Abstract
Globally, subtropical circulation in the lower troposphere is characterized by anticyclones over the oceans. Subtropical anticyclones locate over subtropical belts, modulating weather and climate patterns in those regions. The Mascarene High is an anticyclone located over the Southern Indian Ocean and has a vital role in weather and climate variability over Southern Africa. The warm Western Indian Ocean is a major source of moisture for the subcontinent also permitting tropical cyclone genesis. In this study, we review the dynamics of the Mascarene High, its interactions with the ocean, and its impact on weather and climate over Southern Africa. We also review studies on the evolution of subtropical anticyclones in a future warmer climate. The links between SST modes over the Indian Ocean and the strengthening and weakening of the Mascarene High have been demonstrated. One important aspect is atmospheric blocking due to the Mascarene High, which leads to anomalous rainfall and temperature events over the subcontinent. Blocking leads to landfall of tropical cyclones and slow propagation of cut-off lows resulting in severe weather and flooding over the subcontinent. Understanding how expansion of the Mascarene High due to warming will alter trade winds and storm tracks and change the mean climate of Southern Africa is crucial.
Highlights
Subtropical anticyclones are semi-permanent synoptic-scale weather systems that influence weather and climate over the subtropical regions around the world
Most studies have dealt with subtropical anticyclones collectively, but this study focuses on the Mascarene High and will provide a starting point for future studies with a focus on the regional climate
A systematic review approach [15] employed in this paper identifies and synthesizes research knowledge from individual studies based on subtropical anticyclones and circulations over Southern
Summary
Subtropical anticyclones are semi-permanent synoptic-scale weather systems that influence weather and climate over the subtropical regions around the world. Cooling in Eurasia in the same season, gives strengthening to the Siberian High [8] In these regions, large-scale subsidence is balanced with strong large-scale low-level divergence at the surface [9], playing an important role in modulating global weather and climate [10]. Low. Tropical cyclones that develop over the Southwest Indian Ocean every summer are steered by the Mascarene High sometimes towards the interior of Southern Africa. Severe weather events such as floods and extreme cold during cut-off low pressure events are linked to atmospheric blocking caused by the Mascarene High [14].
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