Post on 29-Jan-2016
transcript
Copyright © 2003 WGN-TV
Computer ModelsComputer Models are the Primary Source are the Primary Source of Information for All Weather & Climate of Information for All Weather & Climate
PredictionsPredictions
The Prediction ProcessThe Prediction Process
Analyze ResultsAnalyze Results
Com
pare
and
Ver
ify
Com
pare
and
Ver
ify
Observe the AtmosphereObserve the Atmosphere
Identify and ApplyIdentify and ApplyPhysical LawsPhysical Laws
Create a MathematicalCreate a MathematicalModelModel
Create and Run aCreate and Run aComputer ModelComputer Model
The Prediction ProcessThe Prediction Process
Analyze ResultsAnalyze Results
Com
pare
and
Ver
ify
Com
pare
and
Ver
ify
Observe the AtmosphereObserve the Atmosphere
Identify and ApplyIdentify and ApplyPhysical LawsPhysical Laws
Create a MathematicalCreate a MathematicalModelModel
Create and Run aCreate and Run aComputer ModelComputer Model
Observe the Atmosphere Observe the Atmosphere
Upper-AirUpper-AirBalloonsBalloons
SatellitesSatellites
NEXRAD NEXRAD Doppler Doppler
RadarRadar
Commercial AircraftCommercial Aircraft
AutomatedAutomatedSurface Surface
NetworksNetworks
The Prediction ProcessThe Prediction Process
Analyze ResultsAnalyze Results
Com
pare
and
Ver
ify
Com
pare
and
Ver
ify
Identify and ApplyIdentify and ApplyPhysical LawsPhysical Laws
Create a MathematicalCreate a MathematicalModelModel
Create and Run aCreate and Run aComputer ModelComputer Model
Observe the AtmosphereObserve the Atmosphere
Identify & Apply Physical Identify & Apply Physical LawsLaws
F=ma
The Prediction ProcessThe Prediction Process
Analyze ResultsAnalyze Results
Com
pare
and
Ver
ify
Com
pare
and
Ver
ify
Create a MathematicalCreate a MathematicalModelModel
Create and Run aCreate and Run aComputer ModelComputer Model
Observe the AtmosphereObserve the Atmosphere
Identify and ApplyIdentify and ApplyPhysical LawsPhysical Laws
Create a Mathematical ModelCreate a Mathematical Model
The Prediction ProcessThe Prediction Process
Analyze ResultsAnalyze Results
Com
pare
and
Ver
ify
Com
pare
and
Ver
ify
Create and Run aCreate and Run aComputer ModelComputer Model
Observe the AtmosphereObserve the Atmosphere
Identify and ApplyIdentify and ApplyPhysical LawsPhysical Laws
Create a MathematicalCreate a MathematicalModelModel
Create Computer Model Create Computer Model
Solve highly nonlinear partial differential equations Solve highly nonlinear partial differential equations East/West WindEast/West Wind North/South WindNorth/South Wind Vertical WindVertical Wind TemperatureTemperature Water VaporWater Vapor Cloud WaterCloud Water Precipitating WaterPrecipitating Water Cloud IceCloud Ice GraupelGraupel HailHail Surface TemperatureSurface Temperature Surface MoistureSurface Moisture Soil TemperatureSoil Temperature Soil MoistureSoil Moisture Sub-Grid TurbulenceSub-Grid Turbulence
Run the Computer Model Run the Computer Model
Over the course of a single forecast, the Over the course of a single forecast, the computercomputermodel solves billions of model solves billions of equationsequations
Requires the fastest Requires the fastest supercomputers in the supercomputers in the world -- capable ofworld -- capable ofperforming quadrillionsperforming quadrillionsof calculationsof calculationseach secondeach second
Run the Computer Model Run the Computer Model
Computer Weather Prediction Began with Computer Weather Prediction Began with a Vision in the early 1920s -- L.F. a Vision in the early 1920s -- L.F. Richardson’s “Forecast Factory”Richardson’s “Forecast Factory”
Richardson’s Forecast Grid – Richardson’s Forecast Grid – Predictions Done by HandPredictions Done by Hand
25 point mesh!
