The role of Atlantic overturning circulation in the recent decline of Atlantic major hurricane frequency

Abstract

Observed Atlantic major hurricane frequency has exhibited pronounced multidecadal variability since the 1940s. However, the cause of this variability is debated. Using observations and a coupled earth system model (GFDL-ESM2G), here we show that the decline of the Atlantic major hurricane frequency during 2005–2015 is associated with a weakening of the Atlantic Meridional Overturning Circulation (AMOC) inferred from ocean observations. Directly observed North Atlantic sulfate aerosol optical depth has not increased (but shows a modest decline) over this period, suggesting the decline of the Atlantic major hurricane frequency during 2005–2015 is not likely due to recent changes in anthropogenic sulfate aerosols. Instead, we find coherent multidecadal variations involving the inferred AMOC and Atlantic major hurricane frequency, along with indices of Atlantic Multidecadal Variability and inverted vertical wind shear. Our results provide evidence for an important role of the AMOC in the recent decline of Atlantic major hurricane frequency.

A Multivariate AMV Index and Associated Discrepancies Between Observed and CMIP5 Externally Forced AMV

“…For both detrending methods, the observed AMOC fingerprint exhibits a similar dipole pattern with opposite signs in the SPNA and the Gulf Stream region (Figures a and e) and similar multidecadal variations (Figures b and f), as found in previous studies (Joyce & Zhang, ; Yan et al, , ; Zhang, , ; Zhang & Zhang, ). The low‐pass filtered observed AMOC fingerprint (Figures b and f) has significant ( p < 0.05) positive correlations with various observed AMV‐related indices (Figures a–e and k–o) and the observed MAI (Figures e and e), for both detrending methods.…”

A Review of the Role of the Atlantic Meridional Overturning Circulation in Atlantic Multidecadal Variability and Associated Climate Impacts

“…The directly observed AMOC at 26°N from the RAPID program exhibits a significant downward shift over the recent decade since 2004, which has been widely interpreted as arising from intrinsic decadal/multidecadal AMOC variability and a reversal from the previous AMOC strengthening (e.g., Jackson et al, ; Robson, Hodson, et al, ; Robson et al, ; Smeed et al, , ; Yan et al, , ). The total reduction of the directly observed AMOC at 26°N between 2004–2009 and 2009–2014 is 2.9 Sv and is statistically significant (Frajka‐Williams et al, ).…”

“…Reviews of Geophysics Robson et al, 2016;Smeed et al, 2018;Yan et al, 2017). In a recent study, the high correlation between the observed AMV index (based on linearly detrended basin-averaged low-pass-filtered North Atlantic SST anomalies) and the simulated ensemble mean AMV index from a large ensemble of twentieth-century…”

Impacts of Extratropical Weather Perturbations on Tropical Cyclone Activity: Idealized Sensitivity Experiments With a Regional Atmospheric Model

“…These phenomena include synopticscale tropical waves (e.g., Thorncroft & Hodges, 2001), tropical intraseasonal variability (e.g., Maloney & Hartmann, 2000), interannual sea surface temperature (SST) variability (Chen & Lin, 2011), and Atlantic multidecadal variability involving the Atlantic meridional overturning circulation (e.g., Goldenberg et al, 2001;Gray, 1984;Yan et al, 2017). These phenomena include synopticscale tropical waves (e.g., Thorncroft & Hodges, 2001), tropical intraseasonal variability (e.g., Maloney & Hartmann, 2000), interannual sea surface temperature (SST) variability (Chen & Lin, 2011), and Atlantic multidecadal variability involving the Atlantic meridional overturning circulation (e.g., Goldenberg et al, 2001;Gray, 1984;Yan et al, 2017).…”