NBP1402 diatom data

Totten Glacier is the termination of the largest marine-based portion of the East Antarctic Ice Sheet, the Aurora Subglacial Basin. Yet little is known about the glacial evolution of the catchment and the factors influencing its present and past behavior. Due its remote location and heavy sea ice, the continental shelf in front of the Totten Glacier had not been comprehensively surveyed prior to this study. Satellite observations indicate that the Totten ice drainage system is thinning, and it has been hypothesized that this thinning is in response to undermelting by warm ocean waters over the continental shelf. While this process is observed elsewhere in Antarctica (e.g. the rapidly retreating Pine Island Glacier in West Antarctica), the Totten Glacier system is potentially Antarcticas most important glacial drainage system due to its large size; it is three times larger than any system in West Antarctica. </br>The main goals of this proposal were: </br>To generate multibeam bathymetric maps of the continental shelf proximal to the Totten Glacier system to understand the recent regional glacial history and to document the pathways, if any, for circumpolar deep water to move onto the shelf. </br>To conduct a physical oceanographic survey of the region proximal to the Totten Glacier system, to determine the presence, if any, of warm ocean waters over the continental shelf.</br>To conduct a seismic survey of the continental shelf to assess the long-term evolution of the glacial system in the Aurora Subglacial Basin.</br>To collect marine sediment cores to determine the regional deglacial to Holocene climate history and the influence of warm circumpolar deep water.

托滕冰川（Totten Glacier）是东南极冰盖（East Antarctic Ice Sheet）最大的海洋性冰体分支——奥罗拉冰下盆地（Aurora Subglacial Basin）的末端。然而，学界对该冰川流域的演化过程，以及调控该冰体现今与过去冰态的驱动因素仍知之甚少。由于地处偏远且海冰覆盖密集，本研究开展前，托滕冰川前方的大陆架尚未得到全面勘测。卫星观测显示，托滕冰川的冰体排泄系统正经历变薄过程，且已有假说提出，该变薄现象源于大陆架上方暖洋水对冰体的底熔侵蚀。这一底熔过程在南极洲其他区域已被观测证实，例如西南极洲快速消退的松岛冰川（Pine Island Glacier）；但托滕冰川系统因规模庞大，堪称南极洲最为关键的冰川排水系统——其规模是西南极洲所有冰川排水系统的三倍。
本项目的核心研究目标如下：
1. 绘制托滕冰川系统邻近海域大陆架的多波束测深图，以解析该区域近期的区域性冰川演化历史，并探明绕极深层水（circumpolar deep water）流入陆架的潜在路径；
2. 开展托滕冰川系统邻近海域的物理海洋学勘测，以确定大陆架上方是否存在暖洋水；
3. 对该大陆架开展地震勘测，以评估奥罗拉冰下盆地内冰川系统的长期演化历程；
4. 采集海洋沉积岩芯，以重建该区域从冰消期到全新世（Holocene）的气候演化历史，并厘清暖绕极深层水的影响机制。