#newfcsystem

Description of upgrade

IFS Cycle 43r1 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.

With this cycle upgrade, the medium-range ensemble and its monthly extension see a major upgrade in the dynamical ocean model (NEMO): the resolution is increased from 1 degree and 42 layers to 0.25 degrees and 75 layers (ORCA025Z75). Furthermore, NEMO model version v3.4.1 with the interactive sea-ice model (LIM2) is implemented. The ocean and sea-ice components of the ENS initial conditions are provided by the new ocean analysis and reanalysis suite ORAS5, which uses the new ocean model and revised ensemble perturbation method.

 

The page will be updated as required. It was last changed on 18.10.2016. Latest change: Meteorological impact of the new cycle and update to New model output parameters.

The next update to this page is expected to be on 24.10.2016.

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 IFS cycle 43r1 is as follows:

DateEvent
22 Sep 2016Initial announcement via e-mail to Member States contact points
Week beginning 24 Oct 2016Availability of test data in dissemination and confirmation of implementation date
22 Nov 2016

Expected date of implementation

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

Meteorological content of the new cycle

Data Assimilation methodology (atmosphere, land and ocean)

Observations

Model changes

Medium-range/monthly ensemble (ENS)

Technical changes

New model output parameters

New model output fields for HRES and ENS comprise four cloud and freezing diagnostics (for aviation), and a new direct-beam solar radiation diagnostic

In addition, eight new wave model output fields are provided.

All the new output fields are available at the usual post-processing time steps except where specified otherwise in the table:

Further technical information is provided in the table.

paramIdshortNamenamedescriptionunitsGRIB editionComponentTest data availableDisseminationProposed for Catalogue
260109ceilCeilingCloud-base height relative to the ground.m2

HRES / ENS

(tick)TBCTBC
228046hcctHeight of convective cloud top m1HRES / ENS(tick)TBCTBC
228047hwbt0Height of zero-degree wet-bulb temperatureSee 43r1 new parameters: Height of zero-degree (and one-degree) wet-bulb temperaturem1HRES / ENS(tick)TBCTBC
228048hwbt1Height of one-degree wet-bulb temperatureSee 43r1 new parameters: Height of zero-degree (and one-degree) wet-bulb temperaturem1HRES / ENS(tick)TBCTBC
47dsrpDirect solar radiation Incident on a plane perpendicular to the sun's direction. This is an accumulated field.J/m21

HRES / ENS

NB: only forecast

(tick)TBCTBC
140112

wefxm

Wave energy flux magnitude

Integral over all frequencies and directions of the product of the group speed and the two-dimensional energy wave spectrum.W/m1HRES-WAM / ENS-WAM / HRES-SAW(tick)TBCTBC
140113wefxdWave energy flux mean directionSpectral mean direction over all frequencies and direction of the product of the group velocity vector and the two-dimensional energy wave spectrum.Degree true1HRES-WAM / ENS-WAM / HRES-SAW(tick)TBCTBC
140114

h1012

Significant wave height of all waves with periods within the inclusive range from 10 to 12 seconds

Significant wave height of all waves with periods within the inclusive range from 10 to 12 seconds, where the significant wave height is defined as 4 times the square root of the integral over all directions and all frequencies between 1/12 and 1/10 Hz of the two-dimension wave spectrumm1HRES-WAM / ENS-WAM / HRES-SAW(tick)TBCTBC
140115h1214Significant wave height of all waves with periods within the inclusive range from12 to 14 secondsSignificant wave height of all waves with periods within the inclusive range from 12 to 14 seconds, where the significant wave height is defined as 4 times the square root of the integral over all directions and all frequencies between 1/14 and 1/12 Hz of the two-dimension wave spectrumm1HRES-WAM / ENS-WAM / HRES-SAW(tick)TBCTBC
140116h1417Significant wave height of all waves with periods within the inclusive range from 14 to 17 secondsSignificant wave height of all waves with periods within the inclusive range from 14 to 17 seconds, where the significant wave height is defined as 4 times the square root of the integral over all directions and all frequencies between 1/17 and 1/14 Hz of the two-dimension wave spectrumm1HRES-WAM / ENS-WAM / HRES-SAW(tick)TBCTBC
140117h1721Significant wave height of all waves with periods within the inclusive range from 17 to 21 secondsSignificant wave height of all waves with periods within the inclusive range from 17 to 21 seconds, where the significant wave height is defined as 4 times the square root of the integral over all directions and all frequencies between 1/21 and 1/17 Hz of the two-dimension wave spectrumm1HRES-WAM / ENS-WAM / HRES-SAW(tick)TBCTBC
140118h2125Significant wave height of all waves with periods within the inclusive range from 21 to 25 secondsSignificant wave height of all waves with periods within the inclusive range from 21 to 25 seconds, where the significant wave height is defined as 4 times the square root of the integral over all directions and all frequencies between 1/25 and 1/21 Hz of the two-dimension wave spectrumm1HRES-WAM / ENS-WAM / HRES-SAW(tick)TBCTBC
140119h2530Significant wave height of all waves with periods within the inclusive range from 25 to 30 secondsSignificant wave height of all waves with periods within the inclusive range from 25 to 30 seconds, where the significant wave height is defined as 4 times the square root of the integral over all directions and all frequencies between 1/30 and 1/25 Hz of the two-dimension wave spectrumm1HRES-WAM / ENS-WAM / HRES-SAW(tick)TBCTBC

The following new variable resolution parameter is also provided in the ensemble forecast variable resolution overlap stream (STREAM=EFOV) at T+360 (STEP=360) from the Monday and Thursday runs of the ensemble forecast monthly extension.

paramIdshortNamenamedescriptionunitsGRIB editionComponentTest data availableDisseminationProposed for Catalogue
230047dsrpvarDirect solar radiation (variable resolution)Variable resolution companion to dsrp.J/m21ENS (STREAM=EFOV)(tick)TBCTBC

Meteorological impact of the new cycle

Comparison of scores between IFS cycle 43r1 and IFS cycle 41r2 for HRES can be found in the IFS Cycle 43r1scorecard.

