Collaborative Research: Interannual Variability of Coastal Phytoplankton Blooms in the Gulf of Maine and Their Relationships to Local and Remote Forcings

本研究的目的是通过一个耦合的生物-物理模型，探索远程气候强迫与本地强迫的相互作用，以影响沿海和陆架地区浮游植物的繁殖。浮游植物水华动态是海洋中生物-物理相互作用的一个经典例子（Gran and Braarud, 1935; Sverdrup, 1953）。然而，在多尺度生物和物理过程相互作用的沿海和陆架海域，确定控制浮游植物繁殖年际变化的主导过程仍然是一个挑战。非结构网格、有限体积、沿海海洋模型（FVCOM）是在GLOBEC Georges Bank项目中建立的，它连接了缅因湾的多尺度物理过程，包括本地和远程强迫。12年的预测模拟和同化实验产品，加上与实地测量的仔细比较/验证，为探索缅因湾生态系统动态的年际变化提供了独特的背景和工具。该提案将研究海湾地区春季和秋季浮游植物大量繁殖的动态与本地和远程强迫之间的关系。特别关注的是苏格兰陆架水和斜坡水流入的可变性。将进行一系列数值实验，以检验长期存在的和新提出的假设，包括北大西洋涛动的影响，因为它影响暖坡水与拉布拉多坡水的动力学，这反过来影响缅因湾的营养通量和表层和深水之间的垂直通量。还将讨论地表水的淡水化（与斯科修斯大陆架水流入有关，而流入又被认为受到全球变暖的影响）对水柱垂直密度结构、冬季对流的影响，以及由此导致的水华发生的时间/幅度。面向过程的耦合生物和物理模式实验将集中在1998-2001年数据丰富的时期，当时发生了明显的大尺度强迫条件。为大规模强迫对沿海海洋生态系统的动力学和生产力的影响提供新的见解，将是我们对浮游植物繁殖动力学的理解的重大进步，传统上，浮游植物繁殖动力学主要集中在局部强迫和季节变化上。该项目将提供一个基于网络的1995-2006年耦合模型每小时物理和生物输出的开放档案，并产生一个经过测试的耦合生物-物理模型系统，可用于缅因湾和其他沿海海洋的其他正在进行的（例如ECOHAB）和未来的生态系统研究。UMASSD-WHOI正在开发的基于网络的海洋预报模式系统将直接受益于该项目，因为它有助于优化海洋观测站的设计，并有助于塑造相互依存的模式观测系统的未来。更广泛的影响：拟议工作的结果将通过使用提案机构现有基础设施的基于网络的服务器广泛传播给一般研究、本科和研究生教育社区、K-12机构以及感兴趣的公众。基于web的用户将能够访问项目描述、科学成果、模型输入和输出档案、各种物理和生物领域的动画等。与新贝德福德SEALAB海洋科学教育中心和WHOI/马萨诸塞大学COSEE项目的合作将促进与K-12教师和学生以及国内和国际公众的交流。

The aim of this proposal is to explore the interaction of remote climate based forcing with local forcing to impact phytoplankton blooms in coastal and shelf regions with a coupled biological-physical model. Phytoplankton bloom dynamics are a classic example of biological-physical interactions in the ocean (Gran and Braarud, 1935; Sverdrup, 1953). Yet it is still a challenge to identify the dominant processes controlling the interannual variability of phytoplankton blooms in coastal and shelf seas where multiple-scale biological and physical processes interact. The unstructured-grid, finite-volume, coastal ocean model (FVCOM, built within the GLOBEC Georges Bank Program) bridges the multi-scale physical processes of the Gulf of Maine and includes both local and remote forcing. Twelve years of prognostic simulation and assimilation experiment products, with careful comparison/validation with field measurements, provide a unique background and tools with which to explore the interannual variability of ecosystem dynamics in the Gulf of Maine. This proposal will examine relationships between the dynamics of spring and fall phytoplankton blooms in the Gulf and local and remote forcing. A specific focus is the variability Scotian Shelf Water and Slope Water inflows. A series of numerical experiments will be conducted to test long-standing and newly-proposed hypotheses, including the impact of the North Atlantic Oscillation as it influences Warm Slope Water versus Labrador Slope Water dynamics, which in turn affect nutrient fluxes to the Gulf of Maine and vertical fluxes between surface and deep waters. The influence of surface water freshening (related to Scotian Shelf Water inflow, in turn believed to be affected by global warming) on the vertical density structure of the water column, winter convection, and consequently, the timing/magnitude of blooms, will also be addressed. The process-oriented coupled biological and physical model experiments will focus on the date-rich period 1998-2001 when pronounced large-scale forcing conditions occurred. Providing new insights into the influence of large-scale forcing on the dynamics and productivity of coastal ocean ecosystems will be a significant advance in our understanding of phytoplankton blooms dynamics, which has been traditionally focused on local forcing and seasonal changes. The project will provide a web-based open archive of the 1995-2006 coupled model hourly physical and biological output, and produce a tested coupled biological-physical model system available for other ongoing (e.g. ECOHAB) and future ecosystem studies in the Gulf of Maine and other coastal oceans. The web-based ocean forecast model system being developed by UMASSD-WHOI will benefit directly from this project by helping to optimize the design of ocean observatories and help shape the future of interdependent model-observing systems.Broader Impacts: Results of the proposed work will be broadly disseminated to the general research, undergraduate and graduate education communities, K-12 institutions, and to the interested public through web-based servers using existing infrastructure at the proposers' institutions. Web-based users will be able to access project description, scientific results, model input and output archives, animations of various physical and biological fields, etc. Collaboration with the New Bedford SEALAB Marine Science Education Center and the WHOI/UMASS COSEE program will foster communication with K-12 teachers and students and the public both nationally and internationally.