NSF-NERC: Thwaites-Amundsen Regional Survey and Network (TARSAN) Integrating Atmosphere-Ice-Ocean Processes affecting the Sub-Ice-Shelf Environment

该项目有助于美国国家科学基金会（NSF）和英国联合发起的联合倡议。自然环境研究理事会（NERC）将大幅改善对南极洲西部Thwaites冰川造成的冰损失和海平面上升的十年期和长期预测。 由于最近的气候变暖和海洋环流的相关变化，阿蒙森海湾的斯威特冰川和邻近冰川正在迅速失去质量。阿蒙森海湾的质量损失可能导致南极西部冰盖的最终崩溃，在短短500年内将全球海平面提高2.5米（8英尺）。导致冰川流失的过程似乎是温暖的海洋环流以及冰川宽度和流速的变化，但需要更好地了解这些变化，以完善对冰川演变的预测。一个高度敏感的过程是冰川冰从陆地到海洋的过渡流动，成为一个浮动的冰架。冰从地面到漂浮的流动受到以下因素的影响：气温和表面降雪的变化;上游冰的速度和厚度;以及冰流入的海洋温度，盐度，水深和水流。项目团队将收集这些当地环境条件的新测量结果，以便更好地预测未来空气，海洋或冰的变化将如何影响该地区冰向海洋的流失。 目前和预期不久的将来从斯韦茨冰川和附近的阿蒙森海海湾地区的质量损失主要是由于减少冰架支撑由于冰架下融化的相对温暖的极地周围的深水入侵到冰架下的空腔。然而，对质量损失的这种预测仍然缺乏对接地区及其附近主要过程的了解，特别是其空间和时间变化，以及这些过程的大气和海洋驱动因素。该项目旨在限制和比较这些过程的Thwaites和Dotson冰架，这是通过上游冰动力学连接，但不同的海底槽的影响。该小组的具体目标是：1）在冰架上安装大气-冰-海洋多传感器远程自主站，为期两年，以提供对同时发生的海洋、冰川和大气状况的亚日常连续观测; 2）测量冰架前沿附近大陆架上的海洋特性（利用海豹标记、滑翔机和船舶勘测以及现有的系泊和电导率-温度-深度-预测数据），3）测量冰架下洞穴的海洋特性（使用自主水下航行器）详细说明海洋运输和热通量; 4）限制当前冰架和冰架下空洞的几何形状、冰流和冰架的积雪特性（利用雷达、有源地震和重力测量方法）更好地了解海洋和大气对冰盖变化的影响。 该团队还将通过“冰上直播”活动吸引公众，社会媒体活动，公众可以从标记的海豹和自主站的角度关注行动和数据收集。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查进行评估，被认为值得支持的搜索.

This project contributes to the joint initiative launched by the U.S. National Science Foundation (NSF) and the U.K. Natural Environment Research Council (NERC) to substantially improve decadal and longer-term projections of ice loss and sea-level rise originating from Thwaites Glacier in West Antarctica. Thwaites and neighboring glaciers in the Amundsen Sea Embayment are rapidly losing mass in response to recent climate warming and related changes in ocean circulation. Mass loss from the Amundsen Sea Embayment could lead to the eventual collapse of the West Antarctic Ice Sheet, raising the global sea level by up to 2.5 meters (8 feet) in as short as 500 years. The processes driving the loss appear to be warmer ocean circulation and changes in the width and flow speed of the glacier, but a better understanding of these changes is needed to refine predictions of how the glacier will evolve. One highly sensitive process is the transitional flow of glacier ice from land onto the ocean to become a floating ice shelf. This flow of ice from grounded to floating is affected by changes in air temperature and snowfall at the surface; the speed and thickness of ice feeding it from upstream; and the ocean temperature, salinity, bathymetry, and currents that the ice flows into. The project team will gather new measurements of each of these local environmental conditions so that it can better predict how future changes in air, ocean, or the ice will affect the loss of ice to the ocean in this region. Current and anticipated near-future mass loss from Thwaites Glacier and nearby Amundsen Sea Embayment region is mainly attributed to reduction in ice-shelf buttressing due to sub-ice-shelf melting by intrusion of relatively warm Circumpolar Deep Water into sub-ice-shelf cavities. Such predictions for mass loss, however, still lack understanding of the dominant processes at and near grounding zones, especially their spatial and temporal variability, as well as atmospheric and oceanic drivers of these processes. This project aims to constrain and compare these processes for the Thwaites and the Dotson Ice Shelves, which are connected through upstream ice dynamics, but influenced by different submarine troughs. The team's specific objectives are to: 1) install atmosphere-ice-ocean multi-sensor remote autonomous stations on the ice shelves for two years to provide sub-daily continuous observations of concurrent oceanic, glaciologic, and atmospheric conditions; 2) measure ocean properties on the continental shelf adjacent to ice-shelf fronts (using seal tagging, glider-based and ship-based surveys, and existing moored and conductivity-temperature-depth-cast data), 3) measure ocean properties into sub-ice-shelf cavities (using autonomous underwater vehicles) to detail ocean transports and heat fluxes; and 4) constrain current ice-shelf and sub-ice-shelf cavity geometry, ice flow, and firn properties for the ice-shelves (using radar, active-source seismic, and gravimetric methods) to better understand the impact of ocean and atmosphere on the ice-sheet change. The team will also engage the public and bring awareness to this rapidly changing component of the cryosphere through a "Live from the Ice" social media campaign in which the public can follow the action and data collection from the perspective of tagged seals and autonomous stations.This 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.