Oceanic concentrations and emissions toward atmosphere of carbon monoxide simulated by the PISCES biogeochemical model

The ocean constitutes a minor source of atmospheric carbon monoxide (CO) at the global scale, but could play an important role far from continental anthropized emission zones. Here we use the NEMO-PISCES (Nucleus for European Modelling of the Ocean, Pelagic Interaction Scheme for Carbon and Ecosystem Studies) ocean general circulation and biogeochemistry model to dynamically assess the oceanic CO budget and its emission to the atmosphere at the global scale. The main bio-chemical sources and sinks of oceanic CO are explicitly represented in the model. The main processes driving the CO concentration are photoproduction and bacterial consumption and are estimated to 19.2 and 21.9 Tg C yr−1 respectively with our best-guess modelling setup. There are however very large uncertainties on their respective magnitude. Despite the scarcity of the in situ CO measurements in terms of spatio-temporal coverage, the proposed best simulation is able to represent most of the data (~ 300 points) within a factor of two. Overall, the global emissions of CO to the atmosphere are 3.6 Tg C yr−1, in the range of recent estimates, but very different from the ones published by Erickson in 1989, which were the only gridded global emission available to date. These oceanic CO emission maps are relevant for use by atmospheric chemical models, especially to study the oxidizing capacity of the atmosphere above the remote ocean.

从全球尺度来看，海洋是大气一氧化碳（carbon monoxide, CO）的次要来源，但在远离大陆人为排放区的海域中，海洋可能发挥着重要作用。本研究采用NEMO-PISCES（欧洲海洋建模核心、碳与生态系统研究中上层相互作用方案）海洋环流与生物地球化学耦合模式，对全球尺度下的海洋一氧化碳收支及其向大气的排放进行动态评估。该模式明确刻画了海洋中一氧化碳的主要生物化学源与汇。通过本研究最优的模式配置方案，主导一氧化碳浓度变化的核心过程为光化学生成与细菌消耗，其通量分别约为19.2和21.9太克碳每年（Tg C yr⁻¹）。然而，这两类过程的通量规模存在极大不确定性。尽管原位一氧化碳观测的时空覆盖范围极为有限，但本研究提出的最优模拟结果能够将约300个观测点的数值控制在两倍误差范围内。整体而言，全球海洋向大气排放的一氧化碳通量为3.6太克碳每年（Tg C yr⁻¹），处于近期研究估算的区间内，但与1989年Erickson发布的估算结果差异显著——后者是迄今为止仅有的网格化全球海洋一氧化碳排放数据。这套海洋一氧化碳排放场数据可用于大气化学模式研究，尤其适用于偏远洋面上方大气氧化能力的相关研究。