Timeline of the implementation

Meteorological content

Assimilation

• New RTTOV coefficients for hyperspectral infrared (IR) sounders
• New height reassignment for low level AMVs
• Add representativeness error in the total observation error for Aeolus
• Weak-constraint 4D-Var active in the stratosphere for the EDA system

Observations

• Assimilation of all-sky AMSU-A

Model

• A more consistent formulation of boundary layer turbulence, shallow convection and sub-grid cloud including:
  • Simplified and more consistent treatment of sub-grid cloud saturation adjustment
  • Consistent treatment of subgrid cloud from boundary layer turbulent mixing without separate statistical cloud scheme
  • Consistent computation of mixing height for unstable turbulent boundary layer and convection scheme
  • Change from double to single iteration of turbulent mixing scheme
• New method for computing inversion strength based on moist entropy for distinguishing stratocumulus and cumulus cloud
• Limit to convective overshoot based on tropopause stability
• New parametrized deep convection closure with an additional dependence on total advective moisture convergence
• Change from exponential-exponential cloud vertical overlap to random-exponential overlap in closer agreement with observations
• Include vapour deposition process for growth of falling snow particles 
• Change from linear to cubic interpolation for cloud liquid, ice, rain and snow semi-Lagrangian departure point calculations, including 3D quasi-monotone limiter
• Interpolation of cloud and precipitation to radiation grid changed from in-cloud to grid-mean
• Inclusion of full supersaturation adjustment in the ensemble SPPT stochastic perturbations
• Mass-weighting and relaxation timescale introduced for ensemble SPPT stochastic perturbations
• Revised simplified moist physics and associated tangent-linear and adjoint
• Bug fix for vertical interpolation of 3D aerosol climatology
• Improved calculation of extinction coefficients for near-surface visibility in fog, rain and snow
• Revised gustiness parametrization
• Improved calculation of the peak wave period for multi-peaked ocean wave spectra

Meteorological impact

• Extratropical upper-air geopotential and wind in the first few days of the forecast improved by a few percent
• Tropical upper-air winds throughout the medium-range improved by up to 7%, reducing with lead time
• Tropical upper-air temperature improved in HRES, but degraded CRPS in ENS due to small (~0.2K) increase in bias. Low level temperatures (including 850hPa and 2m) temperature approximately neutral versus observations but degraded versus analysis over subtropical ocean.
• Tropical Cyclones: 10% improvement in position error in HRES and ENS and weaker central pressure
• Improved MJO prediction and amplitude
• More realistic precipitation PDF in strongly convective regimes
• Increased convective precipitation (reduced dry bias) in arid regions
• Increase in small scale structure for cloud and precipitation but total cloud cover degraded
• Reduced biases for wind gusts and for visibility in fog, rain and snow

The separate document 47r3 Impact on Surface Weather representation highlights the changes with 47r3 in the characteristics of many frequently used forecast fields and products.

Evaluation

Scorecards presenting the new cycle performance are regularly updated: 

• HRES scorecard 
• ENS scorecard

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.

Param ID	Short Name	Name	units	Component & type	GRIB edition	Level type	MARS	Added to Catalogue	ecCharts	Dissemination
2280451	trpp	Tropopause pressure	Pa	HRES FC	2	sfc			TBD
228020	degm10l	-10 degrees C isothermal level (atm)	m	HRES FC ENS CF/PF	1	sfc			TBD
228131	u10n	Neutral wind at 10 m u-component	m s-1	ENS CF/PF	1	sfc			TBD
228132	v10n	Neutral wind at 10 m v-component	m s-1	ENS CF/PF	1	sfc			TBD
2282312	mlcape50	Mixed-layer CAPE in the lowest 50 hPa	J kg-1	HRES FC ENS CF/PF	2	sfc			TBD
2282322	mlcin50	Mixed-layer CIN in the lowest 50 hPa	J kg-1	HRES FC ENS CF/PF	2	sfc			TBD
2282332	mlcape100	Mixed-layer CAPE in the lowest 100 hPa	J kg-1	HRES FC ENS CF/PF	2	sfc			TBD
2282342	mlcin100	Mixed-layer CIN in the lowest 100 hPa	J kg-1	HRES FC ENS CF/PF	2	sfc			TBD
2282352	mucape	Most-unstable CAPE	J kg-1	HRES FC ENS CF/PF	2	sfc
2282372	mudlp	Departure level of the most unstable parcel expressed as Pressure	Pa	HRES FC ENS CF/PF	2	sfc			TBD
260290	cat	Clear air turbulence (CAT)	m2/3 s-1	HRES FC	2	ml			TBD

¹Please note that the current MARS client, built with MIR 1.7.2, will issue a warning when interpolating parameter 228045 (Tropopause pressure). As MIR uses the default interpolation for this parameter in any case, this warning can be ignored and will be addressed in a future version of the MARS client.

²For more details see 47r3 new parameters: CAPE and CIN

Changes to existing GRIB parameters

In Cycle 47r3 the grid descriptions for the surface fields ci and sst in the analysis are now identical to those of the land-sea mask (lsm). 

