Andreas Alexander

• Alexander, Andreas; Kruusmaa, Maarja; Tuhtan, Jeffrey; Hodson, Andrew; Schuler, Thomas & Kääb, Andreas (2020). Pressure and inertia sensing drifters for glacial hydrology flow path measurements. The Cryosphere.  ISSN 1994-0416.  14(3), s 1009- 1023 . doi: 10.5194/tc-14-1009-2020 Fulltekst i vitenarkiv. Vis sammendrag

  Glacial hydrology plays an important role in the control of glacier dynamics, of sediment transport, and of fjord and proglacial ecosystems. Surface meltwater drains through glaciers via supraglacial, englacial and subglacial systems. Due to challenging field conditions, the processes driving surface processes in glacial hydrology remain sparsely studied. Recently, sensing drifters have shown promise in river, coastal and oceanographic studies. However, practical experience with drifters in glacial hydrology remains limited. Before drifters can be used as general tools in glacial studies, it is necessary to quantify the variability of their measurements. To address this, we conducted repeated field experiments in a 450 m long supraglacial channel with small cylindrical drifters equipped with pressure, magnetometer, acceleration and rotation rate sensors and compared the results. The experiments (n=55) in the supraglacial channel show that the pressure sensors consistently yielded the most accurate data, where values remained within ±0.11 % of the total pressure time-averaged mean (95 % confidence interval). Magnetometer readings also exhibited low variability across deployments, maintaining readings within ±2.45 % of the time-averaged mean of the magnetometer magnitudes. Linear acceleration measurements were found to have a substantially higher variability of ±34.4 % of the time-averaged mean magnitude, and the calculated speeds remained within ±24.5 % of the time-averaged mean along the flow path. Furthermore, our results indicate that prominent shapes in the sensor records are likely to be linked to variations in channel morphology and the associated flow field. Our results show that multimodal drifters can be a useful tool for field measurements inside supraglacial channels. Future deployments of drifters into englacial and subglacial channels promise new opportunities for determining hydraulic and morphologic conditions from repeated measurements of such inaccessible environments.

• Alexander, Andreas; Obu, Jaroslav; Schuler, Thomas; Kääb, Andreas & Christiansen, Hanne H (2020). Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard. The Cryosphere.  ISSN 1994-0416.  14(11), s 4217- 4231 . doi: 10.5194/tc-14-4217-2020 Fulltekst i vitenarkiv.
• Alexander, Andreas; Obu, Jaroslav; Schuler, Thomas; Kääb, Andreas & Christiansen, Hanne H (2020). Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard. The Cryosphere Discussions.  ISSN 1994-0432. . doi: https://doi.org/10.5194/tc-2020-124
• Tuhtan, J.A.; Alexander, Andreas; Kruusma, Maarja & Fuentes-Pérez, J.F. (2020). Multiscale change detection in a supraglacial stream using surface drifters, In  River Flow 2020 Proceedings of the 10th International Conference on Fluvial Hydraulics (Delft, Netherlands, 7-10 July 2020).  CRC Press.  ISBN 978-0-367-62773-7.  Chapter. Fulltekst i vitenarkiv.

Se alle arbeider i Cristin

• Alexander, Andreas (2021). InnovateGLOF: Interdisciplinary observations of the Setevatnet Glacier Lake Outburst Flood.
• Alexander, Andreas (2021). InnovateGLOF: Interdisciplinary observations of the Setevatnet Glacier Lake Outburst Flood.
• Alexander, Andreas (2020). Go with the flow - Glacier investigations with drifters.
• Alexander, Andreas (2020). New insights into glacial hydrology.
• Alexander, Andreas (2020). Sensing drifters as tool for glacial hydrology flow path measurements.
• Alexander, Andreas (2020). Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events.
• Alexander, Andreas; Obu, Jaroslav; Schuler, Thomas; Kääb, Andreas & Christiansen, Hanne H (2020). Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard.
• Alexander, Andreas; Piho, Laura & Kruusma, Maarja (2020). Topology and pressure distribution reconstruction of an englacial channel.
• Tuhtan, J.A.; Alexander, Andreas; Kruusma, Maarja & Fuentes-Pérez, J.F. (2020). Multiscale change detection in a supraglacial stream using surface drifters.
• Alexander, Andreas (2019). Winter rain induced soft-bed warming - A potential acceleration mechanism.
• Alexander, Andreas; Kruusma, Maarja; Tuhtan, Jeffrey; Hodson, Andrew; Schuler, Thomas & Kääb, Andreas (2019). Sensing drifters as tool for glacial hydrology measurements.
• Alexander, Andreas; Kruusma, Maarja; Tuhtan, Jeffrey; Hodson, Andrew; Schuler, Thomas & Kääb, Andreas (2019). Sensing drifters as tool for glacial hydrology measurements.

Se alle arbeider i Cristin