Changing Arctic: Estimation of freshwater changes over the full Arctic basin including land and ocean from satellite observations

不断变化的北极：根据卫星观测估计整个北极盆地（包括陆地和海洋）的淡水变化

• 批准号: 2438969
• 金额: --
• 依托单位: University of Edinburgh
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2438969
• 关键词: Changing; Arctic; Estimation; freshwater; changes

Rapid Arctic warming drives profound change in the marine environment. It has strong socio-economic impacts in the Arctic but also affecting Europe including climate and weather hazards and food security [1]. The Arctic Ocean (AO) is a semi-closed basin mostly covered by sea ice but with a fast-declining pace of 13% per decade [NSIDC 1979-2019 September]. Air-sea exchange of heat and momentum are increased in this opening ocean in addition to freshwater input from the Greenland ice sheet and an intensification of the global water cycle leading to a freshwater input in the AO. Freshwater content in the AO is critical for the Atlantic Meridional Overturning Circulation (AMOC) which is responsible for 25% of heat transport to polar latitude [2] and its strength has significant impact on European climate [3].Our knowledge of the AO is very limited compared to other ocean basins due to its difficult access and depend on very sparse in situ measurements. Despite this, we know its sea surface salinity (SSS) variability to be very high, both spatially from 27 to 35 psu and seasonally with variation higher than 4 psu. The AO drainage basin is covering Greenland, most of Russia and Canada and is characterized by big river runoff driving most of the variability on Siberian and Canada continental shelf [4].AO satellite observations are generally difficult due to mix of sea and sea ice in observations. However, specific processing of satellite observations in altimetry and SSS [5] have recently shown promising results.In this project, you will combine satellite observations of satellite precipitation (GPM) over the full Arctic basin, with satellite observations of land soil moisture or freezing state (e.g. from SMOS), river run-off (altimetry, SWOT), land ice changes and sea surface water content from surface (SSS, sea ice) and integrated (altimetry) measurements, to produce a complete picture of freshwater changes in the Arctic freshwater system.Research questionsWhat is the freshwater content over the Arctic Ocean drainage basin and its spatio-temporal variability?What are the physical processes governing the spatio-temporal variability and as function of the different time scales (seasonal, interannual)?How do these Arctic Ocean processes impact the Earth climate system?MethodologyWe will use satellite data that are freely available from NASA, ESA, EUMETSAT repositories and specifically the relevant ESA Climate Change Initiative Essential Climate Variable, ice sheet, permafrost, sea surface salinity, sea ice, sea level, .... NASA-CNES (+ CAS, UKSA participation) SWOT satellite mission data will be used at the end of the PhD project.Regional numerical model outputs are freely available from the EU Copernicus Marine Environment Monitoring Service (CMEMS) and reanalysis from ECMWF (ERA5). In addition, we will also take advantage of the high-resolution coupled model developed conjointly between NOC and MetOfficeTrainingIn addition to the comprehensive personal and professional development training provided within the SENSE programme, you will have the opportunity to participate in a research oceanographic cruise. You will also have the opportunity to work closely with the European Space Agency with a 3-month placement in Frascati (ESA-ESRIN) close to Roma, Italy.

北极快速变暖导致海洋环境发生深刻变化。它在北极地区具有强烈的社会经济影响，但也影响到欧洲，包括气候和天气灾害以及粮食安全问题。北冰洋（AO）是一个半封闭的盆地，大部分被海冰覆盖，但以每十年13%的速度快速下降[NSIDC 1979-2019年9月]。除了来自格陵兰冰原的淡水输入和全球水循环的加剧导致AO的淡水输入外，这一开放海洋的海气热和动量交换也增加了。大西洋经向翻转环流（AMOC）的淡水含量对大西洋经向翻转环流（AMOC）至关重要，AMOC负责25%的极纬热输送，其强度对欧洲气候[3]有重要影响。与其他海洋盆地相比，我们对AO的了解非常有限，因为它很难接近，而且依赖于非常稀疏的现场测量。尽管如此，我们知道它的海面盐度（SSS）变化非常大，空间变化在27 ~ 35 psu之间，季节变化大于4 psu。AO流域覆盖了格陵兰岛、俄罗斯和加拿大的大部分地区，其特征是大河径流驱动了西伯利亚和加拿大大陆架地区的大部分变率。由于观测中存在海洋和海冰的混合，因此AO卫星观测通常很困难。然而，卫星观测在测高和SSS[5]方面的具体处理最近显示出有希望的结果。在这个项目中，你将把整个北极盆地的卫星降水（GPM）卫星观测与陆地土壤湿度或冻结状态（例如来自SMOS）、河流径流（高程，SWOT）、陆地冰变化和海洋表面水含量（SSS，海冰）的卫星观测以及综合（高程）测量相结合，生成北极淡水系统淡水变化的完整图像。研究问题：北冰洋流域的淡水含量及其时空变异性是什么？在不同的时间尺度（季节、年际）下，控制时空变化的物理过程是什么？这些北冰洋过程是如何影响地球气候系统的？方法：我们将使用NASA、ESA、EUMETSAT数据库免费提供的卫星数据，特别是相关的ESA气候变化倡议基本气候变量、冰盖、永久冻土、海面盐度、海冰、海平面，....NASA-CNES （+ CAS， UKSA参与）SWOT卫星任务数据将在博士项目结束时使用。区域数值模式的输出可从欧盟哥白尼海洋环境监测服务（CMEMS）和ECMWF （ERA5）免费获得。此外，我们还将利用NOC与metoffictrainings.com联合开发的高分辨率耦合模型，除了在SENSE计划中提供的全面的个人和专业发展培训外，您还将有机会参加海洋研究游轮。您还将有机会与欧洲航天局密切合作，在意大利罗马附近的弗拉斯卡蒂（ESA-ESRIN）进行为期3个月的实习。