Hurricane Frequency and Sea Surface Temperature

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Hurricane Frequency and Sea Surface Temperature

• EAS 4803
• Sheliza Bhanjee

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Background

• Hurricane formation is dependent on
• Sea surface temperature
• Vertical wind shear
• Sea level pressure
• Latent heat flux
• Hurricanes can form when sea surface temperatures
  reach 26.5C

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• Over the past 100 years, increase in SST (0.3C)
• Also increase in hurricane frequency and
  intensity
• Category 4 and 5 hurricanes in the past 35 years
  have doubled
• However, technology has also improved
• Better data collection methods

Curry et al., 2005
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Data

• Monthly average Tropical N Atlantic SST data
• Number of hurricanes per month (frequency)
• 1948-2004
• Obtained from NOAA
• Climate Indices Monthly Atmospheric and Ocean
  Time Series
• Regression and time series analysis

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Data
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Correlation and Regression Analysis
Low correlation, noisy data
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Periodograms

• Seasonal variation with hurricane frequency
• Highly variable temperature across years, but
  steady increase (1970s)

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Cross Spectral Analysis

• As years increase, relationship strengthens
• Large dip in correlation around 1953

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Coherence

• Low correlation
• Variable at first, then stabilizes

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Conclusions

• No strong, direct relationship shown across all
  statistical techniques
• Although sea surface temperatures may not
  directly affect hurricane frequency, might have
  indirect effect
• Short data time period- maybe long term SST
  /frequency relationship is better
• Measuring techniques not uniform until recently