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Comment: Added upgrade to 48r1.
Warning

Due to the move of our Data Handling System (DHS) to the new Data Centre in Bologna there will be no or degraded access to to public datasets and data in MARS at times between September and December 2021. Please visit our dedicated data centre migration pages for more information. Thank you for your patience and support during this important move, which will allow exciting scientific developments and overall better service.

Every day, ECMWF produces various global Analyses and Forecasts and archives them in MARS. The first ECMWF numerical model in 1979 was a grid-point model with 15 levels in the vertical and a horizontal resolution of 1.875 degrees in latitude and longitude, corresponding to a grid length of 200 kilometres. A number of major changes have occurred since ECMWF's activity started:

  • The upgrade to IFS Cycle 47r2 on 11 May 2021 48r1, implemented on 27 June 2023, increased the vertical horizontal resolution for of the medium-range ensemble  (ENS, streams enfo, enfh, efov, efho) NS) from 91 to 137 model levels, bringing it in-line with the HRES resolution.
  • 5 Nov 2017: Implementation of Seasonal Forecast SEAS5
  • ) from 18 to 9 km and introduced a major upgrade to the configuration of the  extended-range ensemble  (ENS extended): Rather than being  an extension of the medium-range forecasts starting twice a week at day 15 it will  be a completely separate system, running daily from 00 UTC out to day 46 with 101 members. Over the entire forecast range the resolution will remain unchanged at 36 km horizontally and 137 model levels. As a result of these configuration changes Cycle 48r1 will offer two sets of re-forecasts (=hindcasts), one for the medium range and one for the extended range.

  • The upgrade to IFS Cycle 47r2 on 11 May 2021 increased the vertical resolution for the ensemble (ENS, streams enfo, enfh, efov, efho) from 91 to 137 model levels, bringing it in-line with the HRES resolution.

  • 5 Nov 2017: Implementation of Seasonal Forecast SEAS5
  • With the upgrade on 22 November 2016, the medium-range ensemble and its monthly extension see a major upgrade in the dynamical ocean model (NEMO): the resolution is increased from 1° and 42 layers to 0.25° and 75 layers (ORCA025Z75). Furthermore, NEMO model version v3.4.1 with the interactive sea-ice model (LIM2) is implemented. The ocean and sea-ice With the upgrade on 22 November 2016, the medium-range ensemble and its monthly extension see a major upgrade in the dynamical ocean model (NEMO): the resolution is increased from 1° and 42 layers to 0.25° and 75 layers (ORCA025Z75). Furthermore, NEMO model version v3.4.1 with the interactive sea-ice model (LIM2) is implemented. The ocean and sea-ice components of the ENS initial conditions are provided by the new ocean analysis and reanalysis suite ORAS5, which uses the new ocean model and revised ensemble perturbation method.
  • On 8 March 2016 with the introduction of cycle 41r2 the horizontal resolution was upgraded, equivalent to about 9 km for HRES and the data assimilation (the outer loop of the 4D-Var) and to about 18 km for the ENS up to day 15. The resolution of the ENS extended (day 16 up to day 46) is about 36 km. Cycle 41r2 also introduced a new reduced Gaussian grid, the octahedral grid. > Full description


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titleearlier changes
  • In Apr 2015 with cycle 41r1 the domain of the limited-area ocean wave model has been extended to the full globe and is now referred to as HRES-SAW. The ENS configuration has been changed and new climate files have been introduced. > Full description
  • In

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  • June 2013 IFS cycle 38r2 introduced higher vertical resolution

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titleearlier changes
  • In June 2013 IFS cycle 38r2 introduced higher vertical resolution in the high-resolution in the high-resolution (T1279) forecast and data assimilation of the operational runs at 00 and 12 UTC (HRES) as well as the 06 and 18 UTC cycles of the Boundary Conditions (BC) optional programme. The number of model levels increases from the current 91 levels (L91) to 137 levels (L137).In January 2010 the horizontal resolution of the deterministic model has been increased to T1279. The resolution of the EPS went up to T639/T319 for Leg A/B, respectively.
  • In March 2008 VarEPS and monthly forecasting were combined into a single system. On Thursday of each week, the 00 UTC VarEPS forecast are extended from 15 to 32 days at a resolution of T255 L62 with ocean coupling introduced from day 10.
  • In March 2007 the operational seasonal forecasting system has been upgraded from System 2 to System 3 and integrated in the Multi-Model Seasonal Forecast stream. The resolution of the atmospheric model has been increased to T159L62.
  • In November 2006 the EPS has been upgraded to Variable Resolution Ensemble Prediction System (VarEPS). In particular, the forecast range was extended to 15 days using the VarEPS system with a resolution of T399 L62 for day 1 to day 10 and T255 L62 for day 11 to day 15.
  • In February 2006 the resolution of the deterministic model has been increased to T799 and 91 model levels. The resolution of the Ensemble Prediction System (EPS) went up to T399 and 62 model levels.
  • In June 2004, the Early Delivery Forecasting System was implemented, comprising two main 6-hour 4d-Var analysis and forecast cycles for 00 and 12 UTC and two additional 12-hour 4d-Var analysis and first guess forecast cycles.
  • In November 2000, the spectral truncation was extended to wave number 511.
  • In September 2000, 4d-Var cycling was increased to 12 hours. Type First Guess has been discontinued.
  • In October 1999, the number of levels was increased to 60.
  • In October 1999, the number of levels was increased to 60.
  • In March 1999, the number of levels was increased to 50.
  • In June 1998, the atmospheric model and the wave model were coupled in order to take advantage of the boundary conditions they represent to each other.
  • In April 1998, the spectral truncation was extended to wave-number 319.
  • In November 1997, 4d-Var (four-dimensional variational Analysis) became operational.
  • In 1992, a wave model used for ocean wave forecasting (the WAM model) became operational, followed after a few months by a Mediterranean implementation.
  • In December the Ensemble Prediction System (EPS) with 32 members and a resolution of T63L31 became operational.
  • In September 1991, a much higher resolution spectral model was put into operation. The spectral truncation was extended to wave-number 213 and the number of levels was increased to 31 (i.e. T213L31).
  • In May 1985, the spectral truncation was extended to wave-number 106. The number of levels was increased to 19 in 1986.
  • In April 1983, the grid-point model was replaced by a T63 spectral model (i.e. a spectral representation in the horizontal with a triangular truncation at wave-number 63). The number of levels in the vertical was increased to 16.

