1. European Centre for Medium-Range Weather Forecasts
ECMWF STRATEGY : THE STRENGTH OF A COMMON GOAL
European Centre for Medium-Range Weather Forecasts

2. European Centre for Medium-Range Weather Forecasts
THE STRENGTH OF A COMMON GOAL
ECMWF’s purpose is to develop a capability for medium-range weather forecasting and to provide such weather forecasts to the Member and Co-operating States
ECMWF is complementary to the National Meteorological Services and works with them in research, numerical weather predictions, supercomputing and training.
European Centre for Medium-Range Weather Forecasts

3. European Centre for Medium-Range Weather Forecasts
THE STRENGTH OF A COMMON GOAL
Evolution of ECMWF medium-range skill over the past 35 years
European Centre for Medium-Range Weather Forecasts

4. European Centre for Medium-Range Weather Forecasts
THE STRENGTH OF A COMMON GOAL
Evolution medium-range skill (NH Z500>0.8)
European Centre for Medium-Range Weather Forecasts

5. European Centre for Medium-Range Weather Forecasts
THE STRENGTH OF A COMMON GOAL
New emphasis: Percentage of large 2m temperature errors in the ensemble
European Centre for Medium-Range Weather Forecasts

6. European Centre for Medium-Range Weather Forecasts
THE STRENGTH OF A COMMON GOAL
The size of the challenge # 1
The difficulty: Sharp ensembles two weeks ahead
Severe weather: Hurricane Bertha
6-9 days
2-5 days
European Centre for Medium-Range Weather Forecasts

7. European Centre for Medium-Range Weather Forecasts
The size of the challenge # 2
THE STRENGTH OF A COMMON GOAL
Springtime cold spell over Europe
2m Temperature, April 2017
European Centre for Medium-Range Weather Forecasts

8. European Centre for Medium-Range Weather Forecasts
THE STRENGTH OF A COMMON GOAL
Forecast targets by 2025
Ensemble predictions of high impact weather up to two weeks ahead
Seamless approach, aiming towards predictions of large scale patterns and regime transitions up to four weeks ahead and global-scale anomalies up to a year ahead
European Centre for Medium-Range Weather Forecasts

9. European Centre for Medium-Range Weather Forecasts
Goals
THE STRENGTH OF A COMMON GOAL
Research at frontiers of knowledge
Ensemble-based analyses and predictions that raise the international bar for quality and operational reliability reaching a 5 km horizontal resolution
European Centre for Medium-Range Weather Forecasts

10. European Centre for Medium-Range Weather Forecasts
THE STRENGTH OF A COMMON GOAL
How do we achieve these goals?
Observations
High resolution ensemble
Earth-system
Scalability
Funding
People
European Centre for Medium-Range Weather Forecasts

11. European Centre for Medium-Range Weather Forecasts
THE STRENGTH OF A COMMON GOAL
Use of satellite data at ECMWF
ECMWF processes an average of 40 million observations every day, from over 70 instruments. Collaboration with sister organisation EUMETSAT, and also ESA, CMA, JMA, NASA, NOAA among others ensures that ECMWF has access to the observations meteorology requires.
European Centre for Medium-Range Weather Forecasts

12. European Centre for Medium-Range Weather Forecasts
THE STRENGTH OF A COMMON GOAL
Contributions to WIGOS data quality monitoring system
In situ observation monitoring with data from ECMWF, NCEP, DWD and JMA Data availability and quality
European Centre for Medium-Range Weather Forecasts

13. IRMA operational v. 5km
As IRMA had such large consequences in the Caribbean including for some of our MSs, we used this case study to have a first view of what a 5 lm ENS could look like. Still too expensive to run a large set of experiments on current computer, and no DA, but one single forecast with 51 members.
Trajectories not too dissimilar although ens mean better.
Fit to observed surface pressure remarkably improved.

