Global Weather Prediction -Possible developments in the next decades- Professor Lennart Bengtsson ESSC, University of Reading MPI for Meteorology, Hamburg

Global Weather Prediction -Possible developments in the next decades- Introduction (some personal remarks) Predictive skill in NWP The future of NWP Concluding remarks

The First Operational NWP October 1954, “ Dalamanövern“ Meteorological Institute, Stockholm and the Swedish Airforce

The First Operational NWP

Predictive skill and Predictability Northern hemisphere 500hPa height Winter

Predicting super hurricane Floyd at ECMWF

The future of NWP Modeling and data-assimilation Extended predictions Computational possibilities Provisions of forecast information to users

L.F. Richardson, 1922 “Imagine a large hall like a theatre, except that the circles and the galleries go right round through the space usually occupied by the stage. The walls of this chamber are painted to form a map of the globe. The ceiling represents the north polar regions, the tropics in the upper circle, and the antarctic in the pit. A myriad computers are at work upon the weather of the part of the map where each sits, but each computer attends only to one equation or part of an equation. The work of each region is co-ordinated by an official of higher rank. Numerous little “night signs” display the instantaneous values so that neighbouring computers can read them. From the floor of the pit a tall pillar rises to half the height of the hall. It carries a large pulpit on its top. In this sits the man in charge of the whole theatre. One of his duties is to maintain a uniform speed of progress in all parts of the globe. In this respect he is like the conductor of an orchestra in which the instruments are slide-rules and calculating machines. But instead of waving a baton he turns a beam of rosy light upon any region that is running ahead of the rest, and a beam of blue light upon those who are behindhand. Four senior clerks at the central pulpit are collecting the future weather as its is being computed, and despatching it by pneumatic carrier to a quiet room. There it will be coded and telephoned to the radio transmitting stations”

Richardson‘s dream

Modeling and data-assimilation Ensemble prediction Non-hydrostatic models Resolution issues Physical parameterization Data-assimilation

Ensemble prediction

Predictability of weather

1 Feb UTC Surface Pressure & Gusts Analysis

Surface Pressure1 Feb UTC Analysis Forecast +1 Day

Surface Pressure1 Feb UTC Analysis Forecast +1.5 Day

Surface Pressure1 Feb UTC Analysis Forecast +2 Day

10 m Gusts 1 Feb UTC Analysis Forecast +1 Day

10 m Gusts 1 Feb UTC Analysis Forecast +1.5 Day

10 m Gusts 1 Feb UTC Analysis Forecast +2 Day

Ensemble Forecasts: D+3.5

Ensemble Forecasts: D+4.5

Data assimilation The physical aspects of data-assimilation ( What are the key observations?) Coupled atmosphere - ocean models

Extended prediction Where are the limits?

Predictive skill and Predictability Northern hemisphere 500hPa height Winter

An example of potential super-predictability Simulation of QBO Giorgetta et al., 2003 ECHAM 5: T42/L90

Supercomputer performance 1970s Mega flops 1990s Giga flops 2000s Tera flops 2010s Peta flops 2020s Exa flops?

Weather on Internet ICM Warsaw 48hr forecasts four times a day ( Meteogrammes (

meteorogram number : x = 4, y = , start t0 0:00 GMT

Concluding remarks NWP in the future Non-hydrostatic models and advanced data-assimilation Increased skill in predicting extreme events Ensemble prediction for all time-scales Major improvements in extended prediction Very powerful computers and communication systems will change the way NWP is being done today Major changes in the global structure of NWP Many users will be making their own forecasts

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