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The page will be updated as required. It was last changed on 0501.0709.2017
For a record of changes made to this page please refer to Document versions.
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The planned timetable for the implementation of SEAS5 is as follows:
| Date | Event |
|---|---|
| 05 July 2017 | Initial announcement. Data available in MARS |
| mid September 2017 | Availability of test data in dissemination |
| early November 2017 | Expected date of implementation |
The timetable represents current expectations and may change in light of actual progress made.
Current Status
The Beta testing phase of SEAS5 has startedWe have made good progress with the beta testing and aim to enter release candidate testing by the 8th of September. SEAS5 re-forecast and forecast data are both fully available in MARS. Forecast data will become available in MARS and through dissemination.
Summary description of SEAS5
Graphical products will also be made available on our website
New release day for SEAS5 data
We are pleased to announce that the SEAS5 products (data and charts) will be released 3 days earlier, on the 5th of each month at 12UTC. System 4 products are currently released on the 8th of each month.
Summary description of SEAS5
With a few With few exceptions, SEAS5 is configured to be identical to the extended part of the ENS, as implemented with IFS Cycle 43r1. In particular, the same resolution is used for both the monthly and seasonal forecast ranges. However, while the ENS will be regularly upgraded over the next few years with each new cycle of the IFS, the SEAS5 will remain fixed at IFS Cycle 43r1. Previous seasonal forecast systems have had a lifetime of about 5 years, and although future upgrades of SEAS may happen more often there is not yet a planned date for the introduction of SEAS6.
The table below summarizes the upgrades in model components and initialization for SEAS5.
| System 4 | SEAS5 | |
|---|---|---|
| IFS Cycle | 36r4 | 43r1 |
| IFS horizontal resolution | TL255 | TCO319 |
| IFS Gaussian grid | N128 (80 km) | O320 (35 km) |
| IFS vertical resolution (TOA) | L91 (0.01 hPa) | L91 (0.01 hPa) |
| IFS model stochastic physics | 3-lev SPPT and SPBS | 3-lev SPPT and SPBS |
| Ocean model | NEMO v3.0 | NEMO v3.4 |
| Ocean horizontal resolution | ORCA 1.0 | ORCA 0.25 |
| Ocean vertical resolution | L42 | L75 |
| Sea ice model | Sampled climatology | LIM2 |
| Atmosphere initialization (Re-forecast/Forecast) | ERA-Interim/Operations | ERA-Interim/Operations |
Land Initialization | ERA-Interim land ( |
| 36r4)/Operations | ERA-Interim land (43r1)/Operations | |
| Ocean initialization | ORA-S4 | ORS-S5 |
|---|---|---|
| Forecast ensemble size | 51 (0-7m) 15 (8-13m) | 51 (0-7m) 15 (8-13m) |
| Re-forecast years | 30 (1981-2010) | 36 (1981-2016) |
| Re-forecast ensemble size | 15 (0-7m) 15 (8-13m) | 25 (0-7m) 15 (8-13m) |
| Calibration period | 1981-2010 | 1993-2016 |
Meteorological content of SEAS5
Atmosphere model
| Products Release Date | The 8th of each month at 12UTC | The 5th of each month at 12UTC |
|---|
Meteorological content of SEAS5
Atmosphere model
The The IFS has been upgraded from cycle 36r4 to 43r1. In this time many changes have been made to model physics (surface drag, boundary layer entrainment, shallow convection, vertical diffusion, orographic drag, surface climate fields, CO2/CH4 climatologies, convective detrainment, cloud scheme physical processes, introduction of a lake model, radiation-surface interactions, solar zenith angle calculations, freezing rain physics, cloud erosion, CAMS O3 climatology, boundary layer cloud) and to model numerics (revised semi-Lagrangian extrapolation, revised interpolation of moist variables, cubic truncation and octahedral grid, semi-lagrangian departure point iterations, spectral viscosity). Further details can be found in the documentation of the evolution of the IFS.
