James B. Elsner

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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 Emanuels 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. 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
North Atlantic
southern Indian
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South Pacific
northern Indian
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Regression of satellite-derived lifetime maximum
wind speed onto global SST
Regression of best-track lifetime maximum wind
speed onto global SST
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GFDL Model Data
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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?
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Percentiles Cyan 99th Blue 95th Green
90th Red 75th Black 50th
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• 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.

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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.
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Summary
The strongest tropical cyclones worldwide are
getting stronger. The increase in intensity is
consistent with Emanuels 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
• jelsner_at_fsu.edu

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