stored as nested directories in the Zarr store
• Unlimited Dimensions: NF90_UNLIMITED works in NcZarr just like NetCDF-4/HDF5
• Mixed Variables: Root and child groups can have independent variables with different dimensions
• Column-Major Ordering: Fortran arrays have reversed dimension order compared to C (x varies fastest in Fortran)

Prerequisites:

• f_nczarr_simple.f90 - Basic NcZarr Fortran example
• f_groups.f90 - NetCDF-4 groups in Fortran

Related Examples:

• nczarr_enhanced.c - C equivalent
• f_nczarr_simple.f90 - Basic NcZarr without groups
• f_nczarr_chunking.f90 - Chunking in NcZarr
• f_nczarr_compression.f90 - Compression in NcZarr
• f_groups.f90 - Groups in NetCDF-4/HDF5

Compilation:

gfortran -o f_nczarr_enhanced f_nczarr_enhanced.f90 -lnetcdff -lnetcdf

Usage:

./f_nczarr_enhanced
ncdump 'file://f_nczarr_enhanced.zarr#mode=nczarr'

Expected Output: Creates the directory f_nczarr_enhanced.zarr containing:

• Root group with dimensions time(unlimited), x(5) and variables temperature(x, time), pressure(x, time)
• Child group obs/ with dimension station(unlimited) and variables obs_value(station), obs_time(station)

Note

Companion code for "The NetCDF Developer's Handbook: The Authoritative Guide to Writing High-Performance Programs for Scientific Data Management, Second Edition" (https://www.amazon.com/dp/B0H7Q1Z75L)

Author

Edward Hartnett, Intelligent Data Design, Inc.

Date

2026-06-27

Function/Subroutine Documentation

f_nczarr_enhanced()

program f_nczarr_enhanced

handle_err()

subroutine f_nczarr_enhanced::handle_err

(

integer, intent(in)

status

)