Implementation of IFS cycle 50R1 for CAMS

Last modified on Apr 01, 2026 10:27

Table of Contents

Description of upgrade

The CAMS IFS cycle 50R1 is based on ECMWF's IFS Cycle 50r1.

The CAMS datasets affected by the upgrade are:

CAMS global atmospheric composition forecasts (COMPO)
CAMS global greenhouse gas forecasts (GHG)

Timetable for implementation

The planned timetable for the implementation of the cycle 50R1 is as follows:

Date	Event
12 May 2026	Implementation

The timetable represents current expectations and may change in light of actual progress made.

Current Status

IFS cycle 50R1 is going through its final preparation phase.

Meteorological content of the new cycle

The meteorological changes can be found on the ECMWF IFS CY50R1 page.

Atmospheric composition and greenhouse gas upgrades of the new cycle

Assimilation

Updated background errors for NWP, now taken from the operational EDA (COMPO)
Updated background errors for O3 to remove spurious long-range correlations (COMPO)
The EDA-based B matrix used in 49r1 is tapered in the stratosphere in 50r1 for CH4 (GHG)
The EDA-based B matrix used in 49r1 is tapered near the surface in 50r1 for CO2 (GHG)

Observations

Sentinel 3 AOD over ocean actively assimilated (COMPO)
TROPOMI for CH4 (GHG)

Emissions

CAMS-GLOB-ANT-M1, a merged emission data set using regional emissions inventories for North-America (EPA), Europe (CAMS-REG) and China (MECS) and Edgar 6.2 elsewhere (COMPO)
Activation of weekly cycle in anthropogenic emissions
Online BVOC emissions simulation (COMPO)
New GFAS emissions 1.4.2 (MODIS and VIIRS-based)

Model changes

Aerosol developments (COMPO):

Implementation of an equilibration time parameterization for nitrate/ammonium formation
Revision of hydrophilic growth of OM, SOA and fine mode nitrate
Correction of hydrophilic growth factor of sea salt for sedimentation
Sedimentation velocity computed online for all species, using the Stokes formula

Reactive gases developments (COMPO):

Update of heterogeneous chemistry parameterization
Revision of SO2 + H2O2 aqueous phase reaction

Impact of the new cycle

Technical details of the new cycle

Please note: With the implementation of the IFS Cycle 50r1 a subset of model levels forecast fields, listed below, is now available every hourly step at 0, 1, 2 ... 119 and 120.

paramId	shortName	name	units	GRIB edition	Components	Test data available
Model levels
130	t	Temperature	K	2		yes
133	q	Specific humidity	kg kg^-1	2		yes
152	lnsp	Logarithm of surface pressure	~	2		yes
210001	aermr01	Sea Salt Aerosol (0.03 - 0.5 um) Mixing Ratio	kg kg^-1	2	CAMS aerosol model	yes
210002	aermr02	Sea Salt Aerosol (0.5 - 5 um) Mixing Ratio	kg kg^-1	2	CAMS aerosol model	yes
210003	aermr03	Sea Salt Aerosol (5 - 20 um) Mixing Ratio	kg kg^-1	2	CAMS aerosol model	yes
210004	aermr04	Dust Aerosol (0.03 - 0.55 um) Mixing Ratio	kg kg^-1	2	CAMS aerosol model	yes
210005	aermr05	Dust Aerosol (0.55 - 0.9 um) Mixing Ratio	kg kg^-1	2	CAMS aerosol model	yes
210006	aermr06	Dust Aerosol (0.9 - 20 um) Mixing Ratio	kg kg^-1	2	CAMS aerosol model	yes
210007	aermr07	Hydrophilic Organic Matter Aerosol Mixing Ratio	kg kg^-1	2	CAMS aerosol model	yes
210008	aermr08	Hydrophobic Organic Matter Aerosol Mixing Ratio	kg kg^-1	2	CAMS aerosol model	yes
210009	aermr09	Hydrophilic Black Carbon Aerosol Mixing Ratio	kg kg^-1	2	CAMS aerosol model	yes
210010	aermr10	Hydrophobic Black Carbon Aerosol Mixing Ratio	kg kg^-1	2	CAMS aerosol model	yes
210011	aermr11	Sulphate Aerosol Mixing Ratio	kg kg^-1	2	CAMS aerosol model	yes
210121	no2	Nitrogen dioxide	kg kg^-1	2	CAMS chemistry model	yes
210122	so2	Sulphur dioxide	kg kg^-1	2	CAMS chemistry model	yes
210123	co	Carbon monoxide	kg kg^-1	2	CAMS chemistry model	yes
210124	hcho	Formaldehyde	kg kg^-1	2	CAMS chemistry model	yes
210203	go3	Ozone	kg kg^-1	2	CAMS chemistry model	yes
215180	aerext355	Aerosol extinction coefficient at 355 nm	m^-1	2	CAMS aerosol model	yes
217107	glyoxal	Glyoxal	kg kg^-1	2	CAMS chemistry model	yes

Change to GRIB encoding

The GRIB model identifiers (generating process identification number) for cycle 50r1 will be changed as follows:

GRIB 1 Section 1 Octets	GRIB 2 Section 4 Octets	ecCodes key	Component	Model identifier
GRIB 1 Section 1 Octets	GRIB 2 Section 4 Octets	ecCodes key	Component	49r1	50r1
6	14	generatingProcessIdentifier	Atmospheric model	158	161
6	14	generatingProcessIdentifier	Ocean wave model	106	109
6	14	generatingProcessIdentifier	soil moisture model	146	146

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

GRIB 2

Section 1

Octets

ecCodes key

Master Tables Version Number

49r1

50r1

10

tablesVersion

33

35

Software

To handle the data of Cycle 50r1 we recommend to use the ECMWF software packages

ecCodes (2.44.0)
CodesUI (minimum version)
Magics (4.16.0)
Metview (5.26.1)
ODC (1.6.0)

On the ATOS HPC these versions correspond to ecmwf-toolbox/2025.1

Availability of test data from the cycle 50r1 test suites

The CAMS operational ECMWF data portal (aux.ecmwf.int; SFTP/FTP/HTTPS data access) will serve the most recent 3 days of test data, once the e-suite is running in near-real-time, in the directories "/DATA/CAMS_GLOBAL_TEST" and "/DATA/CAMS_EUROPE_BC_TEST" for global and regional boundary condition data, respectively.

In addition, surface level fields (model level 137) will be provided as individual files in the "/DATA/CAMS_GLOBAL_ADDITIONAL_TEST" directory.

Users wanting to access the output from the current test system for a longer period can access the data from directly on MARS, ECMWF dissemination or through the Atmosphere Data Store. More details can be found here: Accessing CAMS 50r1 test data.

_{This document has been produced in the context of the} _{Copernicus Atmosphere Monitoring Service (CAMS)}_.

_{The activities leading to these results have been contracted by the European Centre for Medium-Range Weather Forecasts, operator of CAMS on behalf of the European Union (Delegation Agreement signed on 11/11/2014 and Contribution Agreement signed on 22/07/2021). All information in this document is provided "as is" and no guarantee or warranty is given that the information is fit for any particular purpose.}

_{The users thereof use the information at their sole risk and liability. For the avoidance of all doubt , the European Commission and the European Centre for Medium - Range Weather Forecasts have no liability in respect of this document, which is merely representing the author's view.}

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