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ECMWF's Ensemble Prediction System has a coupled atmospheric and wave model. On 28 November 2006 the Variable Resolution Ensemble Prediction System (VarEPS) has been introduced by extending the forecast range from 10 to 15 days with a resolution of T399L62 for day 1 to day 10 (Leg 1) and T255L62 for day 11 to day 15 (Leg 2). On 11 March 2008 the Monthly Forecasting System, running once a week, has been integrated with the VarEPS. The new monthly forecast products were produced for the first time on 13 March 2008. With Cycle 48r1, 12 May 2015, Leg 2 was extended to 46 days (instead of 32) on Mondays and Thursday (at 00UTC) and the number of re-forecasts increased to 11 members twice per week. On 8 March 2016, Cycle 41r2, the upgraded horizontal resolution increased to about 18 km up to day 15 and about 36 km for the extended range. The resolution of the ensemble of data assimilations (EDA) is increased to 18 km. With Cycle 43r1, 22 November 2016, the resolutions of the dynamical ocean model (NEMO) increased from 1 degree and 42 layers to 0.25 degrees and 75 layers. The upgrade to IFS Cycle 47r2 on 11 May 2021 increased the vertical resolution for the ensemble (ENS, streams enfo, enfh, efov, efho) from 91 to 137 model levels.
IFS Cycle 48r1, implemented on 27 June 2023, increased the horizontal resolution of the medium-range ensemble  (ENS) from 18 to 9 km and introduced a major upgrade to the configuration of the  extended-range ensemble  (ENS extended): Rather than being  an extension of the medium-range forecasts starting twice a week at day 15 it will  be a completely separate system, running daily from 00 UTC out to day 46 with 101 members. Over the entire forecast range the resolution will remain unchanged at 36 km horizontally and 137 model levels. As a result of these configuration changes Cycle 48r1 will offer two sets of re-forecasts (=hindcasts), one for the medium range and one for the extended range.

  • Control forecast: an unperturbed forecast at a lower resolution than the main HRES 10-day forecast. Forecast runs to 15 days, with lower resolution from truncation step 240 onwards. Data is available on Surface, Model levels, Pressure levels and Isentropic levels.
  • Calibration/Validation forecast: VarEPS includes two constant-resolution forecasts for calibration and validation purposes which run for both resolutions from day 1 - 15. Data is available on Surface, Model levels, Pressure levels and Isentropic levels.
  • Perturbed forecasts: different forecasts to 10 days with perturbed initial conditions. They are numbered from 1 to N depending on the EPS setup. Data is available on the Surface and on Pressure levels and Isentropic levels.
  • Initial condition perturbations: the initial conditions for the EPS are designed to represent the uncertainties inherent in the operational analysis. They are created by adding perturbations to the operational analysis which produce the fastest energy growth during the first two days of the forecast period, defined using the singular vector technique.
  • Forecast probabilities: a statistical distribution of the weather parameters from all ensemble members is used to produce probabilistic weather forecasts. With the introduction of VarEPS this data type has been discontinued.
  • Event probabilities: provide the probabilities of the occurrence of weather events at each grid point. The probabilities are calculated on the basis that each ensemble member is equally likely.
  • Ensemble means: are means of the ensemble forecast members.
  • Clusters: similar ensemble members are grouped together into clusters. The mean and standard deviation of these clusters are computed (as well as the mean and standard deviation of the overall ensemble). Five sets of clusters are computed, one for the entire European area, and four for smaller areas.
  • Tubes: another clustering method which averages all ensemble members which are close to the ensemble mean and excludes members which are significantly different.
  • Extreme Forecast Index (EFI): measures the difference between the probability distribution from the EPS and the model climate distribution.

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