The ECMWF forecast system IFS was upgraded to the version 43r3. In this upgrade there are 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 main changes included in this upgrade: 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.
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