Page History

This page describes how to complete the OpenIFS Data Hub's data request form.

The description is for relaxation files for nudged experiments. In order to carry out an OpenIFS experiment you will also need initial experiment data (either meteo-only or with atmospheric composition). 

Above the data request form you can find a selector for the Product category. This offers the opportunity to conveniently switch between different data type request forms.

When the relaxation file option is selected, the Data Hub will generate 6-hourly forcing files that contain (at the desired model grid resolution) relative vorticity and temperature fields obtained from the ERA5 reanalyses. The data request form for this data type (on the right) contains fewer fields compared with the initial experiment data requests:

• Data Parameters:
  
  • At this time relaxation files can only be generated from ERA5 reanalysis data.  
    
    
• Date Range parameters:
  • These dates determine the first and the last calendar day for which relaxation files will be generated. For each day between the two selected dates four relaxation files (at 00, 06, 12, and 18 UTC) will be generated per day. The data time period includes also the two selected dates.
    
    
• Model Parameters:
  • Atmospheric composition initial data is only available Relaxation files can be generated for OpenIFS 48r1 (i.e. from CY48R1)43r3 and 48r1. Earlier model cycles are not supported. A choice of two chemistry schemes is offered: Either Tropospheric chemistry with aerosol (TM5 + AER), or alternatively Stratospheric + tropospheric chemistry with aerosol (BASCOE + TM5 + AER). Please contact OpenIFS support if you have questions about the chemistry scheme options. 
  • The initial data needs to have the grid type, horizontal resolution and vertical level numbers that are required for the experiment.
  • Users can select between several Gaussian grid types. Please refer to the section on model grid and resolution in the OpenIFS User Guide for more information. For atmospheric composition we only support model grids up to the resolution of the CAMS operational analysis. Therefore a much more limited choice of model grid resolutions  is available in comparision with the meteo-only forecast. 
  • The choice of vertical model levels is restricted to 60, 91, or 137 levels to ensure availability for all possible grid resolutions. 

• • Note that model cycle, grid resolution and type, and number of vertical levels all need to match with the initial experiment data for which the relaxation files are intended to be used.

The choice of model cycle for the relaxation files determines primarily the IFS climate version that is to be used to provide inputs (e.g. orography) required for the vertical level interpolation. contains at this time no variation in time. This means that no change to the emissions fluxes is applied over the duration of the forecast. Please also note that due to the unavailability of updated aircraft emissions for the years 2024 and 2025, emissions fluxes for 2023 are used consistently for all emissions (i.e., aircraft and also non-aircraft).