Inferring large-scale patterns of nutrient regeneration in the ocean using a global biogeochemical inverse model

使用全球生物地球化学反演模型推断海洋中养分再生的大规模模式

• 批准号: 1436922
• 负责人: Francois Primeau
• 金额: $ 38.49万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1436922&HistoricalAwards=false
• 关键词: Inferring; large; scale; patterns; nutrient

Sustained biological production in the world ocean is heavily dependent on the recycling of the decomposition products of pre-existing organisms. In particular for the microscopic algae (phytoplankton) at the base of the marine food chain, the decomposition products (for example, carbon, nitrogen, phosphorous, and silicon) of pre-existing organisms become the fertilizer (or nutrient materials) that nourishes later generations. But dead particles that fall out of the sunlit surface ocean where photosynthesis takes place do not necessarily have the same proportions of nutrient elements as that required for making a living algal cell. To understand how this system manages to keep going as well as how it can vary during global climatic change, the research team on this project will use a set of sophisticated mathematical models that account for biological production, regeneration of nutrients, and ocean circulation patterns to create a global model relating production in the surface ocean to the elemental composition of regenerated nutrients. A postdoctoral researcher will be trained in advanced modeling techniques during this study. The stoichiometric ratios of biological export production are critical to our understanding of the major biogeochemical cycles of the ocean. Limited measurements of the elemental composition in phytoplankton and in sinking particulate organic matter suggest that the ratios can vary significantly in space and time. However the number of direct measurements is inadequate to reliably determine coherent large-scale patterns. As a result most global ecosystem and biogeochemical models assume a fixed stoichiometry - an assumption that may limit their ability to correctly simulate changes in ecosystem dynamics in response to climate change. In this study, a small research team will conduct an inverse modeling study using a global ocean circulation model and a global database of hydrographic measurements of dissolved inorganic carbon, nitrate, phosphate, silicic acid and oxygen concentrations together with abiotic tracers including temperature, salinity, chlorofluorocarbons, and radiocarbon to jointly estimate the global ocean circulation and spatially varying elemental ratios (carbon : nitrogen : phosphorous : silicon : oxygen) of the organic matter exported from the euphotic zone. The proposed work has a high intellectual merit because of the innovative computational and inverse modeling strategies that will make it possible to jointly assimilate biotic and abiotic tracer information to estimate the ocean circulation and the major marine biogeochemical cycles. A global database with maps of export production stoichiometry and three-dimensional gridded fields of regeneration ratios will be made available to the community, which will help guide the development of global marine ecosystem and biogeochemical modules used in Earth System Models.

世界海洋的可持续生物生产在很大程度上依赖于回收利用现有生物的分解产物。特别是对于海洋食物链底部的微小藻类(浮游植物)来说，先前存在的生物的分解产物(例如碳、氮、磷和硅)成为滋养后代的肥料(或营养物质)。但是，从发生光合作用的阳光照耀的表层海洋中掉出来的死亡颗粒，其营养元素的比例不一定与制造活的藻细胞所需的比例相同。为了了解这个系统如何维持运行，以及它在全球气候变化期间如何变化，该项目的研究团队将使用一套复杂的数学模型来解释生物生产、营养物质的再生和海洋环流模式，以创建一个全球模型，将表层海洋的生产与再生营养物质的元素组成联系起来。在这项研究中，一名博士后研究员将接受高级建模技术方面的培训。生物出口产品的化学计量比对于我们理解海洋的主要生物地球化学循环至关重要。对浮游植物和下沉颗粒有机物中元素组成的有限测量表明，这些比例在空间和时间上可能会有很大差异。然而，直接测量的数量不足以可靠地确定连贯的大尺度模式。因此，大多数全球生态系统和生物地球化学模型采用固定的化学计量比--这一假设可能会限制它们正确模拟生态系统动态变化以应对气候变化的能力。在这项研究中，一个小型研究小组将利用全球海洋环流模型和溶解无机碳、硝酸盐、磷酸盐、硅酸和氧浓度的全球水文测量数据以及包括温度、盐度、氯氟烃和放射性碳在内的非生物示踪剂进行反向模拟研究，以联合估计全球海洋环流和从真光带输出的有机物的空间变化元素比率(碳：氮：磷：硅：氧)。拟议的工作具有很高的智力价值，因为创新的计算和反向模拟战略将使人们能够联合吸收生物和非生物示踪信息，以估计海洋环流和主要的海洋生物地球化学循环。将向该社区提供一个全球数据库，其中载有出口产品化学计量和再生率三维网格场地图，这将有助于指导地球系统模型中使用的全球海洋生态系统和生物地球化学模块的开发。