Coupled Bio-Physical Models for the Coastal Gulf of Alaska

阿拉斯加沿海湾的耦合生物物理模型

• 批准号: 9711329
• 负责人: Dale Haidvogel
• 金额: $ 20.52万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-10-01 至 2001-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9711329&HistoricalAwards=false
• 关键词: Coupled; Bio; Physical; Models; Coastal

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).

美国GLOBEC东北太平洋实施计划的一个核心假设是，阿拉斯加湾环流和水文的年际至年代际变化驱动了沿海地区浮游动物生产力的变化，从而对海湾地区鲑鱼和其他物种的摄食成功产生影响。由于物理强迫的空间相关变化，阿拉斯加沿海湾（CGOA）和加利福尼亚洋流的生产状况可能在年际到年代际尺度上共变。为了解决这些问题，CGOA使用了一组关联循环模型，加上较低营养水平的营养浮游植物浮游动物（NPZ）生物学模型和鲑鱼个体模型（IBM）。涡、潮解析CGOA环流模式嵌入盆地/全球尺度环流模式。这组模型要解决的具体问题包括：1)近海阿拉斯加流（AC AS）和阿拉斯加海岸流（ACC）的相对强度如何影响大陆架和斜坡之间的交换，从而影响向大陆架区域供应营养物质和深海浮游动物？2)风驱动的Ekman通量是否能解释海洋浮游动物向陆架的大部分运输，还是涉及更复杂的横锋过程？3) ACC季节模式的年际/年代际调节如何影响大陆架的二次生产和向更高营养水平的转移？更强的ACC是提高还是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沿海生产？如果是这样的话，非常低频率的潮汐调制是否可以解释沿海动态的一些年代际变化，从而导致生产？所提出的耦合（全球/流域和区域/沿海）环流模式是由现实风和河流径流时间序列强迫的。沿海环流模式的输出将用于驱动包含陆架和陆架断裂的近海岸区域的NPZ模式。以这种方式产生的循环和猎物场将被用作幼鲑鱼空间显性IBM的输入。这组模型将比过去和现有的阿拉斯加湾模型有重大的进步，除了少数例外，这些模型倾向于使用粗糙的空间网格或简化的物理，这些模型排除了与生物相关的过程，如沿海地区的斜压不稳定。本研究的结果将有助于确定阿拉斯加湾环流、浮游动物和鲑鱼生产的过去和未来趋势和空间格局，并有助于确定陆架斜坡交换的机制。模式的输出将提供给东北太平洋GLOBEC的其他PI，并且作为更精细的区域模式（例如威廉王子湾）的物理和生物边界条件应特别有用。