Description of upgrade

The CAMS IFS cycle 48R1 is based on ECMWF's  IFS cycle 48R1 . This is a major upgrade with various scientific contributions. Key elements are the addition of full stratospheric chemistry, changes to the modelling of dust aerosol resulting in a redistribution of aerosol particles towards larger sizes and therefore a significant increase in global dust mass burden, and the addition of two new aerosol species (anthropogenic and biogenic secondary organic aerosol). In addition, four new species have been added to the tropospheric chemistry scheme, and prescribed emissions have been updated to more recent versions. In terms of technical changes, there is an important change to the GRIB encoding. More information can be found below.

The page will be updated as required. It was last changed on 12 June 2023.

For a record of changes made to this page please refer to Document versions .

Further information and advice regarding the upgrade can be obtained from our User Support.

Timetable for implementation

The planned timetable for the implementation of the cycle 48r1 is as follows:

March 2023Announcement of expected implementation date
27 June 2023


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

Current Status

IFS cycle 48r1 is going through its final preparation phase.

Meteorological content of the new cycle

The meteorological changes can be found on the ECMWF  IFS CY48R1 page.

Atmospheric composition content of the new cycle


  • Instrument specific bias correction for AOD
  • Data assimilation for separate volcanic SO2 tracer (optional) 
  • Enable modification Nitrate and Ammonium aerosols by data assimilation (bugfix)  


  • Activation of assimilation of Sentinel-5p/TropOMI CO retrievals 
  • AOD from VIIRS (activated already in 47r3 1.2.2023) 
  • Passive monitoring of IASI SO2 retrievals 


  • CAMS_GLOB_ANT v5.3 with sectoral diurnal cycles and injection heights
  • CAMS_GLOB_BIO v3.1 climatology
  • CAMS_GLOB_OCE v.3.1 climatology DMS
  • CAMS_GLOB_AIR v3.1 CO2/NOx  (aircraft)
  • Using IS4FIRES injection heights (from GFAS version 1.4)
  • Sector-specific emission input to the IFS and application of sector specific injection height ranges and diurnal cycle profiles 
  • Natural emissions as as used previously 

Model changes

  • Activation of stratosphere chemistry using the BASCOE scheme - adding 63 reactive gas species 
  • New tropospheric species: HCN, CH3CN, Glyoxal and Glycoladehyde
  • Improved isoprene oxidation simulation
  • Update of dry deposition formulation for reactive gases 
  • Two new secondary organic aerosol tracers (anthropogenic and biogenic) and respective precursor gas tracers 
  • Major update of dust emissions and removal simulation (resulting in a redistribution of dust aerosol towards larger particles with an increase in the global dust mass burden by a factor of 2 as a result)   
  • Review of aerosol optical properties (dust , brown carbon) 
  • Improved secondary inorganic aerosol simulation 
  • Use of COMADH advection for aerosols, reactive gases and GHG

Impact of the new cycle

A comprehensive evaluation report of the 48r1 e-suite, documenting all the changes and their impact on the forecasts, has now been provided and can be found here: Upgrade Verification Note. It summarizes the impact as follows: The aerosol optical depth evaluation shows improvements for most regions. The Angstrom exponent, which is a measure representative of the aerosol size distribution, shows some improvement on the global scale but over the Sahara the performance deteriorates showing a too large fraction of coarse particles. Particulate matter (PM10 and PM2.5) at the surface is reduced in e-suite, which led to worse performance in East Asia and similar performance over North America and Europe. Surface ozone and tropospheric ozone shows similar performance. Stratospheric ozone and total column ozone have improved against observations, especially in the Tropics. The performance for CO has generally improved against all observations, except MOPITT. NO2 and SO2 both show improved validation results against multiple observations. The overestimation of HCHO in the Tropics is more pronounced in the e-suite compare to TROPOMI. Finally, the UV evaluation shows only minor changes.

