Transcript James B. Elsner Department of Geography, Florida State

Quantile and Poisson Regression
Models in Hurricane Studies
January 11, 2009
Phoenix, AZ
 Trends in lifetime maximum intensity
 Solar activity and near-coastal hurricane activity
James B. Elsner
Department of Geography, Florida State University
Climatek, Inc.
Acknowledgments: Thomas H. Jagger, Jim Kossin; Funding: NSF, RPI
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Take-Home Points
The strongest tropical cyclones worldwide are getting stronger.
The increase in intensity is consistent with Emanuel’s heatengine theory of tropical cyclone intensity.
There is a detectable solar signal in U.S. hurricane activity due to
increases in tropical cyclone intensity when the sun is “cooler”.
This finding is also in accord with the heat-engine theory.
The R program for statistical computing is arguably the best way
to analyze and model climate data.
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western North Pacific
eastern North Pacific
southern Indian
North Atlantic
South Pacific
northern Indian
Regression of satellite-derived
lifetime maximum wind speed
onto global SST
Regression of best-track
lifetime maximum wind
speed onto global SST
GFDL Model Data
Together the three covariates explain between 40 and
48% of the variation in tropical cyclone counts
depending on start year.
But, what is left over?
Percentiles
Cyan: 99th
Blue: 95th
Green: 90th
Red: 75th
Black: 50th
According to Bister & Emanuel (1998), the potential velocity of a
hurricane is proportional to the SST and inversely proportional
to the temperature above the hurricane.
Thus during a period of inactive sun, the upper atmosphere is
cooler increasing the potential hurricane intensity. But this is
only over regions of sufficiently warm SST (high oceanic heat
content) like the Caribbean and western tropical Atlantic. Over
regions of marginal oceanic heat content (eastern tropical
Atlantic), SST is the limiting factor for hurricane intensity.
Aug-Oct avg air T vs Aug-Oct SSN count. P is the pressure level with lower values indicating
higher elevations. Positive correlation (r) indicates cooler air with fewer SSN.
Summary
The strongest tropical cyclones worldwide are getting stronger.
The increase in intensity is consistent with Emanuel’s heat-engine
theory of tropical cyclone intensity.
There is a detectable solar signal in U.S. hurricane activity due to
increases in tropical cyclone intensity when the sun is “cooler”.
This finding is also in accord with the heat-engine theory.
Next: Use R for Climate Research
Download and open the tutorial, then get some lunch!
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More Information
• Google hurricane climate
• http://myweb.fsu.edu/jelsner
• [email protected]
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