Quaternary Research Center

Jaakko Putkonen

Research Assistant Professor, Quaternary Research Center

Email: putkonen@u.washington.edu

Ph.D., University of Washington, 1997

After Jaakko Putkonen received his Ph.D at University of Washington 1997 he has been a Post Doctoral Researcher at the Department of Geological Sciences and Quaternary research Center at University of Washington, and recently (2001) joined the Faculty of the Department of Earth and Space Sciences and Quaternary Research Center at University of Washington at a rank of Research Assistant Professor.

Professor Putkonen strives to understand the Earth System in order to interpret the past, understand the present and predict the future.

His research approach ideally involves a strong field component, on the one hand consisting of the identification of structures and relations, as well as sampling and data gathering, and on the other hand computer modeling which provides a rigorous framework to analyze and organize observations. These two aspects allow effective testing of hypotheses and guide his research to sensitive areas of a particular problem.

Furthermore, he finds that field experience is invaluable in interpreting observations; therefore, He takes every opportunity to work in contrasting landscapes and to gain insights into diverse geologic processes that are best observed in varying climatic and geologic settings.

Recognizing the exciting opportunities that modern electronics combined with traditional field methods can yield, He excels in the use of cutting edge electrical instruments and digital sampling devices. These allow unprecedented measurement accuracy, temporal coverage both in terms of sampling frequency and duration of monitoring period, access to hazardous conditions, and continuous tracking of events. In an attempt to keep up with innovations in instrumentation, He follows closely industrial and research instrument literature. He also continues to design, develop, and personally test instruments in order to cater to the special needs of earth science projects.

Current Research

1) Geomorphic-Geodynamic Coupling at the Orogen Scale: A Himalayan Transect in Central Nepal
In this project we bring together expertise in process-based geomorphology, glaciology, geology, geochronology, and climatology for a multi-pronged approach to understanding the linkages between climate, erosion, and tectonics. This integrated study will be carried out across a large transverse catchment that spans the major structural elements and a pronounced climatic gradient in a very active collisional orogen (the Himalayas), allowing us to quantify the relationships between erosion, tectonics, climate, and topography. Order-of-magnitude differences exist in precipitation and are expected in both rock uplift and erosion rates in different parts of the proposed study area. Despite the uncertainties inherent in many of the proposed methodologies, the strong contrasts in different rock uplift, erosion, and climate regimes will insure that the signal of interest rises well above the noise of the measurements. The key to success lies in strategic choices of the key processes for detailed study, design of field sites so that there is a synergism among the multiple data sets, and innovative strategies to permit useful extrapolation of modern data, elimination of or compensation for anthropogenic effects, and integration of data relevant to a breadth of time scales. The result of this on going research will be the first integration at the orogen scale of the diverse array of forcing functions, controls, and potential products of interactions among climate, erosion, and tectonics. We suggest that the optimal means to assess hypotheses concerning orogenic evolution is through calibration, comparison, and integration of multiple relevant variables. Such broad-based research can only be undertaken through a multi-disciplinary project, such as ours.

2) Exposure age variation of surface boulders on moraines: quantifying the dating accuracy.
Analyses of all published cosmogenic-radionuclide dated moraine boulders show an average age variation of 43% between the oldest and youngest boulders from each moraine. This variation conflicts with the conventional assumption that surface boulder ages simply equate to the age of the landform. We suggest that the wide boulder age distribution is caused by erosion and subsequent exhumation of fresh boulders to the moraine surface. A standard surface degradation model shows that a randomly sampled small set of boulders (n=3-10), will always yield a younger age for the moraine than the true age of its formation. For a young or slowly degrading moraine, the boulder ages should approach the moraine age. The model further indicates that by dating seven 1 meter tall boulders from an eroding moraine surface, the oldest boulder age will generally be younger than the moraine but within 10% of the moraine age (95% probability). This result is only weakly sensitive to a broad range of diffusion parameters. Based on our analysis and modeling, 2% of all moraine boulders have prior exposure, and 90% of these boulders are older than the formation.

3) Stability of Land Surfaces in the Dry Valleys, Antarctica: Insights Based on the Dynamics of Sub-Surface Ice and Sand Wedge Polygons.
Shallow subsurface ice formations in the Dry Valleys have been indirectly dated back to 8 My which suggests an extraordinary stability of the underground ice. This is in clear contradiction with the theoretical vapor transfer rates for this type of soil. By launching multi-pronged research on vapor transfer in soil and geomorphic activity in the area we propose to solve this intriguing inconsistency and shed light on climatic variability of East Antarctica. See McMurdo Dry Valleys website for more information.

4) Soil Thermal Processes and Active Layer Properties near Ny Alesund, Spitsbergen.
A long term project was initiated in 1983 to gain insights on the physics of exceptionally well developed patterned ground and thermal aspects of the active layer. More recently the extensive instrumentation packages were amended and the surface energy balance is being studied as well. Strong effort has been gone into automated collection of continuous data from a remote arctic field site.

