Description of the upgrade

With IFS Cycle 48r1, the horizontal resolution of the medium-range ensemble (ENS) will increase from 18 to 9 km. This will bring the ENS to the same horizontal resolution as the high resolution forecast (HRES). The vertical resolution for both ENS and HRES will remain at 137 model levels and the ENS will continue to have 51 members. 

Cycle 48r1 will also bring 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.

This major upgrade to Cycle 48r1 is currently planned for 13 June 2023 (TBC) and will be the first new scientific model upgrade to run in ECWMF's new Data Centre in Bologna. 

The information presented on this page is subject to further change. To get notified about any updates please "watch" this page. 

For any questions or issues please contact us via the Support Portal. 

#IFS48r1 #newfcsystem @ECMWF

News

Timeline of the implementation

Datasets affected

• HRES (day 1-10)

• ENS (day 1-15)

• ENS extended (day 1-46)

• HRES-WAM (day 1-10)

• ENS-WAM (day 1-15)

• ENS-WAM extended (day 1-46)

Resolution

Resolutions in bold increased/changed from previous IFS cycle.

Meteorological content

Assimilation

• Increase of HRES 4DVar inner loop resolution to T_L511
• Switch to OOPS, the object-oriented prediction system
• Reduced thinning of ASCAT L2 products
• Various optimisations for hyperspectral IR sounders
  • Unified VarBCsetup for IR sounders
  • Allow usage of all pixels from IASI
  • Aerosol type classification in IR data
  • Update on the IR trace gas detection
• Upgrade RTTOV to v13
  • Latest version of RTTOV: technical upgrade + additional capabilities to prepare for future
  • Microwave gas optical depth coefficient file upgrade, using new predictors (v13)
  • Major scientific upgrade of cloud and precipitation microphysics in RTTOV-SCATT
• ATMS snow, Lambertian, slant-path
  • Activate ATMS humidity channels over snow
  • ATMS Lambertian surface reflection over snow and sea-ice
  • Slant-path interpolation for selected MW sensors assimilated in the all-sky system
• Improved treatment of surface-sensitive channels in all-sky
  • Assimilate polewards of 60 degrees over land and ocean; relying on new sea-ice detection
  • Improved treatment of mixed land-water and water-sea-ice scenes

Observations

• Improved observation pre-processing
• Assimilation of microwave imagers over land surfaces
  • 89 GHz, 150/166 GHz channels of GMI, SSMIS + GMI 183 GHz over land
  • Add 37 GHz channels, Add AMSR2; improved bias correction, QC and error models

Model

• Improved water and energy conservation (dynamics and physics)
• Radiatively interactive prognostic ozone using new HLO scheme
• Multi-level snow scheme
• New precipitation category - freezing drizzle
• Revised climate fields – improved orographic fields for atmospheric drag
• Revised computation of Semi-Lagrangian advection departure points
• New model top sponge layer formulation and semi-Lagrangian vertical filter
• Revised SPPT, removed cloud saturation adjustment from tendency perturbations 

Key configuration changes

Atmospheric model

• The HRES configuration will not change
• There will be no change in the vertical resolution
• The resolution of ENS will increase to match that of the HRES
• The ENS control forecast will be different from HRES
• Stream enfo and enfh will not provide any products beyond step 360. For the extended range ensemble streams eefo and eefh need to be used instead.

• As ENS extended will be produced with constant resolution from step 0, overlap fields are no longer required and stream efov will be discontinued. 

  
  

• Cycle 48r1 will have two sets of re-forecasts: One at a high resolution (Tco1279) up to day 15 to calibrate the high-resolution medium-range ensemble, and one at a low resolution (Tco319) for extended-range forecasts. Both re-forecasts will run twice per week, on Monday and Thursday.  
• The extended range re-forecasts will have two streams: eefh for the individual control and perturbed forecasts, and eehs for hindcast statistics
• Stream enfh will no longer have products beyond step 360

Wave model

• The HRES-WAM configuration will not change

• Cycle 48r1 will have two sets of re-forecasts: One at a high resolution (0.125°) up to day 15 to calibrate the high-resolution medium-range ensemble, and one at a low resolution (0.5°) for extended-range forecasts
• The extended range re-forecasts will have two streams: weeh for the individual control and perturbed forecasts, and wees for hindcast statistics. Both re-forecasts will run twice per week, on Monday and Thursday.  
• Stream enwh will no longer have products beyond step 360

New and changed parameters

New parameters

The table contains the list of parameters expected to be available with the model implementation. They will be available as part of the test data. With implementation the parameters will be available in MARS and dissemination.  

