根据全球热带气旋频率的统计,这些频率有明显的年际变化。在过去二十年中全球热带气旋数年变化的百分率为其平均数的-13％一+23％,最多和最少年热带气旋数差达28个,相当于全球年平均热带气旋数(79)的35％。目前认为有三个原因可能影响热带气旋频率:大尺度环流,海面温度和地球以外的因子。 According to statistics of global tropical cyclone frequencies, these frequencies have obvious interannual variations. The percentage change of the global tropical cyclone over the past two decades over several years has been between -13% and + 23% of its average value, with a difference of at most 28 years from the minimum annual tropical cyclone, equivalent to the global annual average number of tropical cyclones (79) Of 35%. There are currently three reasons why tropical cyclone frequencies may be affected: large-scale circulation, sea surface temperature and factors beyond Earth.