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 (TBCtarget date) 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 (requires to log in). 

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 

Meteorological impact

ENS

• Improvements to surface variables, e.g. 2m temperature, 10m wind, total precipitation etc., around 2% to 6%.

• Improved tropospheric upper air variables, around 1% to 3%

• Improved stratospheric winds and some degradations of stratospheric temperatures due to increased biases.

• Arctic and Antarctic scores improved.

• Upper air ensemble spread reduced in the midlatitudes (around 1% to 2%) but mainly increased in the tropics (around 2% to 3%). Ensemble spread of surface variables increased (around 2% to 6%).

• Improved TC track and intensity forecasts, with position errors reduced by ca. 10% and core pressure errors reduced by around 20%.

HRES

• Northern hemisphere and topics, troposphere improved (ca. 1% - 3%)
• Improved stratospheric winds and some degradations of stratospheric geopotential and temperatures due to increased biases. 
• Arctic and Antarctic scores improved.
• Surface winds in the tropics appear degraded in verification against own-analysis because of analysis changes due to the increased number of scatterometer observations. Verification against observations does not show the degradation.
• 2m temperature scores appear degraded due to increased forecast activity caused by the multi-level snow scheme. 

ENS extended 

• Improvements due to the increase in ensemble size and more frequent initialisation
• In addition, 48r1 model changes on their own result in modest but overall positive impact on weekly mean bias-corrected scores (CORR, RMSE, CRPSS), e.g. the HLO scheme improves forecasts of stratospheric zonal wind anomalies despite increasing stratospheric temperature biases

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 and HRES are not bit identical but should be considered equally likely unperturbed runs
• Stream enfo will no longer provide products beyond step 360. For the extended range ensemble stream eefo needs to be used instead.

• ENS extended will be produced with constant resolution from step 0. Therefore the overlap stream efov is no longer needed and will be discontinued. 

• While 47r3 has just one, 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, as before, run twice per week from 00 UTC, 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 provide products beyond step 360. For the extended range ensemble stream eefh needs to be used instead.
• ENS extended will be produced with constant resolution from step 0. Therefore the overlap stream efho is no longer needed and will be discontinued. 

Wave model

• The HRES-WAM configuration will not change
• The resolution of ENS-WAM will increase to match that of the HRES-WAM
• The ENS-WAM control forecast will be different from HRES-WAM are not bit identical but should be considered equally likely unperturbed runs
• Stream waef will no longer provide products beyond step 360. For the extended range ensemble streams weef needs to be used instead.
• ENS extended will be produced with constant resolution from step 0. Therefore the overlap stream weov is no longer needed and will be discontinued. 

• While 47r3 has just one, 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. Both re-forecasts will, as before, run twice per week from 00 UTC, on Monday and Thursday
• The extended range re-forecasts will have two streams: weeh for the individual control and perturbed forecasts, and wees for hindcast statistics. 
• Stream enwh will no longer have products beyond step 360. For the extended range ensemble stream weeh needs to be used instead.
• ENS-WAM extended will be produced with constant resolution from step 0. Therefore the overlap stream ewho is no longer needed and will be discontinued. 

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.  

¹On up to 5 snow levels, in addition to the already produced 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 HRES 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 

With 48r1 mxcape6, mxcapes and capes will be based on MUCAPE rather than the old and physically less correct CAPE.

Discontinued parameters

As the resolution of both medium-range ensemble (ENS) and extended-range ensemble (ENS extended) no longer varies over the forecast period, streams efov, efho, weov and ewho, providing ensemble forecast overlap fields, will be discontinued. Also, ENS model level fields at step 336 will no longer be produced.

Technical content

Changes to GRIB encoding

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

For gridded data in GRIB 2 format the default packing type will change as follows: 

Default packing types for data from Dissemination and MARS

With 48r1 all gridded GRIB2 "raw" data will use the new CCSDS packing type. The default behaviour for data from dissemination (from 00 UTC run 21/3/2023) and MARS will be as follows:

While by default all 48r1 gridded GRIB2 data will be disseminated in CCSDS packing, MARS will by default only write gridded GRIB2 data in CCSDS if derived from (gridded) CCSDS-packed GRIB2 fields. 