14. European Centre for Medium-Range Weather Forecasts
Pillar 1– we started a few years back to experiment with an Earth system approach, and the new strategy places a strong emphasis on the positive results gained from such approach, and this a direction we are continuing to develop and implement.
European Centre for Medium-Range Weather Forecasts

15. European Centre for Medium-Range Weather Forecasts
THE STRENGTH OF A COMMON GOAL
Availability and use of GTS snow depth information
Impact of revised IMS snow
cover assimilation on rms 1000hPa
temperature and humidity errors  
European Centre for Medium-Range Weather Forecasts

16. European Centre for Medium-Range Weather Forecasts
THE STRENGTH OF A COMMON GOAL
Impact of coupled assimilation during a cyclone
The dotted line shows the time series of ocean temperature observations at a depth of 40 metres by an Argo float located on the track of the cyclone Phailin.
European Centre for Medium-Range Weather Forecasts

17. European Centre for Medium-Range Weather Forecasts
Seamless modelling systems
THE STRENGTH OF A COMMON GOAL
Scientific and infrastructure advantages of convergence of approaches across timescales
Seasonal SEAS5 only differs from the 43r1 ENS extended (monthly) system when testing demonstrated clear improvement in forecast skill or mean state
Horizontal (Tco319/ORCA25) and vertical resolution (L91/L75) identical
Improvements found on one timescale applicable for others
Decreasing non-orographic gravity wave drag ameliorates the effect of stratospheric temperature and winds biases on the QBO
Preferred seasonal setting now found suitable for adoption for medium-range to monthly
SEAS4
43r1
SEAS5
Forecast lead (months)
Layout out the targets for our forecasts
European Centre for Medium-Range Weather Forecasts

18. ECMWF Scalability Programme
Governance:
ECMWF, Member states, Regional consortia
Projects:
Observation processing:
Lean workflow in critical path
Object based data store
Screening/bias correction
Data assimilation:
Flexible algorithms (C++)
IFS integration
Coupling with ocean and sea-ice
Parallel minimization
Numerical methods:
Numerical methods
h/v/t-discretization, multiple grids
Prognostic variables, coupling
Model output
processing:
Broker-worker workflow
Near-memory processing
Data compression
Code adaptation:
· Benchmarking · Vectorization · Programming models · Precision · DSL/libraries · Transition to operations
Computer architecture support:
· Benchmarking · Novel architectures · Compilers · Vendor support · Transition to operations
European Centre for Medium-Range Weather Forecasts

19. European Centre for Medium-Range Weather Forecasts
Scalability across the NWP chain: Single precision to deliver efficiency gains
Moving to another prospect, the possibility to run on single precision.
How much faster can our weather forecasts run with single precision?
The magnitude of savings with single precision depends on various factors. When computing speed is limited by memory bandwidth, single precision can typically increase performance by a factor of two since data volume is halved. If floating point operations are the performance bottleneck, the speed-up factor will depend on the level of code vectorization. Single precision is twice as efficient when the code is fully vectorised.
For forecast simulations with the ECMWF IFS on our Cray supercomputer, single precision runs are typically ~40% faster compared to double precision references. However, those numbers depend on the model resolution and the number and configuration of processors that are used in parallel.
The use of single precision will potentially allow significant savings of computing cost in the near-term future and an increased throughput on supercomputers. Single precision will also help us to perform tests with the IFS at very high resolution. For these simulations, a very large number of computing nodes is needed to fit the model into the memory that is available. Single precision is reducing memory requirements significantly and less nodes can be used. Tests with single precision in simulations at 2.5 and 1 km global resolution are being performed at the moment.
Another interesting factor of this project is that it started as part of a type of collaboration that we have created a few years back, the ECMWF Fellowship, whereas we invite an academic to work with our teams on a specific area of work. Single precision was started as part of Tim Palmer and his team at Oxford University’s Fellowship.
Surface temperature in degree Celsius for five day forecasts for 8th January :00 UTC. This date is during the European cold wave that caused very low temperature in Eastern and Central Europe. Results are shown for single precision and double precision simulations at 9km (TCo1279) resolution (left and middle) and the analysis as a reference (right). Differences between single and double precision are very small.
European Centre for Medium-Range Weather Forecasts

20. ExtremeEarth co-design approach
How
What

21. European Centre for Medium-Range Weather Forecasts
THE STRENGTH OF A COMMON GOAL
Collaboration
Partnering with universities, research institutes and NHMSs
Strategic partnerships in Earth observation
Providing collaborative data bases (e.g. TIGGE, S2S)
European Centre for Medium-Range Weather Forecasts

22. European Centre for Medium-Range Weather Forecasts
THE STRENGTH OF A COMMON GOAL
In summary
Operational forecasts AND Research
High-impact weather, regime transitions and global-scale anomalies
Integrated ensemble at 5km resolution by 2025
Earth-System model and analysis
Scalable computation
Environmental information services: Copernicus
Collaboration
European Centre for Medium-Range Weather Forecasts