Data and calculations to support the study of the sea-air flux of methane and carbon dioxide on the West Spitsbergen margin in June 2014

A critical question for assessing global greenhouse gas budgets is how much of the methane that escapes from seafloor cold seep sites to the overlying water column eventually crosses the sea-air interface and reaches the atmosphere. The issue is particularly important in Arctic Ocean waters since rapid warming there increases the likelihood that gas hydrate--an ice-like form of methane and water stable at particular pressure and temperature conditions within marine sediments--will break down and release its methane to the overlying ocean. Some researchers have even proposed the possibility of an Arctic methane catastrophe characterized by wholesale breakdown of gas hydrates in marine sediments and release of the methane to the atmosphere as climate warms. This dataset collected on the West Spitsbergen margin during U.S. Geological Survey Coastal and Marine Geology Program Field Activity 2014-013-FA, which was carried out in conjunction with the University of Tromso and the GEOMAR Helmholtz Centre for Ocean Research Kiel on the R/V Helmer Hanssen, records 30-second-gridded methane and carbon dioxide concentrations in near-surface seawater and the atmospheric marine boundary layer, the carbon-13 isotopic composition of methane and carbon dioxide in the near-surface waters, and also environmental parameters (e.g., seawater salinity, wind speed, water and air temperatures). The results of calculations required to determine the sea-air flux of methane and carbon dioxide are also provided.

评估全球温室气体预算的核心问题之一，是海底冷渗漏（seafloor cold seep）区域逸散至上覆水柱的甲烷，最终有多少能够穿过海-气界面进入大气。这一问题在北冰洋海域尤为关键，因为该区域快速升温会提升天然气水合物（gas hydrate）分解并向其上覆海洋释放甲烷的概率——天然气水合物是一种在海洋沉积物特定压力与温度条件下稳定存在的冰状甲烷水合物。甚至有研究者提出了北极甲烷灾变的假说：随着气候变暖，海洋沉积物中的天然气水合物大规模分解并将甲烷释放至大气，进而引发此类灾变。本数据集采集于斯匹次卑尔根西部陆缘（West Spitsbergen margin），由美国地质调查局（U.S. Geological Survey）海岸与海洋地质计划2014-013-FA野外作业项目完成，该项目与特罗姆瑟大学（University of Tromso）以及基尔亥姆霍兹海洋研究中心（GEOMAR Helmholtz Centre for Ocean Research Kiel）合作开展，搭载于“赫尔默·汉森号”（R/V Helmer Hanssen）科考船。数据集记录了近表层海水与海洋大气边界层中甲烷、二氧化碳的30秒网格化浓度，近表层水体中甲烷与二氧化碳的碳-13同位素组成，以及环境参数（例如海水盐度、风速、水温与气温）。此外还提供了计算甲烷与二氧化碳海-气通量所需的相关结果。