Collaborative Research:Influences of Cyclonic Eddy Activity on Planktonic Food Web Dynamics and Carbon Export in the Lee of Hawaii

在这个项目中，来自南卡罗来纳大学、夏威夷大学、加州大学圣巴巴拉分校和国际科学技术组织的研究人员将对形成于夏威夷主岛背风处的冷核气旋涡旋的物理、化学和生物学特性进行跨学科的研究。该区域作为一个自然实验室，提供了极好的（如果不是独特的）机会来了解亚热带低营养环境中涡流增强的生产和碳出口。计划进行三次巡航，其中涡流将在三个阶段进行采样：自旋上升（巡航I）、成熟（巡航II）和自旋下降（巡航III）。卫星数据将用于指导船舶密集观测的时间和采样地点。通过涡流采样的设计是为了平衡水平分辨率（即XBT和CTD站之间的间距）和天气性。研究小组将描述涡旋中浮游植物和食草动物的生物量、大小结构和分类组成，并与夏威夷附近的低营养水域进行比较。这些信息将与浮游植物生长和微型浮游动物放牧率的估计结合起来，并与初级生产力和新产量/出口产量的同步速率估计（Th-234通量估计、沉积物圈闭、养分清单和稳定碳同位素质量平衡）相关。利用GOES-10卫星、SeaWiFS卫星、MODIS卫星和TOPEX/ERS卫星分别监测目标涡的轨迹和地下温度结构，估算局地气旋涡场对碳输出的贡献。提出的采样策略将提供一个四维（x,y,z,t）数据集，用于研究营养输入、生物响应和有机碳向下通量之间的联系和时间滞后。这些生物地球化学和物理数据集将提供缺失的环节，以增进我们对涡流在促进有机碳输出方面的性质和重要性的理解，并为建模者提供检验其基本假设和公式的硬数据。最终目标是提供中尺度涡旋对当地营养和食物网动态影响的上限和下限的原位估计，以便它们可以用于测试，评估和重新制定正在开发的各种模型，以研究涡旋现象及其在区域和盆地尺度上的生物地球化学后果。为此目的，将对基于高度计的硝酸盐通量模型进行实验模拟。这种比较应该允许使用混合TOPEX/ERS产品和用当地原位数据校准的计算硝酸盐通量，将结果从夏威夷岛的背风处外推到北太平洋副热带环流的涡流场。

ABSTRACTOCE-0241645 / OCE-0241897 / OCE-0241121 / OCE-0241852In this project, investigators at the University of South Carolina, the University of Hawaii, the University of California - Santa Barbara, and Science and Technology International will conduct interdisciplinary investigation of the physical, chemical, and biological characteristics of cold-core cyclonic eddies that form in the lee of the main Hawaiian Islands. This area serves as a natural laboratory, providing excellent, if not unique, opportunities for understanding eddy-enhanced production and carbon export in an accessible subtropical oligotrophic setting. Three cruises are planned in which eddies will be sampled during three phases: spin-up (cruise I), maturity (cruise II), and spin-down (cruise III). Satellite data will be used to direct the timing and sampling locations of the intensive ship-based observations. Sampling through the eddy is designed to balance horizontal resolution (i.e., spacing between XBT and CTD stations) with synopticity. The team will characterize the biomass, size structure and taxonomic composition of phytoplankton and grazers in the eddy relative to the ambient oligotrophic waters off Hawaii. This information will be coupled with estimates of phytoplankton growth and microzooplankton grazing rates and related to concurrent rate estimates of primary productivity and new/export production (Th-234 flux estimates, sediment traps, nutrient inventories and stable carbon isotope mass balance). The trajectory and subsurface temperature structure of the target eddy will be monitored using satellites (GOES-10, SeaWiFS, MODIS, and TOPEX/ERS) and drifters, respectively, and the contribution of the local cyclonic eddy field to carbon export will be estimated. The proposed sampling strategy will provide a 4-dimensional (x,y,z,t) data set for investigating the linkages and temporal lags between nutrient inputs, biological responses, and the downward flux of organic carbon. These biogeochemical and physical data sets will provide missing links for advancing our understanding of the nature and importance of eddies in facilitating organic carbon export, as well as hard data for modelers to test their fundamental assumptions and formulations. The ultimate goal is to provide in situ estimates for the upper and lower limits of mesoscale eddy effects on local nutrient and food web dynamics such that they can be used to test, evaluate and reformulate the various models being developed to study eddy phenomena and their biogeochemical consequences on regional and basin scales. Towards that end, experimental simulations of altimeter-based nitrate flux models will be performed. This comparison should allow extrapolation of the results from the lee of the Island of Hawaii to the eddy field in the North Pacific Subtropical Gyre, using the blended TOPEX/ERS product and calculated nitrate fluxes calibrated with local in situ data.