Data Services Products: EMC-ContributionGuide IRIS EMC - Model Contribution Guidelines


EMC, as a repository of the Earth models, provides research community with access to various tomographic models, visualization tools for model preview and access to the contributed processing software and scripts.


To contribute Earth models to IRIS EMC, please include the following:

  • The original distributable model bundle or a link to a model bundle
  • Model coefficients and associated computer code
  • Pre-gridded model
  • The reference model
  • A model summary

A more detailed description of the above items is provided below. Please forward your model bundle and/or your questions to

The original distributable model bundle

The original model bundle or a link to a model bundle that includes model, data, scripts, notes and any other relevant material that is intended for direct distribution to the users (a link to this bundle will be placed on the model web page).

Model coefficients

The model coefficients and the computer code that reads the coefficients and outputs the model values for a specified mesh size and depth. If public distribution of the parameters and codes are desired, they should be included in the public bundle described above.

Pre-gridded model

The model (expressed as both percent velocity perturbation and km/s, when possible) in netCDF (network Common Data Form) format or a CDL (Common Data form Language) text representation of the netCDF dataset that is compatible with the EMC visualization software tools on this website. For more information on the netCDF data format and how to create netCDF files, visit:

The following is the CDL template used by EMC. This file holds necessary metadata for the Earth model. In this template the model is assumed to be a latitude-longitude-depth velocity grid. Modify the bold content as needed to conform to the model parameters. Other variables such as density and time may be added similar to the VP section below and by defining the corresponding variables (see the link above).

Visit the CDL Guide page at to learn more about CDL Syntax, ncgen tool to generate a netCDF file from a CDL file and ncdump tool to convert NetCDF file to text form (CDL).

NOTE: Before submitting your model, please use the following website to check CF-Convention compliance of your netCDF file:
netcdf MODEL_NAME {
// ***********************************************************************************************************
// Incorporated Research Institutions for Seismology (IRIS)
// Data Management Center (DMC)
// Data Products Group
// ***********************************************************************************************************
// All earth models contributed to the IRIS Earth Model Collaboration (EMC) are converted to a
// common netCDF (network Common Data Form) format that is compatible with the EMC
// visualization software.
// For more information on using the netCDF data format, visit:
// The following is the CDL file for a model with velocity in km/s.
// ***********************************************************************************************************
// dimensions – model size (integer) that provide length or size of the
// variable arrays
depth = 21 ;
latitude = 301 ;
longitude= 461 ;

// variables – represent coordinate values and model data as one-dimensional
// arrays
// in a 3D grid, each point is defined by a set of (depth,latitude,longitude)
float depth(depth) ;
"depth:long_name = "depth below earth surface ;
depth:units = "kilometer ";
depth:positive = "down ";

float latitude(latitude) ;
latitude:long_name = "Latitude; positive north" ;
latitude:units = "degrees_north" ;
latitude:standard_name = "latitude" ;

float longitude(longitude) ;
longitude:long_name = "Longitude; positive east" ;
longitude:units = "degrees_east" ;
longitude:standard_name = "longitude" ;

// data values as a function of latitude, longitude and depth as indicated in the variable definition.
// define as many variables as needed
float vs (depth,latitude,longitude);
vs:long_name = "S-velocity in km/s" ;
vs:units = "kilometer sec^-1" ;
vs:valid_range = "-1000.f, 1000.f";
// missing_value – if provided, this value should be outside the valid
// range so that the generic applications would treat them as missing
vs:missing_value = 99999.f;
vs:_FillValue = 99999.f;
// add_offset – if provided, this number would be added to the data
// after it is read by the application
vs:add_offset = "10.f";
// scale_factor – if provided, data would be multiplied by this value
// after they are read by the application
vs:scale_factor = "2.f" ;
// global attributes
// :title = "MODEL TITLE" ; :id = "MODEL_ID"; :summary = "Put a summary here.\n",
"You may break the summary to multiple lines.\n",
"Just make sure that each line ends with a ‘,’\n ",
"and the last line ends with a’;’\n";

:keywords = "seismic, shear, shear wave, s wave, velocity";
// Conventions – if provided, it is a global attribute that is a character
// array for the name of the conventions followed by the file. See:
// :Conventions = "CF-1.0" ;
// Metadata_Conventions – the global attribute indicating the convention that
// the metadata are conforming to for more information see:

:Metadata_Conventions = "Unidata Dataset Discovery v1.0";

:creator_name = "your name" ;

:creator_url = "" ;

:creator_email = "" ;

:institution = "Your Organization" ;

:acknowledgment = "acknowledgment statement" ;

:references = " Put as many references as necessary.\n",
"one reference per line.\n",
"Just make sure that each line ends with a ‘,’\n ",
" and the last line ends with a ‘;’\n";

:history = "model version" ;

:comment = "model converted to netCDF by IRIS DMC" ;

:geospatial_lat_min = 10.00;

:geospatial_lat_max = 85.00;

:geospatial_lat_units = "degrees_north" ;

:geospatial_lat_resolution = 0.5;

:geospatial_lon_min = -170.00;

:geospatial_lon_max = -55.0;

:geospatial_lon_units = "degrees_east" ;

:geospatial_lon_resolution = 0.5;

:geospatial_vertical_min = 669;

:geospatial_vertical_max = 70;

:geospatial_vertical_units = "kilometer" ;

:geospatial_vertical_resolution = 1;

:geospatial_vertical_positive = "down" ;

:time_coverage_start = "start" ;

:time_coverage_end = "present" ;


Reference model

The reference model in netCDF format and/or as coefficients of the polynomials describing the reference Earth model. This requirement could be dropped if the contributed model is referencing one of the reference models already in used by EMC.

Model summary

Information on the model for posting on the model web page (see the existing Models web pages ).

Citations and DOIs

To cite IRIS DMC Data Products effort:

  • Trabant, C., A. R. Hutko, M. Bahavar, R. Karstens, T. Ahern, and R. Aster (2012), Data Products at the IRIS DMC: Stepping Stones for Research and Other Applications, Seismological Research Letters, 83(5), 846–854, doi:10.1785/0220120032.

To cite IRIS Earth Model Collaboration (EMC) data product or reference use of its repository:

To cite the source or reference the use of a particular Earth model hosted by EMC: