Net Community Production from O2 measurements on Argo Floats

生物产生的有机物从阳光充足的上层水域流向深海的过程被称为“生物泵”。海洋生物泵的地理分布和时间变异性影响大气二氧化碳水平，并维持阳光照明区以下海洋中的氧气分布。确定这一通量对于理解与气候变化有关的海洋碳循环反馈至关重要。目前使用的船载氧气测量方法是准确的，可以解决微小的变化，但它们不能提供解决初级生产力全球地理变异性所需的区域和时间氧气分布。该项目的目标是通过在三个碳出口梯度较大的海洋横断面上的自主平台上的传感器测量准确的氧气年度循环，获得必要的地理多样性的实验结果。这项研究的结果将扩大由实验确定的海洋生物泵观测的地理分布。该项目将包括对博士后研究人员的培训，并将为高中教师开发一个关于碳循环科学的教育模块。氧质量平衡法已被用于确定海洋时间序列地点的净生物氧产量，方法是使用船上的氧气测量和由Winkler滴定校准的系泊氧气传感器。到目前为止，这种方法很难用在浮标的剖面上，因为氧气传感器一直不准确。最近的研究表明，与温克勒滴定相比，在ARGO浮标上使用光伏测量氧气浓度的准确性有所提高。在这个项目中，一名研究人员将在大西洋和太平洋的三个横断面上部署经过校准和专门安装的Aanderaa Optode氧气传感器的Argo浮标，这三个横断面跨越生物碳出口的鲜明对比区域。这些数据将与上层海洋模型一起用于确定年度生物氧净生产量，这在化学计量上与年度净群落生产量(ANCP)和年度有机碳出口有关。这项工作的目标是确定ANCP的地理分布，并将其与通过卫星方法确定的碳出口值进行比较。此外，研究人员还将开发一种氧气-ARGO系统，能够监测氧气最小区域的氧气浓度的微小变化。

The flux of biologically-produced organic matter out of the upper, sun-lit waters to the deep ocean is known as the "biological pump". The geographic distribution and temporal variability of the marine biological pump influences atmospheric carbon dioxide levels, and maintains the oxygen distribution in the ocean below the sun-lit zone. Determining this flux is essential for understanding the marine carbon cycle feedback related to climate change. Shipboard oxygen measurements, the currently-used method, are accurate and can resolve small changes, but they cannot provide the areal and temporal oxygen distribution necessary to resolve global geographic variability in primary productivity. The goal of this project is to attain the necessary geographic diversity of experimental results by measuring accurate annual cycles of oxygen using sensors on autonomous platforms along three ocean transects with strong gradients in carbon export. Results from this study will broaden the geographic distribution of experimentally-determined marine biological pump observations. The project will involve training for a postdoctoral researcher and will develop an educational module on carbon cycle science for high school teachers.The oxygen mass balance method has been used to determine net annual biological oxygen production at marine time-series sites using shipboard oxygen measurements and mooring-based oxygen sensors that are calibrated by Winkler titrations. It has thus far been difficult to use this method on profiling floats because the oxygen sensors have not been accurate. Recent studies have shown improved accuracies in oxygen concentration measurements using Optodes on Argo floats compared with the Winkler titrations. In this project, a researcher will deploy Argo floats with calibrated and specially mounted Aanderaa Optode oxygen sensors along three transects in the Atlantic and Pacific Oceans that cross regions of stark contrasts in biological carbon export. The data will be used along with an upper ocean model to determine annual net biological oxygen production, which is stoichiometrically related to annual net community production (ANCP) and annual organic carbon export. The goal of this work is to determine the geographic distribution of ANCP, and compare it with carbon export values determined from satellite-based methods. In addition, the researcher will also develop an oxygen-Argo system capable of monitoring small changes in the oxygen concentration of the oxygen minimum zone.