My main research interests are in different aspects of glaciology. My current focus is oon the thermodynamics of polythermal glacoiers as well as glacier climate interactions. I have also performed much work on the hydrology and coupled dynamics of glaciers.
|A longitudinal profile of the cold surface layer of Storglaciären measured in 2009|
Polythermal glaciers, with a cold surface layer overlaying a temperate core, are common to the sub-Arctic and Arctic environments. Essentially they constitute permafrost on glaciers. Unlike permafrost in ground the cold sirface layer ofn glaciers depends on many factors such as the dynamics of the glacier, the glacier mass balance and the moisture content of the temperate ice. The seasonaly melting surface of the glacier also provides special conditions where heat can escape during winter but is difficult to conduct into the ice during the warm season because of the zero-degree melting temperature at the surface. These complications make the observed changes in cold surface layer thicknes difficult to assess and a very interesting process to study.
Relevant publications on polythermal glaciers :
Relevant publications on polythermal glaciers :
Gusmeroli, A., Jansson, P., Pettersson, R., & Murray, T., 2012. Twenty years of cold surface layer thining at Storglaciären, sub-Arctic Sweden, 1989–2009. J. Glaciol. 58 (207), 3–10. doi:10.3189/2012JoG11J018.
Gusmeroli, A., Murray, T.,Jansson, P., Pettersson, R., & Aschwanden, A., 2010. Vertical distribution of water within the polythermal glacier Storglaciären, Sweden. J. Geophys. Res. F., 115, F04002, doi:10.1029/2009JF001539.
Pettersson, R., Jansson, P., Blatter, H. & Huwald, H., 2007. Spatial pattern and stability of the cold surface layer of Storglaciären, Sweden. J. Glaciol. (180), 99–109.
Pettersson, R., Jansson, P. & Blatter, H., 2004. Spatial variability of water content at the cold-temperate transition surface of the polythermal Storglaciären, Sweden. J. Geophys. Res. 109 (F2): F02009, doi:10.1029/2003JF000110.
Pettersson, R., Jansson, P. & Holmlund, P., 2003. Cold surface layer thinning on Storglaciären, Sweden, observed by repeated ground penetrating radar surveys, J. Geophys. Res., 108 (F1): 6004, doi:10.1029/2003JF000024.
Jansson, P., Näslund, J.-O., Pettersson, R., Richardson-Näslund, C. & Holmlund, P., 2000. Polythermal structure and debris entrainment in the terminus of Storglaciären. In: Nakawo, M., Raymond, C.F. and Fountain, A. (eds.): Debris-covered glaciers. Proceedings of a workshop held at Seattle, September 2000. IAHS Publ. No. 264: 143-151.
Glacier hydrology and ice dynamics
Several projects within which I have been active have focussed on the rrelationship between glacier hydrology and ice dynamics. During the 1980s and 1990s I participated in a long-term program run by rof Roger LeB. Hooke on Storglaciären which in its early years focussed on the coupling between the glacier hydrology and the dynamics of a glacier. My PhD dissertation was part of this effort. During the 1990s the project focussed more on the role of deforming subglacial sediments for the sliding of glaciers over their substrate. Prof. Neal R. Iveson was a driving force in this effort. During the the yers 2003-2005, I participated in a project headed by Prof. Andrew G. Fountain and Robert Jacobel on the englacial hydrology of glaciers. I curently am running a program on the processes of sediemtn entrainment at the col-temperate transition of polythemal glaciers in colaboration with Prof. Neal R. Iverson. The project on coupling the hydrology and dynamics of a glacier yielded many significant results. We carefully resolved the velocity variations ofg a small glacier such as Storglaciären (jansson, 1995) and could show the very sensitive response in velocity to water influx from melt and rain. An analysis of subglacial water pressure records allowed us to verify the behaviour of other glaciers occurred on Storglaciären. By studying the ice surface with extremely sensitive tiltmeters, we could also show that the glacier undergoes a very rapid dynamic response to melting in the early season (Jansson & Hooke 1989). This in conjunction with the observations of velocities are the first examples of the spring acceleration event which has later been observed on many glaciers. The studies also revealed that longitudinal coupling effects may be responsible for the observed velocity observations on the glacier (Jansson, 1997) but these ideas have been challenged and remain unsolved.
