#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 31.03.2017.

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 Alpha testing of cycle 43r3 will continue and the cycle is being passed to the Forecast Department to start the Beta testing.

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

Preliminary results, based on the Alpha testing, for HRES are positive, with many of the scores over NH, SH and Europe indicating statistically significant improvements (at the 99.7% 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.

More information, including on the (extended) ENS forecasts will be given after the new cycle has passed the Beta testing.

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