Studying glacier calving fluxes and calving styles through a novel combination of acoustic and optical methods
The project aims to complete two major research tasks:
- to get new insight into the mechanical loss of ice from tidewater glaciers (‘calving’)
and
- to transform passive acoustics into a practical tool for the long-term monitoring of calving.
The proposed project answers the growing need for studying and monitoring the vulnerability of marine-terminating glaciers to the changing climate. The contribution of melting glaciers to the eustatic sea level rise poses a threat to coastal communities. Moreover, the freshening of the ocean caused by the meltwater input affects large-scale circulation patterns that distribute salt, heat, and critical nutrients. Consequently, understanding and monitoring physical processes acting at the glacier-ocean boundary are essential to predict and mitigate future effects of climate change. However, studying and monitoring glacier mass loss is problematic because of two main reasons.
First, taking measurements near calving glaciers is difficult and dangerous due to icebergs breaking off from glacier termini and the inaccessibility of glacial bays and fjords. As a result, there is a lack of data required to parametrize glacier-ocean interactions in numerical models.
Second, standard remote sensing techniques are often insufficient in terms of monitoring glaciers. For example, obtaining high-quality images during the polar night and cloudy conditions is usually impossible. Submarine parts of glacier termini are invisible for optical instruments. What is more, changes in the position of a glacier terminus observed using satellites depend not only on calving rates but also on the ice velocity. As a result, optical techniques alone often do not provide accurate estimates of calving fluxes; therefore, new methods for studying and monitoring marine-terminating glaciers are urgently required. Recent studies have demonstrated that passive acoustics can be a suitable tool for measuring glacier mass loss.
Calving fluxes can be quantified using the underwater noise produced as icebergs fall onto the sea surface, provided that sound propagation conditions and the average drop height of calving icebergs are known. However, there are still many open questions and difficulties. For example, noise emission from iceberg/water interactions depends on the calving style. The variability in sound-source mechanisms associated with different calving styles causes high uncertainties in ice loss estimates for individual calving events. Moreover, the acoustic technique has been tested so far only for a single glacier; therefore, the impact of site-specific conditions remains unknown. Finally, the use of a single acoustic receiver does not allow for the analysis of the spatial variability in calving fluxes.
The project aims to contribute to the global effort to understand and monitor the reaction of marine-terminating glaciers to dramatic climate shifts through a novel combination of passive acoustics, optical remote sensing, and physical oceanography. The spatial variability of calving fluxes along the glacier terminus will be measured using an acoustic array and linked to external driving factors, including ice velocity and activity of subglacial discharge plumes. Seasonal variability of calving fluxes and calving styles at three different glaciers in Hornsund fjord, Svalbard will be investigated and linked to the evolution of thermal conditions in glacial bays and the development of ice mélanges. The analysis of calving styles will allow identifying potential causal relationships between different calving
mechanisms; this includes subaerial and submarine calving events. Additional insight into the underwater noise from pre-calving glacier activity, including ice fracturing and cracking, is also expected. Measurements taken with a ground-based microphone array will provide quantitative data on poorly-known directionality, spectra, and sources of airborne calving noise. A multi-sensor approach to investigate sound-source mechanisms, together with the development of data processing techniques, will provide new methodologies and strategies for the long-term monitoring of calving fluxes and calving styles.
Additional Info
| Field | Value |
|---|---|
| Agreement number | 2021/43/D/ST10/00616 |
| Call | SONATA-17 |
| Project Financing Institution | National Science Centre, Poland |
| Project Supervisor | Oskar Głowacki |
| Time | 14.06.2022 – 13.06.2026 |