Form of Output

ECMWF provides data from several different IFS models, each available according to when the IFS models are run, and each with different temporal resolutions in the output data.

Output data is in the form:

• most commonly as absolute values:  
  • instantaneous values,
  • averages over a period,
  • totals over a period,  
  • maxima or minima over a period.
• sometimes as:
  • anomalies relative to re-forecast data
  • an assessment of how extreme the anomalies might be (Extreme Forecast Index and Shift of Tails).

Medium range forecasts

The Control Forecast (ex-HRES) model:

• • is run four times daily:
    • base times 00 UTC and 12 UTC, covering the forecast period Day 0 to Day 15 (T+0 to T+360).  
      • Dissemination schedule and forecast step frequency - Atmospheric model analysis and 15 day forecast of Ensemble Control Forecast (ex-HRES) (Sets I-i, I-ii, I-iii as shown for 00UTC and 12UTC base times).
    • base times 06UTC and 18UTC, covering the forecast period Day 0 to Day 6 (T+0 to T+144).
      • Dissemination schedule and forecast step frequency - Atmospheric model analysis and 6 day forecast of Ensemble Control Forecast (ex-HRES) (Set I-i as shown for 06UTC and 18UTC base times).
  • has horizontal resolution of 9 km
  • has vertical resolution of 137 model levels.
  • has land-atmosphere and ocean-atmosphere coupling.
  • Results from these runs are:
    • used in Early cut off analysis (SCDA) and Long window data analysis (LWDA).

The link gives a description of higher detail output and derived products of the medium range forecast output.  Some are additional products that are available by arrangement.

Note: HRES and Ensemble Control are scientifically, structurally and computationally identical.  For the benefit of users:

• The Ensemble Control Forecast (ex-HRES) output runs on the schedule of HRES in Cy48 and earlier.   It runs before the medium range ensemble starts.  It is labelled HRES for the convenience of users but the name will be withdrawn in a future update cycle.
• Ensemble Control Forecast (ex-HRES) also continues to be issued at the times given below, even though it is identical to the earlier issue labelled HRES.

In Cy50r scheduled for summer 2025:

• The Ensemble Control Forecast (ex-HRES) will continue to be issued at the times given above.
• The perturbed ensemble members will be issued at the times given below (without ensemble control forecast (ex-HRES) which will have been issued earlier).

The medium range ensemble:

• • is run four times daily:
    • base times 00 UTC and 12 UTC, covering the forecast period Day 0 to Day 15 (T+0 to T+360).
      • Dissemination schedule and - Atmospheric model analysis and 15 day forecast ensemble (Set III as shown for 00UTC and 12UTC base times).
    • base times 06UTC and 18UTC, covering the forecast period Day 0 to Day 6 (T+0 to T+144).
      
      • Dissemination schedule - Atmospheric model analysis and 6 day forecast ensemble (Set III as shown for 06UTC and 18UTC base times).
  • has horizontal resolution of 9 km
  • has vertical resolution of 137 model levels.
  • has land-atmosphere and ocean-atmosphere coupling.

The link gives a description of higher detail output and derived products of the medium range ensemble forecast output.  Some are additional products that are available by arrangement.

Note: HRES and Ensemble Control are scientifically, structurally and computationally identical.  For the benefit of users:

• The Ensemble Control Forecast (ex-HRES) output runs on the schedule of HRES in Cy48 and earlier.   It runs before the medium range ensemble starts.  It is labelled HRES for the convenience of users but the name will be withdrawn in a future update cycle.
• Ensemble Control Forecast (ex-HRES) also continues to be issued at the times given below, even though it is identical to the earlier issue labelled HRES.

In Cy50r scheduled for summer 2025:

• The Ensemble control forecast (ex-HRES) will continue to be issued at the times given above.
• The perturbed ensemble members will be issued at the times given below (without ensemble control forecast (ex-HRES) which will have been issued earlier).

The Artificial Intelligence Forecasting System (AIFS)  (Medium range)

• • is run four times daily:
    • base times 00UTC, 06UTC, 12UTC, 18UTC covering the forecast period Day 0 to Day 15 (T+0 to T+360).
      • Dissemination schedule - Deterministic AIFS forecast (Set IX-i-a,  IX-i-b) released one hour after medium range forecasts given at Atmospheric model analysis and 15 day forecast of Ensemble Control Forecast (ex-HRES) (Sets I-i, I-ii, I-iii as shown for 00UTC and 12UTC base times).

