ICEFLOW: Short-term movements in the Cryosphere

Living Planet Fellowship research project carried out by Bas Altena.

A multitude of optical satellite constellations have been set in orbit over the last decade. Their similar sun-synchronous orbit has created the opportunity to look at fast and vast changing processes in the cryosphere. During the fellowship I have explored if it is already technically feasible to exploit such opportunities.

The mapping of steep and fast flowing glaciers is challenging but knowing how it flows makes glacier travelling safer. We established a multi-temporal method^[1] for Sentinel-2, to make high resolution velocity mapping possible. This technique was applied to Khumbu glacier, which needs to be traversed to reach mount Everest.

Each year during spring a lot of damage occurs at northern latitudes when ice is transported downriver. We created a proof-of-concept^[2] for river ice monitoring from PROBA-V and Sentinel-2 satellites, making use of their different overflight times.

How glaciers and icesheets will react to the ocean is an area where a lot of uncertainty is present. This is partly due to the dynamics, but its data sparseness. We created a minimal viable product with a triplet of satellite overpasses, to map the upper and lower surface circulation in a fjord, by combining Sentinel-2, Landsat and Planet data.

In order to integrate geo-physical models with observations, it is helpful to have an understanding of the precision and accuracy of these observations. For velocity products, these were mostly based upon group statistics, while the quality of such products do change over space and time. We have created an efficient method^[3] to describe individual precision estimates, and in that way improving inversion and error-propagation.

Typically the geometric datasets from glaciers come from different satellite systems, where timesteps or coverage are different. This makes merging problematic, especially when a lot of dynamics is involved. Hence we explored the possibility to extract both velocity and elevation change[4] from one satellite system, namely Sentinel-2.

The field of geodetic imaging has grown in the last couple of years, partly due to the open access policy of the Sentinel systems. In order to have an overview of the different techniques and applications, a book has been written. In this book I have contributed to a chapter on displacement estimation from microwave data^[4], and one specific to glacier displacement estimation^[5]. While writing, we continued our discussions further and developed an improved method^[6], which was applied on case foir tectonic and sea surface displacement estimation.

^[1] doi.org/10.1017/jog.2020.66

^[2] doi.org/10.1016/j.jag.2021.102315

^[3] doi.org/10.5194/tc-16-2285-2022

^[4] doi.org/ 10.5194/isprs-archives-XLII-2-W13-1723-2019

^[5] doi.org/10.1002/9781119986843.ch3

^[6] doi.org/10.1002/9781119986843.ch11

^[7] doi.org/10.1016/j.srs.2022.100070