Interactions among the Pacific, Atlantic and Indian Oceans through ocean-atmosphere coupling have gained increasing research interest because these interactions can initiate and/or modulate climate variability. For example, North Atlantic sea surface temperature anomalies (SSTAs) could stimulate El Nino–Southern Oscillation (ENSO) events across the tropical Pacific through two pathways—directly through regulating the tropical atmospheric circulation, and indirectly via stimulating the mid-latitude atmospheric teleconnection.
Recently, in a paper published in
Geophysical Research Letters, scientists from the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics of the Institute of Atmospheric Physics at the Chinese Academy of Sciences, in collaboration with the scientists from Sun Yat-sen University, reveal that the Tibetan Plateau (TP), though far from any of the three oceans, plays an important bridging role in the indirect pathway, which has
seldom been considered in previous studies.
Tibetan Plateau in summer (Image taken by YU Wei on August 2022)
Both observations and model simulations suggest that winter–spring positive North Atlantic tripole SSTAs can trigger downstream-propagating Rossby wave train, which leads to atmospheric circulation anomalies over the western TP and central-western Pacific during April and June, favoring the occurrence of subsequent autumn–winter El Nino events.
"When we remove the TP in the climate model, we find the overall responses of atmospheric and oceanic processes associated with El Nino development to the North Atlantic tripole SSTAs are significantly weakened." Said Prof. LIU Yimin, corresponding author of the study. "Quantitatively, the TP's bridging effect accounts for about 38% contribution in these processes."
The TP locates in the subtropical central-eastern Eurasian continent with the westerly flow on its north and easterly flow on its south. "The study provides a new insight in understanding the mid-latitude pathway, since the atmospheric perturbations forced by the SSTAs in the North Atlantic can hardly penetrate the easterly belt and then influence the tropical Pacific." Prof. LIU highlights their study.
Citation: Yu, W., Liu, Y., Zhang, T., et al. 2023. Potential impact of winter–spring North Atlantic tripole SSTAs on the following autumn–winter El Nino–Southern Oscillation: Bridging role of the Tibetan Plateau. Geophysical Research Letters, 50, e2022GL100663. https://doi.org/10.1029/2022GL100663.
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