The biological productivity and diversity of the California Current System (CCS) is at the leading edge of major emerging climate trends, including hypoxia and acidification. We present results from a hindcast simulation (reanalysis) of an eddy-resolving oceanic physical-biogeochemical model of the CCS, to characterize its mean state and its patterns and drivers of variability in marine biogeochemical and ecosystem processes from 1995 to 2010. This is a companion paper to a physical analysis in Renault et al. (2021). The model reproduces long-term mean distributions of key ecosystem metrics, including surface nutrients and productivity and subsurface $O_2$ and carbonate undersaturation. The spatial patterns of Net Primary Productivity (NPP) are broadly consistent with measured and remotely sensed rates, and they reflect a predominant limitation by nitrogen, with seasonal and episodic limitation by Fe nearshore in the central CCS, and in the open ocean northern CCS. The vertical distribution of NPP is governed by the trade-off between nutrient and light limitation, a balance that reproduces and explains the observed spatial variations in the depth of the deep Chl maximum. The seasonal to interannual variability of biogeochemical properties and rates is also well captured by model simulations. Because of the prevailing nutrient limitation, fluctuations in the depth of the pycnocline and associated nutricline are the leading single factor explaining interannual variability in the interior biogeochemical state, and the relationships between density and biogeochemical rates and tracers are consistent between model and observations. The magnitude and relationship between density structure and biogeochemical processes is illustrated by the 1997–98 El Niño event, which faithfully reproduces the single largest deviation from the mean state in the simulated period. A slower decadal shoaling of the pycnocline also accounts for the concomitant trends in hypoxic and corrosive conditions on the shelf. The resulting variability is key to understanding the vulnerability of marine species to oceanic change, and to the detection of such changes, soon projected to exceed the range of conditions in the past century.

加利福尼亚现行系统（CCS）的生物生产力和多样性处于主要新兴气候趋势（包括缺氧和酸化）​​的前沿。我们提出了CCS的涡旋分辨海洋物理生物地球化学模型的后验模拟（再分析）结果，以描述其平均状态及其在1995年至2010年期间海洋生物地球化学和生态系统过程的变异性和动因。这是一个有关雷诺等人进行物理分析的论文。（2021年）。该模型再现了关键生态系统指标的长期平均分布，包括地表养分，生产力和地下${Ø}_{\mathrm{2个}}$和碳酸盐饱和度不足。净初级生产力（NPP）的空间格局与测得的遥感速率基本一致，它们反映了氮的主要局限性，CCS中部和北海的远洋中Fe的季节性和偶发性局限性。NPP的垂直分布取决于养分与光限之间的权衡，该平衡再现并解释了深Chl深度中观察到的空间变化最大。通过模型模拟也可以很好地捕获生物地球化学性质和速率的季节性到年际变化。由于目前主要的养分限制，比索菌碱和相关营养素的深度波动是解释内部生物地球化学状态年际变化的主要因素，模型和观测值之间的密度，生物地球化学速率和示踪剂之间的关系是一致的。1997-98年的厄尔尼诺事件说明了密度结构与生物地球化学过程之间的大小和关系，该事件忠实地再现了模拟时期与平均状态的最大偏差。碧萝oc在年代际上较慢的暗沙作用还解释了货架上低氧和腐蚀性条件的伴随趋势。