SPI Exploratory Grants 2018

Beneficiaries and their projects

 

Dr. Jan Henneberger, ETHZ

 

 

Cloud microphysics measurements with HoloBalloon
at Ny Ålesund

 

Prof. Dr. Fabian Walter, ETHZ

 

 

Confirming seismogenic stick-slip flow of a Greenland outlet
glacier using helicopter-borne GPS installations

 

Dr. Guillaume Jouvet, ETHZ

 

 

Automated in-situ ice flow monitoring of Bowdoin Glacier
through a network of GPSs deployed by UAVs

 

Dr. Basil Davis, UniL

 

 

Holocene climate and environmental records from the Central Siberian Plateau

 

 

Dr. Akçar Naki, University of Bern

 

 

DEAIS: Changes in the Drainage Pattern of the Eastern Antarctic Ice Sheet through Time

 

 

Prof.  Alexis Berne, EPFL

 

 

A transect of micro rain radars to investigate Antarctic
precipitation in complex terrain

Projects

Dr. Jan Henneberger

Project: Cloud microphysics measurements with HoloBalloon at Ny Ålesund

Keyword: Arctic field measurements, atmospheric science, mixed-phase clouds, cloud phase partitioning, holography.

Summary

The Arctic is warming faster than the rest of the world, which causes an alarming melting of sea ice. Despite clouds in the Arctic having a strong influence on the surface energy budget, they are poorly understood. One reason for the poor understanding is a lack of in-situ measurements due to the limited availability of measurements in particular during the winter months, because of the harsh environmental conditions and remoteness of the region. The project aims at filling this gap by performing in-situ high-resolution measurements of the cloud structure in Ny Ålesund to identify and understand the key processes in Arctic mixed-phase clouds, containing liquid droplets and ice crystals. In particular, phase partitioning and secondary ice formation are crucial for understanding the cloud glaciation process and the cloud-radiation feedbacks in the Arctic, which are of high importance for the atmospheric radiation balance.

In this project, we will investigate aerosol occurrence, ice crystal formation, and the spatial structure of ice crystals and liquid droplet during the autumn and spring period. We will use a tethered balloon system (HoloBalloon) to measure in-situ vertical profiles of cloud properties up to 1 km above the surface with high temporal and spatial resolution. HoloBalloon will be equipped with our holographic cloud imager HOLIMO, which is able to retrieve the size distribution of cloud droplets and ice crystals. HOLIMO has the unique ability to measure the 3D spatial distribution of cloud particles allowing the investigation of the small-scale structure down to the mm-scale. Additional sensors on HoloBalloon will provide information on the temperature, radiation, aerosol concentration, the wind direction and velocity.

The collaboration with the MOSAiC expedition, during which the German icebreaker Polarstern will be trapped in the Arctic between September 2019 and September 2020, will increase the impact of the project. Furthermore, two collaborations will increase the impact of our project: The group of Prof. Paul Zieger (Stockholm University, Sweden) will take in-situ aerosol measurements by adding a sensor on HoloBalloon and cloud radar retrievals from the group of Dr. Kerstin Ebell (University of Cologne, Germany) will be validated with our in-situ measurements. The enormous amount of simultaneous measurements will allow to gain a deeper understanding of microphysical processes occurring in Arctic mixed-phase clouds.

In this project, we will investigate aerosol occurrence, ice crystal formation, and the spatial structure of ice crystals and liquid droplet during the autumn and spring period. We will use a tethered balloon system (HoloBalloon) to measure in-situ vertical profiles of cloud properties up to 1 km above the surface with high temporal and spatial resolution. HoloBalloon will be equipped with our holographic cloud imager HOLIMO, which is able to retrieve the size distribution of cloud droplets and ice crystals. HOLIMO has the unique ability to measure the 3D spatial distribution of cloud particles allowing the investigation of the small-scale structure down to the mm-scale. Additional sensors on HoloBalloon will provide information on the temperature, radiation, aerosol concentration, the wind direction and velocity.

