There are no well accepted mechanisms that can explain the annual frequency of tropical cyclones (TCs) both globally and in individual ocean basins. Recent studies using idealized models showed that the climatological frequency of TC genesis (TCG) is proportional to the Coriolis parameter associated with the intertropical convergence zone (ITCZ) position. In this study, we investigate the effect of the ITCZ position on TCG on the interannual time scale using observations over 1979-2020. Our results show that the TCG frequency is significantly correlated with the ITCZ position in the North Atlantic (NA) and Western North Pacific (WNP), with more TCG events in years when the ITCZ is further poleward. The ITCZ-TCG relationship in NA is dominated by TCG events in the tropics (0-20°N), while the relationship in WNP is due to TCs formed in the east sector (140-180°E). We further confirmed that the ENSO has little effect on the ITCZ-TCG relationship despite it can affects the ITCZ position and TCG frequency separately. In NA and WNP, a poleward shift of ITCZ is significantly associated with large-scale environment changes favoring TCG in the Main Development Region (MDR), However, the basin-wide TCG frequency has a weak relationship with the ITCZ in other ocean basins. We showed that a poleward ITCZ in the Eastern North Pacific and South Pacific favors TCG on the poleward flank of the MDR, whilst it suppresses TCG on the equatorward flank, leading to insignificant change in the basin-wide TCG frequency. In the South Indian Ocean, the ITCZ position has weak effect on TCG frequency due to the mixed influences of environmental conditions.

Wind is defined as the movement of air parcels in a particular direction. The wind speed detected by meteorological instruments increases or decreases suddenly as a result of the different amounts of kinetic energy carried by each air parcel. Peak wind gusts, defined as the maximum based on running mean wind speeds in a short sampling period, are a sudden increase in wind speed caused by air parcels with high kinetic energies (Huschke, 1959). Gusts are closely related to physical parameters such as the mean wind speed, the boundary layer turbulence, the roughness of the underlying surface and the atmospheric stability (Cheng et al., 2012;Letson et al., 2018;Vickery & Skerlj, 2005). Gust records are also affected by instrument characteristics and sample intervals (Holmes & Ginger, 2012).The World Meteorological Organization (WMO) (2018), has specified the mean wind speed as the average wind speed over 10 min and the gust wind speed as the maximum of 3-s running mean wind speed (WMO, Harper