Collaborative Research: A new system for air-sea CO2 flux measurements from moored and unmanned surface platforms

海洋在全球碳预算中发挥着关键作用，目前吸收了大约四分之一的人为二氧化碳排放量。CO2在海气界面上的通量在模型中使用交换系数或“转移速度”表示，这种系数在大小和空间分布上都非常不确定，导致当前和未来碳预算的不确定性。在短时间尺度上测量海气CO2交换的能力是必要的，在广泛的海洋和大气条件下，发展更准确的参数化的气体交换与更现实的物理过程的代表性影响湍流在海气界面。这项研究的目的是发展直接测量浮标的海气CO2通量的能力，并有可能大大扩大直接通量测量数据库。如果成功，该项目将提供海洋时间序列观测的新能力，并有可能纳入现有和未来的海洋观测系统。这些能力可以适用于其他低功率、移动的平台（柱形浮标、双体船、滑翔机），从而能够采用新的观测方法，并深入了解各种时空尺度的过程。该项目所实现的未来测量也有可能影响更广泛的政策，为各机构和决策者提供更准确的信息，说明海洋如何以及在何处吸收和释放碳。该项目将建立和测试第一个可部署在浮标平台上的二氧化碳通量测量系统。测量方法利用涡度协方差技术，该技术提供具有高空间（1-10平方公里）和时间（10-60分钟）分辨率的直接通量测量。此前，涡度相关海气CO2通量测量仅限于研究船，导致可用于提高对海气气体交换理解的数据收集在空间和时间上受到限制。本研究旨在通过直接解决发展基于涡度相关CO2通量系统的主要技术障碍来开发鲁棒，高分辨率，低功耗，基于涡度相关CO2通量测量的能力：通量的小幅度（信噪比差），传感器性能限制，低功耗可用性和苛刻的采样条件。与仪器制造商合作改进传感器CO2性能将为更广泛的海洋学研究界的商业化和使用提供一条明确的途径。的生存能力和功率优化的挑战将通过适应主要调查？的经验与舰载和舰载系统。该项目将利用现成的广泛实验室和现场设施，包括船舶，浮标，室内深潜池，并进入缅因州海湾进行实地工作。

The oceans play a key role in the global carbon budget, currently absorbing roughly one quarter of anthropogenic CO2 emissions. The flux of CO2 across the air-sea interface is represented in models using an exchange coefficient or "transfer velocity" that is highly uncertain both in magnitude and spatial distribution, leading to uncertainty in current and future carbon budgets. The ability to measure air-sea CO2 exchange on short time scales over a broad range of ocean and atmospheric conditions is necessary to develop more accurate parameterizations of gas exchange with more realistic representation of physical processes affecting turbulence at the air-sea interface. This research aims to develop the capability to directly measure air-sea CO2 fluxes from buoys, with the potential to dramatically expand the database of direct flux measurements. If successful, this project will provide new capabilities for ocean time-series observations and the potential for incorporation into existing and future buoy-based ocean observing systems. These capabilities can adapt to other low-power, mobile platforms (spar buoys, catamarans, gliders) that will enable new observational approaches and insights into processes at a range of spatial and temporal scales. Future measurements enabled by this project also have the potential to impact broader policy by providing more accurate information for agencies and policy makers on how and where oceans take up and release carbon.This project will build and test the first CO2 flux measurement system that can be deployed on a buoy platform. The measurement approach utilizes the eddy covariance technique, which provides a direct flux measurement with high spatial (1-10 km2) and temporal (10-60 min) resolution. Previously, eddy covariance air-sea CO2 flux measurements have been restricted to research vessels, resulting in spatial and temporal limits on the collection of data that can be used to improve understanding of air-sea gas exchange. This research aims to develop the capability for robust, high-resolution, low-power, buoy-based CO2 flux measurements by directly addressing the primary technological obstacles to development of buoy-based eddy covariance CO2 flux systems: the small magnitude of the flux (poor signal-to-noise ratio), sensor performance limitations, low power availability, and harsh sampling conditions. Improvements to the sensor CO2 performance in collaboration with an instrument manufacturer will provide a clear pathway to commercialization and use by the broader oceanographic research community. The survivability and power-optimization challenges will be addressed by adapting the principle investigator?s experiences with both shipboard and buoy-based systems. The project will leverage ready access to extensive lab and field facilities that include ships, buoys, an indoor deep dive tank, and access to the Gulf of Maine for field work.