Open AccessThe Impact of the El Niño–Southern Oscillation and Atlantic Meridional Mode on Seasonal Atlantic Tropical Cyclone Activity
Author(s) -
Christina M. Patricola,
R. Saravanan,
Ping Chang
Publication year - 2014
Publication title -
journal of climate
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.315
H-Index - 287
eISSN - 1520-0442
pISSN - 0894-8755
DOI - 10.1175/jcli-d-13-00687.1
Subject(s) - climatology , tropical atlantic , sea surface temperature , tropical cyclone , atlantic equatorial mode , zonal and meridional , tropical cyclogenesis , atlantic multidecadal oscillation , el niño southern oscillation , atlantic hurricane , environmental science , multivariate enso index , african easterly jet , forcing (mathematics) , north atlantic oscillation , geology , oceanography , la niña , cyclone (programming language) , tropical wave , field programmable gate array , computer science , computer hardware
Atlantic tropical cyclone (TC) activity is influenced by interannual tropical Pacific sea surface temperature (SST) variability characterized by the El Niño–Southern Oscillation (ENSO), as well as interannual-to-decadal variability in the interhemispheric gradient in tropical Atlantic SST characterized by the Atlantic meridional mode (AMM). Individually, the negative AMM phase (cool northern and warm southern tropical Atlantic SST anomalies) and El Niño each inhibit Atlantic TCs, and vice versa. The impact of concurrent strong phases of the ENSO and AMM on Atlantic TC activity is investigated. The response of the atmospheric environment relevant for TCs is evaluated with a genesis potential index. Composites of observed accumulated cyclone energy (ACE) suggest that ENSO and AMM can amplify or dampen the influence of one another on Atlantic TCs. To support the observational analysis, numerical simulations are performed using a 27-km resolution regional climate model. The control simulation uses observed SST and lateral boundary conditions (LBCs) of 1980–2000, and perturbed experiments are forced with ENSO phases through LBCs and eastern tropical Pacific SST and AMM phases through Atlantic SST. Simultaneous strong El Niño and strongly positive AMM, as well as strong concurrent La Niña and negative AMM, produce near-average Atlantic ACE suggesting compensation between the two influences, consistent with the observational analysis. Strong La Niña and strongly positive AMM together produce extremely intense Atlantic TC activity, supported largely by above average midtropospheric humidity, while strong El Niño and negative AMM together are not necessary conditions for significantly reduced Atlantic tropical cyclone activity.