Apr 4, 2007

Environmental Factors Affecting Tropical Cyclone Power Dissipation

Kerry Emanuel
American Meteorological Society
  • Presents revised estimates of kinetic energy production by tropical cyclones in the Atlantic and western North Pacific are presented
  • These show considerable variability on interannual-to-multidecadal time scales
  • Finds that, in the Atlantic, variability on time scales of a few years and more is strongly correlated with tropical Atlantic sea surface temperature, while in the western North Pacific, this correlation, while still present, is considerably weaker
  • Uses a combination of basic theory and empirical statistical analysis to show that much of the variability in both ocean basins can be explained by variations in potential intensity, low-level vorticity, and vertical wind shear
  • Finds that potential intensity variations are in turn factored into components related to variations in net surface radiation, thermodynamic efficiency, and average surface wind speed
  • Finds that, in the Atlantic, potential intensity, low-level vorticity, and vertical wind shear strongly covary and are also highly correlated with sea surface temperature, at least during the period in which reanalysis products are considered reliable
  • Finds that, in the Pacific, the three factors are not strongly correlated
  • Quantifies the relative contributions of the three factors