Relationship between ITCZ position and tropical cyclone genesis in observations

Previous studies have shown that the climatological variability of TC frequency could be regulated by the ITCZ location in idealized models, and the Coriolis parameter is an important determinant. As ITCZ moves poleward, the increased Coriolis parameter and cyclonic absolute vorticity will favor more TC genesis. Using observations, the relationship between the ITCZ position and the TC frequency, as well as the ENSO influence, have been examined in this study on interannual timescale over different ocean basins. The result shows the expected linkage between the ITCZ position and TC frequency. The correlation coefficient is significant over North Atlantic (NA), Western North Pacific (WNP) and Northern Hemisphere (NH) both before and after removing the ENSO influences. The TC genesis location follows the ITCZ migration in almost all basins except that in NA, but further analysis shows the relationship in the tropical NA (south of 20˚N) agrees with that in other basins. Both ITCZ and TC activities could be affected by ENSO on interannual timescale since they are all related to tropical SST (sea surface temperature) spatial distributions. There is a better relationship between ITCZ position and TC genesis location than TC frequency over basins in South Hemisphere.