The collaboration with the MOSAiC expedition, during which the German icebreaker Polarstern will be trapped in the Arctic between September 2019 and September 2020, will increase the impact of the project. Furthermore, two collaborations will increase the impact of our project: The group of Prof. Paul Zieger (Stockholm University, Sweden) will take in-situ aerosol measurements by adding a sensor on HoloBalloon and cloud radar retrievals from the group of Dr. Kerstin Ebell (University of Cologne, Germany) will be validated with our in-situ measurements. The enormous amount of simultaneous measurements will allow to gain a deeper understanding of microphysical processes occurring in Arctic mixed-phase clouds.

Prof. Fabian Walter

Project: Confirming seismogenic stick-slip flow of a Greenland outlet glacier using helicopter-borne GPS installations

Keyword: Ice flow, glacier seismology, basal sliding, Greenland.

Summary

The vast majority of our planet’s ice resides in the two polar ice sheets in Greenland and Antarctica. The fate of these ice sheets in a changing climate has a profound influence on the state of global environments, in particular sea level. Over recent decades, ice sheet research has focused on ice streams, which are akin to “ice rivers” within the ice sheet transporting mass from the interior to the ocean at much higher velocities that the surrounding slow flowing ice. It is well accepted that this fast ice flow is possible, because ice can slide rapidly over its bed. The physical details of this sliding mechanism are not yet fully understood, but may induce rapid changes such an increase in iceberg production or the stagnation of an ice stream. Unless glaciologists improve models of ice stream sliding, prediction of ice sheet evolution will therefore remain uncertain.

In the context of this project, Fabian and his team will investigate if ice stream sliding is a smooth process as typically assumed or occurs via sudden sliding episodes, similar to earthquakes on tectonic faults. Focusing on fast-flowing yet highly crevassed regions of an ice stream in North-West Greenland, they aim to provide data from a glacial environment, which is underrepresented in high-rate ice flow measurements. At the same time, seismic monitoring suggests that these regions are subject to sudden earthquake-like sliding motion. For ice flow measurements, the highly crevassed ice surface demands more portable GPS instruments and access via helicopter.

Dr. Guillaume Jouvet

Project: Automated in-situ ice flow monitoring of Bowdoin Glacier through a network of GPSs deployed by UAVs

Keyword: Unmanned aerial vehicles, in-situ measurements, ice flow.

Summary

Monitoring the ice flow of ocean-terminating glaciers is a challenging, but necessary task to validate/calibrate physical models able to compute reliable future ice volume loss of the polar ice sheets by calving and the resulting sea-level rise. Yet, today’s monitoring techniques by remote sensing and in-situ measurements cannot capture surface velocities in same time high spatial and time resolutions — a major limitation leading to high model uncertainties. By contrast, a dense network of GPS-stations deployed on the ice can fill this gap. The installation and the management of GPS-stations on glaciers are performed manually, and it is therefore difficult to install and maintain a high number of devices. Additionally, many glaciers are crevassed and dangerous areas making this task tedious, expensive (requiring helicopter) and risky when not impossible.
The latest developments in aerial robotic systems, coupled together with the recent release of low-cost cm-accurate differential GNSS receivers offers a unique opportunity to automatize the deployment of GPS-stations over a glacier by Unmanned Aerial Vehicles (UAVs), and thus increase the number of measurement points while reducing costs and human risks. That is precisely the goal of this pilot project. Currently light-weight and low-power consumption miniature GPS-stations together with delivery multirotor UAVs are developed by ETHZ Autonomous Systems Laboratory and will be tested in summer 2019 at Gornergletscher, Switzerland, and Bowdoin Glacier, North-West Greenland.
Beyond this specific application, this project aims to demonstrate that UAVs shouldn’t only be considered as remote sensing platforms, but are already primed for in-situ sensing. If successful, this technique will give rise to new applications for monitoring various glacier dynamical processes in extreme environments.

Dr. Basil Davis

Project: Holocene climate and environmental records from the Central Siberian Plateau

Keyword: Holocene, Pollen, Macrofossils, Testate Amoebae, Geochemistry, Palaeoclimate, Palaeoecology, Heavy Metals, Climate Change.

