solidFIDEMO – a firn densification model for volumetric mass balances

降雪描述了雪和冰川冰之间的中间阶段产物。正在进行的雪到冰的压实通常被称为降雪致密化。例如，将测量到的冰盖高度变化转换为质量变化或从冰芯重建气候时，需要了解这一过程。通过我们的SolidFIDEMO项目，我们开发了一个有效的降雪致密化模型框架。在我们以前的工作中，我们使用了这个框架和越来越多的数据来推进基于过程的降雪致密化模型的发展。我们能够在一个应用程序中使用我们的模型来模拟格陵兰79°N冰川表面的积雪密度和年龄。此外，我们特别注意了降雪致密化的第一阶段，评估了描述降雪中晶界滑移过程的本构关系。在整个研究过程中，我们的发现之一是，冷杉密度模拟中常见的一维模型方法不足以表示冷杉体内的应力状态。因此，我们建议将我们的项目延长一年。在这一年的时间里，我们希望将我们的模型框架扩展到三个空间维度。通过这种方式，我们能够研究水平应力对降雪的影响，到目前为止，大多数降雪致密化模型都忽略了水平应力的影响。此外，这一扩展将使我们能够分析极地冰川表面特征，如雪丘和雪松对降雪密度横向变化的影响。由于我们看到其他研究领域对降雪密度产品的强烈需求，特别是来自测高领域对降雪密度产品的需求，我们还希望在达姆施塔特大学举办为期两天的研讨会，与社区内不同领域的研究人员会面。我们想讨论如何建立不同模式之间的互联互通，以及我们可以为社会提供什么样的数据产品、应用和服务。

Firn describes the intermediate stage product between snow and glacier ice. The ongoing compaction of snow to ice is commonly called firn densification. Knowledge about this process is for example needed to transform measured height changes of the ice shields to mass changes or to perform climate reconstructions from ice cores.Throughout our project SolidFIDEMO we developed an efficient framework for firn densification modelling. In our previous work we used this framework and a growing amount of data to advance the development of a process based firn densification model. We were able to utilise our model within an application simulating the firn density and age at the surface of 79°N Glacier, Greenland. Furthermore, we paid special attention to the very first stage of firn densification, assessing a constitutive relation describing the process of grain boundary sliding in firn. One of our findings throughout this study was that the common one dimensional model approach in firn density modelling is not sufficient to represent the stress regime acting within the firn body.We therefore propose for a one year extension of our project. Within this one year period we want to extend our model framework to three spatial dimensions. In this way we were able to investigate the influence of horizontal stresses acting on the firn, neglected in most firn densification models so far. Further this extension would enable us to analyse the influence of surface polar glacial surface features such as snow dunes and sastrugi on the lateral variability of the firn density.As we see a strong demand from other research fields, especially from the altimetry community for firn density products, we also want to hold a two day workshop at TU Darmstadt to meet researchers from different fields within the community. We want to discuss how an interconnection between different models can be established and what kind of data products, applications and services we can provide to the community.