Implementation of IFS cycle 43r3

#newfcsystem

Description of upgrade

IFS Cycle 43r3 is an upgrade with many scientific contributions, including changes in data assimilation (both in the EDA and the 4DVAR), in the use of observations, and in modelling. The new cycle only includes meteorological changes; there are no technical changes, e.g. new resolutions.

The page will be updated as required. It was last changed on 24.05.2017.

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 User Support.

Timetable for implementation

The planned timetable for the implementation of the cycle 43r3 is as follows:

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

Current Status

The Beta testing phase of cycle 43r3 has started, test data are available in MARS. We are running HRES and ENS to catch up with real time and have started work on the post processing of the cycle 43r3 data, including the data dissemination and graphical charts.

Meteorological content of the new cycle

Assimilation

• • Improved humidity background error variances directly from the EDA like for all other variables.
  • Revised wavelet filtering of background error variances and revised quality control of drop-sonde wind observations in 4DVAR to improve tropical cyclone structures.

Observations

• • Increased use of microwave humidity sounding data by adding new sensors (SAPHIR, GMI 183 GHz channels).
  • Activation of 118 GHz channels over land from MWHS-2 instrument on-board FY-3C.
  • Harmonised data usage over land and sea-ice for microwave sounders (adding MHS channel 4 over snow, adding some ATMS channels, lower observation errors for MHS data over land).
  • Improved screening of infrared observations for anomalously high atmospheric concentrations of hydrogen cyanide (HCN) from wildfires.
  • Improved quality control for radio occultation observations and radiosonde data.

Model

• • New, more efficient radiation scheme with reduced noise and more accurate longwave radiation transfer calculation.
  • New aerosol climatology based on ‘tuned’ CAMS aerosol re-analysis including dependence on relative humidity.
  • Increased super-cooled liquid water at colder temperatures (down to -38C) from the convection scheme.
  • Visibility calculation changed to use ‘tuned’ CAMS aerosol climatology.

Meteorological impact of the new cycle

Comparison of scores between IFS Cycle 43r3 and IFS Cycle 43r1 for HRES can be found in the IFS Cycle 43r3 scorecard.

Results for the HRES from alpha- and beta-testing are positive, with many of the scores over NH, SH and Europe indicating statistically significant improvements at the 95% level up to about forecast day 5 when forecasts are verified against own analysis. When forecasts are verified against observations, the positive impact of 43r3 is also evident. Improvements are larger in summer than in winter and are to a large extent due to changes to the deep convection scheme and the aerosol climatology, which improved the temperature gradient between extra-tropics and tropics. Improvements are significant for temperature and vector wind throughout the extra-tropical troposphere. In the tropics there is some deterioration in temperature and humidity at certain vertical levels associated with the changes to the deep convection scheme. Surface parameters show partially statistically significant improvements both in the tropics and extra-tropics (2-m humidity, 10-m wind speed, total cloud cover, precipitation), except for 2-m temperature which shows neutral results.

Over the ocean, statistically significant improvements are seen for verification against own analysis for 10-m wind speed, significant wave height, and mean wave period.

Results for the ENS based on alpha-testing are mainly positive and similar to the HRES both for upper-air and surface variables for the NH, SH, and Europe when verified against analysis. In the tropics there is some deterioration in upper tropospheric wind speed and lower tropospheric temperature associated with reduced spread. There are also some slight deteriorations in tropical 2-m temperature and precipitation scores. The scorecard for the ENS will be made available when we have completed more runs.

Technical details of the new cycle

Changes to GRIB encoding

Model identifiers

The GRIB model identifiers (generating process identification number) for cycle 43R3 will be changed as follows:

New model output parameters

There are no new parameters introduced with cycle 43r3.

Impact on users

Software

The versions of EMOSLIB and GRIB API used to decode the existing operational cycle 43r1 data are suitable to handle the cycle 43r3 data as well. Note that ecCodes has now replaced GRIB API on the ECMWF platforms.

Availability of test data from the cycle 43r3 test suites

Test data in MARS

IFS data from the cycle 43r3 suite are available in MARS with experiment version 0071 (MARS keyword EXPVER=0071) starting from 26 March 2017 at 06UTC.

The data can be accessed in MARS from:

• HRES (class=od, stream=oper, expver=71)
• Wave HRES (class=od, stream=wave, expver=71)
• ENS (class=od, stream=enfo, expver=71)
  • 00 UTC cycle only
• ENS Wave (class=od, stream=waef, expver=71)
  • 00 UTC cycle only

Only registered users of ECMWF computing systems will be able to access the test data sets in MARS.

The data are intended for testing technical aspects only and should not be used for operational forecasting.  Please report any problems you find with this data to User Support.

Further Reading

• Flemming, J., Benedetti, A., Inness, A., Engelen, R. J., Jones, L., Huijnen, V., Remy, S., Parrington, M., Suttie, M., Bozzo, A., Peuch, V.-H., Akritidis, D., and Katragkou, E.: The CAMS interim Reanalysis of Carbon Monoxide, Ozone and Aerosol for 2003–2015, Atmos. Chem. Phys., 17, 1945-1983, doi:10.5194/acp-17-1945-2017, 2017.
• Hogan, R., and Bozzo, A., 2016: ECRAD: A new radiation scheme for the IFS. ECMWF Research Department Technical Memorandum No. 787, pp 33. Available at http://www.ecmwf.int/sites/default/files/elibrary/2016/16901-ecrad-new-radiation-scheme-ifs.pdf.

Document versions