ENSO Influence on Atlantic hurricanes via tropospheric warming

Abstract

A new pathway for the negative impact of ENSO on tropical North Atlantic (NAtl) storm activity is examined empirically. Anomalous tropospheric temperatures communicated from the Pacific by wave dynamics are hypothesized to impact storm development by affecting column stability relative to equilibrium with NAtl sea surface temperature (SST). This combines recent teleconnection theory with the role of tropospheric temperature-SST differences in hurricane intensity theory. An equilibrium principle component (EQ PC) in which NAtl SST and tropospheric temperature covary, explains most of their variance. A disequilibrium PC (DEQ PC), measuring column stability relative to SST, correlates highly with hurricane season indices for storm frequency and intensity. The hurricane season (Jun.-Nov.) DEQ PC is closely related to ENSO SST just prior to and within the season, consistent with NAtl SST not having had time to adjust to the teleconnected tropospheric warming from onsetting ENSO events. The EQPC is related to prior winter ENSO SST. Copyright 2004 by the American Geophysical Union.