1,3,4,2- 1Key Laboratory of Polar Ecosystem and Climate Change, Ministry of Education and School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
- 2Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Helsinki, Finland
- 3Shanghai Key Laboratory of Polar Life and Environment Sciences, Shanghai Jiao Tong University, Shanghai, China
- 4Shanghai Frontiers Science Center of Polar Science, Shanghai Jiao Tong University, Shanghai, China
The Northern Antarctic Peninsula (NAP) marine ecosystem is experiencing rapid environmental changes, yet the evolving relationships among atmospheric forcing, sea ice dynamics, and primary productivity remain poorly understood. This study investigates the interannual variability of summer chlorophyll-a (Chl-a) concentration and its physical drivers over the past two decades (2001–2024), utilizing multi-source satellite data and atmospheric reanalysis products. We identify a significant regime shift in climate-ecosystem interactions occurring around 2014.
Since 2014, major climate modes have shown concurrent trends: the Southern Annular Mode (SAM) accelerated towards a positive phase, while the Interdecadal Pacific Oscillation (IPO) shifted towards a negative phase. These combined trends led to a significant deepening of the Amundsen Sea Low (ASL), resulting in intensified regional winds (r=−0.79, p<0.01). This change in atmospheric circulation coincided with a rapid retreat of sea ice, marked by a significant increase in Ice-Free Days (IFD) in the NAP after 2014.
The significant change in climatic and physical conditions fundamentally altered the biological response patterns. Prior to 2014, the correlation between climate indices and summer Chl-a concentrations was weak, likely limited by the presence of sea ice cover. However, under low sea ice conditions after 2014, this association was notably strengthened. The correlation between the spring SAM index and summer Chl-a increased from 0.39 to 0.58 (p<0.1). The retreat of sea ice exposed the surface ocean directly to atmospheric forcing, enhancing the availability of irradiance and wind-driven vertical mixing. The enhanced mixing can facilitate the replenishment of limiting nutrients (e.g., iron) to the euphotic zone, thereby sustaining summer phytoplankton blooms. These findings suggest that the NAP ecosystem has entered a new state where productivity is tightly coupled with atmospheric dynamics.
How to cite: Ye, S., Zhang, Z., and Uotila, P.: Synergistic Climate Modes Drive a Regime Shift in Physical-Biological Coupling in the Northern Antarctic Peninsula Region, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18273, https://doi.org/10.5194/egusphere-egu26-18273, 2026.
