Contrasting Algorithm Dependence of Extratropical Cyclone and Bomb Cyclone Statistics over the North Pacific

Bomb cyclones are high-impact extratropical cyclones characterized by rapid deepening. Although their climatology and long-term changes over the North Pacific (NP) have attracted considerable attention recently, it remains unclear whether bomb cyclone statistics are robust across different cyclone tracking algorithms. This study compares NP extratropical cyclone and bomb cyclone statistics derived from two widely used tracking algorithms based on relative vorticity and mean sea-level pressure (MSLP), respectively, using reanalysis data from 1980 to 2017. Results show that extratropical cyclone statistics are highly sensitive to the choice of tracking algorithms. The vorticity-based method identifies much more weak cyclones than the MSLP-based method. In contrast, bomb cyclone statistics are remarkably robust. The two algorithms show strong agreement in the event frequency, interannual variability, spatial distribution, and intensity of bomb cyclones. These findings indicate that bomb cyclones, as the most intense subset of extratropical cyclones, are less sensitive to tracking algorithms. This conclusion increases confidence in previous and future studies of bomb cyclone variability and changes.