Research

Glacier and ice cap contribution to future sea level rise (postdoc @ TUDelft) (with S. Lhermitte & B. Wouters)

As a Marie Skłodowska-Curie postdoctoral fellow, I will aim at improving projections of the future sea level contribution from glaciers and ice caps (GICs). The goal is to make use of a variety of state-of-the art remote sensing products to constrain and validate a numerical ice flow model. The adopted strategy will consist of only modelling a subsample of all >200 000 GICs, but which represent a large fraction of the total GIC volume. This will allow us to use more complex methods than those used so far for global glacier and ice cap modelling (typically dimensionless or 1-D approaches).

Alpine glacier modelling (postdoc @ ETH Zürich & WSL Birmensdorf) (with M. Huss & D. Farinotti)

The aim of my first postdoctoral project (2017-2019) was to extend the GLObal Glacier Evolution Model (GloGEM) of Huss & Hock (2015, Frontiers in Earth Science) by incorporating a dynamic ice flow component. The newly developed model, GloGEMflow, was applied to the European Alps in order to project the future evolution of all glaciers under the EURO-CORDEX RCM ensemble. These results were also submitted to the second phase of GlacierMIP and are the starting point for creating a response time inventory of all glaciers in the European Alps (to be presented during the 27th IUGG General Assembly in Montreal).

Antarctic meteorites

From December 2012 to February 2013, I had the unique chance to join a Belgian-Japanese meteorite search expedition on the Nansen ice field on the Antarctic plateau (ca. 2900 m elevation), 120 km south of the Belgian Antarctic Station (Princes Elisabeth). During this expedition hundreds of blue ice samples surface samples were collected and these revealed clear climatic signals at the surface. To constrain the age of the ice, the terrestrial age of selected meteorites (i.e. the time since they entered the atmosphere) was determined. By combining this with satellite derived surface velocities and other sources of information, we tried to better constrain the mechanism behind the Nansen blue ice trap.

PhD (Vrije Universiteit Brussel) (supervised by P. Huybrechts)

My PhD (2013-2017) entitled ‘modelling the evolution of glaciers and ice caps in a changing climate’, consisted of modelling the dynamics of a Swiss mountain glacier (Vadret da Morteratsch) and a Greenlandic ice cap (Hans Tausen Iskappe). For this, I used 3-D higher-order ice flow models, which were coupled to surface mass balance models. Additionally, I also developed a visualization toolbox (TopoZeko), and performed a statistical regression analyses on the surface mass balance of the Morteratsch glacier complex.

Interests

  • Alpine glaciology
  • Arctic ice caps
  • Numerical ice flow modeling
  • Palaeoglaciology
  • Regional glacier evolution modelling
  • Stable isotope geochemistry of ice
  • Surface mass balance modelling and statistical techniques
  • Visualisation techniques

Research Projects

  • Alpine glacier modelling

    Modelling the time evolution of the European ice mass with a novel glacier model - GloGEMflow

    Glaciers in the European Alps play an important role in the hydrological cycle, act as a source for hydroelectricity and have a large touristic importance. The future evolution of these glaciers is driven by surface mass balance and ice flow processes, of which the latter is to date not included explicitly in regional glacier projections for the Alps. In my first postdoctoral project (@ETH Zürich & WSL Birmensdorf), we modelled the future evolution of glaciers in the European Alps with GloGEMflow, an extended version of the Global Glacier Evolution Model (GloGEM), in which both surface mass balance and ice flow are explicitly accounted for. The mass balance model was calibrated with glacier-specific geodetic mass balances, and forced with high-resolution regional climate model (RCM) simulations from the EURO-CORDEX ensemble. The evolution of the total glacier volume in the coming decades was found to be relatively similar under the various representative concentrations pathways (RCP2.6, 4.5 and 8.5), with volume losses of about 47-52% in 2050 with respect to 2017. We found that under RCP2.6, the ice loss in the second part of the 21st century is relatively limited and that about one-third (36.8% ± 11.1%, multi-model mean ± 1σ) of the present-day (2017) ice volume will still be present in 2100. Under a strong warming (RCP8.5) the future evolution of the glaciers is dictated by a substantial increase in surface melt, and glaciers are projected to largely disappear by 2100 (94.4±4.4% volume loss vs. 2017). For a given RCP, differences in future changes are mainly determined by the driving global climate model (GCM), rather than by the RCM, and these differences are larger than those arising from various model parameters (e.g. flow parameters and cross-section parameterization). We find that under a limited warming, the inclusion of ice dynamics reduces the projected mass loss and that this effect increases with the glacier elevation range, implying that the inclusion of ice dynamics is likely to be important for global glacier evolution projections.

