J. Clim.http://doi.org/mjh (2013)
Large-scale modes of climate variability such as the El Niño/Southern Oscillation influence the frequency of tropical cyclones. A statistical analysis of tropical cyclone data suggests that, in the North Central Pacific, the Madden–Julian Oscillation is also a key driver of tropical cyclone intensification.
Philip Klotzbach, of Colorado State University, and Eric Blake, of the National Hurricane Center, used reanalysis and observational data collected between 1974 and 2010 to identify the oceanic and atmospheric conditions associated with tropical cyclone activity in the North Central Pacific. As expected, tropical cyclone frequency was greater during El Niño years. Cyclone frequency was also enhanced when the wet phase of the Madden–Julian Oscillation occurred over the eastern and central tropical Pacific, which they attribute to a concomitant reduction in vertical wind shear. At the same time, the likelihood of rapid intensification was also enhanced, such that the wet phase of the Madden–Julian Oscillation was responsible for the majority of tropical cycles that intensified rapidly over the measurement period.
Consideration of both El Niño and Madden–Julian Oscillation dynamics could improve sub-seasonal forecasts of both the frequency and intensity of tropical cyclones in the Pacific, argue the researchers.