Where Does the Moisture for North Atlantic Tropical Cyclones Come From?

In this study, we identified the origin of the moisture associated with the tropical cyclones' (TCs) precipitation in the North Atlantic Ocean basin during their three well-differentiated life stages between 1980 and 2018. The HURDAT2 database was used to detect the location of 598 TCs during their genesis, maximum intensification peak, and dissipation phases. The global outputs of the Lagrangian FLEXPART model were then used to determine the moisture sources. Using a k-means cluster analysis technique, seven different regions were identified as the most common locations for the genesis and maximum intensity of the TC phases, while six regions were found for the dissipation points. Our results showed that the origin of moisture precipitating was not entirely local over the areas of TC occurrence. The North Atlantic Ocean to the north of the intertropical convergence zone at 10 degrees N (NATL)-especially from tropical latitudes, the Caribbean Sea, and the Gulf of Mexico-provides most of the moisture for TCs (similar to 87%). The Atlantic Ocean basin southward of the ITCZ (SATL) played a nonnegligible role (similar to 11%), with its contribution being most pronounced during the TC genesis phase, while the eastern tropical Pacific Ocean made the smallest contribution (similar to 2%). The moisture supported by TCs varied depending on their category, being higher for hurricanes than for major hurricanes or tropical storms. Additionally, the approach permitted the estimation of the mean residence time of the water vapor uptake that produces the precipitation during TC activity, which ranged between 2.6 and 2.9 days. Significance StatementAtmospheric moisture transport plays an important role in the genesis and intensification of tropical cyclones (TCs). In this study, we investigated the moisture source for the genesis, intensification, and dissipation of TCs in the North Atlantic Ocean basin using a Lagrangian approach. This model allowed us to track air masses backward in time from the target area to identify regions where air masses experienced an uptake of moisture prior to reaching the area of interest. The sources were identified individually for each TC, and the results were then combined to provide a broad general picture with some surprising outstanding results, such as the role of the North and South Atlantic and the eastern tropical Pacific as important moisture sources during the different TCs phases and intensities.

Automated summary

This study investigates the moisture source for the genesis, intensification, and dissipation of tropical cyclones (TCs) in the North Atlantic Ocean basin using a Lagrangian approach. Results show that the North Atlantic Ocean to the north of the intertropical convergence zone is the main source of moisture for TCs, followed by the South Atlantic and the eastern tropical Pacific. The moisture carried by TCs varies depending on their category.