One Level
Grid Spacing = 250 km
The Vision Becomes Reality… ENIACThe Vision Becomes Reality… ENIAC
ENIAC Versus TodayENIAC Versus Today
Weighed 30 tonsWeighed 30 tons Had 18,000 vacuum tubes, 1,500 Had 18,000 vacuum tubes, 1,500
relays thousands of resistors, relays thousands of resistors, capacitors, inductorscapacitors, inductors
Peak speed of 5000 adds/second Peak speed of 5000 adds/second and 300 multiplies/secand 300 multiplies/sec
A 1.2 GHz Pentium IV processor is A 1.2 GHz Pentium IV processor is 500,000 times faster than the 500,000 times faster than the ENIACENIAC
A desktop PC with 1 Gbyte of RAM A desktop PC with 1 Gbyte of RAM can store 5 million times as much can store 5 million times as much data as the ENIAC data as the ENIAC
Done on ENIAC: 1.2 Done on ENIAC: 1.2 million times slower million times slower than my laptopthan my laptop
Numerically integrated Numerically integrated one equation at one one equation at one altitudealtitude
736 km grid spacing736 km grid spacing 24 hour forecast took 24 hour forecast took
24 hours to compute!24 hours to compute! Forecast below up due Forecast below up due
to lack of smoothing of to lack of smoothing of data – but rerun today, data – but rerun today, it was ok!it was ok!
450 Miles
1950: The First 1950: The First ComputerComputer Weather Weather Forecast ModelForecast Model
……And Things Have Been And Things Have Been Improving Ever SinceImproving Ever Since
Supercell Storms – The Big Supercell Storms – The Big Tornado Producers!Tornado Producers!
Occur most often during springOccur most often during spring Isolated and very intenseIsolated and very intense Updraft rotates in the Updraft rotates in the verticalvertical direction direction Can last for a few hoursCan last for a few hours
Structure of a Supercell Structure of a Supercell StormStorm
Updra
ft
Dow
ndraf
t
Schematic Diagram of a Supercell Storm (C. Doswell)
Structure of a Supercell Structure of a Supercell StormStorm
A Supercell on NEXRAD Doppler A Supercell on NEXRAD Doppler RadarRadar
Hook Echo
Starting with SimulationStarting with Simulation
Early Contour Plot of Early Contour Plot of Horizontal Wind from 3-D Horizontal Wind from 3-D
SimulationSimulation
Courtesy R. Wilhelmson, University of Illinois
Early “Animation” of a 3-D Early “Animation” of a 3-D SimulationSimulation
Courtesy R. Wilhelmson, University of Illinois
3-D Structure Based on 3-D Structure Based on TrajectoriesTrajectories
Courtesy R. Wilhelmson, University of Illinois
Pipe Cleaner Perspective!Pipe Cleaner Perspective!
Courtesy R. Wilhelmson, University of Illinois
Computer-Generated Pipe Computer-Generated Pipe Cleaners!Cleaners!
Courtesy R. Wilhelmson, University of Illinois
Where Does the Rotation Come Where Does the Rotation Come From?From?
Courtesy NCAR
To the Dome!!To the Dome!!
Today’s State-of-the-Art Today’s State-of-the-Art Computer ForecastComputer Forecast
The Real AtmosphereThe Real Atmosphere
Why the Lack of Detail in the Why the Lack of Detail in the Model? Model?
This ThunderstormFalls Through the Cracks
A Foundational QuestionA Foundational Question
. . . explicitly predict this. . . explicitly predict thistype of weather?type of weather?
Can computer forecastCan computer forecasttechnology. . .technology. . .
The Billion Dollar The Billion Dollar Question: Will Question: Will
Computer Models Ever Computer Models Ever Be Able to Be Able to PredictPredict
Tornadoes?Tornadoes?
Current: Warn-on-Detection
NSSL Warn on Forecast Briefing March 5, 2007, Courtesy R. Schneider
Hazard Based Tornado Warning
30%Developing Thunderstorm
Vision: Warn-on-Forecast
Developing thunderstormMostLikelyTornadoPath
T=2120 CST
T=2150
T=2130T=2140
T=2200 CST
70%
50%
30%
NSSL Warn on Forecast Briefing March 5, 2007, Courtesy R. Schneider
MostLikelyTornadoPath
T=2120 CST
T=2150
T=2130T=2140
T=2200 CST
70%
50%
30%
Hurricanes vs Tornadoes?Hurricanes vs Tornadoes?
What May What May be be
Impossible Impossible to Predict!to Predict!