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冰川质量平衡。除了提高绝对精度外，我们的目标是全面改进误差量化和误差估计。在第一个SETP中，将通过对不同日期和来源的数字高程模型(DEM)进行差分来计算高程和体积变化。DEM将通过摄影测量或合成孔径雷达干涉测量(特别是使用德国Tandem-X任务的数据)生成。目前大地测量法的局限性是由于雷达信号对干雪或冻结雪盖的穿透深度未量化，以及通过假设固定密度或特定密度剖面将体积转换为质量。我们建议通过将冰川表面质量平衡和降雪压实模型与遥感结果相结合来提高转换。为了启动和验证这一模式，我们将依靠实地调查以及申请者以及捷克和阿根廷同行的丰富数据库。我们将通过比较夏季和冬季情况以及与全球导航卫星系统的现场测量进行比较，量化x波段雷达穿透深度的影响。此外，我们还将比较大地测量法和输入-输出(或磁通门)方法的结果。该项目是在来自布尔诺和布拉格大学的捷克合作伙伴以及阿根廷南极洲研究所的合作伙伴密切合作下进行的。我们建议将位于南极半岛东北端的詹姆斯罗斯岛作为研究地点。尽管它位于南极洲，但我们的主要目标是可以转移到其他地区和地点的方法发展。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协作和后勤准入对于拟议的工作来说几乎是理想的条件，与具有类似冰川大小的地点相比，这不会导致显著的额外费用。具体地说，筹备工作表明，在不同冰川上观测到的海拔变化是相当不同的，这使得除了不同的气象条件外，还能够分析非常狭窄区域内不同幅度、方向和潜在机制的变化。这种情况对拟建场地非常特殊，并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.