The influence of the Atlantic Meridional Mode on the frequency, duration, and intensity of tropical North Atlantic cyclones

Abstract

This paper describes the Atlantic Meridional Mode (AMM) and its influence on tropical storm activity in the North Atlantic Basin. The Atlantic Meridional Mode is the oscillating sea- surface temperature (SST) gradient anomaly between the Northern Hemisphere (NH) and Southern Hemisphere (SH) portions of the Tropical Atlantic Ocean (TAO). Synthetic data generated from computer simulations as well as actual reanalysis data from North Atlantic Basin tropical storms was examined. A moderate correlation exists between increased (decreased) North Atlantic tropical storm activity and the high (low) phase of the AMM. The AMM correlates more strongly with the duration and intensity of tropical storms than the frequency. Increased understanding about the AMM and its affects on tropical storm activity will lead to improved forecasting of tropical systems, which affect many human lives each year.