IMOS - Southern Ocean Time Series (SOTS) - Net Community Production (NCP) Calculation Procedure and MATLAB Code

The Southern Ocean Time Series (SOTS) Observatory, located in Subantarctic waters near 141°E and 47°S, consists of autonomous moorings that provide high temporal resolution observations. It is focused on the Subantarctic Zone because waters formed at the surface in this region by deep wintertime convection slide under warmer subtropical and tropical waters, carrying CO2 and heat into the deep ocean, where it is out of contact with the atmosphere. This process also supplies oxygen for deep ocean ecosystems, and exports nutrients that fuel ~70% of global ocean primary production.

Local biological production also impacts carbon cycling and the SOTS moorings measure several variables important to these processes including solar radiation, chlorophyll fluorescence, optical backscatter, dissolved nitrate, dissolved oxygen, and total dissolved gases (using a total gas tension device). The oxygen and total gas tension observations can be combined to separate physical and biological contributions to surface mixed layer oxygen budgets and thus to yield estimates of net community production. This procedure, and the associated MATLAB code, are the subjects of this report. The code is currently enabled explicitly for the first three mooring deployments at SOTS with full suites of successful biogeochemical sensors required for the NCP calculations: Pulse-7, Pulse-9, and SOFS-7.5. It is constructed to allow expansion to future SOTS data sets, as well as other time series observations.

南大洋时间序列（Southern Ocean Time Series, SOTS）观测站位于东经141°、南纬47°附近的亚南极海域，由可提供高时间分辨率观测数据的自主系泊系统构成。该观测站聚焦亚南极带，原因在于该区域表层经冬季深层对流形成的水团会滑入暖亚热带与热带水团之下，将二氧化碳与热量带入与大气隔绝的深海之中。这一过程同时为深海生态系统提供氧气，并输送营养盐以支撑全球约70%的海洋初级生产活动。

区域生物生产活动同样会影响碳循环，SOTS系泊系统会测量与这些过程密切相关的多项参数，包括太阳辐射、叶绿素荧光、光学后向散射、溶解态硝酸盐、溶解氧以及总溶解气体（采用总气体张力仪进行测量）。可将溶解氧与总气体张力的观测数据相结合，以区分物理过程与生物过程对表层混合层氧收支的贡献，进而估算净群落生产（NCP, net community production）水平。本报告正是围绕这一分析流程及其配套的MATLAB代码展开。目前该代码已针对SOTS前三次系泊部署进行了显式适配，这三次部署搭载了用于NCP计算所需的全套合格生物地球化学传感器：Pulse-7、Pulse-9与SOFS-7.5。该代码的架构设计支持后续扩展至SOTS的其他数据集，以及其他时间序列观测项目。