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

海洋在全球碳收支中发挥着关键作用，目前吸收了大约四分之一的人为二氧化碳排放。通过海气界面的CO2通量在模式中使用交换系数或“传递速度”来表示，该系数在大小和空间分布上都高度不确定，从而导致当前和未来碳收支的不确定性。在大范围的海洋和大气条件下，在短时间尺度上测量海气二氧化碳交换的能力对于开发更精确的气体交换参数化是必要的，这样可以更真实地表示影响海气界面湍流的物理过程。这项研究旨在发展从浮标直接测量大气-海洋二氧化碳通量的能力，有可能大大扩大直接通量测量数据库。如果成功，该项目将为海洋时间序列观测提供新的能力，并有可能纳入现有和未来的浮标海洋观测系统。这些能力可以适应其他低功率、移动平台（浮筒、双体船、滑翔机），这将使新的观测方法和对一系列空间和时间尺度的过程的见解成为可能。该项目支持的未来测量也有可能影响更广泛的政策，为各机构和政策制定者提供有关海洋吸收和释放碳的方式和地点的更准确信息。该项目将建立和测试第一个可以部署在浮标平台上的二氧化碳通量测量系统。测量方法利用涡旋相关方差技术，提供高空间（1-10平方公里）和时间（10-60分钟）分辨率的直接通量测量。以前，涡旋相关的海气二氧化碳通量测量仅限于研究船，这就限制了可用于提高对海气交换的了解的数据收集的空间和时间限制。本研究旨在通过直接解决浮标涡流相关CO2通量系统开发的主要技术障碍，开发鲁棒、高分辨率、低功耗、基于浮标的CO2通量测量能力：通量的小幅度（差的信噪比）、传感器性能限制、低功率可用性和苛刻的采样条件。与仪器制造商合作改进传感器的二氧化碳性能将为更广泛的海洋学研究界的商业化和使用提供明确的途径。生存能力和功率优化方面的挑战将通过调整主要研究者来解决。具备使用船载和浮标系统的经验。该项目将利用广泛的实验室和现场设施，包括船舶、浮标、室内深潜水池，并进入缅因湾进行现场工作。

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.