Intraseasonal Teleconnections between South America and South Africa

Abstract

Teleconnection of climate anomalies between various parts of the tropics and extratropics is a well-established feature of the climate system. Building on previous work showing that a teleconnection exists between the South American monsoon system and interannual summer rainfall variability over southern Africa, this study considers intraseasonal variability over these landmasses. It is shown that strong teleconnections exist between South African daily rainfall and that over various areas of South America, with the latter leading by 4-5 days, for both winter and summer, involving regions with strong rainfall in these seasons. During the summer, the mechanisms involve both a modulation of the local Walker cell as well as extratropical Rossby wave trains. For winter, the latter mechanism is more important. While in summer tropical convective anomalies over South America play an important role, in winter the subtropics become more important. In both cases, these modulations lead to regional changes in circulation over southern Africa that are favorable for the dominant synoptic rainfall-producing weather systems such as cutoff lows and tropical extratropical cloud bands.