October 29, 2014

Using High-Performance

Computing to Predict Extreme

WeatherPeter Bauer

October 29, 2014October 29, 2014

Independent intergovernmental organisation

established in 1975

with19 Member States15 Co-operating States

European Centre for Medium-Range Weather Forecasts

October 29, 2014

The success story of Numerical Weather Prediction: Wind storms28-29 October 2013 ‘Christian’ wind gusts

5-day forecast of probabilities for wind gusts exceeding > 10m/s

October 29, 2014

The success story of Numerical Weather Prediction: Heat wavesMaximum observed temperature

Maximum forecast temperature day-3 – day-4

Temperature anomaly ensemble forecast week-2

… and week-3½

Week 2-3½ forecast of probabilities for temperature anomalies exceeding > 5-10K

October 29, 2014

29-09-15 30-09-15 01-10-15

Individual trajectories for JOAQUIN during the next 240 hourstracks: thick solid=HRES; thick dot=CTRL; thin solid=EPS members [coloured]

The success story of Numerical Weather Prediction: Hurricanes

October 29, 2014

Day 0

Day 2Southern Gaza Strip, on April18, 2012

Day 4

The success story of Numerical Weather Prediction: Dust storms

October 29, 2014

Previously on …?

John von Neumann (1903-1957), Mathematician:• Function theory, abstract algebra,

quantum physics• Leader of Electronic Computer Project

(1946-52)

Jule Charney (1917-1981), Meteorologist:• Set of equations for numerical prediction of planetary waves• Founder of theory of baroclinic instability

Electronic Numerical Integrator and Computer (ENIAC)• 140 kW, 30 tons, 18,000 thermo-ionic valves• 1-layer model, resolution 400-700 km, North American domain• Single 24-hour forecast needed 24 hours compute time

ENIAC 1950

The same prediction needed 1 second on a Nokia 6300 mobile phone (2006)!

Lewis Fry Richardson (1881-1953), Physicist, Meteorologist, Psychologist, Pacifist:• Basics of numerical weather prediction• First explicit calculation of weather on 20 May 1910

October 29, 2014

Computer power

Model complexity

Model resolution

Tomorrow

Today

Multiple dimensions

EnsemblesLong climate runs

October 29, 2014

What is the challenge?

Observations Models

Volume 20 million = 2 x 107 5 million grid points100 levels10 prognostic variables = 5 x 109

Type 98% from 60 different satellite instruments

physical parameters of atmosphere, waves, ocean

Observations Models

Volume 200 million = 2 x 108 500 million grid points200 levels100 prognostic variables = 1 x 1013

Type 98% from 80 different satellite instruments

physical and chemical parameters of atmosphere, waves, ocean, ice, vegetation

Today:

Tomorrow:

Factor 10 Factor 2000per day per time step

(10-day forecast = 1440 time steps)

October 29, 2014

scalability range

scalability range

Ensemble

Single

Simple compute projection (only resolution)

2015 2025

M€ electricity/year

Power limit

[Bauer et al. 2015]

October 29, 2014

2015 Time critical• 21 TB/day written• 22 million fields• 85 million products• 11 TB/day sent to customers

Non-time critical• 100 TB/day archived• 400 research experiments• 400,000 jobs / day

20202025?

Time critical• 128 TB/day written• 90 million fields• 450 million products• 60 TB/day sent to customers

Non-time critical• 1 PB/day archived• 1,000 research experiments• 1,000,000 jobs / day

Data projection

Factor 5-10 every 5 years!

time

October 29, 2014

[Schulthess 2015]

Traditional science workflow

October 29, 2014

[Schulthess 2015]

Future science workflow

science specific code generic code

Energy efficient SCalable Algorithms for weather Prediction at Exascale www.hpc-escape.eu

October 29, 2014October 29, 2014

‘The quiet revolution of numerical weather prediction’ by P. Bauer, A.J. Thorpe, G. Brunet

in Nature, 3 September 2015:

The future of Numerical Weather Prediction

[IPCC]