Abstract
AbstractIt has been suggested that changes in the Atlantic Meridional Overturning Circulation (AMOC) can drive sea surface temperature (SST) on monthly time scales (Duchez et al., 2016, https://doi.org/10.1007/s00382‐015‐2918‐1). However, with only 11 years of continuous observations, the validity of this result over longer, or different, time periods is uncertain. In this study, we use a 120 yearlong control simulation from a high‐resolution climate model to test the robustness of the AMOC fingerprints. The model reproduces the observed AMOC seasonal cycle and its variability, and the observed 5‐month lagged AMOC‐SST fingerprints derived from 11 years of data. However, the AMOC‐SST fingerprints are very sensitive to the particular time period considered. In particular, both the Florida current and the upper mid‐ocean transport produce highly inconsistent fingerprints when using time periods shorter than 30 years. Therefore, several decades of RAPID observations will be necessary to determine the real impact of the AMOC on SSTs at monthly time scales.
Highlights
Anomalies in Atlantic sea surface temperatures (SSTs) have been long thought to drive important climate impacts (Delworth et al, 1993)
The variances of the observed deseasonalized and detrended Atlantic Meridional Overturning Circulation (AMOC) indices are similar to the simulated variances, at both at monthly and interannual time scales (Table S2)
In order to narrow down the SST anomalies that may be driven directly by the AMOC at 26°N we focus on the 5–45°N region
Summary
Anomalies in Atlantic sea surface temperatures (SSTs) have been long thought to drive important climate impacts (Delworth et al, 1993). Changes in the strength of the horizontal gyre circulation and the AMOC are strongly linked to changes in upper ocean temperature, on multiannual to decadal time scales (Häkkinen, 2000; Knight et al, 2005) These coherent patterns of response to the ocean circulation are generally known as fingerprints (Zhang, 2008). A recent study (Duchez et al, 2016; D16) has suggested that there is a statistically significant link between the AMOC at 26°N (as measured by the RAPID array) and SSTs on monthly time scales They argue that changes in the upper mid-ocean component of the AMOC led a dipole of SST anomalies with negative correlations in the tropics and positive correlations in the subtropics at a lead of 5 months.
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