CY48R1 scorecard

Scorecard for the relative performance of the e-suite versus the performance of the o-suite against observations. Meaning of the “relative score” symbols: (++) e-suite performs significantly better than the o-suite (+) e-suite shows small improvements, (n) (neutral) no significant difference between o-suite and e-suite, (-) score is somewhat degraded in the e-suite, (–) e-suite performs significantly worse than the o-suite. Remote: Remote Sensing from surface station, AOD: Aerosol Optical Depth at 550nm, Angstrom exponent between 440nm and 870nm, PM10: Particulate matter less than 10 microns, PM2.5: Particulate matter less than 2.5 microns.

Technical details of the new cycle

New and discontinued parameters

Several of the upgrades in CY48R1 have resulted in new parameters, some of which will be added to the dissemination through the Atmosphere Data Store (ADS) and the ECPDS ftp server. For now, the main new parameters are listed in the table below. Others might be added based on user requests.

paramIdshortNamenameunitsGRIB editionComponentsTest data available

Model levels

210252aermr19Biogenic secondary organic aerosol mass mixing ratiokg kg-12CAMS aerosol modelyes
210253aermr20Anthropogenic secondary organic aerosol mass mixing ratiokg kg-12CAMS aerosol modelyes


glyoxalGlyoxalkg kg-12CAMS chemistry modelyes
Pressure levels
210252aermr19Biogenic secondary organic aerosol mass mixing ratiokg kg-12CAMS aerosol modelyes
210253aermr20Anthropogenic secondary organic aerosol mass mixing ratiokg kg-12CAMS aerosol modelyes
217107glyoxalGlyoxalkg kg-12CAMS chemistry modelyes

Surface level

215226soaod550Secondary organic aerosol optical depth at 550 nmdimensionless2CAMS aerosol modelyes
218107tc_glyoxalTotal column of glyoxalkg m-22CAMS chemistry modelyes

Change to GRIB encoding

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


Section 1



Section 4


ecCodes key 

Model identifier








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

Section 1
ecCodes key Master Tables Version Number
 10 tablesVersion2830

While by default all 48r1 gridded GRIB2 data will be disseminated using a CCSDS defined compression method (Data representation template 5.42), MARS will by default write gridded GRIB2 data in CCSDS only if derived from (gridded) CCSDS-packed GRIB2 fields. See below how to override the default behaviour. 

ecCodes, our encoding/decoding package, uses libaec (Adaptive Entropy Coding Library) which implements a Golomb-Rice coding as defined in the CCSDS recommended standard 121.0-B-3.  

Users are strongly advised to test that their software applications and data processing chain can handle this new compression method. 

To handle CCSDS compressed fields from 48r1 with ecCodes, version 2.30.0 or newer is recommended. 

For a discussion of available GRIB packing methods and the use of compression algorithms see the Technical Memo Impact of GRIB compression on weather forecast data and data-handling applications

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

Section 5

ecCodes key 





(GRIB2 only)


(simple packing)


(CCSDS compression)


(edition independent) 



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:

Input field MARS output packing type 
(with keyword grid=... )
Dissemination output packing type 
(with keyword grid=... )
GRIB1/GRIB2 griddedinherited from inputinherited from input
GRIB1 SHsimplesimple

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


To handle the data of Cycle 48r1 we recommend to use the ECMWF software packages 

ecCodes 2.30.0
CodesUI 1.7.3
Magics 4.13.0
Metview 5.19.0
ODC 1.4.6

which will become the default on ECMWF platforms on Wednesday 31 May 2023, see Change of default versions of ECMWF and third-party software packages - May 2023. All packages listed above can be loaded with the command

   module load ecmwf-toolbox/may23 

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 test data from the cycle 48r1 test suites

The CAMS operational FTP server (ECPDS) 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 1 September 2022 onwards directly on MARS or through the Atmosphere Data Store. More details can be found here: Accessing CAMS 48r1 test data.

Document versions

DateReason for update
16 February 2023

Initial version

29 March 2023

Detailed list of changes and expected implementation date

19 April 2023

Added table with new parameters

25 April

Update of Impact section

05 May 2023

Update of Change to GRIB encoding section and Default packing types section

12 June 2023

Addition of evaluation report