NWP SymposiumUniversity of Maryland June 2004
The 1954 start of operational
Numerical Weather Predictionin
Sweden
NWP SymposiumUniversity of Maryland June 2004
Why Sweden?
-C. G. Rossby back from the US 1947(home-longing, management and politics)
-Swedish state-of-art computers(BARK 1950, BESK 1953)
-International support(from the USA and Belgium)
NWP SymposiumUniversity of Maryland June 2004
1953 BESK=Binary ElectronicSequence Calculator
NWP SymposiumUniversity of Maryland June 2004
BESK
In 1953 the world’s “best” computer
Electrostatic drum memory
“Williams tube” memory
Control deskArithmetic unit
NWP SymposiumUniversity of Maryland June 2004
The International Meteorological Institute
Rossby wanted, like V. Bjerknes after WWI, to play an international role in the political reconstruction after WWII
Eady
V. Mieghem
Rossby
Steyer
HubertVuorela
NWP SymposiumUniversity of Maryland June 2004
Baroclinic or barotropic models?…yes, but the
large scale motion can kinematically be described by a barotropic model
The atmospheric motions are driven by
thermal processes as reflected in
baroclinic developments
R. C. Sutcliffe C. G. Rossby
NWP SymposiumUniversity of Maryland June 2004
Common misinterpretations of Rossby’s barotropic concept
-Only valid for stationary waves
-Can only perform linear extrapolations
-Only valid for barotropic features
-Group velocity….
NWP SymposiumUniversity of Maryland June 2004
The concept of group velocity tells us The concept of group velocity tells us that any boundaries have to be placed that any boundaries have to be placed far enough away far enough away from the verification from the verification regionregion
24-hour compu-tational areas for
- MISU- UKMO
NWP SymposiumUniversity of Maryland June 2004
A +24 hour forecast from the UKMO system winter 1953-54A +24 hour forecast from the UKMO system winter 1953-54
BoundaryBoundaryerrors anderrors andnumericalnumericalinstabilityinstability
NWP SymposiumUniversity of Maryland June 2004
Only in 1965 did the UKMO go operational with NWP aftera personal intervention by the new Director General John Mason
Oh dear...
Dear members of thepress, radio and TV...
NWP SymposiumUniversity of Maryland June 2004
In Stockholm tendency calculations were carried out, first by hand in 1952, later on BESK in 1953
The Swedish tabloid “Expressen” published the results almost a year before “Tellus” (forecast left, analysis right)
NWP SymposiumUniversity of Maryland June 2004
+24 h baro-+24 h baro-tropic forecasttropic forecast 3 January 1954 00 UTC3 January 1954 00 UTC
2 January2 January1954 00 UTC1954 00 UTC
Barotropic re-run of the “tree-feller” Barotropic re-run of the “tree-feller” storm the 2-3 January 1954 storm the 2-3 January 1954
NWP SymposiumUniversity of Maryland June 2004
First real time NWP in late September 1954
Not quite the 72 hour computational area
72 hour verification area
NWP SymposiumUniversity of Maryland June 2004
-Professor Dahlqvist,when is
Spring coming?
From the operational period Dec 1954-May 1955
NWP SymposiumUniversity of Maryland June 2004
-Tomorrow at 2 pm!
+72 hours
NWP SymposiumUniversity of Maryland June 2004
…and Spring came!
NWP SymposiumUniversity of Maryland June 2004
Why Sweden succeeded:
-C. G. Rossby back from the USA 1947-Swedish state-of-art computers -International support
-Choice of barotropic model (skilful and providing operational experience)
-Efficient automatic analysis system (Bergthorsson-Döös, 1955)
-Not too small NWP area (but not too big either, avoiding retrogression of the planetary waves!)
NWP SymposiumUniversity of Maryland June 2004
From wheat to bread! Bert Bolin shows automated 500 mb forecasts for Ragnar Fjørtoft (Norway) and George Corby (UK) around 1956
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