Yuanyuan Song

As anthropogenic greenhouse gases increase heat retention in the Earth system, the ocean absorbs nearly 98% of the excess heat. Understanding where and how ocean temperature changes occur is central to assessing impacts on human activities and marine ecosystems. My research focuses on identifying the physical mechanisms that shape patterns of ocean temperature change under atmospheric forcing, and how sea surface temperature anomalies feed back onto atmospheric circulation.

I investigated zonal differences in upper-ocean temperature changes in the Southern Ocean (south of 35°S) from the perspectives of both anthropogenic trends (Song et al., 2025, Nature Communications) and decadal internal variability (Song et al., 2024, Journal of Climate). These studies reveal pronounced zonal contrasts between the Atlantic–Indian Ocean and Pacific sectors, previously overlooked due to prevalent use of zonal-mean diagnostics. Using large ensemble climate models (CESM2, CMIP6), stand-alone ocean modeling, and reanalysis datasets, I demonstrated that surface wind changes dominantly drive zonal temperature contrasts via modulating ocean heat transport, rather than through local surface heat fluxes.

Polar regions are among the most sensitive components of the climate system. Arctic surface temperatures have risen at nearly four times the global mean rate, accompanied by rapid sea-ice decline, while mid-latitude regions experience increasingly frequent and intense extreme weather events. My research seeks to clarify the dynamical connections between Arctic sea-ice decline and mid-latitude and tropical atmospheric circulation.

I found that autumn sea-ice loss north of Russia enhances wintertime atmospheric blocking circulation, leading to cold anomalies over northern Eurasia (Song et al., 2023). The results reveal a positive feedback between sea-ice-induced stratospheric circulation and intensified tropospheric blocking, mediated by vertical wave propagation. I also examined the combined roles of Arctic sea-ice loss and Indian Ocean SST anomalies in driving the record-breaking 2020 rainfall over central–eastern China and Japan (Chen et al., 2021; Chen et al., 2022).

My ongoing and future research integrates state-of-the-art coupled climate models, stand-alone ocean and atmosphere models, Lagrangian ocean analysis, and advanced multivariate statistics. Current projects include understanding temperature changes in mode water source regions and investigating the coupled air-sea interactions that drove and sustained the 2013–2016 North Pacific marine heatwaves.