Bio:
Dr. Hongdou Fan completed her Bachelor's degree in Atmospheric Science at Yunnan University, followed by a Master's degree in Meteorology at the Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences. She earned her PhD at the Max Planck Research School on Earth System Modelling (IMPRS-ESM) in Germany. Her recent research focuses on the Atlantic Meridional Overturning Circulation (AMOC), including the dynamics of its downward limb, coherence and variability around Flemish Cap, and the impacts of greenhouse gas forcing via sea surface height fingerprints.
Absract：
In the first part of my talk, I will introduce the roles of the North Atlantic subpolar gyre (SPG) and the North Atlantic Oscillation (NAO) in variability and predictability of upper ocean properties in the Subarctic Atlantic. Although temperature and salinity are both modulated by the SPG and the NAO, they exhibit differently in terms of the governing mechanisms and the corresponding predictability. Salinity as a passive tracer is driven by the ocean dynamics, resulting in high predictability up to 8 years in the Subarctic Atlantic. The upper ocean temperature in the Subarctic Atlantic communicates with atmosphere and is dominated by the NAO especially on the subdecadal time scale, which limits the predictability to 1-2 years. The results highlight the challenge of predicting temperature variability, and the potential to improve predictions via ocean memory.
In the second part of the talk, I will focus on the downward limb of the AMOC. The water mass transformation framework infers the overturning stream function from volume and buoyancy budgets, but obscures kinematics of the AMOC. Whereas the classical subduction framework illustrates the kinematics of volume transport yet lacks a consistent buoyancy budget and a clear link to the AMOC. Using km-scale global coupled ICON simulations and isopycnal diagnostics, we reconcile transports diagnosed in density and depth coordinates. The results reveal lateral, nonlinear, and eddy-rich pathways that feed the lower limb of the AMOC.
