Oceanic and atmospheric modes in the Pacific and Atlantic Oceans since the Little Ice Age (LIA): Towards a synthesis

Abstract

Understanding the variability of the oceanic and atmospheric modes from the Little Ice Age (LIA, ∼1250–1850) to the present can help evaluate their behaviors under future warming scenarios. Numerous proxy-based reconstructions of the oceanic and atmospheric modes were presented. It is highly needed for a synthesis study to evaluate the existing reconstructions of the dominant oceanic and atmospheric modes since the LIA. We found that the El Niño-Southern Oscillation (ENSO) reconstructions are only robust on interannual and interdecadal scales, while the reconstructed Pacific Decadal Oscillation (PDO) and Atlantic Multi-decadal Oscillation (AMO) are robust on multi-decadal (50–100 years) timescales. We generated synthesized ENSO, PDO and AMO reconstructions as the average of the existing reconstructions on the most suitable timescales identified using timescale dependent correlation methods. In the 20th century, the interannual variability and periodicity of the ENSO and the multi-decadal periodicity of the PDO and AMO were most pronounced. The ENSO shows the strongest multi-decadal periodicity from mid-18th century onwards, while the multi-decadal periodicity of the PDO and AMO was particularly low in the 18th century. Multi-decadal variations of the AMO showed a prompt and positive response to solar irradiation, while the ENSO showed a lagged and negative response to solar irradiation from the 18th century to the present.