US west coast variability of low-oxygen conditions

The California Current System (CCS), as any eastern boundary coastal upwelling systems, exhibits intense biological productivity supporting high marine biodiversity. It is characterized by a significant variability of biogeochemical properties, in particular of oxygen, resulting in episodes of low-oxygen conditions particularly stressful for the biology. The CSS variability, dominated by a well-known large scale seasonality of the wind-driven coastal upwelling, also evidences important temporal variability at higher frequencies and an interestingly large spatial variability along shore on local and regional scales. To assess this variability and better understand its drivers, a 10 years hindcast simulation of a 1km resolution physical-biogeochemical model (ROMS-BEC) was performed. It extends from Baja California to Vancouver Island, covering the whole US West coast at an unprecedented resolution. The model allows to better characterize regions whose ecosystems are likely under stressful episodic low-oxygen conditions. Moreover, it is used to quantify the balance of oxygen fluxes and to explore the role of small-scales dynamic in material fluxes and small-scales heterogeneity in non-linear biogeochemical reactions.