¹In addition to the single level parameter on the surface (levtype=sfc). 
²The 1 hour parameters will be available for steps 1-90, the 3 hour parameters for steps 3-144 and the 6 hour parameters from step 6 to the end of the forecast, step 240 for ENS and 360 for ENS.

Precipitation type parameters are using the following subset of WMO table 4.201. For "most-severe" precipitation type parameters the severity is also given, with 0 being the lowest. 

Changes to existing parameters 

Discontinued parameters

As the resolution of both medium-range ensemble (ENS) and extended-range ensemble (ENS extended) no longer varies over the forecast period, stream efov, providing ensemble forecast overlap fields, will be discontinued. 

Technical content

Changes to GRIB encoding

The GRIB model identifiers (generating process identification number) for cycle 48r1 will be changed as follows:

For gridded 48r1 model output in GRIB 2 format the packing type will change as follows: 

If CCSDS compression is not desired when retrieving gridded GRIB 2 fields from MARS or dissemination, simple packing can be requested with keyword 

packing = si 

Using ecCodes, already retrieved CCSDS compressed fields can be converted to other packing types. This is how you can convert all messages in file ccsds.grib which have grid_ccsds as their packingType, and only those, to use grid_simple packing, i.e. what we used before 48r1: 

grib_set -r -w packingType=grid_ccsds -s packingType=grid_simple ccsds.grib grid_simple.grib

To compare the statistics of the fields before and after the conversion, the following command could be used:

grib_ls -n statistics ccsds.grib grid_simple.grib

Software

The software packages listed below are recommended for full support for all 48r1 parameters and the new CCSDS compression. 

ecCodes 2.28.0
Magics 4.13.0
Metview 5.18.0

On the ECMWF Atos system these packages can be loaded via the module ecmwf-toolbox/2023.01.0.0. Before the implementation software versions compatible with 48r1 will be made the default on ECMWF platforms. 

Users are strongly encouraged to test their software applications and data processing chain with the new versions of the various software packages before this change. 

Availability of 48r1 test data

Test data in MARS

IFS Cycle 48r1 beta test data is available from MARS with E-suite experiment version (expver) 0078 (MARS keywords EXPVER=0078, CLASS=OD): 

• HRES (stream = OPER)

• HRES-WAM (stream = WAVE)

• ENS (stream = ENFO)

• ENS hindcast (stream = ENFH)

• ENS-WAM (stream = WAEF)

• ENS-WAM hindcast (stream = ENWH)

New streams for the extended-range ensemble

• ENS extended (stream = EEFO)
• ENS extended hindcasts (stream = EEFH)
• ENS extended hindcast statistics (stream = EEHS)
• ENS-WAM extended (stream = WEEF)
• ENS-WAM extended hindcasts (stream = WEEH)
• ENS-WAM extended hindcast statistics (stream = WEES)

Only users registered with access to MARS will be able to access these test data sets. The data should not be used for operational forecasting.  Please report any problems you find with this data via the ECMWF Support Portal.

Resources

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References

• Impact of GRIB compression on weather forecast data and data-handling applications; Eugen Betke, Tiago Quintino, Simon Smart, Tomas Wilhelmsson, 2022, Technical memorandum

• The next extended-range configuration for IFS Cycle 48r1, ECMWF Newsletter No. 173 - Autumn 2022
• A new way of computing semi-Lagrangian advection in the IFS, ECMWF NewsletterNo. 173 - Autumn 2022
• Upgrade of forecasts is at the centre of our plans for 2023, says DG; ECMWF News item