Summer high-wind events and phytoplankton productivity in the Arctic Ocean

Abstract:

A suite of studies in recent years have established that the decline of sea ice in the Arctic Ocean over the past few decades has coincided with an increase in open-water net primary productivity (NPP). However, summer NPP is also limited by nutrient availability. Access to nutrients is enhanced by vertical mixing of the water column, which can be induced by sustained high winds (> 10 ms^-1) such as those associated with synoptic-scale storms. Past research has linked individual storm events to short-term increases in NPP, but the impact of storminess on seasonal NPP or long-term trends in NPP is still uncertain. Using a combination of satellite-derived NPP and sea-surface temperature and wind fields from the ERA-Interim atmospheric reanalysis, we show that a greater occurrence of high-wind events in summer is associated with higher NPP in the Barents, Laptev, East Siberian, and southern Chukchi Seas. In the Beaufort Sea, on the other hand, NPP appears to be more closely associated with wind direction than wind speed, with easterly winds, which are more favorable for upwelling along the shelf break, being associated with higher NPP in some months. The occurrence of high-wind events has increased recently on the Siberian side of the Arctic Ocean. This suggests that recent increases in NPP in the Barents, Laptev, and East Siberian Seas may be caused in part by wind-induced mixing.