Subantarctic zone oceanography - SAZ Project 1997-1998

Data were collected during the 1997-1998 austral summer on voyages by the Aurora Australis and Southern Surveyor.

Taken from the abstract of the referenced paper:

Oceanographic processes in the subantarctic region contribute crucially to the physical and biogeochemical aspects of the global climate system. To explore and quantify these contributions, the Antarctic Cooperative Research Centre (CRC) organised the SAZ Project, a multidisciplinary, multiship investigation carried out south of Australia in the austral summer of 1997-1998. Here we present a brief overview of the SAZ Project and some of its major results, as detailed in the 16 papers that follow in this special section.

The Southern Ocean plays an important role in the global oceanic overturning circulation and its influence on the carbon dioxide contents of the atmosphere. Deep waters upwelled to the surface are rich in nutrients and carbon dioxide. Air-sea interaction modifies the upwelled deep waters to form bottom, intermediate, and mode waters, which transport freshwater, oxygen, and carbon dioxide into the ocean interior. The overall effect on atmospheric carbon dioxide is a balance between outgassing from upwelled deep waters and uptake via both dissolution in newly formed waters (sometimes referred to as the solubility pump) and the transport of photosynthetically formed organic carbon to depth in settling particles (referred to as the biological pump). Determining the variations in the overturning circulation and the associated carbon fluxes in the past and their response to increased anthropogenic emissions of carbon dioxide in the future is essential to a full understanding of the controls on global climate. At present the upwelled nutrients are incompletely used. Low light in deep wind-mixed surface layers, lack of the micronutrient iron, and other factors restrict phtyoplankton production so that Southern Ocean surface waters represent the largest high-nutrient, low chlorophyll (HNLC) region in the world.

本数据集采集于1997-1998年南半球夏季，搭载于"南极光号（Aurora Australis）"与"南方调查号（Southern Surveyor）"的科考航次。

本内容取自参考文献论文摘要：

亚南极海域的海洋学过程，对全球气候系统的物理与生物地球化学特征发挥着至关重要的调控作用。为探究并量化这些调控贡献，南极合作研究中心（Antarctic Cooperative Research Centre, CRC）牵头实施了SAZ项目，该项目为多学科、多船协同科考计划，于1997-1998年南半球夏季在澳大利亚以南海域开展。本文简要概述了SAZ项目的整体情况与若干核心研究成果，相关细节详见本特刊后续刊载的16篇专题论文。

南大洋在全球大洋翻转环流以及其对大气二氧化碳含量的调控中扮演着核心角色。上升至表层的深层海水富含营养盐与二氧化碳。气海相互作用会改造上升的深层海水，形成底层水、中层水与模态水，这些水团将淡水、氧气与二氧化碳输送至海洋内部。大气二氧化碳的整体收支平衡，取决于上升深层海水的脱气过程，与两种固碳途径的综合作用：一是通过新形成水团的溶解作用（亦称溶解泵）吸收二氧化碳，二是通过沉降颗粒将光合生成的有机碳输送至深海（亦称生物泵）。厘清过去翻转环流与相关碳通量的变化规律，以及其未来对人为二氧化碳排放增加的响应机制，是全面理解全球气候调控机制的关键。当前，上升至表层的营养盐并未被完全利用：深水风混合表层的光照不足、微量营养元素铁的匮乏，以及其他诸多因素限制了浮游植物的生长，使得南大洋表层海域成为全球规模最大的高营养盐低叶绿素（High-Nutrient Low-Chlorophyll, HNLC）区域。