Role of the Southern Ocean Meridional Overturning Circulation in the Oceanic Distributions of N2O

一氧化二氮（N2 O）是一种微量的大气气体，其自然浓度正受到人类活动的影响，其大气浓度以每年约十亿分之0.7的速度从工业化前的270 ppb增加到目前的325 ppb以上。这种微量气体既作为温室气体，又有助于消耗高层大气中的臭氧。 海洋是大气中N2 O的重要来源-占全球每年向大气输入的近1/4。 N2 O是在海洋中通过影响这种化合物海洋分布的生物介导过程产生的。 然而，对世界海洋中N2 O浓度的测量相对较少。 为了更好地模拟N2 O浓度如何随气候变化而变化，必须监测海洋中这种痕量气体的当前分布，并确定浓度变化的速率。在过去的十年中，已经开发了一种用于测量人为示踪剂（即CFC-11，CFC-12和SF6）的海水样品中N2 O浓度的分析方法。在GO-SHIP的几个水文剖面上对N2 O浓度进行了初步测量。这项建议的一个组成部分是最后确定这些数据集，确保它们以相同的校准比例报告，并在数据的最后处理中经过相同的步骤。 这些N2 O数据随后将与水文数据合并，并通过气候和碳水文数据办公室提供给更广泛的科学界。这项研究将特别侧重于南大洋，那里以前只进行过几次N2 O测量，但它是确定海洋深层和底层沃茨内痕量气体浓度的重要区域。我们建议分析溶解N2 O从五个调查到南大洋和内。 这将使南大洋的海气交换和一氧化二氮的就地产生的影响的特点，并将使南大洋水团的一氧化二氮量化。 这些将提供关键的端元信息的生产率估计在毗邻的盆地，从而提高我们的理解和监测海洋的可能变化的N2 O cycleThis奖项反映了NSF的法定使命，并已被认为是值得支持，通过评估使用基金会的智力价值和更广泛的影响审查标准。

Nitrous oxide, N2O, is a trace atmospheric gas whose natural concentrations are being affected by the activities of man. Its atmospheric concentrations have increased at the rate of approximately 0.7 parts per billion (ppb) per year from pre-industrial levels of 270 ppb to over 325 ppb at present. This trace gas both acts as a greenhouse gas and contributes to the depletion of ozone in the upper atmosphere. The ocean is a significant source of N2O to the atmosphere – contributing nearly ¼ of the annual global input to the atmosphere. N2O is produced within the ocean by the biologically-mediated processes that affect the oceanic distribution of this compound. However, measurements of the concentrations of N2O in the world oceans are relatively sparse. In order to better model how the N2O concentrations may change in response to changes in the climate, it is important to monitor the current distributions of this trace gas in the ocean and to determine the rates at which the concentrations are changing. Over the past decade, an analytical method for measuring the N2O concentrations from seawater samples collected for measurement of the anthropogenic tracers (i.e. CFC-11, CFC-12, and SF6) has been developed. Preliminary measurements of N2O concentrations have been made on several GO-SHIP hydrographic sections. One component of this proposal is to finalize these data sets by ensuring they are reported on the same calibration scale and that they have undergone the same steps in the final processing of the data. These N2O data will then be merged with the hydrographic data and made available for the broader scientific community via the Climate and Carbon Hydrographic Data Office. This research will specifically focus on Southern Ocean, where only a few previous measurements of N2O has been made but is an important region for setting the concentrations of trace gases within the deep and bottom waters of the ocean. We propose to analyze dissolved N2O from five surveys into and within the Southern Ocean. This will allow the Southern Ocean influence of air-sea exchange and of in-situ production of N2O to be characterized, and will allow the N2O of Southern Ocean water masses to be quantified. These will provide critical endmember information on the production rate estimates in the adjoining basins, thus improving our understanding and monitoring of the ocean’s likely changing N2O cycleThis 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.