Summary

Recent and future projected climate warming has increased interest in the study of periods in the Earths past when the climate was warmer than today. One of the most recent was around 6-8000 years ago, at least over the higher latitudes of the Northern Hemisphere, when temperate trees extended north into the cold Boreal forest, and when the Boreal forest itself extended further north into the present-day treeless tundra of the high Arctic. Evidence of these climate and vegetation changes can be found in the records of pollen and other biological remains preserved in the sediments of lakes and bogs throughout the Arctic and sub-Arctic, but one remote and inaccessible region remains almost entirely unexplored. Over 3000 km east of Moscow, the Central Siberian Plateau is an area over 3 times the size of France, largely unpopulated and with virtually no road network, the region has traditionally been impossible to access without military support. Working with Russian scientists from Lomonosov Moscow State University, the expedition will undertake fieldwork in the area during the brief Siberian summer to take peat and lake sediment cores for pollen, macrofossil, charcoal, testate amoeba and geochemical analysis. The results of this work will fill a crucial spatial gap in reconstructions of past climate during the mid-Holocene ‘thermal optimum’, which are directly used to evaluate and improve the ability of climate models to simulate the kinds of warmer worlds that we can expect to experience in the future.

Dr. Akçar Naki

Project: DEAIS: Changes in the Drainage Pattern of the Eastern Antarctic Ice Sheet through Time

Keywords: Antarctica, Quaternary, Glacial Deposits, Surface Exposure Dating, Nunatak.

Summary

During the last few million years, the ice sheets in Antarctica, especially in the eastern part, were dramatically thinning as a response to the global warming during 130,000 to 115,000 years ago and 5 to 2.6 million years ago. During these two periods of global warming, the polar temperatures and global mean sea level were slightly higher than today as indicated by recent ice sheet reconstructions and climate models. In order to explore spatial distribution of this dramatic surface lowering in response to these warmings, the research team focuses on the Sør Rondane Mountains in the Queen Maud Land in the eastern Antarctica. Today, these mountains acts as a barrier to the ice, i.e. ice surface reaches altitudes above 2500 meters above sea level to the south and lowlands of ice are found at altitudes of around 1500 meters to the north. Such an ice-landscape makes the Sør Rondane Mountains an ideal field laboratory to track the pace of past global warmings. In this project, we apply classic geology tools and new technologies and then associate them with cutting-edge geochemical techniques to combine landform with sedimentological and stratigraphical analysis to reconstruct Antarctic ice surface, drainage and flow in the past.

Based on first results, we suggest that the ice surface was at least 400 meters higher than today and stable until the first global warming around 5 million years ago. At that time, the ice from the plateau was drained towards northeast over the mountain range. At the beginning of first global warming, ice surface started to decrease and the south-north linkage was already broken. This surface lowering caused the ice drainage to be channelized into either across or around the mountain range. Afterwards, a second dramatic decrease in the ice surface elevation occurred during the following global warming 130,000 to 115,000 years ago. In contrast to the previous warming, this decrease seems to be limited to the ice lowlands to the north of the mountain chain and the ice plateau to the south were not affected by the dramatic changes occurred on the northern side of the mountain range.

Prof. Dr. Alexis Berne

Project: A transect of micro rain radars to investigate Antarctic precipitation in complex terrain

Keywords: Precipitation, microphysics, radar, Antarctica.

Summary

Precipitation is a crucial term in the mass balance of the Antarctic ice sheet, directly influencing sea level rise. Precipitation over Antarctica however remains largely unknown because of the difficulty to collect reliable and representative observations, and hence the difficulty to evaluate precipitation products from satellite platforms and meteorological/climate models. The present project aims to address this lack of reference observations about Antarctic precipitation, by deploying an innovative instrumental set-up. In the framework of a larger project, a field campaign involving various instruments to monitor precipitation is planned at the Princess Elizabeth (PE) station, in Queen Maud Land (East Antarctica). The present project is a unique opportunity to complement the planned instrumental suites by deploying 3 Doppler profiling micro rain radars together with weather stations and pyrgeometers (downward longwave radiation) along a transect to sample the vertical structure of precipitation and the environmental conditions at various locations in the complex terrain around PE corresponding to various stages of orographic precipitation. The expected unique data set collected from this project will be made available to the community. It will moreover contribute to shed light on the complex interactions between atmospheric flow, cloud microphysics and topography, combining multiple sources of observations and atmospheric models. This will be a significant step to unravel the complexity of orographic precipitation in Antarctica, a key question for the accurate quantification of precipitation at the continental scale.