Statistical Challenges in Climatology

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Statistical Challenges in Climatology

• Chris Ferro
• Climate Analysis Group
• Department of Meteorology
• University of Reading

Also featuring David Stephenson, Abdel
Hannachi, Sergio Pezzulli, Cristina Carollo
(ESSC), Barbara Casati, Caio Coelho, Pascal
Mailier, Tim Mosedale, Fotis Panagiotopoulos,
Matt Sapiano and Neeraj Teeluk (UCL)
Young Statisticians Meeting, Cambridge, 14-15
April 2003
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Statistical Climatology?
computer forecasts
manual forecasts
primitive equations
1950
1922
1904
2002
Jule G. Charney
Vilhelm Bjerknes
The Earth Simulator Speed 40 Tflops Memory
10Tbytes
Lewis Fry Richardson
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General Issues

• Dependent
• Nonstationary
• Huge datasets
• Limited data

• space and time many scales
• space and time periodicities,
• shocks, external forcings
• station, satellite, simulation
• short record, no replication

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errors
parameters
Differential Equations
Numerical Scheme
structure
Initial Conditions
External Forcings
Circulation Model
deterministic
sensitivity
estimation
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Climate Change

• PRUDENCE
• European climate
• 30-year control simulation, 1961-1990
• 30-year scenario simulation, 2071-2100

Intergovernmental Panel on Climate
Change www.ipcc.ch
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Mean Winter Precipitation
mm/day
mm/day
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Mean Winter Precipitation
mm/day

• Two-sample block bootstrap simultaneously at each
  grid point
• accounts for temporal dependence
• preserves spatial structure

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Mean Winter Precipitation
mm/day

• Two-sample block bootstrap simultaneously at each
  grid point
• accounts for temporal dependence
• preserves spatial structure

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Observations

• Buoys
• Field Stations
• Ships Aircraft

• Satellites
• Radiosondes
• Palaeo-records

• homogeneity, missing data, errors and outliers
• network design and adaptive observations
• statistical models to reconstruct past climates

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Data Assimilation

• State
• Observation
• Solution
• Assumptions, approximations and choice of

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Forecast Calibration
climate model
Caio Coelho Sergio Pezzulli
Prior climate-model forecast Likelihood
regression model
combined
regression model
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Forecast Verification
Barbara Casati
false wet false dry
Wavelet decomposition identifies contributions to
the forecast performance measure from different
spatial scales.
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Other Topics

• Multivariate methods
• Stochastic models
• Statistical models

• identify climate modes
• investigate climate dynamics
• attribute climate change
• downscale simulated data

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Conclusions

• Huge amount of complex data produced
• Frustrated by inadequate statistical methods
• Sophisticated techniques required
• Collaboration and education

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Further Information

• Climate Analysis Group
• Data Assimilation
• Research Centre
• PRUDENCE
• 9th International Meeting on Statistical
  Climatology, Cape Town, May 2004

• www.met.rdg.ac.uk/cag
• www.darc.nerc.ac.uk
• www.dmi.dk/fu/klima/prudence
• www.csag.uct.ac.za/IMSC