Nutrient-Rich Winter Water Formation on the Beaufort Shelf, Arctic Ocean

Abstract

Newly ventilated winter water (NVWW) is a cold, salty, nutrient-rich water mass that is critical for supporting the ecosystem of the western Arctic Ocean and for ventilating the halocline in the Canada Basin. While the formation of NVWW is well-documented on the Chukchi shelf, there remain fundamental questions regarding its formation on the western Beaufort shelf. In this study, we use hydrographic data from two late-fall cruises in 2018 and 2022 to investigate the roles of sea ice production and wind-driven upwelling in the formation of NVWW and the implications for the nutrient content of the water. For each of the shipboard transects, we apply proxies for the extent of the winter water formation and the strength of the associated upwelling, respectively. It is demonstrated that the NVWW attains higher levels of nitrate due to two factors: (a) more active formation of the water associated with enhanced sea ice production and (b) more extensive upwelling of water high in nutrients from the basin to the shelf following an easterly wind event. The latter process would be less common on the wide Chukchi shelf. These findings have significant implications for the regional primary production.