Wet and Dry Periods in Regions Surrounding the Atlantic Ocean Basin

DRUMOND A.; RODRIGUEZ-FONSECA B.; REASON C.; SILVINA A SOLMAN

Frontiers in environmental science

Lausanne : Frontiers Media S.A., 2013

Año: 2016 vol. 4

The Atlantic Ocean is the second-largest of the world?s oceanic divisions. It is bounded by the continents of America, Europe, and Africa and at its polewards margins by the Arctic and the Southern Oceans. Different climatic patterns can be observed along its large latitudinal domain, which extends from the equator to sub-polar regions. Thus, different tropical and extra-tropical meteorological systems may have some influence on the characterization of precipitation regimes observed surrounding the basin, such as the Intertropical Convergence Zone (ITCZ), tropical monsoon systems, westerly storm tracks, and atmospheric rivers. The subtropical regions of the Azores and South Atlantic high pressure systems are large evaporative areas which act as important moisture sources for the adjacent continents. Variations in the oceanic characteristics may influence the moisture transport toward the neighboring landmasses and alter the precipitation. The influence of climatic variability modes manifest not only over the Atlantic Ocean, but also over other oceanic regions, may also interact with the regional hydrological budget, thereby generating long periods of drought, or excessive precipitation over the Atlantic rim landmasses.This Research Topic intends to highlight the advances of the scientific community in investigating the continental precipitation surrounding the Atlantic Ocean and its variability on various temporal and spatial scales. Out of the 10 works published, three of them are focused on the Northeastern Brazil (NE), a region prone to social-economical problems associated with arid climatic conditions and one of the tropical areas with the largest interannual variability in rainfall (de Albuquerque Cavalcanti). Although the linear component of the inter-annual variability may be modulated by the Equatorial Eastern Pacific and tropical South Atlantic sea surface temperature (SST) variability and the associated modifications in the Hadley and Walker cells, the non-linear signal may be influenced by others oceanic regions (da Silva and Mendes). For example, the composite analysis of de Albuquerque Cavalcanti revealed extratropical atmospheric influences of the North and South Atlantic in the pre-rainy season of NE. The non-stationary influence of the Atlantic and Pacific Niños on North Eastern South American rainfall in the twentieth century was investigated by the numerical study of Torralba et al. The authors found that while the Atlantic El Niño was of influence at the beginning of the last century, the Pacific El Niño plays a major role from 1970 onwards. However, the combined effect of both basins after the 1970s amplifies the anomalous rainfall response in the NE. The importance of considering the non-linear processes for a more accurate local precipitation forecast was verified by da Silva and Mendes, who suggested the use of an Artificial Neural Network as a complementary forecast tool for improving the simulation of the daily precipitation over NE during the rainy season by general circulation models.