***** Draft ********

This page aims at documenting the steps to follow when a data provider plans to implement a new version of their model.

There are two types of changes:

1. A change that does not affect the number of fields ingested in the database, for example, a change in resolution or an improved version of the model.
2. A change that affects the number of fields. This could be in the form of:
   1. change to the frequency of time-steps or extend/shorten the length of the forecast
   2. addition/removal of parameters
   3. change to the number of ensembles
   4. change to the frequency of the forecast (eg, from once a week to twice a week), etc...

In both cases, data providers must document the new version of the model (see example of ECMWF Model).

In the second case above, where a change of configuration occurs, we ask data providers to:

• notify in advance ECMWF and CMA about their change,
• provide test data, and
• update the Models summary page.

Provision of test data

ECMWF and CMA would like to have access to test data in advance, so the ingestion suites can be adapted.

This is achieved by naming files as test instead of prod, and by setting in the GRIB header Production status of data to 7:

6: S2S operational products
7: S2S test products

Once you have a full cycle of test data (whether real-time and/or hindcast) we ask you to contact s2s.support@lists.ecmwf.int.