Abstract
The El Niño-Southern Oscillation (ENSO), the primary driver of year-to-year global climate variability, is known to influence the North Tropical Atlantic (NTA) sea surface temperature (SST), especially during boreal spring season. Focusing on statistical lead-lag relationships, previous studies have proposed that interannual NTA SST variability can also feed back on ENSO in a predictable manner. However, these studies did not properly account for ENSO’s autocorrelation and the fact that the SST in the Atlantic and Pacific, as well as their interaction are seasonally modulated. This can lead to misinterpretations of causality and the spurious identification of Atlantic precursors for ENSO. Revisiting this issue under consideration of seasonality, time-varying ENSO frequency, and greenhouse warming, we demonstrate that the cross-correlation characteristics between NTA SST and ENSO, are consistent with a one-way Pacific to Atlantic forcing, even though the interpretation of lead-lag relationships may suggest otherwise.
Highlights
The El Niño-Southern Oscillation (ENSO), the primary driver of year-to-year global climate variability, is known to influence the North Tropical Atlantic (NTA) sea surface temperature (SST), especially during boreal spring season
The spring NTA warming appears to contribute to the following La Niña development in the Pacific Ocean (Fig. 1b) with a relatively weak correlation at about 8-month lag
We must emphasize here that an NTA warming in spring following an El Niño will automatically be correlated with La Niña conditions 8 months later, because El Niño conditions are usually followed by La Niña in the following year, without involving a physical NTA-to-ENSO relationship
Summary
The El Niño-Southern Oscillation (ENSO), the primary driver of year-to-year global climate variability, is known to influence the North Tropical Atlantic (NTA) sea surface temperature (SST), especially during boreal spring season. Focusing on statistical lead-lag relationships, previous studies have proposed that interannual NTA SST variability can feed back on ENSO in a predictable manner These studies did not properly account for ENSO’s autocorrelation and the fact that the SST in the Atlantic and Pacific, as well as their interaction are seasonally modulated. NTA SST warming lags the El Niño mature winter phase, peaking in the following spring (Fig. 1a) and persisting into early summer[30] It is caused by El Niño-induced atmospheric forcing that both modulates the Walker Circulation and excites the Pacific-North America teleconnection pattern[31,32,33,34,35]. The proposed mechanism is consistent with ENSO forcing NTA, rather than the opposite
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