Simulation of air-sea CO2 flux in an ocean model: understanding processes and using data assimilation

海洋模型中海气二氧化碳通量的模拟：理解过程并使用数据同化

• 批准号: 2072326
• 金额: --
• 依托单位: UNIVERSITY OF EXETER
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2072326
• 关键词: Simulation; air; sea; CO2; flux

Background: The Southern Ocean plays a key role in the global carbon system, with many studies indicating that it may account for 40% of anthropogenic carbon dioxide (CO2) ocean uptake, and thus significantly slowing the rate of climate change due to fossil fuel use. Despite it's significance, the Southern Ocean remains one of the most poorly sampled and understood areas of the global ocean, with winter-time measurements of carbon uptake almost non-existent. As a result, large uncertainties remain in quantifying how carbon fluxes may vary both spatially and temporally in the Southern Ocean. For example, recent findings from the US Southern Ocean Carbon and Climate Observations and Modeling program (SOCCOM: https://soccom.princeton.edu/), which has deployed a network of specially equipped floats able to capture winter-time CO2 fluxes, suggest that the Southern Ocean is a net source of CO2 to the atmosphere. The implication of the SOCCOM results is that our understanding of the global carbon system may need some radical revision. This PhD project will tackle the important need for better quantification and understanding of the spatial and temporal patterns of Southern Ocean CO2 flux measurements through both cutting-edge autonomous instrumentation and satellite observations.MethodologyThe student will investigate CO2 flux estimates in the recent Met Office ocean model. Results will be compared with the Surface Ocean Carbon Atlas (SOCAT: www.socat.info) and SOCCOM measurements and possible the MIT GCM.The student will derive CO2 flux estimates from satellite observations of the Southern Ocean e.g. by exploiting salinity-alkalinity relationships (Land et al., 2015) using the ESA's SMOS satellite, launched in 2009. A recent study, led by the University of Exeter, is the first to demonstrate such techniques. Estimated CO2 flux patterns will be used to better understand the physical processes that modulate carbon uptake by the Southern Ocean e.g. upwelling regions, eddy variability, storms, fronts, mixed layer depth, the Southern Annular Mode and potentially the implications for global meridional overturning circulation patterns. This work will complement both the US SOCCOM initiative and current NERC funded UK programs: CaPASOS and the Role of the Southern Ocean in the Earth System (RoSES).The student will also work in collaboration with the recently funded NERC project Calibrated pCO2 in Air and Surface Ocean Sensor (CaPASOS), to aid the development of a novel carbon-flux instrument that can be mounted on unmanned surface vehicles. The student will be immediately integrated into the project (with trials starting in winter 2019/20), for which NEXUSS training will be highly relevant.Project is partly funded by the NEXUSS CDT and the student will have access to NEXUSS training evens: There will be extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial / government / policy partners

背景：南大洋在全球碳系统中发挥着关键作用，许多研究表明，它可能占海洋人为二氧化碳（CO2）吸收量的40%，从而显著减缓了由化石燃料使用引起的气候变化的速度。尽管南大洋意义重大，但它仍然是全球海洋中采样和了解最少的地区之一，冬季对碳吸收的测量几乎不存在。因此，在量化南大洋的碳通量如何在空间和时间上变化方面仍然存在很大的不确定性。例如，美国南大洋碳和气候观测与模拟项目（SOCCOM: https://soccom.princeton.edu/）最近的发现表明，南大洋是大气中二氧化碳的净来源。该项目部署了一个由专门装备的浮标组成的网络，能够捕捉冬季的二氧化碳通量。SOCCOM结果的含义是，我们对全球碳系统的理解可能需要一些彻底的修正。这个博士项目将通过尖端的自主仪器和卫星观测，解决更好地量化和理解南大洋二氧化碳通量测量的时空格局的重要需求。该学生将研究最近英国气象局海洋模型中二氧化碳通量的估计。结果将与表层海洋碳图谱（SOCAT: www.socat.info）和SOCCOM测量结果以及可能的麻省理工学院GCM进行比较。该学生将利用2009年发射的欧空局SMOS卫星，通过对南大洋的卫星观测，例如利用盐度-碱度关系（Land等人，2015年），得出二氧化碳通量估计。最近由埃克塞特大学领导的一项研究首次展示了这种技术。估计的二氧化碳通量模式将用于更好地理解调节南大洋碳吸收的物理过程，如上升流区、涡旋变率、风暴、锋面、混合层深度、南环模以及对全球经向翻转环流模式的潜在影响。这项工作将补充美国SOCCOM计划和目前NERC资助的英国项目：CaPASOS和南大洋在地球系统中的作用（RoSES）。该学生还将与最近资助的NERC项目“校准空气和海洋表面二氧化碳传感器”（CaPASOS）合作，帮助开发一种新型的碳通量仪器，该仪器可以安装在无人驾驶的水面车辆上。该学生将立即融入该项目（从2019/20冬季开始试验），NEXUSS培训将与此高度相关。项目部分由NEXUSS CDT资助，学生将有机会参加NEXUSS培训课程：通过与广泛的学术、研究和工业/政府/政策合作伙伴网络的互动，学生将有广泛的机会扩展他们的多学科前景