Assessment of the oceanic channel dynamics responsible for the IOD-ENSO precursory teleconnection in CMIP5 climate models

Abstract

Existed studies have suggested a precursory relation between Indian Ocean Dipole (IOD) and El Niño and the Southern Oscillations (ENSO) with 1-year time lag. The underlying mechanisms were attributed to atmospheric bridge and/or oceanic channel processes. In this study, the oceanic channel dynamics in 23 climate models of the Coupled Model Intercomparison Project phase 5 (CMIP5) are assessed by correlation analyses in comparison with observations. The results show that the lag correlations between the IOD and ENSO anomalies associated with oceanic channel are significant, suggesting important role of oceanic channel dynamics in the cross-basin teleconnection in the analyzed CMIP5 models, consistent with observational analyses. In comparison, the correlations associated with atmospheric bridge are highly dispersive among the models and generally inconsistent with the observational analyses, suggesting model deficiencies. In a single climate model, the lag correlations associated with oceanic channel dynamics are consistent among different ensemble experiments, whereas those associated with atmospheric bridge processes are dispersive.

Sea level anomalies in the southeastern tropical Indian Ocean as a potential predictor of La Niña beyond one-year lead

“…Existing studies have focused on atmospheric teleconnection via the Walker circulation (Kug and Kang, 2006;Izumo et al, 2010;Ha et al, 2017). Other studies suggest that the "oceanic channel" of the Indonesian Throughflow (ITF) may provide an important connection between the Indian and Pacific Ocean climate variabilities (Yuan et al, 2011;Yuan et al, 2013;Mayer et al, 2018;Yuan et al, 2018;Wang et al, 2022;Xu et al, 2022;Yuan et al, 2022). The cold tongue SSTA were found to correlate significantly with sea level anomalies (SLA) in the southeastern tropical Indian Ocean (SETIO), the eastern pole of the IOD, one year before.…”