Relationship between Antarctic Sea ice and the variability of March to May precipitation in Tanzania

Abstract

AbstractThis study investigates the relationship between the Antarctic sea ice concentration (SIC) and the precipitation variability in Tanzania during March to May (MAM) season from 1978 to 2017. It is found that the MAM SIC over the Weddell (Ross) sea is negatively correlated with the MAM precipitation, particularly over northern (southern) Tanzania, signifying that the high (low) MAM SIC over the Weddell (Ross) sea is associated with suppressed (enhanced) rainfall in Tanzania. The atmospheric circulations related to the MAM SIC anomalies were further analysed. It is revealed that the positive MAM SIC anomalies in the Weddell sea and the Ross sea are associated with the upper‐level wave train patterns propagating from the high latitudes to the low latitudes of the Southern Hemisphere, which results in anomalous upper‐level cyclonic circulation over the western Indian Ocean and Tanzania. The upper‐level cyclonic circulation anomaly favours the low‐level divergence and results in the subsidence over Tanzania. Moreover, the low‐level wind outflow over Tanzania due to divergence reduces the water vapour supply to Tanzania. This background is unfavourable for the occurrence of precipitation and thus decreases the precipitation in Tanzania. The situation is reversed for the negative MAM SIC anomalies over the Weddell sea and the Ross sea, conducive to the increase of precipitation over Tanzania.