Interannual Variations of the Mid-tropospheric Dry Air and its Impacts on Tropical Cyclone Activity over the Atlantic Basin

The presence of dry air at the midtroposphere in the tropics is well known to affect tropical cyclone formation in all the ocean basins. In the Atlantic basin, the dry air may be associated with the Saharan Air Layer or mid-latitude frontal systems, and their impacts on tropical cyclone formation have been studied in some previous work. The interannual variations of the dry air frequency in the tropical North Atlantic, however, remain unclear. In this study, we examined the interannual variations of dry air frequency over the Atlantic Ocean, its relationship with the large-scale circulation and its impacts on the variability of the Atlantic tropical cyclone activity.