Net Community Production from O2 measurements on Argo Floats

生物产生的有机物质从上层阳光照射的沃茨流向深海，这被称为“生物泵”。海洋生物泵的地理分布和时间变化影响大气二氧化碳水平，并维持阳光照射区以下海洋中的氧气分布。确定这一通量对于了解与气候变化有关的海洋碳循环反馈至关重要。目前使用的船上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，通过利用位于沿着三个碳输出梯度很大的海洋断面的自主平台上的传感器，精确测量氧气的年循环，实现实验结果的必要地理多样性。这项研究的结果将扩大实验确定的海洋生物泵观测的地理分布。该项目将包括培训一名博士后研究员，并将为高中教师开发一个碳循环科学教育模块，利用船上氧气测量和系泊氧气传感器（经温克勒滴定校准），采用氧质量平衡法确定海洋时间序列地点的净年度生物氧气生产量。由于氧传感器不准确，因此迄今为止难以在剖面浮标上使用这种方法。最近的研究表明，与Winkler滴定法相比，在Argo浮标上使用Optodes测量氧气浓度的精度有所提高。在这个项目中，一名研究人员将沿着大西洋和太平洋的三个断面部署Argo浮标，这些浮标带有校准和专门安装的Aanderaa Optode氧传感器，这些断面跨越生物碳出口形成鲜明对比的区域。这些数据将与上层海洋模型一起沿着使用，以确定年度净生物氧产量，这与年度净群落产量（ANCP）和年度有机碳输出量有化学计量关系。这项工作的目标是确定ANCP的地理分布，并将其与基于卫星的方法确定的碳输出值进行比较。此外，研究人员还将开发一种能够监测氧气最小区氧气浓度微小变化的氧气-Argo系统。

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.