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全流域大气环流模式（GCM）量化控制北太平洋生物碳输出速率和人为二氧化碳（CO2）吸收速率的物理机制。该模式已投入运行，并已用于北太平洋俯冲和水团形成机制的评估，目前正在使用氯氟烃示踪剂（CFCs）进行测试。该方法将首次将炸弹产生的14 C纳入模式，以验证其平流场和扩散场。通过添加这种碳基示踪剂，该模型将用CFCs和14 C进行验证-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（及其溶解的有机对应物DON和DOP），三种溶解的大气气体（氧气，氩气和氮气），以及溶解的无机碳（DIC）的13 C/12 C比率。 然后，PI将模拟人为CO2扰动，并利用北太平洋人为DIC和13 C/12 C变化的独立重建来验证模型预测。最后，将检验模式对强迫的年代际变化的响应。选择北太平洋作为海盆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，产生观测到的碳通量和人为CO2信号，以与模型预测进行比较。与北大西洋和南部海洋相比，其向极边界缺乏深水形成简化了纬向环流，并证明了较短的模式运行是合理的。最后，在过去10年里，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、14 C和13 C/12 C。 研究人员将把建模工作的重点放在量化可能控制上层海洋示踪剂，营养物和二氧化碳通量的物理过程上：（1）赤道-副热带和副热带-副极地交换;（2）有无涡旋的温跃层通风和等密度输送;（3）在上层温跃层的底辟混合和涡旋的影响。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.