Abstract
Atmospheric moisture transport plays an important role in the genesis of tropical cyclones (TCs). In this study, the moisture sources associated with the genesis of TCs in the tropical Atlantic Ocean near West Africa, from June to November in the period 1980–2018, were identified. To detect the location of the TCs geneses, the HURDAT2 database from the National Hurricane Center was used. Additionally, global outputs of the Lagrangian FLEXPART model were used to determine the moisture sources that provided water vapor for the genesis of TCs. This model permitted us to track backward in time the air masses from the genesis region of the TCs and identify regions where air masses uptake moisture before reach the target regions. The results reveal that 18.1% (108 TC) of the total number of TCs that formed in the North Atlantic basin were originated in the region of study. The largest frequency for the TCs geneses was observed in August and September, with each one representing approximately 45% of the total. The transport of moisture associated with the genesis of TCs mainly comes from the east of the North and South Atlantic Ocean, as well as from West Africa and the Sahel region. The patterns of moisture uptake confirmed an interhemispheric moisture transport. Finally, during the El Niño, the moisture uptake is more intense over the Atlantic Ocean close to West Africa around 15 °N of latitude, while during La Niña, the pattern is slightly weaker but covers a wider area over the Atlantic Ocean and the north of Africa.
Highlights
Tropical cyclones (TCs) are the atmospheric phenomena most likely to cause natural disasters [1]
These are the central and eastern tropical North Atlantic Ocean, extending to the north along the African coast, the eastern South Atlantic Ocean, WA, and the Sahel. These two terrestrial sources (WA and Sahel) involve complex hydroclimatic interactions in several atmospheric processes on different time scales such as the low-level atmospheric moisture transport and the West African Monsoon [20,21,22]. Considering these previous findings, in this study, we aim to identify the moisture sources for TCs formed in the eastern tropical Atlantic Ocean near the coast of WA, and assess the role of the El Niño Southern Oscillation (ENSO) on the genesis of TCs at the Environ
By applying the K-means cluster analysis, through the silhouette coefficient, seven regions of TCs genesis were determined in the North Atlantic (NATL) basin, in agreement with results obtained by Corporal-Lodangco et al [33]
Summary
Tropical cyclones (TCs) are the atmospheric phenomena most likely to cause natural disasters [1] These systems form over warm regions in tropical oceans and strengthen when environmental conditions are favorable [2]. Showed that for TC formation, the sea surface temperature (SST) must be higher than 26 °C, while Riehl [5] suggested that the vertical shear of the horizontal wind is an environmental factor that inhibits the genesis of TCs. During the cyclonic season in the North Atlantic (NATL) basin from June to November, many disturbances travel over tropical oceans in each cyclogenetic basin; very few become TCs. During the cyclonic season in the North Atlantic (NATL) basin from June to November, many disturbances travel over tropical oceans in each cyclogenetic basin; very few become TCs This occurs because some preconditions defined by Gray [6] for TC genesis do not occur simultaneously [7]. According to Gray [6], for the formation of a TC, the SST must be higher than 26.5 °C at an ocean depth of approximately 50 m [7], there must be sufficient atmospheric instability that favors the thunderstorms formation for the release of latent heat, there must be a high content of water vapor in layers of the middle atmosphere, and there must be an atmospheric disturbance generally above 5 degrees of latitude (north or south), which obtains from the Earth’s spin a background rotation that can later be amplified, and there must be low vertical wind shear from the surface to the tropopause
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