Chapter 5 - The Case of Hurricanes vs African Dust

Abstract

One of the most powerful tools of signal theory is the so-called wavelet-coherence transform spectral analysis . Using this tool we determine the most prominent signals between North Atlantic hurricanes of all categories, as well as involved terrestrial phenomena: SST, AMO, AD (African dust), and geoexternal phenomena such as solar activity (SS), geomagnetic activities (K p ), and GCR (galactic cosmic rays). Results indicate that among the most prominent common signals for hurricanes, SST, AMO, and GCR are those of period of 30 ± 2 years. The high level of coherence between GCR and hurricanes indicates a stronger modulation effect by GCR, probably on the basis of the mechanisms described by Ram et al. (2009). For the case of SS, the most intense signals remain at the 11 and 22 years frequencies. For AD, the time interval data is relatively short (since 1966), nevertheless, several well-defined signals are found with hurricanes of different categories in the range 0.25 to 13 years. A clear anti-correlation is found between Categories 5, 4, and 3 hurricanes with AD. While the most prominent periodicity for hurricanes of Category 4 or less is 1 year, for Category 5 hurricanes there are well-defined periodicities at 8 and 10 years. These allow for forecasting of Category 5 hurricanes. In preliminary form we can argue that the next one will occur 2014. Also, it is determined for the first time, that hurricanes of Category 4 are able to evolve, or not, into Category 5 depending on whether or not their trajectory crosses the geographic areas of deep waters (10 °W–20 °W latitude).