Improved geodetic glacier mass balance measurements by integrating remote sensing, surface mass balance and firn compaction modelling - a case study from James Ross Island, Antarctica

该项目的目标是改善大地测量冰川质量平衡。除了绝对精度的提高，我们的目标是在误差量化和误差估计的一般改善。在第一步中，将通过不同日期和来源的数字高程模型（DEM）的差异来计算高程和体积变化。数字高程模型将通过摄影测量或合成孔径雷达干涉测量法生成（特别是使用德国TanDEM-X使命的数据）。目前大地测量方法的局限性是由于雷达信号在干雪或冰冻雪盖中的穿透深度无法量化，以及由于假定密度固定或密度分布特定而将体积转换为质量。我们建议通过耦合冰川表面质量平衡和积雪压实模型与遥感结果，以提高转换。为了初始化和验证模型，我们将依靠实地调查以及申请人以及捷克和阿根廷同行的深刻数据库。我们将通过比较夏季和冬季的情况以及与现场GNSS测量结果的比较来量化x波段雷达穿透深度的影响。此外，我们将比较大地测量方法与输入输出（或通量门）方法的结果。该项目是在布尔诺和布拉格大学的捷克合作伙伴以及我们的Antártico Instituto Antártico Pastino的同行的密切合作下进行的。我们建议詹姆斯罗斯岛-位于东北端的南极半岛-作为研究地点。尽管它位于南极洲，但我们的主要目标是可以转移到其他区域和地点的方法发展。拟议的研究地点是有利的，因为它的数据库和联合筹备工作以及国际合作和后勤准入几乎是拟议工作的理想条件，与冰川规模相当的地点相比，不会导致显着的额外费用。具体而言，准备工作表明，观测到的海拔变化在不同冰川上是相当不均匀的，除了不同的气象条件外，还可以在一个非常狭窄的区域内分析不同幅度、方向和基本机制的变化。这种情况对拟定场地非常特殊，为方法开发提供了理想的条件。

The project targets on the improvement of geodetic glacier mass balances. Besides of an improvement of the absolute precision we aim at a general improvement of the error quantification and error estimation. In a first setp elevation and volume changes will be computed by differencing digital elevation models (DEMs) from different dates and sources. The DEMs will be generated by photogrammetry or SAR interferometry (especially using data of the German TanDEM-X mission). The current limitations of the geodetic method result from the unquantified penetration depth of the radar signal into dry snow or a frozen snow cover as well as from the conversion of volume to mass by assuming a fixed density or specific density profile. We propose to improve the conversions by coupling a glacier surface mass balance and firn compaction model with the remote sensing results. In order to initialise and validate the model we will rely on field surveys as well as a profound database of the applicant as well as the Czech and Argentine counterparts. We will quantify the effects of x-band radar penetration depth by comparing summer and winter situations as well as comparison to in-situ GNSS measurements. In addition, we will compare the results of the geodetic method with the Input-Output (or flux gate) approach. The project is carried out in close collaboration of Czech partners from Brno and Prague University as well as our counterparts from the Instituto Antártico Argentino. We propose James Ross Island - located at the northeaster tip of the Antarctic Peninsula - as study site. Despite of its location in Antarctica, we primarily aim at methodological developments that can be transferred to other regions and locations. The proposed study site is favourable due to its database and the joint preparatory work as well as the international collaboration and logistic access almost ideal conditions for the proposed work that does not lead to significant additional costs in comparison to locations with comparable glacier sizes. Specifically, the preparatory work shows that the observed elevation changes are quite heterogeneous on the different glaciers enabling the analysis of changes in different magnitudes, directions and underlying mechanisms within a very narrow area in addition to different meteorological conditions. This situation is very specific to the proposed site and provides ideal conditions for method development.