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Research

I am a PhD student working on ice sheet modeling. My main focus is to develop efficient algorithms for doing simulations of ice sheets during long time spans. My main advisor is Per Lötstedt.

Publications

• Ahlkrona, J. ''Computational Ice Sheet Dynamics- Error control and efficiency'', PhD-thesis (2016)
• Ahlkrona, J., Shcherbakov, V., ''A Meshfree Approach to Non-Newtonian Free Surface Ice Flow: Application to the Haut Glacier d'Arolla'', submitted 2016
• Ahlkrona, J., ''The ISCAL method and the Grounding Line - Combining the Stokes equations with the Shallow Ice Approximation and Shalfy Stream Approximation''
• Ahlkrona, J., Lötstedt, P., Kirchner, N., Zwinger, T., ''Dynamically coupling the non-linear Stokes equations with the Shallow Ice Approximation in glaciology: Description and first applications of the ISCAL method'', Journal of Computational Physics, 2016
• Kirchner, N., Ahlkrona, J., Lötstedt, P., Gowan, E., Lea, J., Noormets, R., von Sydow, L., Dowdeswell J., Shallow Ice Approximation, Second Order Shallow Ice Approximation, and Full Stokes models: a discussion of their roles in palaeo-ice sheet modelling and development, Quaternary Science Reviews, 2016
• Ahlkrona, J., Kirchner, N., Lötstedt, P., ''Accuracy of the zeroth and second order shallow ice approximation - numerical and theoretical results'', Geoscientific Model Development, 2013
• Ahlkrona, J., Kirchner, N., Lötstedt, P., ''A Numerical Study of Scaling Relations for Non-Newtonian Thin-film Flows with Applications in Ice Sheet Modelling'', Quarterly Journal Of Mechanics And Applied Mathematics, 2013
• Ahlkrona, J., ''Implementing Higher Order Dynamics into the Ice Sheet Model SICOPOLIS'', Master's Thesis with Nina Kirchner (supervisor) and Per Lötstedt (reviewer), 2011.

Talks

• Ice Sheet Modelling ISCAL (Ice Sheet Coupled Approximation Levels) - Dynamically Coupling the Non-linear Stokes Equations with the Shallow Ice Approximation - European Numerical Mathematics and Advanced Applications, Ankara, September 2015
• ISCAL (Ice Sheet Coupled Approximation Levels) - an Ice Sheet Model applied in the FROZEN-project - SIAM Conference on Mathematical and Computational Issues in the Geosciences, Stanford, June 2015
• The Fast Full Stokes Method (FFS) Applied to the Greenland Ice Sheet - International Symposium on Contribution of Glaciers and Ice Sheets to Sea Level Change, Chamonix, May 2014.
• Fast Full Stokes (FFS) - Dynamic Coupling of the SIA and full Stokes Equations - American Geophysical Union Fall Meeting 2013, San Francisco, December 2013.
• Improving paleosimulations of Ice Sheet/Ice Stream/Ice Shelf Systems: The development of a Fast Full Stokes numerical ice code, and first applications - Bolin Days 2013 - Stockholm University, November 2013.
• The Second-Order Shallow Ice Approximation - Workshop in Ice Modeling and Simulation, Division of Scientific Computing, Uppsala University, February 2012.
• Ice Sheet Modeling - Improving the Modeling of Ice Dynamics - Seminar at the Department of Numerical Analysis, The Royal Institute of Technology KTH, April 2011.
• Ice Streams in the Past, the Present and the Future: A Challenge for Numerical Modeling - Annual Meeting of the Bert Bolin Centre for Climate Research, Stockholm, November 2010.
• Updating the ice sheet model SICOPOLIS with an improved treatment of ice flow - International Glaciological Society Nordic Branch Meeting 2010, Copenhagen, October 2010.
• Implementing Second Order Equations into SICOPOLIS - Seminar at the Department of Physical Geography and Quaternary Geology, Stockholm University, October 2010.

Posters

• Coupling the full Stokes equations and the SIA (+ SSA), European Geosciences Union General Assembly, Vienna, Austria, 2016.
• Ice Sheet Modelling, eSSENCE Academy 2015, Arlanda stad.
• Ice Sheet Modelling - Combining an Exact Model with Approximations. eSSENCE Academy 2014, Umeå.
• ''The Fast Full Stokes Method (FFS) Applied to the Greenland Ice Sheet'', ISSM Workshop 2014, June 2014.
• ''Ice Sheet Modeling - Validating Approximate Models by Numerical Simlations'', eSSENCE Academy 2013, Lund, and Bolin Days 2013, Stockholm, 2013.
• ''Computing Scaling Relations by Solving the Full Stokes Equations - Assessing the Validity of the SIA'', IGS Nordic Branch, Stockholm, 2012
• ''Second-order Shallow Ice Approximation with Non-linear Rheology: Exploring Validity by Performing Numerical Experiments'', European Geosciences Union General Assembly, Vienna, Austria, 2012.

Teaching

• Scientific Computing I (2016)
• Applied Scientific Computing (2015)
• Applied Scientific Computing (2014)
• Applied Scientific Computing (2013)
• Scientific Computing I (2013)
• Scientific Computing I (2012)
• Scientific Computing I (2011)