Mechanisms Controlling the Biological Pump and CO2 Uptake Rates in the North Pacific

在这个项目中，华盛顿大学的研究人员将使用一个盆地范围的大气环流模式(GCM)来量化控制北太平洋生物碳输出和人为二氧化碳(CO2)吸收的物理机制。该模型是可行的，已经用于评估北太平洋俯冲和水团形成的机制，目前正在使用氯氟化碳示踪剂(CFCs)进行测试。该方法将首次将炸弹产生的14C纳入模型中，以验证其平流和扩散场。通过添加这种碳基示踪剂，该模型将得到氯氟烃和14C的验证，这两种示踪剂具有不同的边界条件和时间历史。接下来，生物碳输出量和再矿化率的三维分布将通过使用几种生物生产力示踪剂的观测分布来确定，特别是硝酸盐和磷酸盐(以及它们的溶解有机对应物DON和DOP)、三种溶解大气气体(氧、氩和氮)以及溶解无机碳(DIC)的13C/12C比率。然后，PIS将模拟人为的二氧化碳扰动，并利用北太平洋的人为DIC和13C/12C变化的独立重建来验证模型预测。最后，将考察模式对强迫年代际变化的响应。选择北太平洋作为盆地尺度模拟研究的地点有几个重要的原因。有三个JGOFS时间序列站点产生了观测到的碳通量和人为的二氧化碳信号，以与模型预测进行比较。与北大西洋和南大洋相比，极地边界没有深水形成简化了经向环流，因此有理由进行较短的模型运行。最后，在过去10年中，北太平洋一直是密集的化学示踪剂测量地点，特别是氟氯化碳、14C和13C/12C。研究人员将集中精力对可能控制上层海洋示踪、营养和二氧化碳通量的物理过程进行量化：1)赤道-副热带和副热带-副极地交换，2)温跃层通风和等周期输送，有无涡流，3)昼夜混合和上层温跃层涡旋的影响，4)年代际变化对生物碳输出的影响。

ABSTRACTOCE-0095106In this project, investigators at the University of Washington will quantify the physical mechanisms controlling the rates of biological carbon export and the uptake of anthropogenic carbon dioxide (CO2) in the North Pacific Ocean using a basin-wide general circulation model (GCM). The proposed model is operational and has already been used to evaluate mechanisms of subduction and water mass formation in the North Pacific and is currently being tested using chlorofluorocarbon tracers (CFCs).The approach will be first to incorporate bomb-produced 14C into the model to validate its advective and diffusive fields. By adding this carbon-based tracer the model will then have been verified with both CFCs and 14C -- two tracers with different boundary conditions and time histories. Next, the three-dimensional distribution of biological carbon export and remineralization rates will be determined by using the observed distributions of several biological productivity tracers, specifically nitrate and phosphate (and their dissolved organic counterparts DON and DOP), three dissolved atmospheric gases (oxygen, argon, and nitrogen), and the 13C/12C ratio of the dissolved inorganic carbon (DIC). The PIs would then simulate the anthropogenic CO2 perturbation and utilize independent reconstructions of the anthropogenic DIC and 13C/12C changes in the North Pacific to validate model predictions. Finally, the model response to decadal variability in forcing would be examined.There are several important reasons to choose the North Pacific Ocean as the site for a basin-scale modeling study. There are three JGOFS time-series sites that yield observed carbon fluxes and anthropogenic CO2 signals to compare to model predictions. The lack of deep-water formation at its poleward boundary simplifies the meridional circulation compared to the North Atlantic and southern oceans and justifies shorter model runs. Finally, the North Pacific has been the site of intensive chemical tracer measurements, specifically CFCs, 14C and 13C/12C, over the last 10 years. The investigators will focus their modeling efforts on quantifying physical processes that likely control tracer, nutrient and CO2 fluxes in the upper ocean: 1) equatorial-subtropical and subtropical-subpolar exchange, 2) thermocline ventilation and isopycnal transport both with and without eddies, and 3) diapycnal mixing and the influence of eddies in the upper thermocline, and 4) the impact of decadal variability on biological carbon export.