New and Export Productivity Regulation by Si and Fe in the Equatorial Pacific Ocean

赤道太平洋地区硅和铁的新出口生产率调节

• 批准号: 9726086
• 负责人: Richard Barber
• 金额: $ 14.72万
• 依托单位: Duke University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-01-01 至 2000-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9726086&HistoricalAwards=false
• 关键词: New; Export; Productivity; Regulation; Si

To identify and quantify the principal processes that control the partitioning of carbon among oceanic reservoirs and between the ocean and atmosphere on focal and regional scales, with a view towards synthesis and prediction on a global scale, is a specific goal of the U.S. JGOFS Synthesis and Modeling Project. As a contribution towards achieving this goal, Drs. Barber, Peng, Chai and Dugdale will develop an ecosystem model for the equatorial Pacific Ocean, with a focus on how silicate and iron affect new and export productivity and the partitioning of carbon between the atmosphere, surface ocean and deep ocean. The study will use an ecosystem model embedded in a state-of-the-art general circulation model for the equatorial Pacific Ocean to investigate how new and export productivity responds to changing physical and chemical forcing. The domain of the model is between 30ÝS and 30ÝN, 120ÝE and 70ÝW, with real geometry and topography, but analysis will focus on the equatorial region from 5ÝN to 5ÝS. The recent upgrade of supercomputers at North Carolina Supercomputing Center (NCSC) (CrayT90) and Arctic Region Supercomputing Center (ARSC) (Cray-YMP) and the award of several hundred hours of CPU time to Peng, Chai and Barber make it possible to embed an ecosystem model with modest complexity in a high resolution, three dimensional prognostic ocean model, and to conduct numerous experiments on the ecosystem model structure and parameters in a timely and efficient manner. Phase 1 of the project will modify an existing five-compartment ecosystem model by adding three more compartments (silicate, diatoms and mesozooplanktonic grazers) following the approach of Dugdale et al. The preliminary objective of this three-dimensional Si/N/light model is to reproduce High Nitrate-Low Silicate-Low Chlorophyll (HNLSLC) conditions. With size-dependent growth rate responses in small phytoplankton and diatoms and varying grazing vulnerability, the role of new diatom production regulating on Si and Fe can be thoroughly investigated. Also in Phase 1, 2:CO2 and total alkalinity () ALK) will be added in order to calculate pCO2. The pre-industrial atmospheric CO2 (280 1latm) will be used to hindcast air-sea flux of CO2 in the equatorial Pacific. New production regulating on silicate should provide a more accurate calculation of CO2 compared to using nitrate as a regulating nutrient. In Phase 2 the effect of iron is added to the model making a, the initial slope of the photosynthesis vs. irradiance curve, a function of iron. The values of a are based on equatorial observations of natural and experimental iron additions. Independently, Ks for Si(OH4) is made a function of iron, an effect that involves only diatoms. The `balance to bloom` transition will be simulated with the two iron effects to reproduce the IronEx 1 and 2 phytoplankton responses to a transient iron addition. This modeling study will provide estimates of new and export productivity, and a formal description of Si and Fe as regulating mechanisms in the equatorial Pacific Ocean. When new and export productivity is modeled accurately and validated with JGOFS studies, it will possible to predict with increased confidence how climate change may alter, via biogenic export, maintenance of the air-sea ApCO2 and hence the ocean's uptake and release of CO2.

确定和量化在局部和区域尺度上控制海洋水库之间以及海洋和大气之间碳分配的主要过程，以期在全球范围内进行综合和预测，这是美国JGOFS综合和建模项目的一个具体目标。作为对实现这一目标的贡献，Barber、Peng、Chai和Dugdale博士将为赤道太平洋开发一个生态系统模型，重点研究硅酸盐和铁如何影响新的和出口的生产力，以及碳在大气、表层海洋和深海之间的分配。这项研究将使用一个嵌入赤道太平洋最先进的大气环流模型的生态系统模型，以调查新的和出口的生产力如何对不断变化的物理和化学强迫做出反应。模式的范围介于S和北纬30之间，东经120和西70之间，具有真实的几何和地形，但分析将集中在赤道地区从北纬5到南纬5≥S。最近北卡罗来纳州超级计算机中心(CRYT90)和北极地区超级计算机中心(CRAY-YMP)的超级计算机升级，以及授予彭、柴和巴伯数百小时的计算时间，使得有可能在高分辨率的三维预报海洋模式中嵌入一个复杂程度不高的生态系统模式，并及时有效地对生态模式的结构和参数进行大量实验。该项目的第一阶段将按照Dugdale等人的做法，通过增加三个隔室(硅酸盐、硅藻和中游浮游食草动物)来修改现有的五个隔室生态系统模型。这个三维Si/N/LIGH模型的初步目标是再现高硝酸盐-低硅酸盐-低叶绿素(HNLSLC)条件。通过小型浮游植物和硅藻的生长速率与大小相关的响应以及不同的放牧脆弱性，可以深入研究新的硅藻生产对硅和铁的调节作用。此外，在第一阶段，第二阶段：二氧化碳和总碱度()将相加，以计算二氧化碳。工业化前大气CO2(280 1latm)将用于赤道太平洋大气-海气CO2通量的后向预报。与使用硝酸盐作为调节养分相比，对硅酸盐的新产量调节应该可以提供更准确的二氧化碳计算。在第二阶段中，将铁的影响添加到模型中，得到光合作用与辐射曲线的初始斜率，这是铁的函数。A的值是基于对自然和实验中的铁添加的赤道观测得出的。独立地，硅(OH4)的Ks是铁的函数，这种效应只涉及硅藻。我们将用两种铁效应来模拟“从平衡到繁盛”的转变，以重现IronEx 1和IronEx 2浮游植物对瞬时铁添加的反应。这项模拟研究将提供对新的和出口生产力的估计，并正式描述作为赤道太平洋调节机制的硅和铁。当新的和出口的生产力被准确地模拟并通过JGOFS的研究得到验证时，就有可能更加自信地预测气候变化可能如何通过生物来源的出口改变海-气相二氧化碳的维持，从而改变海洋对二氧化碳的吸收和释放。