Lev Tarasov

Lev Tarasov
Canada Research Chair in Glacial Dynamics Modelling and Associate Professor
Department of Physics and Physical Oceanography
Memorial University
St. John's, Newfoundland, Canada
A1B 3X7



Office: Chemistry Physics C4043
Telephone: 709.864.2675
Fax: 709.864.8739
E-Mail: lev At mun D0t ca





Home

Research

Research group

Research Opportunities

Publications

C.V.

Collaborations

MOCA (Meltwater routing and Ocean-Cryosphere-Atmosphere response network)

projected glacial cycle movie (9Mb)

deglacial cycle movie (2.7Mb)

Belcher Glacier (Devon island) 2008 field trip

Northern Labrador Sea kayak expedition 2012


Local links

Oceanography

Physics

Memorial University

Climate and Earth and Human systems dynamics journal club

Earth and Human Systems Sustainability Initiative


Other Stuff

Advice for modellers

Recommended software

Pedagogy

strategy for social change

wilderness sports

P2820

P3220

P3340

CREATE training program in Climate Science


Welcome

I'm a generalist figuring out how to survive in an academic specialist world. Along the way I've traveled from a Ph.D. in Quantum Gravity to a Canada Research Chair in glacial systems modelling, with a stop as an organic farmer. I've also long had an on-going interest in radical social change (with a focus on theatrical media), wilderness sports, and systems design. In these pages you will find an overview of my current research, list of collaborations, some thoughts on pedagogy and strategy for social change, and some advice for computer modellers.

Research orientation

I'm generally interested in the modelling of complex systems, with an expertise in glacial systems (combining ice, climate, and earth). Modelling is well suited to those of us who like to build/create things. It offers the opportunity to explore virtual worlds, probe myriads of "what ifs", and create piles of data. The challenge is to come up with meaningful results with limited computational resources. Limited resources and limited understanding implies that models of complex physical systems will invariably require simplifications and parameterizations. Along with uncertainties in initial and boundary conditions, the analysis and interpretation of model results becomes a major challenge.

A key point in this regard (for which ice-sheet and climate modelers have been generally deficient) is the need to create meaningful error bars, or better yet probability distributions, for the results of models when used in the context of prediction or retrodiction. The determination of meaningful probability distributions by means of Bayesian calibration of models against observational constraints has therefore become a central focus of my work.

I am also very interested in improving our ability to constrain the changing variability of systems and associated potential thresholds. In the context of climate change, this is arguably both the greatest scientific challenge and the aspect that carries the highest potential impacts. My current approach to this challenge involves three key steps. First, identify the bounds on dynamical processes potentially controlling variability and thresholds. Second, constrain the spatial and temporal scale sensitivities of the representation of these key dynamical processes and their interactions. Finally, develop probability distributions of potential response through a combination of large ensemble data-calibrated modelling with stochastic probing of the bounding critical dynamics.

Glacial systems model

Probably the favourite aspect of my work (aside from learning) is model building. The MUN/UofT Glacial Systems model has been my baby and continues to undergo development. The core elements are a thermo-mechanically coupled 3D ice-sheet model and a global visco-elastic bedrock deformation model. Other important components include a bed thermal/permafrost module, physically-based surface mass-balance module, ice calving module, sub-glacial till-deformation representation, and a fast surface drainage solver. Optional modules can compute high-resolution Semi-Lagrangian tracer tracking and gravitationally-self-consistent relative sea-level. The newest additions created within my group are a subglacial sediment production/transport module and subglacial hydrology. The critical surface boundary condition is provided by coupling of the glacial systems model to a hierarchy of climate models and forcings.

A number of additional components are or will be under development. These include: a higher order ice-dynamics model that accounts for longitudinal and horizontal shear stresses to improve the representation of ice-streams and ice-shelves, sub-grid mass-balance, and a hierarchy of ice-calving modules. A key focus is improving diagnostic components to enable expanded comparisons of model results against observational data. There are thus a range of opportunities for students to get their hands dirty with model building.

