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The page will be updated as required. It was last changed on 01.09.2017
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.
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Timetable for implementation
The planned timetable for the implementation of SEAS5 is as follows:
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Expected date of implementation
The timetable represents current expectations and may change in light of actual progress made.
Current Status
We have made good progress with the beta testing and aim to enter release candidate testing by the 8th of September. SEAS5 re-forecast data are fully available in MARS. Forecast data will become available in MARS and through dissemination. 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 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.
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Meteorological impact of SEAS5
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 based on analysis of the full set of SEAS5 re-forecasts is 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.
The graphical products for SEAS5 show anomalies with respect to a 1993-2016 base period, whereas System 4 used a 1981-2010 base period. Due to global warming, the use of a more recent base period results in significant changes to the plotted anomalies, particularly for temperature and geopotential height. Thus although the actual (calibrated) temperature forecast may be very similar, the plotted anomaly can look quite different. Users are encouraged to calibrate the forecasts according to their own needs by using the re-forecast data available in MARS. Re-forecasts cover 1981-2016 to maximize the data available for skill estimation and calibration.
Technical details of SEAS5
Changes to GRIB encoding
Model identifiers
The GRIB model identifiers (generating process identification number) for SEAS5 will be changed as follows:
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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.
Use of the octahedral reduced Gaussian grid
SEAS5 introduces a new form of the reduced Gaussian grid, the octahedral grid, for the atmospheric (mostly) single level data. See Introducing the octahedral reduced Gaussian grid for further details.
New model output parameters and changes to existing parameters
Surface parameters added
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).
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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).
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Model level data
SEAS5 model level data are now produced to 6 months instead of 5 months for System 4.
Ocean waves parameters added
All fields are output every 24 hours
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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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ecCodes has now replaced GRIB API on the ECMWF platforms. GRIBEX is no longer available and cannot decode GRB 2 data. |
Increased field sizes
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.
In particular, users should be aware of the increase in memory and CPU time needed to process the increased resolution fields and adjust their programs and batch scripts appropriately.
Availability of SEAS5 Data
Re-forecast data in MARS
The SEAS5 re-forecast data can be accessed in MARS from:
Only registered users with access to MARS will be able to access the re-forecast data sets.
The re-forecast data for all 12 months in the year have been released.
Test SEAS5 Forecast data in MARS
SEAS5 technical test data are available in MARS with experiment version 9001 (MARS keyword EXPVER=9001) for the runs of May, June and July 2017 at 00UTC.
The data can be accessed in MARS from:
- Atmospheric forecasts (class=od, stream=mmsf, expver=9001, system=5, method=1)
- Wave forecasts (class=od, stream=wasf, expver=9001, system=5, method=1)
- Atmospheric monthly means (class=od, stream=msmm, expver=9001)
- Wave monthly means (class=od, stream=swmm, expver=9001)
Seasonal forecast monthly anomalies (class=od, stream=mmsa, expver=9001)
Only registered users with access to MARS with permission to access real-time data will be able to access these test data sets.
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 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.
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.
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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.
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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.
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The release date of these '9004' files in ECPDS will remain the 8th of each month at 12UTC. |
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.
Graphical display of SEAS5 test forecasts
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.
References
Madec G (2008) NEMO ocean engine. Tech. rep., Institut Pierre-Simon Laplace (IPSL), URL https://www.nemo-ocean.eu/doc/
Good, S. A., M. J. M., and R. N. A., 2013: EN4: Quality controlled ocean temperature and salinity profiles and monthly objective analyses with uncertainty estimates. J. Phys. Oceanogr.,118, 6704–6716, doi:10.1002/2013JC009067.
Fichefet T,Maqueda MAM (1997) Sensitivity of a global sea ice model to the treatment of ice thermodynamics and dynamics. Journal of Geophysical Research 102(C6):12,609–12,646, DOI 10.1029/97JC00480,URL http://doi.wiley.com/10.1029/97JC00480
Balmaseda MA, Mogensen K, Weaver AT (2013) Evaluation of the ECMWF ocean reanalysis system ORAS4. Quarterly Journal of the Royal Meteorological Society 139(674):1132{1161
Steffen Tietsche, Magdalena a. Balmaseda, Hao Zuo, and Kristian Mogensen. Arctic sea ice in the global eddy-permitting ocean reanalysis ORAP5. Climate Dynamics, jun 2015. ISSN 0930-7575. doi: 10.1007/s00382-015-2673-3. URL http://link.springer.com/10.1007/s00382-015-2673-3.
Hao Zuo, Magdalena A Balmaseda, and Kristian Mogensen. The new eddy-permitting ORAP5 ocean reanalysis: description, evaluation and uncertainties in climate signals. Climate Dynamics, 2015. doi: 10.1007/s00382-015-2675-1. URL http://link.springer.com/article/10.1007/s00382-015-2675-1.
Zuo, H., M.A. Balmaseda, E. Boisseson and S. Hirahara, 2017: A new ensemble generation method for ocean reanalyses. ECMWF Technical Memorandum 795.
Zuo et al 2018 (in preparation)
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- Initial version
- Availability of data in MARS
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- New release day for SEAS5 - 5th of each month at 12UTC
- Preliminary information about SEAS5 data in dissemination
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