Requesting initial experiment data for the meteo only forecast

When selecting meteo only forecast, the data request form contains the following fields:

• Product category:
  • This drop-down field offers the opportunity to switch between different data types (the meteo only and atmos composition forecast data) request forms.
    
    
• Data Parameters:
  
  • Initial experiment data can be produced either from ERA5 reanalysis data or from historical data in the operational archive. We recommend to use ERA5 data by default, unless there is a good reason to use operational archive data (e.g. for experiments using the highest grid resolution). 
    
    
• 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 ERA5 reanalyses the earliest possible start date is 1940-Jan-01. The end date of the most recent available data is being continually updated and is typically 3 months prior to the present date. If recent start or end dates (e.g., within the past 3-4 months) are required then the user should verify first on the MARS Catalogue or on the Climate Data Store whether ERA5 data for the requested dates is currently available before submitting the request with the OpenIFS Data Hub. If no available data is found in the requested time period, then the data request will be aborted. 

  • For data generated from the operational archive the the most recent available start date is 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 366 days. The timestamp of the final requested data point must be at least 1 day before the present day (for operational archive) or within the available valid data period (for ERA5). 
    
    
• Model Parameters:
  • Initial data for model cycles CY43R3 and CY48R1 can be produced for OpenIFS or the IFS model. Other model cycles before CY48R1 will not be supported. 
  • 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. 
  • The choice of vertical model levels is restricted to 60, 91, or 137 levels to ensure availability for all a possible grid resolutions.