The link gives a description of higher detail output and derived products of the Artificial Intelligence Forecasting System forecast output.

Sub-seasonal Range forecasts

The sub-seasonal range ensemble:

• • is run once daily:
    
    • base times 00 UTC, covering the forecast period Day 15 to Day 46.
      • Dissemination schedule - Atmospheric model sub-seasonal forecast (Set VI).

• • has horizontal resolution of 36 km.
  • has vertical resolution of 137 model levels.
  • has land-atmosphere and ocean-atmosphere coupling.
  • has 100 ensemble members plus an unperturbed control member.

Precipitation forecasts are provided as values accumulated from the start of the forecast integration.  The range of the daily variation of the forecast 2m temperature and wind gust is best estimated by retrieving the forecast maximum and minimum values.  The combination of accumulated and instantaneous forecast information can occasionally lead to inconsistencies as in both cases the valid time is defined as the time at the end of the period (e.g. during the passage of a cold front when significant precipitation amounts might be accumulated by the IFS models over the whole time interval though instantaneous cloud-free conditions will be shown at the end of the interval).

The link gives a description of higher detail output and derived products of the sub-seasonal range ensemble forecast output.    Some are additional products that are available by arrangement.

Seasonal (SEAS) forecasts

The seasonal range ensemble:

• • is run once monthly:
    • base time 00UTC on 1st of each month and run on the 5th of each month covering the forecast period  Month 1 to Month 7 month forecast (extended to Month 13 every quarter).
      
      • Dissemination schedule - Seasonal forecast.

• • has horizontal resolution of 36 Km and vertical resolution of 91 model levels.
  • has land-atmosphere and ocean-atmosphere coupling.
  • has 50 ensemble members plus an unperturbed control member.

    
    

The link gives a description of higher detail output and derived products of the seasonal model output.    Some are additional products that are available by arrangement.

Wave model ECWAM forecasts

Control Forecast (ex-HRES) WAM

• • is run four times daily:
    • base time 00UTC and 12UTC data times giving 15day forecasts (T+0 to T+360).
      • Dissemination schedule - Ocean wave model 15 day forecast Ensemble Control Forecast (ex-HRES) WAM (Set II as shown for 00UTC and 12UTC base times) .
    • base time 06UTC and 18UTC data times giving 6day forecasts (T+0 to T+90).
      • Dissemination schedule - Ocean wave model 6 day forecast Ensemble Control Forecast (ex-HRES) WAM (Set II as shown for 06UTC and 18UTC base times). 

• • is associated with ensemble Control Forecast (ex-HRES) forecasts
  • has horizontal resolution of 9 Km.
  • has ocean-atmosphere coupling.

The link gives a description of higher detail output and derived products of the Ensemble Control Forecast (ex-HRES) WAM.    Some are additional products that are available by arrangement.

Ensemble (medium range) ensemble WAM (ENS WAM)

• • is run twice daily:
    • base time 00UTC and 12UTC data times giving 15 day forecasts (T+0 to T+360).
      • Dissemination schedule - Ocean wave model 15 day ensemble forecast WAM (Sets IV-i, IV-ii, IV-iii).

• • is associated with the medium range forecasts.
  • has horizontal resolution of 9 Km.
  • has ocean-atmosphere coupling.
  • has 50 ensemble members plus an unperturbed control member.

The link gives a description of higher detail output and derived products of the ensemble (medium range) WAM.    Some are additional products that are available by arrangement.

Sub-seasonal WAM

• • is run once daily:
    • base time 00UTC data time daily giving forecasts from Day 16 to Day 46.
      • Dissemination schedule - Ocean wave model sub-seasonal ensemble forecast WAM (Set VI).
  • is associated with the sub-seasonal range forecasts.
  • has horizontal resolution of 36 Km.
  • has ocean-atmosphere coupling.
  • has 50 ensemble members plus an unperturbed control member.

The link gives a description of higher detail output and derived products of the sub-seasonal model output.    Some are additional products that are available by arrangement.

(FUG Associated with Cy49r1)