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Cycle 47r1 has been implemented with the 6 UTC run on 30 June 2020. Should you encounter any issues, please report them to servicedesk@ecmwf.int. |
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Metrics Tropical Cyclone “size” will tocmaxLevelMeteorological content
The changes in this model cycle cover the Data Assimilation, treatment of observations and improvements to the model itself
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Assimilation
LWDA uses first guess from Early Delivery
- The first guess used in LWDA now comes from the analysis derived in the early delivery window.
- This gives effectively 4 extra outer loops in the LWDA system, as they were computed in the early delivery window, albeit with fewer observations.
Weak-constraint 4D-Var
- A new estimate of the model error covariance matrix has been computed from a climatology of the model error vectors estimated by the current weak-constraint 4D-Var
- This new implementation of weak-constraint 4D-Var corrects the diagnosed cold and warm biases of the model over 100 hPa, reducing the mean error by up to 50%.
Revision of skin temperature background errors in the context of TOVS sink variable
- New spatially and in time varying back-ground errors for skin temperature have been derived based upon output from the Ensemble Data Assimilation (EDA) to improve the way the surface skin temperature is allow to adjust to the radiance assimilation scheme during the 4D-VAR. The approach enhances the characterization of the background-error variances for the skin temperature, by providing flow dependent background errors which vary spatially and in time during the 12-hour assimilation window. This is particularly important for land surfaces which can be very heterogeneous and where errors can change rapidly during the day, synoptically and seasonally.
Timestep for last 4D-Var minimisation
- The time step in the last minimisation cycle in the 4D-VAR has been set the same for the outer and inner loop to correct spurious gravity-wave-like increments generated during the 4D-Var analysis.
- This change leads to better balanced initial conditions and a statistically significant increase in forecast skill.
Observations
ATMS observation error correlations
- In Cycle 46r1 inter-channel error correlations were accounted for in Suomi-NPP ATMS.
In Cycle 47r1 inter-channel error correlations will be introduced for NOAA-20 ATMS consistently with Suomi-NPP ATMS.
Channel-specific aerosol rejections for IR sounders
- The use of infrared (IR) data (AIRS, IASI, CrIS) is enhanced by allowing high-peaking channel radiances to be assimilated at those locations where lower-peaking channels are rejected due to being contaminated by aerosol. Previously, the aerosol detection scheme did not distinguish between affected and unaffected channels, but instead rejected full IR spectra where presence of aerosol was found.
Spline interpolation in the 2D GPS-RO bending angle operator
- A cubic spline interpolation is introduced for vertical interpolation of Log(refractivity) within the GPS-RO forward operator.
- This removes unphysical structure in the vertical leading to more realistic vertical variability of the forward modelled bending angle background departures.
Model
Surface albedo changes
A are “size” willAdditional details: Changes in CIN to concur with forecasting practice
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EFIFor the computation of EFI and SOT in IFS cycle 47r1 mxcape6 and mxcapes6 will be used instead of cape and capes, respectively. This change is aiming for a better sampling in the computation of the 24-hour maxima needed for the EFI. In effect with the change we extract the maximum within 24 hourly values, instead of using 4 6-hourly values. Additional details: The EFI (and SOT) for CAPE and CAPE-shear start using mxcape6 and mxcapes6 parameters |
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These events are intended for testing technical aspects only and should not be used for Time Critical activities.
Options 2 and 3
Option 2 or 3 time-critical applications can be tested with theIFS Cycle 47r1 test data retrieved from MARS or received in Dissemination.ResourcesWebinar on 'Cycle 47r1 performance and products'
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