Research questions

My general focus is on constraining and understanding the interactions between the cryosphere and the rest of the climate system. This includes both past, present, and future contexts. The past offers a major opportunity to develop and test our understanding of climate dynamics. The present and future stability of the cryosphere and associated interactions with the rest of the climate system are major environmental concerns. Questions that are currently absorbing my attention include the following:

What is the probability distribution for the future evolution of the Greenland and Antarctic ice sheets?

How can we improve constraints on potential instabilities?

What are the past and potential future impacts of meltwater and iceberg discharge on the climate system? What are the key uncertainties and controls on polar climate stability?

What controlled the climate system response to meltwater pulse 1-a and to the discharge associated with Heinrich events and the Younger Dryas? How will the variability of polar and sub-polar climate change in our future?

What drove the glacial cycle?

What are the critical feedbacks in the cryosphere and climate system that drive the 100kyr glacial cycles? What was the source of the mid-Pleistocene transition? What is the probability distribution for the ice, meltwater, and climate chronology of the last glacial cycle?

What is the phase space of the glacial climate system?

What is the order of the dynamical system? What other limit cycles and attractors are accessible (ie. how robust is the glacial cycle)? What controls the dynamical structure?

How can the calibration of computationally expensive models against observational constraints be improved?

How do different methodologies compare for this type of data inversion problem? How can they be advantageously combined? How can the error associated with the limited phase space of the model be quantified? More generally, how can we generate meaningful uncertainty estimates (and full probability distributions) for climate and glacial system changes (past, present, and future)?

Research group

I am blessed with a keen research group:

Mohammad Hizbul Bahar Arif
MSc research: Dynamical climate representations for long-term integrations.
Taimaz Bahadory
PhD research: Earth Systems (coupled climate-glacial systems) modelling of ice and climate interactions over the past glacial cycle.
Benoit Lecavalier
PhD research: Bayesian calibration of model for past Antarctic Ice Sheet evolution.
Kevin Le Morzadec
PhD research: Scaling issues in glacial dynamics.

Past students (completion date)

Robert Briggs (Jan, 2013), currently research scientist at C-Core, St. John's
PhD research: Data-constrained large-ensemble modelling of Antarctic deglaciation.
Tristan Hauser (Aug, 2009), currently PhD student
MSc research: Comparison of MCMC and Ensemble Kalman Filter methodologies for model calibration.
Tristan Hauser (Nov 2013), currently Post-Doc in Capetown, S. Africa
PhD research: Bayesian Calibration of Earth Systems Models and temporal/spatial downscaling.
Mark Kavanagh (Aug, 2012), currently PhD student
MSc research: The impact of uncertainties in Basal hydrology on the past and future evolution of the Greenland Ice Sheet.
Andrew Keats (Dec, 2011), currently Senior Associate - Financial Advisory - Analytics at Deloitte
Post-Doctoral research: Ice and climate interactions and the Bayesian calibration of a coupled glacial systems and GCM climate model.
Alex Melanson (Aug, 2012), currently PhD student
MSc research: Modeling of subglacial sediment transport over North America. Co-supervised by Trevor Bell.

Research opportunities

(1) I am always keen to hear from potential graduate students who are interested in Earth systems modelling and analysis (NOTE: I do not respond to broadcast queries that have no relevance to my research). With my emphasis on data-integrated modelling, I do expect all of my PhD students (and if feasible, MSc as well) to participate in at least one field project in order to get a hands on view of the real uncertainties associated with field data. Such projects will also help develop physical intuition and understanding of Earth system processes. The spectacular natural environment of Newfoundland also offers incentive and inspiration.

(2) I am part of the CREATE training program in Climate Science and ArcTrain Canada: Processes and impacts of climate change in the North Atlantic Ocean and the Canadian Arctic. I think these are exciting opportunities for a funded multidisciplinary graduate education. I find that much of current interesting science (especially within the global change context) needs researchers who are comfortable in an interdisciplinary setting. These programs should help train such researchers.

(3) If you are considering joining my group, I require:

a) Core strength in one or more of: physics, computational fluid dynamics, climate or ice sheet modelling, and/or applied math (ie undergraduate major or in special circumstances minor).

b) An independent work orientation.

c) Clear specification of what research topics you are interested in working on, (just saying "I'm really interested in your research area" won't cut it, no matter how much you try to flatter me).


WebContact - Lev Tarasov Last updated - Aug 2012