SPMODEL: A Series of Hierarchical Spectral Models for GFD Index

Appendix 2. Input and output of data: gtool4 netCDF convention and gt4f90io library

As described in the main part of this article, considerable efforts are necessary for post-processing to analyze the output data of the numerical results in order to complete researches on numerical models. In particular, as the scale of the model becomes larger, the amount of output data increases drastically, and the weight of post-processing becomes significantly larger than the calculation process of the numerical models. In order to deal with this problem, we have been examining and developing output data formats and utilities for resolving the problem ([15]).

As a fruit of our activities, we will propose a self-descriptive data format for efficient analyses and visualization of large volumes of multi-dimensional data. In order to analyze and visualize the data, not only the values of the variables themselves but also the information associated - such as coordinate values of grid points, title, parameters of numerical experiments - are necessary. The netCDF data format provides a structure for attaching these associated information to the main data values of the variables. "Gtool4 data format" is a convention based on the netCDF data format that proposes the necessary items, their names and usages of those associated information ([14]).

NetCDF data format was originally developed for data having huge scales produced from atmospheric general circulation models and observations by satellites. By implementing netCDF data format into the SPMODEL programs, we confirmed that it is useful for small scale numerical models as well.

It was found that by utilizing "gt4_history" module in "gt4f90io" library, it was quite easy to realize the netCDF gtool4 data output from numerical models. The minimum procedure necessary for the output of netCDF gtool4 data is as follows:

Please browse the SPMODEL sample programs with the tutorials available from the home page of gtool4 ([14]), ([16]).

SPMODEL: A Series of Hierarchical Spectral Models for GFD Index