Collaborative Research: Autonomous eddy covariance air-sea CO2 flux system for moored buoys

准确预测大气和海洋之间的二氧化碳交换是地球系统模式的一项重要要求，但最先进的气候模式中的交换估计仍然不确定。 需要改进的一个模型因素是气-海界面上的气体传输速率，微气象涡动协方差（EC）通量技术可以提供所需的实地测量，以改进和验证各种风浪条件下的传输速率模型。 虽然EC技术在陆地上被广泛采用，但一些技术障碍阻碍了这种方法在海上收集CO2通量数据，特别是在无人值守的浮动平台上。该团队最近的工作表明，快速响应的闭合路径CO2传感器，EC技术的核心，可以修改，以大大减少由于船舶和浮标运动效应的CO2误差。 根据这项新计划，该团队将进一步改进这些传感器，并调整用于大型船载CO2通量系统的方法，以开发一种小型，强大，准确和低功耗的系统，适用于越来越多的自主海洋观测平台。该项目的目标是：1）设计、建造和现场演示下一代红外气体分析仪，该分析仪旨在有效消除困扰先前海气交换现场实验的运动干扰，2）构建和部署一个紧凑的端到端端涡度相关CO2通量系统，适用于在所有天气条件下进行自主测量，并适用于必须满足电力需求的小型海洋观测平台。最小化将在缅因州海湾的一个长期CO2测量站点附近进行海上浮标现场演示，支持海洋和气象观测将提供传感器和系统评估和验证所需的数据。这项工作将采用团队方法进行，正式合作伙伴工业，学术界和海洋观测系统工程师。 该项目的最终基于海洋的通量测量系统将与NSF OOI合作设计，以促进与现有和未来海洋观测平台的集成，为扩大海上直接协方差CO2通量测量铺平道路，以支持广泛的碳循环和空气-该奖项反映了美国国家科学基金会的法定使命，并被认为是值得通过使用基金会的学术价值和更广泛的影响审查标准。

Accurate prediction of carbon dioxide exchange between the atmosphere and oceans is an important earth system model requirement, but the exchange estimates in state-of-the-art climate models remain uncertain. One model factor that requires improvement is the rate of gas transfer across the air-sea interface, and the micrometeorological eddy covariance (EC) flux technique can provide field measurements needed to improve and validate transfer rate models across a broad range of wind and wave conditions. While the EC technique is widely employed on land, several technical hurdles have hindered wider adoption of this approach for CO2 flux data collection at sea, particularly on unattended floating platforms. Recent work by this team has demonstrated that fast-response closed-path CO2 sensors, central to the EC technique, can be modified to substantially reduce CO2 error due to ship and buoy motion effects. Under this new program, the team will further improve these sensors and also adapt approaches used for larger shipboard CO2 flux systems to develop a small, robust, accurate, and low power system suitable for use on a growing number of autonomous ocean observing platforms. The goals of this project are to 1) design, build and field-demonstrate a next generation infrared gas analyzer engineered to effectively remove motion interference that has plagued previous air-sea gas exchange field experiments, and 2) build and deploy a compact end-to-end eddy covariance CO2 flux system suitable for autonomous measurements through all weather conditions and on small ocean observing platforms where power demands must be minimized. Offshore buoy field demonstrations will be conducted near a long-term CO2 measurement site in the Gulf of Maine where supporting ocean and meteorological observations will provide data needed for sensor and system assessment and validation. The work will be performed using a team approach that formally partners industry, academia, and ocean observing system engineers. The project's final buoy-based flux measurement system will be designed in collaboration with NSF OOI to facilitate integration onto existing and future ocean observing platforms, paving a way for expanded at-sea direct covariance CO2 flux measurements to support a broad range of carbon cycle and air-sea interaction studies and applications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.