  • Antarctica

    Blue Ice Area's and Meteorites: Paleoclimatic interpretation

    From December 2012 to February 2013 I had the unique chance to join a Belgian-Japanese meteorite search expedition on the Nansen ice field on the Antarctic plateau (ca. 2900 m elevation), 120 km south of the Belgian Antarctic Station (Princes Elisabeth) (Imae et al., 2015). During this expedition hundreds of blue ice samples surface samples were collected and these revealed clear climatic signals at the surface. To constrain the age of the ice, the terrestrial age of selected meteorites (i.e. the time since they entered the atmosphere) was determined. By combining this with satellite derived surface velocities and other sources of information, we aimed at better understanding the mechanism behind the Nansen blue ice trap.

    Expedition report

    Scientific paper summarising our findings

  • TopoZeko

    A MATLAB function for 3-D and 4-D topographical visualization in geosciences

    TopoZeko is a MATLAB function for plotting a variety of natural environments with a pronounced topography, such as glaciers, volcanoes and lakes in mountainous regions. This function extends existing MATLAB plotting routines and allows for high-quality 3-D landscape visualization, with a single color defining a featured surface type or with a color scale defining the magnitude of a variable. More Info

  • Hans Tausen Iskappe (Greenland)

    Holocene and future evolution of the world's northernmost ice cap

    The second part of my PhD focussd on the dynamics of world’s northernmost ice cap: the Hans Tausen Iskappe in Northern Greenland. Several mass balance and ice thickness measurements occurred in the 1990’s and an ice-core was also drilled. From this we know that the ice cap (partly) disappeared during the Holocene Thermal Maximum and that it subsequently started building up again. By modelling the ice dynamics and the mass balance we will tried to understand how this happened, how stable the present-day ice cap is and how the ice cap may evolve in a warming climate.

    Study on present-day dynamics, sensitivity to climatic forcing and future evolution: Zekollari et al. (2017, The Cryosphere)

    Holocene evolution of the ice cap and implications for the palaeoclimatic evolution of the high Arctic: Zekollari et al. (2017, Quaternary Science Reviews)

  • Vadret da Morteratsch (Switzerland)

    Ice thickness modelling and glacier dynamics

    The first part of my PhD mainly focused on the modelling the dynamics of the Morteratsch (Engadine, Switzerland). This is a medium-sized alpine glacier on which we have field program since 2001 (coordinated by P. Huybrechts, first at the Alfred Wegener Institut – Bremerhaven, since 2005 at the Vrije Universiteit Brussel). Each year we visit the glacier at the end of the ablation season (end of September –  beginning of October) to determine the annual mass balance of the glacier. Besides this we also measure the surface velocities, the ice thickness and perform Unmanned Aerial Vehicle (UAV) flights to reconstruct the surface topography (since 2014). This field data is used to calibrate and validate our ice flow and surface mass balance model.

    Ice thickness reconstruction and ice flow model calibration: Zekollari et al. (2013, Annals of Glaciology)

    Glacier evolution between 1864 and 2100: Zekollari et al. (2014, Journal of Glaciology)

    Glacier climate-geometry imbalance, response time and volume-area scaling: Zekollari and Huybrechts (2015, Annals of Glaciology)

    Statistical modelling of the surface mass balance variability of the Morteratsch glacier, Switzerland: strong control of early melting season meteorological conditions: Zekollari and Huybrechts (accepted, Journal of Glaciology)