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

北极迅速变暖导致海洋环境发生深刻变化。它对北极产生了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[1]。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]。除了来自格陵兰冰盖的淡水输入和全球水循环的加强导致AO的淡水输入之外，在这个开放的海洋中，海-气热交换和动量增加。AO中的淡水含量对大西洋经向翻转环流（AMOC）至关重要，AMOC负责向极地纬度输送25%的热量[2]，其强度对欧洲气候有重大影响[3]。与其他海洋盆地相比，我们对AO的了解非常有限，因为它难以进入，并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）的变化是非常高的，空间从27至35 psu和季节变化高于4 psu。AO流域覆盖格陵兰岛、俄罗斯和加拿大的大部分地区，其特征是大河流径流驱动了西伯利亚和加拿大大陆架的大部分变化[4]。由于观测中海洋和海冰的混合，AO卫星观测通常很困难。然而，在测高和SSS [5]中对卫星观测的具体处理最近显示出有希望的结果。在本项目中，您将结合联合收割机对整个北极盆地卫星降水（GPM）的卫星观测，以及对陆地土壤湿度或冻结状态的卫星观测（例如来自SMOS）、河流径流（测高，SWOT），陆地冰变化和海面水含量从表面（SSS，海冰）和综合（测高）测量，以产生一个完整的图片淡水变化在北极淡水system.Research questionsWhat是淡水含量在北冰洋流域及其时空变异性？控制时空变化的物理过程是什么，以及作为不同时间尺度（季节、年际）的函数是什么？这些北冰洋过程如何影响地球气候系统？方法我们将使用从NASA，ESA，EUMETSAT存储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，......将在博士项目结束时使用NASA-CNES（+ CAS，UKSA参与）SWOT卫星使命数据，区域数值模型输出可从欧盟哥白尼海洋环境监测服务（CMEMS）免费获得，并从ECMWF（ERA 5）重新分析。此外，我们还将利用NOC和Metropolitan Training. In之间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，您将有机会参加海洋学研究巡航。您还将有机会与欧洲航天局密切合作，在靠近意大利罗马的弗拉斯卡蒂（ESA-ESRIN）进行为期3个月的实习。

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.