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A Brief Description of Completed Projects

1) Fresh Boulders on Old Moraines.
In the first prominent paper on cosmogenic isotope dating, the dates obtained were in clear conflict with the geologic record, bringing the merit of this most promising technique into question. I showed with my collaborator, professor Bernard Hallet, how this conflict can be explained by taking into account the geomorphic processes active in the area. We showed how the geomorphic evolution of the moraine, including degradation of boulders and exposure of new boulders, affects the apparent exposure age. I applied the analysis to a key sequence of moraines along the Sierra Nevada in California which records five major glacial advances. The results resolved the apparent conflict between the geologic record and exposure ages at the site. This research was the first to include moraine surface erosion and boulder weathering into a model of boulder exposure ages. The results were published in Science.

2) Climatic Control of the Thermal Regime of Permafrost.
The thermal link between atmosphere and permafrost is central to consideration of climate change consequences in Arctic areas and to interpretation of deep permafrost temperatures that constitute an exceptional archive of past climate change. I studied extensively the Arctic and periglacial environment, concentrating on heat transfer between the atmosphere and soil. The heat transfer problem required computer modeling of snow build-up, rain on snow, and soil and snow temperature. I was engaged in pervasive field instrumentation to monitor micrometeorology, soil and snow temperatures, and soil thermal and physical properties. In addition, I analyzed air mass dynamics in the area and was able to develop an index to predict the occurrence of rain on snow events. This project has contributed to several published and in progress journal articles and conference abstracts.

3) Dating of Thaw Depths in Permafrost Terrain Using Paleomagnetic Approach.
The past climate of the earth is found to be important to the climate modeling community, for testing the models, and better understanding the natural climatic variability. Arctic areas that lack suitable organic deposits (plant remains) or large glaciers (oxygen isotopes) are virtually uncharted territory in terms of understanding past climates or dating main climatic shifts. Therefore in collaboration with professor Reidar Lovlie (University of Bergen, Norway) I developed a concept to date directly permafrost by making use of the paleomagnetic information that is stored in the soil and has remained in a frozen state. This ground breaking, but still experimental method, was published in Geophysical Journal International.

Teaching philosophy

As a science educator I want to teach students how a seemingly random and chaotic natural world can be understood and explained through the laws of physics and chemistry, how intertwined geological processes can be reduced to measurable pieces, and how collected information can be organized with the aid of mathematical and conceptual models. This philosophy allows students to form a firm basis for deterministic and quantitative thinking and provide tools to complete individual earth science projects.

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Selected Papers and Abstracts

Putkonen, J.K, and T. Swanson. submitted. Exposure age variation of surface boulders on moraines: quantifying the dating accuracy. Quaternary Geology.

Putkonen, J.K. 2001. Quantifying the Moraine Degradation by Exposure Age Dating of Surface Boulders. Geological Society of America, annual meeting proceedings.

Blythe, A.E., J.K. Putkonen, and D.W. Burbank. 2001. Detailed Cooling History of the Central Nepalese Himalaya (Annapurna Region), from Apatite Fission Track and (U-Th)/He Analyses. Eos Transactions AGU, 82(47), Fall Meeting Supplement.

Barros. A.P., M.Joshi, J.Putkonen, and D.W.Burbank. 2000. A Study of the 1999 monsoon rainfall in a mountainous region in central Nepal using TRMM products and rain gauge observations. Geophysical Research Letters, Vol. 27, No. 22, pages 3683-3686.

Putkonen, J.K, and T. Swanson. 2000. Exposure age variation of surface boulders on moraines: quantifying the dating accuracy. Geological Society of America, annual meeting proceedings.

Putkonen,J.K., D.W. Burbank, and A.P. Barros. 2000. Automated measurement of the daily snow water content over the winter 1999/2000 in Annapurna region, Nepal. Eos, Fall meeting supplement, Transactions, American Geophysical Union.

Barros, A.P., J. Putkonen, D.W. Burbank, and A.T.C. Chang. 2000. Measurement and Analysis of Orographic Precipitation in the Himalayas - First Results from the TRMM Hydrometeorological Network in Central Nepal. 80th American Meteorological Society meeting Abstracts.

Putkonen, J.K. 1998. Soil Thermal Properties and Heat Transfer Processes near Ny Alesund, northwestern Spitsbergen, Svalbard. Polar Research, Vol. 17 (2), pp.165-179. Norwegian Polar Research Institute.

Putkonen, J.K. 1997. Climatic Control of the Thermal Regime of Permafrost, Northwest Spitsbergen. Eos, Fall meeting supplement, Transactions, AGU. Lovlie, R and J.K. Putkonen. 1996. Dating of Thaw Depths in Permafrost Terrain by Paleomagnetic Method; Experimental Acquisition of a Freezing Remanent Magnetization. Geophysical Journal International, Vol. 125, pp. 850-856.

Putkonen, J.K and B. Hallet. 1995. Importance of Vertical Variations on Thermal Properties in Modeling Heat Conduction in the Thawed Active Layer. Eos, Fall meeting supplement, Transactions, American Geophysical Union.

Hallet, B and J.K. Putkonen. 1994. Surface Dating of Dynamic Landforms: Young Boulders on Aging Moraines. Science, Vol. 265, pp. 937-940. Putkonen, J.K and B. Hallet. 1994. Thermal Link between the Atmosphere and Permafrost. Eos, Fall meeting supplement, Transactions, American Geophysical Union.

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