Biological influences on mixed-layer dynamics and global ocean circulation, OGCM/OCMIP-Caldeira, 2001 (U.S. JGOFS Synthesis & Modeling Phase project results)

<p>It is well known that (1) plankton dynamics are affected by solar radiation and mixed-layer dynamics, (2) plankton dynamics affect water transparency and solar extinction, and (3) solar extinction affects mixed-layer dynamics. We propose to test the hypotheses that:</p> <blockquote> <ol> <li>Solar extinction in the water column is an important factor affecting absorption of excess CO2 in the global ocean.</li> <li>Feedbacks involving marine biology, turbidity, solar-extinction, and mixed-layer dynamics, significantly affect oceanic carbon fluxes and air-sea gas exchange, both in the steady state and in response to climate change.</li> </ol> </blockquote> <p>We will investigate the effect of these factors on CO2 fluxes in the global ocean by performing a suite of ocean general circulation (and one-dimensional) model simulations (some driven with satellite color data, others using a simple trophic-level model), and evaluating these GCM simulations by comparing model results with observations collected at the JGOFS times series sites and process study areas (and other available observations). Our general circulation and carbon-cycle models already exist and run on massively parallel machines; the proposed study involves a modest amount of new model development. This development will focus on estimating export production using satellite-based methods of estimating primary production (e.g., Behrenfeld and Falkowski, 1997; Longhurst et al., 1995).</p> <p>The proposed study supports NASA and JGOFS objectives by using remote sensing, and in situ data from JGOFS, to study the impact on carbon dioxide fluxes of feedbacks involving primary production, transparency, and upper ocean dynamics. This study will emphasize satellite ocean color scanner imagery as a principal data source, although satellite derived fields such as wind speeds and irradiances will also be used in this study to drive the ocean model. In situ data collected as part of JGOFS and other programs will be essential to determining appropriate model parameter values and in evaluating model results. Conversely, the model results should help in understanding the dynamics observed at the U.S. JGOFS process study and time-series stations.</p> <p>By the end of our study, it will be clear if, how, and why subsurface penetration of solar radiation is an important factor affecting global and regional scale air-sea CO2 fluxes and ocean carbon transport.</p>众所周知：(1) 浮游生物动力学（plankton dynamics）受太阳辐射与混合层动力学（mixed-layer dynamics）调控；(2) 浮游生物动力学可改变水体透明度与太阳消光（solar extinction）；(3) 太阳消光会对混合层动力学产生影响。本研究拟验证如下假说： 1. 水柱内的太阳消光是影响全球海洋过量二氧化碳吸收的关键因素。 2. 涉及海洋生物学、水体浊度、太阳消光与混合层动力学的反馈机制，无论在稳态条件下还是应对气候变化过程中，均会显著影响海洋碳通量与海-气气体交换过程。 本研究将通过开展一系列海洋总环流及一维模式模拟（部分模拟以卫星色度数据驱动，其余则采用简单营养级模型），并将模式结果与全球海洋通量联合研究（Joint Global Ocean Flux Study, JGOFS）时间序列站点、过程研究区域及其他可获取观测数据进行对比，以此评估这些总环流模式（General Circulation Model, GCM）的模拟结果，进而明确上述因子对全球海洋二氧化碳通量的影响。目前，我们已开发完成海洋总环流与碳循环模式并可在大规模并行计算机上运行；本研究仅需开展少量新增模式开发工作，该工作将聚焦于基于卫星遥感方法估算初级生产力（primary production）以推算输出生产力（export production）（例如Behrenfeld与Falkowski, 1997；Longhurst等, 1995）。 本研究将借助遥感技术与JGOFS的原位（in situ）观测数据，探究初级生产力、水体透明度与上层海洋动力学相关反馈机制对二氧化碳通量的影响，以此契合美国国家航空航天局（National Aeronautics and Space Administration, NASA）与JGOFS的研究目标。本研究将以卫星海洋色度扫描仪影像作为核心数据源，同时也将采用卫星反演的风速、辐照度等数据驱动海洋模式。作为JGOFS及其他项目组成部分采集的原位观测数据，将为确定合理的模式参数值与评估模式结果提供关键支撑。反之，模式结果也将有助于阐释美国JGOFS过程研究与时间序列站点的观测动力学特征。 在本研究结束时，我们将明确太阳辐射的次表层穿透是否为影响全球及区域尺度海-气二氧化碳通量与海洋碳输运的关键因子，以及其影响方式与内在机制。