Implementation of IFS cycle 48r1 for CAMS

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 25 April 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:

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

Assimilation

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

Observations

• 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 

Emissions

• 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, is in preparation and will be provided before the implementation date. Based on the evaluation of the testing of all individual changes and the preliminary evaluation of the final e-suite, the following aspects for key species should be noted:

• New aerosol species added (anthropogenic and biogenic secondary organic aerosol)
• New tropospheric chemical species added (HCN, CH₃CN, Glyoxal and Glycoladehyde)
• Comprehensive stratospheric chemistry added (including 63 species)
• Stratospheric ozone (O₃): improvement in lower stratosphere with slight degradation in tropical upper stratosphere
• Stratospheric nitrogen dioxide (NO₂): significant improvement due to more comprehensive chemistry
• Tropospheric ozone (O₃): generally neutral with positive impact in south-east Asia
• Tropospheric nitrogen dioxide (NO₂): generally small improvement, which is more pronounced for south-east Asia
• Tropospheric sulfur dioxide (SO₂): generally small improvement, which is more pronounced for south-east Asia
• Tropospheric carbon monoxide (CO): generally small improvement, which is more pronounced for south-east Asia
• Surface NO₂ and SO₂: decrease in surface concentrations leading mainly to reduced biases in Europe, North-America and Europe , especially for background stations.
• UV: no major change
  
• Aerosol Optical Depth (AOD): no major change
• Dust aerosol: redistribution of aerosol particles towards larger sizes and therefore a significant increase in global dust mass burden
• PM2.5: reduced over North-America and China but not in Europe. This means a now negative bias over North America and China, which is expected for a global model that does not resolve detailed polluted areas.

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.

Change 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: 

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

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

Document versions