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Interpolation library (EMOSLIB)


The Interpolation library (EMOSLIB) includes Interpolation software and GRIB, BUFR, CREX encoding/decoding routines. It is used by the ECMWF meteorological archival and retrieval system (MARS) and also by the ECMWF graphics package Metview

Please note this page will no longer be maintained
You will find here the new EMOSLIB web page


Starting from version 000392, this software is licensed under the Apache License Version 2.0. Previous versions of the software are released under the GNU Lesser General Public License which incorporates the terms and conditions of version 3 of the GNU General Public License.


This software covers :

  • Interpolating fields
    • spectral coefficients to spectral coefficients
    • spectral coefficients to rotated spectral coefficients
    • spectral coefficients to regular latitude-longitude grids
    • spectral coefficients to regular gaussian grids
    • spectral coefficients to quasi-regular gaussian grids
    • regular latitude-longitude grids to regular latitude-longitude grids
    • regular latitude-longitude grids to regular gaussian grids
    • regular gaussian grids to regular gaussian grids
    • regular gaussian grids to regular latitude-longitude grids
    • quasi-regular gaussian grids to regular latitude-longitude grids
    • quasi-regular gaussian grids to regular gaussian grids
  • encoding/decoding WMO FM-92 GRIB GRIB code messages
  • encoding/decoding WMO FM-94 BUFR BUFR code messages
  • encoding/decoding WMO FM-95 CREX CREX code messages
  • handling pure binary unix files
  • handling files of GRIB products in an indexed manner
  • multiple(Temperton's) FFT routines (from release 000340 onwards)

All of the above software which is included in the Interpolation library (EMOSLIB) was developed at the European Centre for Medium-Range Weather Forecasts

A new cycle of this public version is created from time to time to consolidate operational extensions.


ECMWF is currently developing a replacement for the GRIBEX part of EMOSLIB called GRIB API. ECMWF also plans to rewrite the Interpolation (INTF) software. When production versions of these two components are ready, ECMWF will not develop GRIBEX and INTF any further.

Mailing list

Subscribers to the EMOSLIB library mailing list will receive information from time to time about EMOSLIB new releases. This is a hidden list, which means that the list of members is available only to the administrator.

To subscribe or unsubscribe from the mailing list, please use this simple web form.

As part of the subscription process, the mailing list server will send you a confirmation e-mail with a password. You must login with your e-mail address and the password provided in order to complete the process. This is a security measure to prevent the addition of subcribers without their permission.


Merging with GRIB_API

Available versions

Available versions of the Interpolation library (EMOSLIB) are 000392,000382,000381,000377,000376,000372,000371,000370,000360,000350, 000340, 000320, 000310, 000300.

The following instructions explain how to build the library and install:

  1. Run first build_library script, to build the library
  2. Then the install script, to install library and GRIB, BUFR, CREX tables and land-sea mask.

Local Definitions Templates refer to ECMWF local extensions to GRIB version 1, section 1 are in external files. Local definitions are described here.

From release 000310 onwards the Emos library can be compiled with Gnu compilers gcc and gfortran. The library compiled with those compilers has been tested on different kinds of data and for the majority of them the results are exactly the same as for the library built by the pgf90 compiler but in some cases they slightly differ.
Please, be aware that this type of library is not in operational use at ECMWF and it is not fully tested.

Latest changes


  • mbufr_mars_filter.F: updates related to satellite instrument MHS (instrument=203)
  • intuvp2.c, intf2.c : improved error code check for grib_util_set_spec
  • describe_input_field.c: updated type of level list with the case when type is missing
  • The coefficients handling: improvements for the case when The file is read into a dynamically allocated memory array.
  • Headers updated with Apache ilicense
  • insane.F: relax criteria for table number check up
  • iggrid.F : fix for NCEP N47 pseudo gaussian grid
  • igsize.F : Bug fix stride and number of points to match east
  • intout.F : added option off for interpolation
  • igsize.F: big fix for gaussian grid subarea
  • added rgauss_064.h
  • intuvu.F: bug fix - preserve output area between each iteration

A complete History of changes is also available.



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