Implementation of IFS Cycle 47r3

Description of the upgrade

Cycle upgrade 47r3 will bring improvements to the assimilation and observations usage and a significantly improved physical basis for moist processes, necessary to facilitate further development of the Integrated Forecasting System (IFS) and future application at convection-permitting resolutions.

The upgrade will bring more accurate upper air fields, particularly tropical winds, as well as precipitation in convective regimes. Several new convection-related products will be available and systematic errors are reduced for wind gusts and visibility for fog and precipitation.

Implementation scheduled for 06 UTC run on 5 Oct 2021, TBC

Page updated on 23 Jun 2021

#IFS47r3 #newfcsystem @ECMWF

NEWS!

23 Jun 2021 IFS Cycle 47r3 content and implementation timeline announced. The new cycle will be introduced in a first webinar on

6 July 2021 at 8:00 UTC: Join the webinar on Zoom

A recording of the webinar will be made available after the event..

Timeline of the implementation

implementation-timeline-47r3

Meteorological content

Assimilation

New RTTOV coefficients for hyperspectral infrared (IR) sounders
New height reassignment for low level AMVs
Add representativeness error in the total observation error for Aeolus
Weak-constraint 4D-Var active in the stratosphere for the EDA system

Observations

Assimilation of all-sky AMSU-A

Model

A more consistent formulation of boundary layer turbulence, shallow convection and sub-grid cloud including:
- Simplified and more consistent treatment of sub-grid cloud saturation adjustment
- Consistent treatment of subgrid cloud from boundary layer turbulent mixing without separate statistical cloud scheme
- Consistent computation of mixing height for unstable turbulent boundary layer and convection scheme
- Change from double to single iteration of turbulent mixing scheme
New method for computing inversion strength based on moist entropy for distinguishing stratocumulus and cumulus cloud
Limit to convective overshoot based on tropopause stability
New parametrized deep convection closure with an additional dependence on total advective moisture convergence
Change from exponential-exponential cloud vertical overlap to random-exponential overlap in closer agreement with observations
Include vapour deposition process for growth of falling snow particles
Change from linear to cubic interpolation for cloud liquid, ice, rain and snow semi-Lagrangian departure point calculations, including 3D quasi-monotone limiter
Interpolation of cloud and precipitation to radiation grid changed from in-cloud to grid-mean
Inclusion of full supersaturation adjustment in the ensemble SPPT stochastic perturbations
Mass-weighting and relaxation timescale introduced for ensemble SPPT stochastic perturbations
Revised simplified moist physics and associated tangent-linear and adjoint
Bug fix for vertical interpolation of 3D aerosol climatology
Improved calculation of extinction coefficients for near-surface visibility in fog, rain and snow
Revised gustiness parametrization
Improved calculation of the peak wave period for multi-peaked ocean wave spectra

Meteorological impact

A summary of the meteorological impact will be provided in July.

New and changed parameters

New parameters

The table contains the list of parameters expected to be available with the model implementation. They will be available as part of the test data.

Param ID	Short Name	Name	units	Component & type	GRIB edition	Level type	Added to Catalogue	ecCharts	Dissemination
228045	trpp	Tropopause pressure	Pa	HRES FC	2	sfc	TBC	TBD	TBC
228020	degm10l	-10 degrees C isothermal level (atm)	m	HRES/ENS FC	1	sfc	TBC	TBD	TBC
228131	u10n	Neutral wind at 10 m u-component	m s^-1	ENS FC	1	sfc	TBC	TBD	TBC
228132	v10n	Neutral wind at 10 m v-component	m s^-1	ENS FC	1	sfc	TBC	TBD	TBC
228231	mlcape50	Mixed-layer CAPE in the lowest 50 hPa	J kg^-1	HRES/ENS FC	2	sfc	TBC	TBD	TBC
228232	mlcin50	Mixed-layer CIN in the lowest 50 hPa	J kg^-1	HRES/ENS FC	2	sfc	TBC	TBD	TBC
228233	mlcape100	Mixed-layer CAPE in the lowest 100 hPa	J kg^-1	HRES/ENS FC	2	sfc	TBC	TBD	TBC
228234	mlcin100	Mixed-layer CIN in the lowest 100 hPa	J kg^-1	HRES/ENS FC	2	sfc	TBC	TBD	TBC
228235	mucape	Most-unstable CAPE	J kg^-1	HRES/ENS FC	2	sfc	TBC		TBC
228237	mudlp	Departure level of the most unstable parcel expressed as Pressure	Pa	HRES/ENS FC	2	sfc	TBC	TBD	TBC
260290	cat	Clear air turbulence (CAT)	m^2/3 s^-1	HRES FC	2	ml	TBC	TBD	TBC

Technical content

Changes to GRIB encoding

The GRIB model identifiers (generating process identification number) for cycle 47r3 will be changed as follows:

GRIB 1 Section 1 Octets	GRIB 2 Section 4 Octets	eccodes key	Component	Model identifier
GRIB 1 Section 1 Octets	GRIB 2 Section 4 Octets	eccodes key	Component	47r2	47r3
6	14	generatingProcessIdentifier	Atmospheric model	152	153
6	14	generatingProcessIdentifier	Ocean wave model	117	118

Software

To handle all output from Cycle 47r3 eccodes 2.22.0 will be required. The relevant versions of Magics and Metview will be announced closer to the availability of test data.

Availability of 47r3 test data

The release candidate test data and products, which are expected to be made available in September 2021, will be generated daily, shortly behind operational high resolution and ensemble runs and based on the operational dissemination requirements. The availability of the test data does not follow any strict schedule.

Resources

Bechtold, P. R. Forbes, I. Sandu, S. Lang, M. Ahlgrimm, 2020: A major moist physics upgrade for the IFS. ECMWF Newsletter, 164, pp. 24-32. DOI:10.21957/3gt59vx1pb
Bechtold, P., M. Bramberger, A. Dörnbrack, M. Leutbecher, L. Isaksen, 2021: Forecasting Clear Air Turbulence (CAT). ECMWF Newsletter, No 168.
David Duncan et al., Assimilation of AMSU-A in all-sky conditions. EUMETSAT/ECMWF Fellowship Programme Research Report, in preparation, 2021
All Physics developments and all new Grib parameters (algorithms) described in the IFS scientific documentation

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