Lawrence Berkeley National Laboratory

The El Niño–Southern Oscillation (ENSO) is a major source of seasonal tropical cyclone (TC) predictability in both local and remote ocean basins. Unusually warm eastern-central equatorial Pacific sea surface temperature (SST) during El Niño tends to enhance eastern and central North Pacific (ECNP) TCs and suppress Atlantic TCs. Here we demonstrate that Atlantic SST variability likewise influences remote TC activity in the eastern-central Pacific through a Walker Circulation-type response analogous to the ENSO-Atlantic TC teleconnection, using observations and 27 km resolution tropical channel model (TCM) simulations. Observed and simulated ECNP TC activity is reduced during the positive Atlantic Meridional Mode (AMM), which is characterized by warm northern and cool southern tropical Atlantic SST anomalies, and vice versa during the negative AMM. Large ensembles of TCM simulations indicate that SST variability, rather than internal atmospheric variability, drives extreme ECNP hurricane seasons.