Springtime Export of Arctic Sea Ice Shapes the Phytoplankton Production in the Greenland Sea

Climatic model projections suggest a substantial decrease of sea ice export into the outflow areas of the Arctic Ocean over the 21st century. Fram Strait, located in the Greenland Sea sector, is the principal gateway for ice export from the Arctic Ocean. The consequences for the Greenland Sea of the predicted lower sea ice flux through Fram Strait on its ocean dynamics and primary production remain unknown. By using the most recent 16 years (2003-2018) of satellite imagery available and hydrographic in situ observations, the role of exported Arctic sea ice in the water column stratification and phytoplankton production of the Greenland Sea is evaluated. The springtime Arctic sea ice export through Fram Strait has a strong interannual variability and influences the sea ice extent and distribution in the Greenland Sea. Years with high Arctic sea ice flux mostly resulted in high sea ice concentration in the Greenland Sea, which can trigger a strong salinity-based water column stratification of the basin and an earlier spring phytoplankton bloom associated with high primary production levels. Similarly, years with low Arctic sea ice flux through Fram Strait were mostly associated with a delayed phytoplankton spring bloom in the Greenland Basin, because of a weak water column stratification. This work emphasized the particularity of the Greenland Sea as being a transition zone between the Arctic and Atlantic Oceans where the springtime phytoplankton production is under the influence of exported Arctic sea ice.