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2010 Unidata NetCDF Workshop

Overview of Unidata

Overview of netCDF

What is netCDF?

What is netCDF, really?

NetCDF Features

Alternatives to netCDF

The NetCDF Web Site

Installing netCDF

Getting Support

The Two NetCDF Data Models

Models, Conventions, and Formats

NetCDF Data Models

NetCDF Files

Dimensions

Variables

Variable Methods

Attributes

Attribute Methods

The "Classic" NetCDF Data Model

Introducing CDL (Common Data Language)

Another Simple Example

A Convention for Coordinates: Coordinate Variables

An Example of Coordinate Variables

Variables Versus Attributes

Classic NetCDF Model Limitations

The NetCDF-4 Data Model

When to Use the Enhanced Data Model

NetCDF Utilities

CDL

ncdump

Examples of ncdump use

NcML

ncgen

Examples of ncgen use

ncdump and ncgen together

nccopy

Examples of nccopy use

nc-config

Special attributes for netCDF-4 data

Other NetCDF Utilities

Goals

Where is CF Metadata Used?

A Brief History of CF

Principles

CF Standard Names

CF Appendices as references

Future Directions for CF

Overview

Purpose of Conventions

Conventions

Coordinate Systems

Variable Grouping

Variable Attributes

Strings and Character Variables

Calendar Date and Time

Packed Data Values

Missing Data Values

Summary

IDV

Introduction to the NetCDF APIs and Example Programs

Overview

The C API

The C++ API

The Fortran-77 API

The Fortran-90 API

The Java API

Architecture of NetCDF APIs and Libraries

Python APIs

The Ruby API

Perl APIs

Other APIs for netCDF

Some Common Errors to Avoid

The NetCDF Examples in C/F77/F90/C++

The NetCDF Example Requirements

The NetCDF Example Data Sets

The Simple XY Example Dataset

Write The Simple XY Example in F90

The Simple XY Write Example in C

The Simple XY Example in C++

Creating a NetCDF Dataset

Read The Simple XY Example in F90

The 2D Example Dataset CDL

The 4D Example Dataset CDL

Reading The 4D Example in C

Reading a NetCDF Dataset with Known Names

Reading a NetCDF Dataset with Unknown Names

Issues in Writing Generic NetCDF Software

Remote Access to Datasets Through netCDF-3

NetCDF-Java and THREDDS Data Services

Formats and Performance

NetCDF Format Versions

Parts of a File in Classic Format

Classic File Format

Benchmark Example

Classic API Performance Tips

Using Less Space for Data

Using Less Time for Data Access

Format and Performance Issues for Discussion

Introduction to NetCDF-4

The NetCDF-4 Data Model

NetCDF-4 Features

Compatibility of NetCDF-4

Groups

Multiple Unlimited Dimensions

Enumerations

Variable-Length Types

NetCDF-4 Performance Improvements

Chunking

Compression

Ample Variable Sizes

Efficient Dynamic Schema Changes

Parallel I/O

Reader Makes Right Conversions

NetCDF-4 Status

Using NetCDF: The Cooperative Arctic Data and Information Service (CADIS)

Using netCDF - NCAR Climate Data

NetCDF Data Models in Detail

Unidata's Common Data Model and NetCDF Java Library API Overview

Chunking and Deflating Data with NetCDF-4

What is Chunking?

Choosing Chunksizes

Setting the Chunksizes in NetCDF-4

Example of Setting Chunksizes in Fortran 90

The Cache in NetCDF-4

Setting the Cache in NetCDF-4

Per-Variable Compression in NetCDF-4

Per-Variable Compression in NetCDF-4

Per-Variable Compression in NetCDF-4, Results

How to Use Per-Variable Compression in NetCDF-4

Contiguous Variables

Using Contiguous Variables

Example of Contiguous Variable

What NetCDF Developers Should Know About HDF5

Parallel I/O with NetCDF

Parallel I/O

Introduction to Parallel I/O

The pNetCDF Package

Parallel I/O in NetCDF-4

Building NetCDF-4 with Parallel I/O

Using Parallel I/O in NetCDF-4

Collective and Independent Operations with Parallel I/O in NetCDF-4

Parallel I/O Example

Example of Simple Parallel I/O Access

Example of Simple Parallel I/O Access (part 2)

Using NetCDF Parallel I/O in Fortran 90

Jumpshot Graph of Independent Parallel Data Writes

Jumpshot Graph of Collective Parallel Data Writes

Using Groups and NetCDF-4 Types

Groups and Types in NetCDF-4

What are Groups?

CDL Example of Groups

Possible Uses for Groups

Strings

Example Creating an Array of Strings

Additional Numeric Types

Using User Defined Types

Writing and Reading Data of User Defined Type

Learning about User Defined Types

Introduction to Compound Types

Example with Compound Types in netCDF-4

Using Enums

Uses for Enumerations

Enum CDL Example

Using the Opaque Type

Variable-Length Types

Example of Variable-Length Types

Using Variable Length Types

Sea Sounding Example

NetCDF-4 Interoperability

libcf: A New Library for CF Conventions Support

LibCF, the NetCDF Library for the Climate and Forecast (CF) Conventions

Current Status of LibCF

File Level Functions in LibCF

Variable Metadata in LibCF

Latitude and Longitude Functions in LibCF

Vertical Dimension Functions in LibCF

Time Functions in LibCF

Geographic Subsetting in LibCF

The LibCF Website

Future Plans for LibCF

GRIDSPEC

The Future of netCDF

Goals for Unidata data access infrastructure

Near-term plans for netCDF

Long-term plans for Unidata data access infrastructure

Speculations

Conclusion of Workshop