Reconciling ocean mass change and GIA from satellite gravity and altimetry (OMCG-2)

根据卫星重力和高度测量协调海洋质量变化和 GIA (OMCG-2)

• 批准号: 313917204
• 负责人: Professor Dr.-Ing. Martin Horwath
• 金额: --
• 依托单位: Lehrstuhl für Astronomische, Physikalische und Mathematische Geodäsie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/313917204?language=en
• 关键词: Reconciling; ocean; mass; change; GIA

Ocean mass change (OMC) is a major component of the sea level budget. Knowledge of OMC is required when inferring steric sea level variability from altimetry, with consequences for ocean heat content estimates and for understanding the Earth energy budget. The GRACE satellite gravity mission has been instrumental for recent OMC estimates, and GRACE-derived OMC is increasingly used in regional studies. Yet, published estimates of OMC, from essentially the same GRACE data, tend to disagree even at the global scale. Recent studies vary from 1.2 to 2.0 mm/a, often claiming unrealistic errors and budget closure at the 0.1-0.2 mm/a level. This is a major obstacle for inferring regional contemporary ocean heat content change from altimetry, e.g. in order to localize the sinks and transports of heat in the ocean. The problem is thus of particular significance for understanding and predicting regional sea level change in South-East Asian seas. The central hypothesis of this project, unchanged to the first phase of the SPP, is that these discrepancies are mostly related to (1) method issues in the analysis of the GRACE data and (2) the unsolved problem of removing the effect of Glacial Isostatic Adjustment (GIA) from the GRACE data. The first phase (OMCG-1) has resolved crucial methodological discrepancies in direct and inverse OMC estimates. In addition, OMCG-1 has improved the understanding of key elements for regional separating the GIA effect from combined geodetic satellite observations. OMCG-1 is further developing the global inverse approach and starting to incorporate results from the regional GIA separation studies into the global framework. The second phase (OMCG-2) will a) investigate improved methods of deriving fingerprints from model ensembles, b) investigate independent estimation of shallow and deep steric components, c) investigate the potential gain of integrating in-situ Argo data, d) implement a time-series-based parameter estimation approach for regional separation of GIA and ice mass change f) assign apparent biases in regional GIA estimates by the use of GNSS, and g) finally, incorporate altimetry over ice sheets as an additional observable in the global inversion to aid the separation of GIA. We will directly quantify physical processes that contribute to sea-level change at global and regional scale. Moreover, we will provide data-sets for modeling projects inside and outside the SPP. Especially our regionalized data for Northern Europe and Southeast Asia will help to improve projections in these areas.

海洋质量变化(OMC)是海平面预算的主要组成部分。在从测高推断海平面的空间变化、海洋热含量估计和了解地球能量收支的结果时，需要掌握海洋气象中心的知识。GRACE卫星重力任务对最近的OMC估计起到了重要作用，GRACE衍生的OMC越来越多地被用于区域研究。然而，即使在全球范围内，发表的对OMC的估计也往往不一致，这些估计来自基本上相同的GRACE数据。最近的研究从1.2毫米/年到2.0毫米/年不等，经常声称不切实际的误差和预算收尾在0.1-0.2毫米/年的水平。这是从测高推断区域当代海洋热含量变化的一个主要障碍，例如，为了定位海洋中的热汇和热传输。因此，这个问题对于了解和预测东南亚海域的区域海平面变化具有特别重要的意义。该项目的中心假设与SPP第一阶段相同，即这些差异主要与(1)GRACE数据分析中的方法问题和(2)从GRACE数据中消除冰川均衡调整(GIA)影响的未解决问题有关。第一阶段(OMCG-1)解决了直接和反向OMC估计中的关键方法差异。此外，OMCG-1提高了对区域分离GIA效应与综合大地测量卫星观测的关键要素的理解。OMCG-1正在进一步发展全球逆方法，并开始将区域GIA分离研究的成果纳入全球框架。第二阶段(OMCG-2)将：a)调查从模型集合中提取指纹的改进方法，b)调查浅层和深层空间分量的独立估计，c)调查整合现场ARGO数据的潜在收益，d)实施一种基于时间序列的参数估计方法，用于区域分离GIA和冰块变化，f)利用全球导航卫星系统在区域GIA估计中分配明显偏差，以及g)最后，将冰盖高度测量作为全球反演中的一个额外可观测指标，以帮助分离GIA。我们将直接量化在全球和区域范围内促成海平面变化的物理过程。此外，我们将为SPP内外的项目建模提供数据集。特别是我们对北欧和东南亚的区域化数据将有助于改善这些地区的预测。