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The page will be updated as required. It was last changed on 08.11.2017
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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Date of implementation
The timetable represents current expectations and may change in light of actual progress made.
We acknowledge the contribution of the Copernicus Climate Change Service (C3S) in the production of SEAS5. C3S provided the computer time for the generation of the re-forecasts for SEAS5 and for the production of the ocean reanalysis (ORAS5), used as initial conditions for the SEAS5 re-forecasts. SEAS5 will be the ECMWF contribution to the C3S multi-model seasonal forecast products, see paragraph 'SEAS5 and Copernicus services'.
Latest news
08.11.2017: We are pleased to confirm that the SEAS5 system was successfully implemented in operations on 5.11.2017. System 4 will keep running for a limited time.
16.10.2017: The long range forecast documentation page has been updated, to include the SEAS5 user guide.
16.10.2017: Pre-operational SEAS5 charts are available under https://www.ecmwf.int/en/forecasts/charts/seasonal_system5/
11.10.2017: We now have modified the operational dissemination requirements to request SEAS5 data. Users can update their operational requirements, as needed. Any change made will be used for the first time in the SEAS5 run of November. Changes to the dissemination requirements for System 4 are no longer possible.
04.10.2017: The re-archiving of the problematic SEAS5 pressure level derived fields has completed last night and we have validated the data this morning.
03.10.2017: We have identified a problem with some archived pressure level fields for some derived fields associated with the real-time forecasts. The fields affected are type=hcmean from stream msmm, and types fcmean and em from stream mmsa. Pressure level fields from 925 hPa up to 1 hPa are affected, for dates from January to September 2017. Surface fields and 1000hPa pressure level fields are not affected.
Note that the main monthly mean fields (stream=msmm, type=fcmean) are *not* affected. We will begin re-archiving the affected pressure level fields in MARS at 14:30UTC on the 3rd October, to correct the problem, and will confirm on this page when the re-archiving is complete. Please accept our apologies for any inconvenience caused.
Current Status
SEAS5 was successfully implemented in operations on 5.11.2017.
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.
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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 of SEAS5 on users
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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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- Release candidate testing
- Data in MARS and dissemination
- SEAS5 in EUROSIP
- SEAS5 and Copernicus Services
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- Re-archiving of some derived SEAS5 data. See Latest news.
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- Re-archiving of some derived SEAS5 data completed.
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- SEAS5 dissemination requirements available
- SEAS5 release candidate charts available
- SEAS5 User guide available
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