An Introduction to Atmospheric and Oceanographic Datasets

Appendix B

Features of Common Scientific Data Formats; Access Information

Table B.1
Comparison of three scientific-data-management systems
Feature	CDF	HDF	netCDF
Languages supported	C, f77	C, f77, f90, C++	C, f77, f90, C++
Inherent data types	char, short,	byte, short,	byte, char,
	int, float,	long, float,	short, long,
	double,	double	float,
	string		double
User-definable types	no	yes	no
Data-conversion method	XDR, native	XDR, native	XDR
Maximum array dimension	10	unlimited	32
Extended array dimension	yes	yes	yes
Hyperset access	yes	yes	yes
User-definable attributes	yes	yes	yes
Attribute types	any	any	any
Named dimensions	no	yes	yes
Array-index ordering	row, column	row, column	row, column
Shareability	yes	yes	yes
Compression	no	yes	no
Supporting tools	yes	many	ncdump, ncgen, a few others
Adapted from: "Software for Portable Scientific Data Management," 1993: Brown, et al., Computers in Physics, 7, 304-308

GRIB is not a "tool" for scientific data management. It is designed for efficient archival and transmission of two dimensional gridded arrays. It is a flat file format which is "quasi-self-describing" ( a table look-up procedure is used). Access would be sequential. It is used for archival by the world's largest operational meteorological centers (NMC and ECMWF).

Table B.2
More CDF, netCDF, HDF, GRIB information
Format	ftp	URL
CDF	nssdca.gsfc.nasa.gov cd pub/cdf	http://nssdc.gsfc.nasa.gov/cdf/cdf
netCDF	unidata.ucar.edu cd pub/netcdf	http://www.unidata.ucar.edu/packages/netcdf
HDF	ftp.ncsa.uiuc.edu cd HDF	http://hdf.ncsa.uiuc.edu:8001/
GRIB	ncardata.ucar.edu cd libraries/grib	ftp://ncardata.ucar.edu/libraries/grib

An Introduction to Atmospheric and Oceanographic Datasets