Unraveling the controls of inorganic carbon dynamics in the Gulf of Alaska with a regional three-dimensional biogeochemical model

阿拉斯加湾生态系统通过旅游业以及自给自足和商业渔业提供了巨大的社会经济效益。然而，由海洋吸收人为二氧化碳引起的气候变化和海洋酸化的综合影响正在改变具有重要商业价值的物种的栖息地。气候导致的冰川融化加剧可能会进一步加速阿拉斯加湾海洋酸化的进程。由于阿拉斯加湾的测量数量有限，人们对关键物种化学栖息地的现状和变化速度知之甚少。阿拉斯加大学费尔班克斯分校的研究人员建议为该地区开发海洋环流、化学和生物学模型，这将使人们能够更好地了解阿拉斯加湾海洋酸化的环境控制。除了通过与阿拉斯加海洋观测系统的合作传播科学外，该项目还将支持一个名为“冰峡湾的女孩”的实地课程，该课程旨在激励因生活环境而机会有限的年轻女性接受大学教育，并可能从事科学事业。该项目将确定阿拉斯加湾北部高二氧化碳环境的主要控制因素和模式。为数不多的可用观测记录了文石在这一大陆架地下水域中不饱和的季节性表现。特别是如果它在时间和空间上扩大，这种不饱和可能会对二氧化碳敏感的生物体产生有害后果，并可能导致食物网络结构改变，最终带来大规模的生态系统和社会经济后果。然而，目前有限的空间和时间数据覆盖范围阻碍了对控制当地碳动态的物理和生物机制的详细概念性理解，从而阻碍了我们预测和缓解未来变化的能力。在这项研究中，研究人员将进行高分辨率的物理-生物地球化学后预测模型集成，并使用神经网络、染料示踪剂和拉格朗日浮子来分离导致研究区域文石不饱和的复杂相互作用的机制。以碳和硝酸盐为模式货币的拟议物理-生物地球化学模式配置已在大北太平洋区域以中等分辨率(10公里)进行了广泛评估。该模式将适用于阿拉斯加湾，具有高水平分辨率(1.5公里)、海岸淡水排放的显式强迫和模拟的铁限制。这样的改进将使这种设置成为许多其他高纬度生物地球化学建模应用的基础，具有吸引力。拟议的实验和分析方法将利用三维模型的输出，并将提供关于加强和抑制海洋酸化控制的季节和年际变化的见解。

The Gulf of Alaska ecosystem provides significant socio-economic benefits through tourism and through subsistence and commercial fisheries. However, the combined effects of climate change and ocean acidification, which is caused by the oceanic uptake of anthropogenic carbon dioxide, are altering the habitat of commercially important species. Climate induced enhancement of glacial melting may accelerate the progression of ocean acidification in the Gulf of Alaska even further. Due to a limited number of measurements in the Gulf of Alaska, little is known about the current state and rate of change of the chemical habitat of key species. Researchers from the University of Alaska Fairbanks propose to develop models of the ocean circulation, chemistry and biology for this region that will enable better understanding of environmental controls on ocean acidification in the Gulf of Alaska. In addition to communicating the science through a collaboration with the Alaska Ocean Observing System, the project will support a field course called "Girls in Icy Fjords", which is designed to inspire young women who have had limited opportunities due to life circumstances to pursue college educations and, possibly, careers in science. This project will identify the dominant controls and patterns of high carbon dioxide environments in the northern Gulf of Alaska. The few available observations document a seasonal manifestation of aragonite undersaturation in subsurface waters on this continental shelf. Particularly if it expands in time and space, such undersaturation could engender detrimental consequences for carbon dioxide sensitive organisms and potentially lead to altered food web structures, ultimately imparting large ecosystem and socio-economic consequences. However, the currently limited spatial and temporal data coverage precludes a detailed conceptual understanding of the physical and biological mechanisms controlling the local carbon dynamics and thus impedes our ability to anticipate and mitigate future changes. In this study, researchers will conduct high-resolution physical-biogeochemical hindcast model integrations and use neural networks, dye tracers and Lagrangian floats to detangle the complex interplay of mechanisms that drive aragonite undersaturation in the study region. The proposed physical-biogeochemical model configuration, which uses carbon and nitrate as model currencies, has been extensively evaluated for the greater North Pacific region at moderate (10 km) resolution. This model will be tailored to the Gulf of Alaska with a high (1.5 km) horizontal resolution, explicit forcing of coastal freshwater discharges, and modeled iron limitation. Such improvements will make this setup an attractive choice as a foundation for many other high-latitude biogeochemical modeling applications. The proposed experiments and analytical methods will take advantage of the three-dimensional model output and will provide insights into seasonal and interannual variability of enhancing and inhibiting controls of ocean acidification.