Technical content

Changes to GRIB encoding

The GRIB model identifiers (generating process identification number) for cycle 47r3 will be changed as follows:

For all parameters in GRIB 2 the Master Tables Version Number will be changed as follows:

Correct decoding of all 47r3 GRIB 2 parameters requires ecCodes 2.23.0 or newer. Users are encouraged to check their data processing with the test data provided.

Software

The software packages listed below are required to provide full support for IFS Cycle 47r3 and will become the default on ECMWF platforms on Wednesday 6 October 2021, see Change of default versions of ECMWF software packages - October 2021:

ecCodes 2.23.0
Magics 4.9.0
Metview 5.13

CDO 1.9.10-01

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 47r3 test data

Test data in MARS

IFS Cycle 47r3 beta test data is available from MARS with experiment version 0076 (MARS keyword EXPVER=0076): 

• HRES (class=od, stream=oper, expver=76)
• HRES-WAM (class=od, stream=wave, expver=76)
• ENS (class=od, stream=enfo, expver=76)
• ENS-WAM (class=od, stream=waef, expver=76)

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.

The release candidate test data and products, available from 14 Sept 2021, will be generated daily, shortly behind operational high resolution and ensemble runs and based on the operational dissemination requirements. The availability of the test data does not follow any strict schedule.

For longer time series available beta test data from 15 April can be used, with a complete set of products from 23 August.

Test data in dissemination

Cycle 47r3 test data from the release candidate stage will be available through the test dissemination system, starting from the 00Z run on 14 Sept 2021. Users with access to ECPDS and the Products Requirements Editor (PREd) can login to the test system at https://ecpds-xmonitor.ecmwf.int/  (or https://msaccess.ecmwf.int:7443) 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 transfers: 193.61.196.104 ( ecpds-xma.ecmwf.int ), 193.61.196.105 ( ecpds-xmb.ecmwf.int ) and 193.61.196.113 ( ecpds-xmc.ecmwf.int )
  

• RMDCN transfers: 136.156.8.132 ( mspds-dm4.ecmwf.int ) and 136.156.8.133 ( mspds-dm5.ecmwf.int )

The IFS Cycle 47r3 test products are available as version number 76 (file names ending with '76') and are intended to be generated shortly behind real-time. The test products will be based on the operational dissemination requirements from 13 Sept 2021 and will be available for HRES, HRES-WAM, ENS, ENS-WAM and ENS extended.

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 11 October. Any changes to the operational requirements can be implemented after 10 UTC on 13 October.

If you don't have access to the ECPDS system or PREd or should you require any assistance with IFS Cycle 47r3 test dissemination products, please contact us via the Support Portal.

Graphical display of test data in ecCharts

Layers of IFS cycle 47r3 release candidate test data will become available in ecCharts on 14 Sept 2021. Cycle 47r3 layers are identified by the label "0076" in their title and a black border around test data layers for better visual identification. Please note that vertical profiles and meteograms in ecCharts will always be based on operational data. However, Cycle 47r3 based vertical profiles and meteogram will become available in the web charts browser, see below.

Web charts based on test data

The ENS meteograms and vertical profiles based on IFS cycle 47r3 release candidate test data will become available on 14 Sept 2021.

WMO Essential and Additional test data

IFS cycle 47r3 WMO Essential test data starting from the 00Z run on 14 Sept 2021is available at ftp://wmo:essential@xpds.ecmwf.int and WMO Additional test data at ftp://xpds.ecmwf.int using the relevant WMO user id and password.

Time-critical applications

Option 1 - simple time-critical jobs

Member State users of the  "Simple time-critical jobs" framework can test that their scripts will work with the IFS Cycle 47r3 test data by using the limited ECaccess 'events' set up for this purpose:

For these events, MSJ_EXPVER environment variable is set to 0076 and can be used to specify the IFS Cycle 47r3 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 47r3 test data retrieved from MARS or received in Dissemination.

Resources

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• Bechtold, P. R. Forbes, I. Sandu, S. Lang, M. Ahlgrimm, 2020: A major moist physics upgrade for the IFS. ECMWF Newsletter, 164, pp. 24-32. DOI:10.21957/3gt59vx1pb

• Bechtold, P., M. Bramberger, A. Dörnbrack, M. Leutbecher, L. Isaksen, 2021: Forecasting Clear Air Turbulence (CAT). ECMWF Newsletter, No 168

• David Duncan et al., Assimilation of AMSU-A in all-sky conditions. EUMETSAT/ECMWF Fellowship Programme Research Report, 2021

• Forbes, R, Laloyaux, P, Rodwell, M, 2021: IFS upgrade improves moist physics and use of satellite observations. ECMWF Newsletter, No 169
• All Physics developments and all new Grib parameters (algorithms) described in the IFS scientific documentation
• ECMWF News article "Forecast upgrade improves moist physics and use of satellite observations"