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

The description is for initial experiment data for global forecasts 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 selecting forecast with atmospheric composition, the data request form (shown on the right) contains the following fields:

• Data Parameters:
  
  • Initial experiment data with atmospheric composition are generated from the CAMS operational analysis of model cycle CY48R1 or newer. This data is only available from 28 June 2023 onwards. No earlier start dates can be offered at present.  
    
    
• Experiment Parameters:
  • The first start date and last start date determine the range of experiment start dates for which initial data will be requested (when multiple start dates are required). If only one start date is required, irrespective of the forecast length, both dates need to be equal and in this case the value of the time increment between forecasts is ignored. 

    Note: Only select different dates for "First start date" and "Last start date" if you require initial data for multiple experiment start dates. If you need only one start date, then make sure both dates are kept the same. It is the "Forecast length in days" that determines the duration for which boundary conditions will be generated.

  •  For data generated from the CAMS operational analysis the earliest possible start date is 2023-June-28. The end date of the most recent available data is being continually updated and is typically 8 days before the current date. If this most recent date is chosen then the forecast length can only be 1 day. 

  • The forecast length determines the number of days for which boundary conditions are supplied (e.g. sea surface temperatures etc), commencing with the initial start date. This value must be between 1 and 31 days (requests with longer forecast lengths are likely to fail). The timestamp of the final requested data point must be at least 1 day before the present day. 
    
    
• Model Parameters:
  • Atmospheric composition initial data is only available for OpenIFS 48r1 (i.e. from CY48R1). Earlier 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. 

Please note that the initial experiment data 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).