Authors
Antonietta Capotondi (CIRES,NOAA/PSL), Yingying Zhao (Laoshan Laboratory Qingdao, China)

Abstract

Variability in the tropical Pacific at both interannual and decadal timescales can exert a large influence on the global climate. In particular, the pattern of sea surface temperature (SST) anomalies in the Tropical Pacific has been shown to affect the Earth’s energy balance and the rate of change of the globally averaged SSTs, highlighting the importance of understanding the processes responsible for those anomalies. While many of these processes arise within the Pacific basin, other ocean basins may significantly contribute to tropical Pacific variability. For example, the cooling trend in the eastern equatorial Pacific after year 2000 has been related to the influence of tropical Atlantic warming. However, due to the coupled nature of tropical basin interactions, clearly assessing the contribution of other basins to Pacific variability is challenging in the context of climate models simulations, where SSTs in one basin are typically restored to observed values to assess their impact on other basins, effectively capturing only one way of the two-ways interactions among tropical basins. As a complementary approach, here we use a linear Inverse Model (LIM), an empirical model trained on observations, to examine the Atlantic Ocean influence on the tropical Pacific. A LIM allows to cleanly discriminate between Atlantic influences on the Pacific due to internal Atlantic variability and those induced in the Atlantic by Pacific feedbacks. Results show that the Atlantic-Pacific interactions significantly contribute to interannual variability in the eastern equatorial Pacific, but they damp tropical Pacific decadal variability if Pacific feedbacks on the Atlantic are enabled.