Long‐term variability of the East African ‘short rains’ and its links to large‐scale factors

摘要: This study utilizes a new 139-year rainfall record for East Africa to evaluate the relationship between ‘short rains’ of October–November and four tropical indices. These indices include zonal winds at surface 200 mb over central equatorial Indian Ocean, Nino 3.4 Ocean Zonal Mode (IOZM). The relationships with these are time dependent, as among change markedly on decadal timescale, consistent regime changes indicated by other authors, links El Nino-Southern Oscillation (ENSO) IOZM appear be weaker than those suggested previous studies. show strongest most rainfall. However, very different wet dry years, play stronger role in producing conditions. Further, several factors act tandem produce extremely but largely independently drought. drought have been since 1982. were also weak roughly 1920 1960, when apparently Walker cell was Pacific particularly strong. At that time, ENSO appeared drive variability rainfall, interannual weak, below average during period. When circulation sector became well-developed c. 1961 weakened, both its increased. Overall, this stresses dependence various African has strong implications seasonal forecasting.