Collaborative Research: Autonomous Measurements of Carbon Fluxes in the North Atlantic Bloom

大西洋50度N以北的二氧化碳净吸收量约占全球总量的25%。生物泵，最重要的是每年春天发生的浮游植物水华，推动了这种吸收。以前的研究表明，在水华期间，小的时间和空间尺度，即生态系统斑块的重要性，但由于船基研究的固有局限性，在解决这些尺度方面取得的成功有限。 自主平台和传感器的最新进展现在使新方法能够持续测量具有潜在广泛影响的关键数量和速率。 在这项研究中，来自华盛顿大学和缅因大学奥罗诺分校的PI提出了一个过程实验，重点是海洋碳系统的一个重要组成部分-北大西洋春季水华-既有其内在的优点，也是开发成功使用这些新方法所需的战略和知识的试验台，以推动下一代海洋观测。PI将使用拉格朗日浮子来跟踪混合层中的水包裹，每个浮子都与漫游滑翔机相结合，以描述其周围环境。 浮子和滑翔机将测量-随着时间的推移在三维空间-垂直和水平混合率，以及关键的碳系统组件和速率。浮游植物和有机碳将通过一套光学代理进行量化，氧气通过两种不同的传感器进行量化，硝酸盐通过紫外光谱法进行量化。传感器的冗余、250- 1000米的参考测量、平台之间的交叉检查和三次航行的水样分析将用于维护和验证自主传感器的校准。通过铱卫星的双向通信将使采样战略能够根据观测到的情况而发展。测量将在2008年3月下旬爆发前的60度N附近进行，直到7月初爆发结束。 初级生产力和碳通量将根据经水平和垂直混合效应校正的氧、硝酸盐和生物量代用指标清单的变化计算。这些数据与伴随分析指导下的生物物理生态系统模型的系统比较，将用于评估这些模型预测小规模斑块和净碳吸收通过演变的水华的适当性。最重要的更广泛影响将是上文所述的海洋碳系统测量技术。拟议的工作还将支持对四名海洋观测研究生和本科实习生进行多学科培训。该计划将与COSEE-Ocean Systems合作，开发一个关于北大西洋海洋生态系统作用的“故事”，该故事将与非科学家产生共鸣，并被纳入国家科学教育内容标准中确定的领域。最后，该项目将与达尔豪西大学的一名加拿大科学家建立国际合作。

Net uptake of carbon dioxide in the Atlantic Ocean north of 50 degN accounts for about 25% of the global total. The biological pump, most importantly the phytoplankton bloom occurring each spring, drives this uptake. Previous studies have shown the importance of small temporal and spatial scales, i.e. ecosystem patchiness, during the bloom, but have had limited success in resolving these scales due to the inherent limitations of ship-based research. Recent advances in autonomous platforms and sensors now enable new approaches to sustained measurement of key quantities and rates that have potentially broad impacts. In this research, PIs from the University of Washington and the University of Maine-Orono, propose a process experiment focusing on an important component of the oceanic carbon system - the North Atlantic Spring Bloom - both for its intrinsic merit and as a test-bed for developing the strategies and knowledge needed to successfully use these new methods to drive the next generation of ocean observations. The PIs will use Lagrangian floats to follow water parcels in the mixed layer, with each float coupled with roving gliders to characterize its surroundings. The floats and gliders will measure - in three dimensions over time - the vertical and horizontal mixing rates, and key carbon system components and rates. Phytoplankton and organic carbon will be quantified through a suite of optical proxies, oxygen by two different sensors, and nitrate by UV spectrometry. Redundancy of sensors, reference measurements at 250-1000m, cross-checking among platforms and water sample analysis on three cruises will be used to maintain and verify the calibration of the autonomous sensors. Two-way communication via Iridium satellite will allow sampling strategies to evolve in response to observed conditions. Measurements will be made near 60 degN from late March 2008, before the bloom, through early July when it has ended. Primary productivity and carbon fluxes will be calculated from changes in inventories of oxygen, nitrate and biomass proxies corrected for the effects of horizontal and vertical mixing. Systematic comparison of these data with a bio-physical ecosystem model guided by adjoint analysis will be used to evaluate the appropriateness of such models for predicting both small-scale patchiness and net carbon uptake through the evolution of the bloom. The most important broader impact will be on the technology of ocean carbon system measurement as described above. The proposed work will also support multidisciplinary training of four graduate students in ocean observing, as well as undergraduate interns. The PIs will collaborate with the COSEE-Ocean Systems to develop a "story" on the role of the North Atlantic ocean ecosystem that will resonate with non-scientists and be integrated into areas identified in the National Science Education Content Standards. Finally, the project will build international collaboration with a Canadian scientist at Dalhousie University.