Kristoffer Rypdal
Kristoffer Rypdal | |
|---|---|
 | |
| Born | December 2, 1951 |
| Residence | Norway |
| Nationality | Norwegian |
| Known for | Complex systems modelling; stochastic-dynamic modelling of Earth's climate |
| Scientific career | |
| Fields | Professor of Physics; plasma physics; complex systems; climate dynamics |
| Institutions | University of Tromsø (UiT The Arctic University of Norway) |
Kristoffer Rypdal is a Norwegian physicist and professor emeritus at UiT The Arctic University of Norway (formerly the University of Tromsø). His research career has ranged over plasma physics, the theory of complex systems, and the statistical and stochastic-dynamic modelling of the Earth's climate. He is affiliated with the university's Department of Mathematics and Statistics and is a member of the Complex Systems Modelling (CoSMo) research group.
Biography
Rypdal completed his undergraduate studies in physics in Oslo in 1973. He then moved to the newly founded University of Tromsø in Arctic Norway, where he began working in plasma physics, the study of many-body systems of charged particles. Over the course of his career his interests broadened from plasma physics toward the study of nonlinear dynamics, deterministic chaos, scale invariance, and complex systems more generally. In his later career his work centred on climate science, in particular the data analysis and stochastic-dynamic modelling of the Earth's climate. He was subsequently affiliated with the Department of Mathematics and Statistics at UiT and is now a professor emeritus.
Research
Rypdal's early research concerned plasma physics, where he worked on the reduction of the complex dynamics of large systems of interacting charged particles into tractable kinetic and fluid descriptions. He has noted that such coarse-grained models, although formally "less accurate" than the underlying time-reversible microscopic equations, introduce dissipation and thereby give time a direction, providing an irreversible description that better matches observed behaviour.
From the 1980s onward his interests followed the emergence of new paradigms in physics, including deterministic chaos and the recognition that simple deterministic systems with few degrees of freedom can produce highly complex behaviour. He was also drawn to the ubiquity of scale invariance in nature, associated with the fractal geometry of Benoit Mandelbrot, and to the concept of self-organized criticality (SOC) introduced by Per Bak, in which systems with many degrees of freedom and simple local interactions spontaneously organize into a critical state exhibiting scale-invariant "avalanche" dynamics across many scales in space and time. This led him to the broader programme of modelling reality as complex systems of many interacting agents that exhibit emergent global behaviour not imposed by any external controller.
In his climate research, Rypdal applied methods from complex systems and statistical physics to the analysis of temperature records and climate models. His work has examined long-memory (long-range dependent) behaviour and scale invariance in the climate system, using linear-response and stochastic models of the Earth's temperature to study climate sensitivity and the implications for future global warming. This work has been carried out within the Complex Systems Modelling group at UiT, which brings together researchers from mathematics, statistics, and physics.
Selected publications
- Rypdal, K.; Rypdal, M. (2008). "Scale-free vortex cascades emerging from random forcing in strongly coupled systems." New Journal of Physics.
- Fredriksen, H.-B.; Rypdal, K. (2016). "Spectral characteristics of instrumental and climate model surface temperatures." Journal of Climate, 29(4), 1253–1268.
Media
- 2004 - Universe - The Cosmology Quest (Video Movie)