2024-2025: Ocean Sciences: Rong Zhang

Rong Zhang
NOAA/GFDL

Biography

Rong Zhang is a senior scientist and head of the Ocean and Cryosphere division at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL). She is also a faculty member of the Program in Atmospheric and Oceanic Sciences (AOS) at Princeton University. Her research focuses on Atlantic multidecadal variability and associated decadal predictability, the role of Atlantic meridional overturning circulation (AMOC) in regional phenomena (e.g., Gulf Stream separation, Intertropical Convergence Zone shift, Atlantic hurricane activity, and Arctic sea ice extent), the mechanism of the multidecadal AMOC variability, and the development of AMOC fingerprints. Rong Zhang is a Fellow of the American Geophysical Union (AGU) and the American Meteorological Society (AMS) and has been recognized as the 2021 AMS Bernhard Haurwitz Memorial Lecturer "for advancing scientific understanding of the causes and impacts of Atlantic multidecadal variability and Arctic Sea ice variations through insightful analysis of models and observations". She has served as Editor of Journal of Climate and served in leadership roles for the U. S. AMOC Science Team. Rong Zhang received degrees from Massachusetts Institute of Technology (Ph. D. in Climate Physics and Chemistry, 2001), Boston University (M. A. in Physics, 1997), and Tsinghua University (B. E. in Electronic Engineering, 1995)

Abstract: Understanding Atlantic Multidecadal Variability and Associated Overturning Circulation

Atlantic Multidecadal Variability (AMV) and associated decadal predictability have a wide range of societal and economic applications. Understanding AMV is crucial for successful decadal predictions of AMV-related climate phenomena, e.g. Intertropical Convergence Zone positions; Sahel/India monsoons; Atlantic hurricanes; North Atlantic Oscillation; North American droughts; European summer temperature; Arctic sea ice extent; and northern hemispheric surface temperature. Observational and modelling evidence suggests an essential role of the Atlantic Meridional Overturning Circulation (AMOC) in AMV and associated decadal predictability. The observed key elements of AMV are crucial for understanding the underlying mechanisms, and it is important to use multivariate metrics to provide a holistic picture of the observed AMV. The observed AMOC fingerprint supports a close AMOC-AMV linkage. The Atlantic decadal predictability is much higher in fully coupled models with relatively stronger multidecadal AMOC variability and almost disappears in slab ocean models without AMOC variability. The observed coherent multivariate variability associated with AMV is consistent with the impacts of multidecadal AMOC variability. To understand key AMOC processes, the long-term mean AMOC structure over the extratropical North Atlantic and the Arctic Mediterranean is reconstructed using a high-resolution coupled model in combination with the observed hydrographic climatology. The reconstruction suggests that the Arctic Ocean is the northern terminus of the AMOC; horizontal circulation across sloping isopycnals contributes substantially to the northeastern subpolar AMOC, whereas open ocean deep convection, in either Greenland or Labrador Seas, contributes minimally to the AMOC. Based on the AMOC reconstruction, a simple conceptual model was established to illustrate the two-way Atlantic-Arctic interactions and associated AMOC delayed oscillator mechanism, suggesting an important role of Arctic salinity anomalies in multidecadal AMOC variability. Monitoring the potential downstream propagations of Arctic salinity anomalies would be valuable for predicting the timing and amplitude of future AMOC changes.