Influence of Internal Climate System Forcing on the Relationship Between North Atlantic Tropical Cyclones and Saharan Dust.

This study explores the role of internal climate system forcing in the relationship between dust and tropical cyclones (TCs). Here internal climate system forcing includes the Atlantic Multidecadal Oscillation (AMO), Atlantic Meridional Mode (AMM), Sahel rainfall, North Atlantic Oscillation (NAO), and El Niño–Southern Oscillation (ENSO). The dust‐TC relationship is evaluated through statistical analyses of 42‐year (1980–2021) reanalysis and observation data sets for TCs and the Saharan dust plume over the North Atlantic. In August, the negative correlation between dust and TCs in the region east of the Florida Peninsula and north of the Caribbean Sea is inhibited by AMO, AMM, and ENSO and promoted by NAO. In September, the positive correlation between dust and TCs in the eastern US and its adjacent ocean is inhibited by Sahel rainfall and promoted by AMO, AMM, and ENSO. In October, the positive correlation between dust and TCs in the southeastern US is promoted by Sahel rainfall and inhibited by AMO, AMM, and ENSO. The leading climate mode influence on the dust‐TC relationship comes from AMO in August and September, and ENSO in October. The dust‐TC relationship in September and October indicates an increase in TC landfalls over the continental US accompanied by a strengthened Saharan dust plume, which further affects the hydrology of the continental US on an interdecadal timescale by reducing land moisture in September and increasing it in October, as determined by the location of TC landfalls, topography, and the impact of climate mode. Plain Language Summary: The relationship between North Atlantic tropical cyclones (TCs) and the Saharan dust plume is an important scientific question. It is found in this study that the response of TCs to variation in the Saharan dust plume, including changes in TC intensity, track, and genesis, varies monthly during the storm season. As far as the effects of climate change on North Atlantic TCs, Saharan dust is differentiated from internal forcing of the climate system. Therefore the role of internal climate system forcing in the dust‐TC relationship is explored in this study. The largest climate mode influence on the dust‐TC relationship comes from the sea surface temperature over the North Atlantic in August and September, and El Niño–Southern Oscillation in October. On the other hand, the dust‐TC relationship is found to be related to interdecadal variability in the hydrology of the continental US. In September and October, an increase in TC landfalls over the continental US accompanied by a strengthened Saharan dust plume can reduce land moisture in September and increase it in October, depending on the location of TC landfalls, topography, and the impact of climate mode. Key Points: The response of tropical cyclones (TCs) to the Saharan dust plume, including TC intensity, track, and genesis, varies monthly during the storm seasonThe leading climate mode influence on the dust‐TC relationship comes from Atlantic Multidecadal Oscillation in August and September, and El Niño–Southern Oscillation in OctoberThe dust‐TC relationship affects the hydrology of US on an interdecadal timescale, determined by TC landfalls, topography, and climate mode [ABSTRACT FROM AUTHOR]