| Abstrakt: |
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. Plain Language Summary: A type of cold, salty, and nutrient‐rich water called newly ventilated winter water (NVWW) plays a critical role in supporting the ecosystem of the western Arctic Ocean and in regulating the layers of different water types in the Canada Basin. While it is well‐known how NVWW forms on the Chukchi shelf, there are still many unanswered questions about its formation on the western Beaufort shelf. To understand this, we studied data collected from two late‐fall research cruises in 2018 and 2022. We focused on the impact of sea ice formation, as well as the influence of wind‐driven upwelling (the transfer of deep ocean water onto the shelf), on the formation of NVWW and its nutrient content. Our findings showed that NVWW on the western Beaufort shelf contains higher nitrate levels due to two main reasons: First, more NVWW is produced when there is increased sea ice formation, and second, when strong winds blow from the east, this brings up more water high in nutrients from the deeper basin onto the shelf—a process that would be less common on the wide Chukchi shelf. These findings have significant implications for the occurrence of phytoplankton blooms. Key Points: Nutrient‐rich Newly Ventilated Winter Water (NVWW) is prevalent across the Beaufort Sea shelf in late fallActive winter water formation associated with increased sea ice production contributes to the nutrient content of NVWWWind‐driven upwelling from the basin to the shelf further enhances the NVWW nutrient content [ABSTRACT FROM AUTHOR] |
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