The default behaviour can be overridden by specifying the packing explicitly, e.g.  

  grid    = 0.1/0.1, 
  packing = CCSDS 

will deliver fields with CCSDS packing for any GRIB2 input field. It will however not be possible to get CCSDS packed fields from GRIB1 input fields. Similarly, if CCSDS compression is not desired when retrieving gridded GRIB 2 fields from MARS or dissemination, simple packing can be requested with keyword 

  packing = simple 

Using ecCodes, already retrieved CCSDS compressed fields can be converted to other packing types. This is how to convert all messages in file ccsds.grib with grid_ccsds as their packingType, and only those, to use 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

Note

The Release Candidate Phase starts started on 14 March. An update of the e-suite is planned for release in the coming weeks due to the correction of the bug described below. In the meantime, users are encouraged to use the test data, prior to correction, to familiarise themselves with the new dataflows and formats from a technical point of view. Due to a bug in the forecast model, unrealistic amounts of supercooled liquid water could sometimes form in very cold/low humidity environments over parts of Canada,  China, Mongolia and Siberia. This results in an increase in precipitating snow in these areas which in turn leads to unrealistic increases in snow depth, which if not corrected, would lead to problems in the melt season in spring. Incorrect snow depth will also adversely affect 2m temperature. In the coming weeks it is planned to fix the bug and reset the snow fields of the e-suite to the values in the current operational suite to avoid future problems with snow melt. Currently the following products are regularly produced: Datasets MARS Test ECPDS Test PREd HRES/HRES-WAM 00/12 UTC - ENS/ENS-WAM 00 UTC   - ENS/ENS-WAM 12 UTC - Control forecast only -  - ENS/ENS-WAM hindcast 00 UTC - - ENS/ENS-WAM extended 00 UTC - - ENS/ENS-WAM extended hindcast 00 UTC - - ENS/ENS-WAM extended hindcast statistics 00 UTC - - BC 06/18 UTC - - - Open data 00 UTC from ECMWF website   Any As usual, any test data provided may not be complete and should not be used commercially or in service provision until the cycle is operational. Test data is provided for technical testing, evaluation and planning purposes only.

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.

Test data in dissemination

Cycle 48r1 test data from the release candidate phase (RCP) will be available through the test dissemination system, starting from the 00Z run on 14 Mar 2023. Users with access to ECPDS and the Products Requirements Editor (PREd) can login to the test system at https://xdiss-monitor.ecmwf.int/and trigger the transmission of test products in the usual manner. To receive the test products, users have to have their firewall open to the relevant ECPDS Data Movers:

INTERNET:

• • 136.156.192.0/26
  • 136.156.193.0/26

RMDCN:

• • 136.156.196.0/26
  • 136.156.197.0/26

The IFS Cycle 48r1 test products are available as version number 78 (file names ending with '78') and are intended to be generated shortly behind real-time. The test products will be based on the operational dissemination requirements from 13 Mar 2023. As streams enfo and enfh will no longer provide any products beyond step 360 these requests will be translated to equivalent requests using streams eefo and eefh. 

The various streams will be released in stages. At the start of the RCP, HRES, HRES-WAM, ENS and ENS-WAM will be available. All extended range products will become available slightly later, precise date TBC. 

Approx. 1 week into the RCP, authorised users will get access to a Products Requirements Editor (PREd) in the test system to edit their requirements for 48r1 test data e.g. to request ENS data in the higher resolution or get daily extended range products. 

Please note that in particular changes to the resolution, e.g. requesting ENS data with 0.1° resolution, will have a significant impact on the requested data volumes.

The new parameters of Cycle 48r1 listed above will become available in dissemination after the implementation date.

Any changes made in the test system will not be ported to operations on implementation day. Access to the operational PREd will be closed at 9 UTC on 12 June. Any changes to the operational requirements can be implemented after 10 UTC on 13 June.

Users are strongly advised to check that their software applications and data processing chain can handle the test data.

If you don't have access to the ECPDS system or PREd or should you require any assistance with IFS Cycle 48r1 test dissemination products, please contact us via the Support Portal.

WMO Essential and Additional test data

WMO Essential and Additional test data will e made available, date TBA. 

Open data

Open data test data is now provided regularly at https://xdiss.ecmwf.int/ecpds/home/opendata/. Please note that all fields are provided as CCSDS compressed GRIB2. Users are strongly advised to check that their software applications and data processing chain can handle the test data. 

Test data in ecCharts

Layers from IFS cycle 48r1 will become gradually available in ecCharts with the aim to have the complete set of layers in the release candidate mode one month before implementation. Cycle 48r1 layers are identified by the label "0078" in their title and a black border around test data layers for better visual identification.

Web charts based on test data

The ENS meteograms based on IFS cycle 48r1 test data are expected to become available shortly after the start of the release candidate phase, TBC. They can be viewed by selecting the "IFS cycle 48r1" model run in the ENS meteograms interface.

Time-critical applications

Option 1 - simple time-critical jobs

During the Release Candidate Phase users of the  "Simple time-critical jobs" framework can test that their scripts will work with the IFS Cycle 48r1 test data by using the limited ECaccess 'events' set up for this purpose:

For these events, MSJ_EXPVER environment variable is set to 0078 and can be used to specify the IFS Cycle 48r1 test data in any MARS retrievals.

These events are  intended for testing technical aspects only and should not be used for actual time-critical activities.

Options 2 and 3

Option 2 or 3 time-critical applications can be tested with the IFS Cycle 48r1 test data retrieved from MARS or received in Dissemination.

Resources

Webinars

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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 
  
  

For any questions, please contact us via the ECMWF Support Portal.