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Hurricane Frequency and Sea Surface Temperature

Hurricane Frequency and Sea Surface Temperature

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Hurricane Frequency and Sea Surface Temperature

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  1. Hurricane Frequency and Sea Surface Temperature EAS 4803 ShelizaBhanjee

  2. 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 26.5°C

  3. Over the past 100 years, increase in SST (~0.3°C) • 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

  4. 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

  5. Data

  6. Correlation and Regression Analysis Low correlation, noisy data

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

  8. Cross Spectral Analysis • As years increase, relationship strengthens • Large dip in correlation around 1953

  9. Coherence • Low correlation • Variable at first, then stabilizes

  10. 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