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Pre-implementation testing showed that the model version planned for SEAS5 gives substantial improvements in SST bias in the tropical Pacific, with consequent improvements in ENSO forecast skill. A more comprehensive assessment of the meteorological impact will be given based on analysis of the full set of SEAS5 re-forecasts once they are completedis being made and will be given shortly. Assessments of mid-latitude forecast skill are subject to considerable sampling error, and the limited sample sizes available from pre-implementation testing are not considered reliable predictors of the eventual outcome of the SEAS5 re-forecast dataset.
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The GRIB model identifiers (generating process identification number) for SEAS5 will be changed as follows:
| GRIB 1 Section 1 Octets | GRIB 2 (only for SEAS5) Octets | grib_api/ecCodes key name | Component | Model ID | |
|---|---|---|---|---|---|
| System 4 | SEAS5 | ||||
| 6 | 14 (in Section 4) | generatingProcessIdentifier | Atmospheric model | 139 | 147 |
| Ocean wave model | 107 | 112
| |||
| 52-53 | 18-19 (in Section 2) | systemNumber | 4 | 5 | |
GRIB 2 data
SEAS5 model level data is coded in GRIB 2, compared to GRIB 1 for System 4. The change to GRIB 2 for model level data was introduced in IFS Cycle 37r2 in 2011. See under User impact below for more information.
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Several new parameters have been added related to the lake model, 6h instantaneous stresses have been added to help user applications such as wave modelling, and top incoming solar radiation has been added with a 24 hour output frequency. Note also that surface and sub-surface runoff are now fully available (in System 4, these parameters were available for the real-time forecasts, but only a limited number of the re-forecasts).
| paramId | name | frequency |
|---|---|---|
| 26 | Lake cover | Step 0 only |
| 228007 | Lake depth | Step 0 only |
| 228008 | Lake mixed layer temperature | 24 hour |
| 228014 | Lake ice depth | 24 hour |
| 229 | Instantaneous eastward turbulent surface stress | 6h |
| 230 | Instantaneous northward turbulent surface stress | 6h |
| 212 | Top incoming solar radiation | 24h |
| 8 | Surface runoff | 24h |
| 9 | Sub-surface runoff | 24h |
Surface fields output at additional timesteps
Some surface fields previously archived every 24 hours are now archived every 6 hours. As well as increased availability of synoptic data, this also changes the monthly means for the instantaneous fields such as SST and soil temperature. These are now calculated from 6 hourly data, and no longer have the diurnal cycle aliased into them. (For accumulated fields, the monthly mean rate of accumulation is independent of whether synoptic data is written at 6 or 24h intervals).
| paramId | name | frequency |
|---|---|---|
| 34 | Sea surface temperature | 6 hr |
| 144 | Snowfall | 6 hr |
| 139 | Soil temperature level 1 | 6 hr |
| 169 | Surface solar radiation downwards | 6 hr |
| 175 | Surface thermal radiation downwards | 6 hr |
| 228 | Total precipitation | 6 hr |
Model level data
SEAS5 model level data are now produced to 6 months instead of 5 months for System 4.
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All fields are output every 24 hours
| paramId | name |
|---|---|
| 140220 | Mean wave period based on the first moment |
| 140221 | Mean wave period based on the second moment |
| 140244 | Mean square slope of waves |
| 140249 | 10 m wind direction (no calculation of monthly mean/max/min/SD) |
Impact on users
Software
EMOSLIB version 443, GRIB API version 1.17.0 or ecCodes version 2.0.0 are the minimum versions recommended to manipulate all SEAS5 fields.
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The size of the fields archived have increased by a factor 2 to 4. . When retrieving data via MARS or dissemination, if no spectral truncation or grid resolutions are specified, fields are provided at the model resolution.
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Only registered users with access to MARS will be able to access the re-forecast data sets.
At present the The re-forecast data for May, June, July, August and November start dates all 12 months in the year have been released. Other re-forecast data will be accessible and validated by ECMWF as they are produced.
Test SEAS5 Forecast data in MARS
Test SEAS5 Forecast data in MARS
SEAS5 technical SEAS5 test data are available in MARS with experiment version 9001 (MARS keyword EXPVER=9001) starting from 1 May for the runs of May, June and July 2017 at 00UTC.
