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The NetCDF Users' Guide

NetCDF Users Guide

This guide describes the netCDF object model. This document applies to netCDF version 4.0.1, and was last updated on 10 March 2009.

Interface guides are available for C (see The NetCDF C Interface Guide), C++ (see The NetCDF C++ Interface Guide), Fortran 77 (see The NetCDF Fortran 77 Interface Guide), and Fortran 90 (see The NetCDF Fortran 90 Interface Guide).

Separate documentation for the netCDF Java library can be found at the netCDF-Java website, http://www.unidata.ucar.edu/software/netcdf-java.

For installation and porting information, see The NetCDF Installation and Porting Guide.

• Foreword: Foreword from 1996 Manual
• Summary: Orientation
• Introduction: What is NetCDF?
• Dataset Components: What's in a NetCDF File?
• Data: How to Store Data
• Structure: Behind the Scenes
• NetCDF Utilities: Ncdump and ncgen and ncgen4
• Units: Using UDUNITS
• Attribute Conventions: Creating Human-Readable Files
• File Format: The Classic Binary Format
• Combined Index: Index of Concepts and Functions

--- The Detailed Node Listing ---

Introduction

• Interface: The NetCDF Interface
• Not DBMS: NetCDF is not a Database
• Format: The NetCDF File Format
• Which Format: Selecting the Underlying NetCDF Format
• Performance: What about Performance?
• Archival: Is NetCDF a Good Archive Format?
• Conventions: Creating Self-Describing Data Conforming to Conventions
• Background: The Evolution of the NetCDF Interface
• Whats New: Latest Developments in NetCDF
• Limitations: Limitations of NetCDF
• Future : Plans for Future Development
• References: Papers Relating to Scientific Data

Components of a NetCDF Dataset

• Data Model: How NetCDF Sees Data
• Dimensions: Specifying Data Shape
• Variables: Storing Data
• Attributes: Storing Metadata
• Attributes and Variables: Attributes vs. Variables

Data

• External Types: Integers, Floats, and so on
• Classic Data Structures: Complex Data in Classic Format
• User Defined Types: Complex Data in NetCDF-4/HDF5 Format
• Data Access: Reading and Writing Data
• Type Conversion: Changing Type of Numeric Data

Forms of Data Access

• C Section Access: A C Example
• Fortran Section Access: A Fortran Example

File Structure and Performance

• Classic File Parts: The Classic and 64-bit Offset File
• NetCDF-4 File Parts: The NetCDF-4/HDF5 File
• XDR Layer: Classic Machine Interoperability
• Large File Support: Files that Exceed 2 GiBytes
• 64 bit Offset Limitations: Limitations on File and Data Size
• Classic Limitations: Limitations on File and Data Size
• The NetCDF-3 IO Layer: Classic I/O Described
• UNICOS Optimization: Some Cray Optimizations
• Parallel Access: Parallel I/O with NetCDF-4
• Interoperability with HDF5: Using HDF5 with NetCDF-4
• DAP Support: Accessing DAP data sources with NetCDF-4

NetCDF Utilities

• CDL Syntax: Creating a File without Code
• CDL Data Types: Describing Types in CDL
• CDL Constants: Constant Values in CDL
• ncgen: Turning CDL into Data Files
• ncdump: Turning Data Files into CDL (or XML)

File Format Specification

• NetCDF-4 Format
• NetCDF-4 Classic Model Format
• NetCDF Classic Format
• 64-bit Offset Format

The NetCDF Classic Format Specification

• Classic Format Spec
• Computing Offsets
• Examples

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