Upper air

The new model cycle provides improved high-resolution forecasts (HRES) and ensemble forecasts (ENS) throughout the troposphere and lower stratosphere. In the extra-tropics, error reductions of the order of 0.5-1% are found for most upper-air parameters and levels. The improvement in the primary headline score for the HRES (lead time at which the 500 hPa geopotential anomaly correlation drops below 80%) is about 1 h.

Improvements are most consistently seen in verification against the model analysis. In the tropics, there is a small degradation (both against analysis and observations) of temperature near the tropopause in terms of root mean square error (RMSE) but not in terms of anomaly correlation. This is due to a slight cooling caused by a modification in the treatment of cloud effects in the vertical diffusion scheme, which overall leads to improved cloud cover. While there is a consistent gain for upper-air parameters on the hemispheric scale, some continental-scale areas, such as North America and East Asia, show statistically significant improvements only at some levels and for some parameters.

Increases in upper-air skill of the ENS are generally similar to the HRES, with a substantial gain for mean sea level pressure. The improvement in the primary headline score for the ENS (lead time at which the CRPSS of the 850 hPa temperature drops below 25%) is small (of the order of 0.5 h). The spread-error relationship is generally improved, partly due to reduced error and partly due to increased spread. For some parameters this improvement is quite significant, such as the 850 hPa wind speed in the tropics, where the under-dispersion is reduced by about 20% in the medium range.

Weather parameters and waves

The new model cycle yields consistent gains in forecast performance in the tropics and extra-tropics for total cloud cover, mostly due to a reduction of the negative bias in low cloud cover.  

Changes in precipitation over land areas are small and overall neutral.

The increase in forecast skill for 2m temperature is most pronounced in the short and medium range, where it amounts to ~1% reduction of the RMSE in the northern hemisphere extra-tropics, and up to 2% over some land areas such as Europe and North America. In the tropics there is an increase of 0.5-1% in the RMSE for 2m temperature, connected to a slight increase of the overall cold bias at low latitudes. In the ENS there is a significant improvement in 2m temperature amounting to a 3% reduction in the continuous ranked probability score (CRPS) in Europe.

There is an increase of the RMSE of 2m humidity by about 1% in winter associated with the introduction of limited evapotranspiration when the uppermost soil layer is frozen. This change contributes to the improvements in 2m temperature.  

10m wind speed shows error reductions of 0.5-1% over the ocean, leading to improvements in significant wave height and mean wave period, especially in the tropics and southern hemisphere. Over land areas, changes in 10m wind speed forecast skill are generally neutral to slightly positive.

Monthly forecast

Verification results show a modest positive effect on skill scores although the differences are not statistically significant. There is a substantial improvement in the skill scores for the Madden-Julian Oscillation (MJO), corresponding to a gain in lead time of 0.5-1 day at a forecast range of 4 weeks. Also, MJO spread is increased, bringing it closer to the RMSE. Verification of precipitation against analysis shows some degradation in the tropics which is not statistically significant, and a reduction of precipitation biases in the northwest Pacific.

Sea ice

The new cycle introduces a prognostic sea-ice model, leading to a significant reduction of the RMSE of sea ice fraction in the later medium range.

Technical details of the new cycle

Upgrade to the dynamical ocean model

The medium-range ensemble and its monthly extension see a major upgrade in the dynamical ocean model.  The main changes are summarised in the table.

 OldNew
Ocean model versionNEMO v3.4.1NEMO v3.4.1
ConfigurationORCA1Z42ORCA025Z75

Horizontal resolution

1.0°0.25°
Vertical layers4275
Time step3600s1200s
Initial conditionsOCEAN4 using NEMO v3.0OCEAN5 using NEMO v3.4.1
Sea-ice couplingNoneLIM2

ORAS5 complements the current ocean reanalysis system (ORAS4) until there is no longer need for the ORAS4 output.

Changes to GRIB encoding

Model identifiers

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

GRIB 1
Section 1
Octets
GRIB 2
Section 4
Octets
grib_api key ComponentModel ID
OldNew
6 14  generatingProcessIdentifierAtmospheric model146147
Ocean wave model111112
HRES stand-alone ocean wave model211212

Software

EMOSLIB

EMOSLIB 443 is needed to  interpolate successfully the wave energy flux mean direction (wefxd) parameter introduced at IFS Cycle 43r1.

GRIB API

GRIB API version 1.17.0 provides full support for the new model output parameters introduced in IFS Cycle 43r1. 

Older versions of GRIB API can decode the IFS Cycle 43r1 products successfully but users are advised to use at least GRIB API version 1.14.5, which provides full support for the octahedral reduced Gaussian grid.

ecCodes

ecCodes version 2.0.0 provides full support for the new model output parameters introduced in IFS Cycle 43r1.

Availability of test data from the IFS Cycle 43r1 test suites

Test data in MARS

Test data from the IFS Cycle 43r1 test suites are available in MARS. The data are available with experiment version 0070 (MARS keyword EXPVER=0070) starting from 06 UTC on 10 August 2016. Currently these data are from the beta testing stage.

The data can be accessed in MARS from:

 

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.

Test data in dissemination

Availability of test data from the release candidate testing stage in dissemination is expected to be announced during the week beginning 24 October 2016.

Document versions

DateReason for update
19.09.2016
  • Initial version.
22.09.2016
  • Initial announcement to Member States.
04.10.2016
18.10.2016