We review the major conceptual models of atmospheric moisture transport, which describe the link between evaporation from the ocean and precipitation over the continents. We begin by summarizing some of the basic aspects of the structure and geographical distribution of the two major mechanisms of atmospheric moisture transport, namely low-level jets (LLJs) and atmospheric rivers (ARs). We then focus on a regional analysis of the role of these mechanisms in extreme precipitation events with particular attention to the intensification (or reduction) of moisture transport and the outcome, in terms of precipitation anomalies and subsequent flooding (drought), and consider changes in the position and occurrence of LLJs and ARs with respect to any associated flooding or drought. We then conclude with a graphical summary of the impacts of precipitation extremes, highlighting the usefulness of this information to hydrologists and policymakers, and describe some future research challenges including the effects of possible changes to ARs and LLJs within the context of future warmer climates.

Extremely dry conditions were experienced across most of southern Africa during the austral summer (October–March) of 2015/2016, associated with one of the strongest observed El Niño events in the Pacific. Dry conditions peaked in the early austral summer months (October–December) producing the most intense drought in the 116‐year historical record, as measured by the intensity of the standardized precipitation index across all spatial scales up to the sub‐continental. We estimate the return period of this extreme early summer drought to be greater than 200 years. The interior and eastern parts of South Africa were particularly hard‐hit with station data showing rainfall totals being at their lowest since at least 1950. The early summer dry conditions make the 2015/2016 event atypical compared to past El Niño events of similar magnitude. We find that key regional circulation patterns, influenced by planetary‐scale processes, play an important role in modulating the spatial and temporal evolution of the summer rainfall during these El Niño events. Specifically, (a) the Angola Low and the South Indian Ocean High, two dominant low‐level circulation features that drive moisture convergence to support convective precipitation in the region, were anomalously weakened in early austral summer of 2015/2016 resulting in less moisture being transported over the continent, and (b) the mid‐level Botswana High was stronger than in previous El Niño years further producing unfavourable conditions for rainfall through stronger subsidence in the mid‐ to upper levels over southern Africa.

The health and functioning of coral reef ecosystems in the Western Indian Ocean are in decline due to anthropogenic stress, and the rate of decline is set to accelerate. Marine reserves have become important tools in mitigating these pressures, and one of the most critical factors in determining their spatial design is the degree of connectivity among populations. However, the spatial scale and strength at which populations are potentially connected by dispersal remain uncertain. In this paper, the potential connectivity of corals was assessed through a Lagrangian particle‐tracking algorithm coupled offline with an ocean circulation numerical model. Connectivity metrics and graph theory were used to analyze the networks and highlight those reefs that are critical for maintaining the connectivity of corals across the region. Western Indian Ocean coral reefs formed about 13 clusters for larvae with short pelagic larval duration (PLD; 5 days) but grouped into stable larger clusters at 15, 30, and 60 days PLDs, with strong westward dispersal from the northern tip of Madagascar and Comoro Islands toward the East African coast. Reefs at Mafia‐Latham Island (Tanzania), Angoche‐Nacala and Pemba‐Mucufi (Mozambique), Anjouan and Ngazidja (Comoros), and Glorieuses (France) were the most significant for multigenerational connectivity, as measured by betweenness centrality. The small islands Agalega and Tromelin were completely disconnected from other sites at all PLDs. These findings identify priority conservation areas and actions to help support coral reef resilience through a connected network of marine protected areas.