PhD Position Quantification of Meltwater Storage in Greenland Using a Statistically-Optimal Inversion of Satellite Gravimetry Data

Challenge: Quantify and analyse meltwater storage in Greenland
Change: Use satellite gravimetry
Impact: Better understanding the ice sheet and its potential contribution to future sea level rise

Since the launch of GRACE satellite mission in 2002, satellite gravimetry became one of the primary tools to study the mass re-distribution in different Earth’s system compartments, including ice sheets. Furthermore, it was already shown by our research team (Ran et al, The Cryosphere, 2018) that a combination of GRACE data with information about the Surface Mass Balance (SMB) allows an accumulation and release of liquid water within the Greenland Ice Sheet (GrIS) to be detected. A quantitative analysis of this process is vital since the increased runoff of meltwater from the GrIS is a major contributor to the acceleration in contemporary sea level rise. Recent research has shown that runoff from the ice sheet to the ocean is delayed by storage on top, inside or underneath the ice sheet.  A lack of detailed knowledge about the meltwater runoff is one of the reasons why the contribution of the GrIS to the future sea level rise remains rather uncertain. It is believed that satellite gravimetry may play an important role in gaining such knowledge, since it is a unique remote sensing technique which is sensitive to water mass variations within the entire ice layer, no matter at what depth they occur.

The project will comprise two major parts. In the first part, the PhD candidate will be engaged in a further development of techniques for processing the data from satellite gravimetry mission GRACE and its successor, GRACE Follow-On (GFO). It is proposed to invert GRACE/GFO level-2 data product (monthly sets of spherical harmonic coefficients) into global sets of mass anomalies (the so-called "mascons"). One of the key tasks at this stage will be to develop a statistically-optimal estimation procedure, taking into account stochastic models of errors in the input data. Furthermore, it will be essential to develop a numerically efficient technique to quantify the accuracy of estimated mass anomalies.

In the second part, the PhD candidate will focus on an extraction of the signal associated with meltwater accumulation within the GrIS. To that end, it will be necessary to clean the input data from all the nuisance signals, including those from Glacial Isostatic Adjustment (GIA), SMB, and ice discharge. Furthermore, it will be important to develop the optimal regularization scheme, which can suppress high-frequency noise in the level-2 data product, while preserving spatial features of the signal to be recovered, including its likely discontinuity along the coastal line. Finally, the PhD candidate will analyse and interpret the obtained signal. For instance, it will be instructive to compare the estimated water mass variations with estimates provided by models of ice sheet hydrology, as well as with air temperatures in a given melt season and with variations in ice flow velocities.

The successfully completed project will lead to better understanding the behaviour of the GrIS, its response to the foreseen climate changes, and its potential contribution to the future sea level rise.

The project will be executed at the Dept. of Geoscienceand Remote Sensing at TU Delft, in a collaboration with Dr. P. Ditmar, Dr. B. Wouters, prof. R. Klees, and other department members. Furthermore, there will be a close collaboration with prof. Michiel van den Broeke and other colleagues from Institute for Marine and Atmospheric research Utrecht (IMAU).

You must have a solid background in programming and math (particularly, in statistical theory and the theory of inverse problems). It will also be essential to have a good command of English language, as well as very good skills in oral and written communications. Additional assets are:

• Knowledge of physical geodesy (including the spherical harmonic expansion).
• Familiarity with physical processes within an ice sheet.
• Knowledge of FORTRAN language.
• Familiar with parallel programming using the MPI library.

Doing a PhD at TU Delft requires English proficiency at a certain level to ensure that the candidate is able to communicate and interact well, participate in English-taught Doctoral Education courses, and write scientific articles and a final thesis. For more details please check the Graduate Schools Admission Requirements .

Doctoral candidates will be offered a 4-year period of employment in principle, but in the form of 2 employment contracts. An initial 1,5 year contract with an official go/no go progress assessment within 15 months. Followed by an additional contract for the remaining 2,5 years assuming everything goes well and performance requirements are met.

Salary and benefits are in accordance with the Collective Labour Agreement for Dutch Universities, increasing from € 2541 per month in the first year to € 3247 in the fourth year. As a PhD candidate you will be enrolled in the TU Delft Graduate School. The TU Delft Graduate School provides an inspiring research environment with an excellent team of supervisors, academic staff and a mentor. The Doctoral Education Programme is aimed at developing your transferable, discipline-related and research skills.

The TU Delft offers a customisable compensation package, discounts on health insurance and sport memberships, and a monthly work costs contribution. Flexible work schedules can be arranged. For international applicants we offer the Coming to Delft Service and Partner Career Advice  to assist you with your relocation.

Delft University of Technology is built on strong foundations. As creators of the world-famous Dutch waterworks and pioneers in biotech, TU Delft is a top international university combining science, engineering and design. It delivers world class results in education, research and innovation to address challenges in the areas of energy, climate, mobility, health and digital society. For generations, our engineers have proven to be entrepreneurial problem-solvers, both in business and in a social context.

At TU Delft we embrace diversity as one of our core values  and we actively engage  to be a university where you feel at home and can flourish. We value different perspectives and qualities. We believe this makes our work more innovative, the TU Delft community more vibrant and the world more just. Together, we imagine, invent and create solutions using technology to have a positive impact on a global scale. That is why we invite you to apply. Your application will receive fair consideration.

Challenge. Change. Impact!

The Faculty of Civil Engineering & Geosciences (CEG) is committed to outstanding international research and education in the field of civil engineering, applied earth sciences, traffic and transport, water technology, and delta technology. Our research feeds into our educational programmes and covers societal challenges such as climate change, energy transition, resource availability, urbanisation and clean water. Our research projects are conducted in close cooperation with a wide range of research institutions. CEG is convinced of the importance of open science and supports its scientists in integrating open science in their research practice. The Faculty of CEG comprises28 research groups in the following seven departments: Materials Mechanics Management & Design, Engineering Structures, Geoscience and Engineering, Geoscience and Remote Sensing, Transport &; Planning, Hydraulic Engineering and Water Management.

Click here  to go to the website of the Faculty of Civil Engineering & Geosciences.

For more information about this vacancy, please contact Dr. Pavel Ditmar, e-mail: [email protected] . 

Are you interested in this vacancy? Please apply no later than 19 April 2023 via the application button and upload your:

• Letter of motivation.
• Detailed CV.
• List of grades/transcripts (bachelor and master).
• Contact information of two references.
• Your master thesis (if already available).

Please note:

• You can apply online. We will not process applications sent by email and/or post.
• A pre-Employment screening can be part of the selection procedure.
• Please do not contact us for unsolicited services.