Shark Team

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Shark Team
Jenny Hodbod Jason Owens Aaron Sidder
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The Question

• Is there a correlation between hurricane strength
  (intensity) and frequency vs. time?

http//www.katrina-hurricane.biz/images/katrina-hu
rricane-pic3.jpg
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Methods

• Analyze the total number of storms per decade
• Analyze the average maximum wind speed per year
  by decade and the maximum wind speed per decade
• Analyze the number of Category 4 5 hurricanes
  per decade

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Chi Squared Tests

• Fo observed data? hurricane data smoothed into
  decadal averages
• Fe expected data? average for the whole data set
• (fo-fe)2/fe
• Sum of the chi squared values
• Compare to the critical chi squared values

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Biases and Data Limitations

• Advances in technology from 1850 (pre-Civil War)
  to 2006
• Limited time frame, no knowledge of historical
  storm data beyond 1850
• 2005 was a crazy year that skewed the data

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Expected and Observed Hurricane Frequencies
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Chi Squared test Frequency

• Null Hypothesis the total number of events is
  not increasing per decade
• Used the average for the entire data set fe 85
  events per decade
• 16 df critical chi squared value at 5 is 26.30
• Chi squared total is 53.02
• Reject null hypothesis

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Chi Squared Frequency cont.
fo fe fo-fe fo-fe2 fo-fe2/fe
1851-1860 60 85 -25 625 7.35
1861-1870 74 85 -11 121 1.42
1871-1880 75 85 -10 100 1.18
1881-1890 82 85 -3 9 0.11
1891-1900 84 85 -1 1 0.01
1901-1910 79 85 -6 36 0.42
1911-1920 54 85 -31 961 11.31
1921-1930 56 85 -29 841 9.89
1931-1940 104 85 19 361 4.25
1941-1950 98 85 13 169 1.99
1951-1960 98 85 13 169 1.99
1961-1970 98 85 13 169 1.99
1971-1980 98 85 13 169 1.99
1981-1990 95 85 10 100 1.18
1991-2000 109 85 24 576 6.78
2001-2006 95 85 10 100 1.18
53.02
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Event Category as a of Total
Biggest increases are in TS, 4 5 Tropical storms
increase (y1.9985x 17.2) Category 1 events show
a slight increase (y 0.3029 16.55) Category 2
events show a decrease (y -0.775x
20.65) Category 3 events show a slight increase
(y 0.1191x 9.425) Category 4 events show an
increase (y0.6162x 0.575) Category 5 events
show an increase (y 0.3456x-1.125)
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Category 45 increase
TS and Category 1 are increasing 23 are
decreasing 45 are increasing
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Frequency of Category 5 Events
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Category 45 increase

• Null hypothesis category 4 5 hurricanes are
  not increasing in frequency
• Fe average number of 45 per decade 8
• Total chi squared value 56.62
• More than the critical chi squared value (26.30)
• Reject the null hypothesis

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Maximum Wind Speeds
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Chi Squared Wind Speed

• Average the maximum wind speed per year by decade
• Average of these 16 speeds 115 mph (fe)
• Null hypothesis no increase in wind speed over
  time
• Sum of the chi squared values 20.02
• Below the critical chi squared value for 16df
  (26.30), therefore accept the null hypothesis

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Chi Squared Wind Speed cont

• Using the maximum wind speed per decade
• Average 142.5 fe
• Sum of chi squared values 29.47
• Reject the null hypothesis at the 5 probability
  level

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Number of Storms Through Time
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(No Transcript)
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Who is this?!
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Trying to Summon Nikola Tesla?
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Number of Storms Through Time
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Troughs and Spikes can clearly be seen
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Cycles drive our dynamic Planet
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Conclusion
Increase in frequency through time?
YES Increase in severity through time?
YES Manifestation of anthropogenic Climate
change? ???
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Manatees and Hurricanes
Source WEST INDIAN MANATEE (Trichechus manatus
latirostris) FLORIDA STOCK U.S. Fish and
Wildlife Service, Jacksonville, Florida
September 2000
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Average of storms by decade as compared to Sea
Surface Temp.
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Average of storms by decade as compared to Sea
Surface Temp.

• Two-way chi squared test
• SST anomaly and Average of storms/yr by decade
• Null Hypothesis no relationship between the two
• Total chi squared value 29.99
• Reject the null hypothesis