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）观测站位于南纬47°、东经141°附近的亚南极水域，由自主系泊设备组成，可提供高时间分辨率的观测数据。该观测站聚焦于亚南极带，因该区域冬季深层对流在表层形成的水体，会滑入温暖的亚热带与热带水体之下，将二氧化碳（CO₂）和热量输送至与大气隔绝的深海。这一过程还可为深海生态系统供氧，并输出营养物质——此类物质支撑着全球约70%的海洋初级生产力。

区域生物生产亦会影响碳循环，SOTS系泊设备可测量多个对这些过程至关重要的变量，包括太阳辐射、叶绿素荧光、光学后向散射、溶解硝酸盐、溶解氧，以及（通过总气体张力装置测量的）总溶解气体。溶解氧与总气体张力观测数据可结合使用，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力（net community production, NCP）。本报告聚焦于这一方法及相关的MATLAB代码。该代码目前已明确适用于SOTS的前三期系泊部署数据——这些部署配备了NCP计算所需的全套成功运行的生物地球化学传感器，具体包括Pulse-7、Pulse-9和SOFS-7.5。代码设计支持扩展至未来的SOTS数据集及其他时间序列观测数据。