Collaborative Research: Quantifying the Relationship between Nitrogen Uptake and Net Community Production using a Synthesis of JGOFS Data and 1-D Modeling

净群落产量（NCP）的测量是对海洋表层水体中产生的有机物质数量的可靠估计。NCP可以作为地表水碳输出和海洋从大气中吸收二氧化碳的能力的模型的起点。然而，大多数海洋生产模型都是基于磷或氮等限制性营养物质，因此这类模型的可靠性将取决于海洋将限制性营养物质的消耗如何准确地转化为对二氧化碳的吸收。pi将校准NCP和新（硝酸盐）产生之间的关系，以帮助预测海洋作为碳汇的作用。如何在表层海洋元素循环之间进行最佳转换的问题将通过零假设进行检验，即在海洋温跃层水域中发现的化学计量氧化比（雷德菲尔德比）是在氮和NCP之间进行转换的定量方法。一种比较的方法将被用来检查表面氮和碳循环之间的耦合程度。在碳和氮在雷德菲尔德意义上似乎是不耦合的情况下，可能的方法原因将被仔细评估。根据这一分析，早花与营养限制条件的作用；主要类群;溶解有机物（DOM）水平；N2固定;铁限制和其他因素将被认为是改变氮和碳通量关系的因素。具有代表性的海洋区域的耦合程度将在具有真实上层物理的一维数值模型中进行评估。这些结果将允许生物地球化学建模者判断何时使用Redfield比率进行转换是合适的，并确定哪些情况（如果有的话）值得采用替代转换方法。这将有助于更准确地预测对相关生物过程敏感的碳通量。

Sambrotto The measurement of Net Community Production (NCP) is a robust estimate of the amount of organic material produced in surface waters of the ocean. NCP can serve as a starting point for models of carbon export from surface waters and the ocean's capacity to absorb carbon dioxide from the atmosphere. However, most models of ocean production are based on a limiting nutrient such as phosphorus or nitrogen and the reliability of this class of models therefore will depend on how accurately the consumption of limiting nutrients can be converted to the absorption of carbon dioxide by the ocean. The PIs will calibrate the relationship between NCP and new (nitrate) production in order to assist in the goal of predicting the role of the ocean as a carbon sink. The question of how to best convert between surface ocean elemental cycles will be examined with the a null hypothesis being that the stoichiometric oxidative ratios found in ocean thermocline waters (the Redfield ratios) are a quantitative way to translate between nitrogen and NCP. A comparative approach will be used to examine the extent of coupling between the surface nitrogen and carbon cycles. In instances where carbon and nitrogen appear to be uncoupled in the Redfield sense, possible methodological causes will be carefully evaluated. Following this analysis, the role of early bloom vs. nutrient limited conditions; dominant taxa; dissolved organic matter (DOM) levels; N2 fixation; iron limitation and other factors will be considered as agents modifying the relationship between nitrogen and carbon fluxes. The degree of coupling in representative ocean regions will be evaluated in a one-dimensional numerical model with realistic upper layer physics. These results will allow biogeochemical modelers to judge when the use of Redfield ratios for conversion is appropriate and identify what (if any) circumstances merit an alternate conversion approach. This will contribute to more accurate predictions of carbon flux that are sensitive to the relevant biological processes.