Coupled Bio-Physical Models for the Coastal Gulf of Alaska

美国GLOBEC东北太平洋实施计划的核心假设是阿拉斯加湾环流和水文的年际至年代际变化驱动沿海区浮游动物生产力的变化，从而影响海湾鲑鱼和其他物种的摄食成功。在阿拉斯加沿海湾（CGOA）和加州电流的生产制度可能在年际到十年尺度上的协变，由于空间相关的物理强迫的变化。为了解决这些问题的CGOA，一组链接的循环模型，再加上较低的营养水平营养浮游植物浮游动物（NPZ）的生物模型，和一个基于个体的模型（IBM）的鲑鱼。涡和潮汐解决CGOA环流模式嵌入在一个流域/全球尺度环流模式。这套模型要解决的具体问题包括：1）阿拉斯加海流（AC AS）和阿拉斯加沿岸流（ACC）的相对强度如何影响陆架和陆坡之间的交换，从而影响陆架区营养物质和深海浮游动物的供应？ 2)风驱动的Ekman通量能解释海洋浮游动物向大陆架的大部分运输吗？还是涉及更复杂的跨锋过程？ 3)如何年际/十年调制的季节性模式的ACC影响二次生产和转移到更高的营养水平的货架上？一个更强的ACC是否会提高或降低货架上的生产力？ 4)潮汐混合是否显著影响阿拉斯加湾的海岸生产？如果是这样的话，潮汐的低频调制能解释海岸动力学的一些年代际变化，从而解释生产吗？ 拟议的一套耦合（全球/流域和区域/沿海）环流模型被迫现实的风和河流径流时间序列。沿海环流模型的输出将用于驱动包括陆架和陆架坡折的近岸区域的NPZ模型。流通和猎物领域以这种方式产生的，然后将被用作输入到空间上明确的IBM的少年鲑鱼。这套模型将包括一个重大的进步，过去和现有的阿拉斯加湾的模型，其中有几个例外，往往使用粗糙的空间网格或简化的物理，其中排除生物相关的过程，如斜压不稳定的沿海地区。 这项拟议研究的结果将有助于确定过去和未来的趋势和空间格局的循环，浮游动物和鲑鱼生产内的阿拉斯加湾，并帮助确定陆架坡交换机制。模型的输出将提供给东北太平洋GLOBEC的其他PI，并应特别有用的物理和生物边界条件，用于更精细的区域模型（如威廉王子湾）。

PROJECT SUMMARY A core hypothesis of the US GLOBEC Northeast Pacific Implementation Plan is that interannual to interdecadal variability in the circulation and hydrography of the Gulf of Alaska drives changes in productivity of zooplankton in the coastal zone, with consequent effects on the feeding success of salmonids and other species in the Gulf. Production regimes in the Coastal Gulf of Alaska (CGOA) and the California Current may covary on interannual to decadal scales, due to spatially correlated changes in physical forcing. To address these issues for the CGOA, a set of linked circulation models, coupled with a lower trophic level Nutrients Phytoplankton Zooplankton (NPZ) biological model, and an individual based model (IBM) of salmon are used. The eddy and tide resolving CGOA circulation model embedded in a basin/global scale circulation model. Specific questions to be addressed by this set of models include: 1) How do the relative strengths of the offshore Alaska Current Alaskan Stream (AC AS) and the Alaska Coastal Current (ACC) affect exchange between the shelf and slope, and hence the supply of nutrients and deep sea zooplankton to the shelf area? 2) Can wind driven Ekman flux account for most of the transport of oceanic zooplankton onto the shelf, or are more intricate cross frontal process involved? 3) How does interannual/decadal modulation of the seasonal pattern of the ACC affect secondary production and transfer to higher trophic levels on the shelf? Does a stronger ACC act to enhance or reduce productivity on the shelf? 4) Does tidal mixing significantly affect coastal production in the Gulf of Alaska? If so, can very low frequency modulation of tides account for some of the decadal change in the coastal dynamics, and hence production? The proposed set of coupled (global/basin and regional/coastal) circulation models are forced by realistic wind and river runoff time series. Output from the coastal circulation model will be used to drive the NPZ model of the near coastal area encompassing the shelf and shelf break. Circulation and prey fields produced in this manner will then be used as input to the spatially explicit IBM of juvenile salmon. This set of models will comprise a significant advance over past and existing models of the Gulf of Alaska, which have with few exceptions tended to use either coarse spatial grids or simplified physics, which exclude biologically relevant processes such as baroclinic instability in the coastal zone. Results of this proposed research will help identify past and future trends and spatial patterns of circulation, zooplankton and salmonid production within the Gulf of Alaska, and help identify mechanisms for shelf slope exchange. Output from the models will be made available to other PI's in Northeast Pacific GLOBEC, and should be especially useful as physical and biological boundary conditions for finer scale regional models (e.g. of Prince William Sound).