The data can be accessed in MARS from:
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The SEAS5 Forecast beta release data are intended for testing technical aspects and should not be used for operational forecasting. Please report any problems you find with this these data to User Support.
Release candidate SEAS5 data will be archived in MARS from January 2017 onwards with experiment version 0001. This archiving should be complete before the 8th of September.
Test real-time SEAS5 data in dissemination
SEAS5 data will soon become available in dissemination before we reach the release candidate testing phase. More details will be provided nearer the time.
Parallel run of System 4 and SEAS5
SEAS5 has run for May 2017. We will continue running SEAS5 for June and July and aim at running SEAS5 in near real-time from August onwards. SEAS5 data will then become available a few days after the System 4 data have been released.
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Users of ECMWF dissemination products can request new SEAS5 products at https://ecaccess.ecmwf.int:7443/do/product/requirements. Note that the SEAS5 requirements now include the directive 'SYSTEM=5'. Any change will be effective with the next run of SEAS5..
SEAS5 T319/O320 products can be requested in their original representation as well as in the previously supported representations in System 4.
Supported latitude/longitude resolutions in the System 5 are:
- multiplies of 0.4/0.4 degrees (as the third leg of the monthly forecast)
- multiplies of 0.75/0.75 degrees, to provide seamless transition from the Seasonal System 4 (current resolution)
Where possible, we would advise users to request the native (Octahedral) resolutions.
SEAS5 test dissemination file names will have EXPVER '9001' as the last part of the file name, e.g. ALL0801000010______9001, to distinguish between operational files ending with '1', e.g. ALL0801000010______1. Note however that the GRIB messages in the SEAS5 test dissemination data will contain the key expver=0001.
SEAS5 test dissemination files are queued into ECPDS in delayed (standby) mode. Users can trigger the transmission of wanted test products at their convenience by logging into the test ECPDS system at https://ecpds-xmonitor.ecmwf.int/ in the usual manner. In order to receive the test products, users will have to open their firewall to the relevant ECPDS Data Movers:
At the moment, SEAS5 test products generated are based on the current (SYSTEM=4) dissemination requirements. Users wishing to test new System 5 products or request fields at a higher resolution can change their requirements as explained above. GRIB headers fully reflect the generating process (systemNumber=5, methodNumber=1).
SEAS5 test data will be made available in dissemination for August, September and October 2017.
| Note |
|---|
| On the day of SEAS5 implementation into ECMWF operations, currently expected for November 2017, no test requirements will be carried into operational mainframe. Users wishing to make their modified test SEAS5 requirements operational on the implementation date will have to let ECMWF (Data Services) know two weeks prior to the announced implementation date. |
Parallel run of System 4 and SEAS5
SEAS5 has run for May, June, July 2017 in beta testing (experiment=9001). SEAS5 will run in near real-time from September onwards. SEAS5 data will then become available shortly after the System 4 data have been released.
On the switch-over date, presently expected to be for the November run, SEAS5 will become the operational system. The SEAS5 dissemination file names will then end with EXPVER '1'. System 4 will continue to be run as a near real-time system, for a limited period of time. Data from System 4 will be available from MARS and, for those interested, through dissemination on request. Those interested should contact Data Services at ECMWF. On the implementation date of SEAS5, users who requested to keep getting System 4 data though dissemination will receive both the SEAS5 and System 4 files via ECPDS, with the System4 file names including EXPVER '9004', e.g. ALL1101000010______9004.
| Note |
|---|
| The release date of these '9004' files in ECPDS will remain the 8th of each month at 12UTC. |
On the switch-over date, presently expected to be for the November run, SEAS5 will become the operational system. System 4 will continue to be run as a near real-time system, for a limited period of time. Data from System 4 will be available from MARS and through dissemination for those interested. We intend to stop running System 4 before March 2018. Users are advised to make sure that all their applications are switched to using SEAS5 data as soon as possible after the implementation.
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Graphical products from the seasonal forecast system are displayed on the Forecast Charts pages of the ECMWF website. We will make the SEAS5 graphical products available on the ECMWF website with the release candidate testing.
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| Date | Reason for update |
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| 05.07.2017 |
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| 01.09.2017 |
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