The project on sediment deformation during the 1990s produced very exciting data that indiacted that sediment deformation under Storglaciären was a passive process. We sould show that large defoemation occurred when the coupling between glacier and bed was large during low water pressures (Iverson et al., 1994, 1995). By combining records of surface velocity, water pressure and till deformation parameters a model was developed indicating that maximum deformation occurs during rising limb of water pressure associated with a speed up of the glacier (Hooke et al., 1997). These results are in clear conflict with earlier assumptions based on e.g. observations beneath Antarctic ice streams.. The difference probably stems rom the fact that the materials underlying glaciers vary in composition. The material at Storglaciären is non-cohesive (typical glacial diamicton) whereas the material beneath Ice Stream B in Antarctica is highly cohesive, perhaps reworked marine sediments.
The project on englacial hydrology has produced a completely new view of the hydrological system of glaciers. we were able to show that the englacial hydrological system of Storglaciären consists of numerous interconnected englacial cracks or crevasses. (Fountain et al., 2005a, b). Englacial crevasses were found at all depths from near surface to near bed . The crevasses seems to be recently formed based on their shape and direction. This study explains the enigma of the high rate of success in hitting englacial drainage when drilling through the glacier ice. Earlier theories spoke mostly of tunnels which would very hard to hit. The crevasses, however, are sloping surfaces that are much easier to encounter when drilling through the ice. These findings have implications on both the drainage system of glaciers as well as the bulk properties of ice when the entire ice volume contain water filled cracks.
|Hot water drilling on Storglaciären, summer 2008|
Fountain, A.G., Schlichting, R., Jansson, P. & Jacobel, R.W., 2005. Observations of englacial flow passages - a fracture dominated system. Ann. Glaciol. 40: 25-30.Fountain, A.G., Jacobel, R.W., Schlichting, R. & Jansson, P., 2005. Fractures as the main pathways of water flow in temperate glaciers. Nature. 433 (7026): 618-621.
Iverson, N.R., Baker, R.W., Hooke, R.LeB., Hanson, B. & Jansson, P., 1999. Coupling between a glacier and a soft bed: I. A relation between effective pressure and local shear stress determined from till elasticity. J. Glaciol. 45 (149): 31-40.
Fischer, U., Iverson, N.R., Hanson, B., Hooke, R.LeB. & Jansson, P., 1998. Estimation of hydraulic properties of the subglacial till layer from ploughmeter measurements. J. Glaciol. 44 (148): 517-522.
Jansson, P., 1997. Longitudinal coupling effects in ice flow across a subglacial ridge. Ann. Glaciol. 24: 169-174.
Hooke, R.LeB., Hanson, B., Iverson, N.R., Jansson, P. & Fischer, U., 1997. Rheology of till beneath Storglaciären, Sweden. J. Glaciol. 43 (143): 172-179.
Jansson, P., 1996. Dynamics and hydrology of a small polythermal valley glacier. Geogr. Ann. 78A (2-3): 171-180.
Jansson, P., 1995. Water pressure and basal sliding, Storglaciären, Sweden. J. Glaciol. 41 (138): 232-240.
Iverson, N.R., Hanson, B., Hooke, R.LeB. & Jansson, P., 1995. Flow mechanism of glaciers on soft beds. Science. 267 (5195): 80-81.
Iverson, N.R., Jansson, P. & Hooke, R.LeB., 1994. In-situ measurement of the strength of deforming subglacial till. J. Glaciol. 40 (136): 497-503.
Hooke, R.LeB., Pohjola, V.A., Jansson, P. & Kohler, J., 1992. Intraseasonal changes in deformation profiles revealed by borehole studies, Storglaciären, Sweden. J. Glaciol. 38 (130): 348-358.
Jansson, P. & Hooke, R.LeB., 1989. Short-term variations in strain and surface tilt on Storglaciären, Kebnekaise, Northern Sweden. J. Glaciol. 35 (121): 201-208.
My involvement with the Tarfala Research Station since 1985 have meant that much research has focussed on the mass balance climate relationship of Swedish glaciers. My interest has mainly foccussed on the glacier measurements in detail (Jansson, 1999, Jansson & Pettersson, in press) and the relationship between the glacier and the surrounding climatology. Summer balance is a well understood parameter but the winter balance (accumulation) is not. It is therefore of perimary interest is to find out how snow accumulation is forced by the circulation.(Jansson et al., 2007).
|Work on the ice cap Riukojietna in late March 2012|
Zemp, M., Jansson, P.<, Holmlund, P., Gärtner-Roer, I., Koblet, T., Thee, P., & Haeberli, W., 2010. Reanalysis of multi-temporal aerial images of Storglaciären, Sweden (1959-1999) – Part 2: Comparison of glaciological and volumetric mass balances. The Cryosphere. 4, 345–357. doi:10.5194/tc-4-345-2010. [Open Access journal].
Koblet, T., Gärtner-Roer, I., Zemp, M., Jansson, P., Thee, P., Haeberli, W., & Homlund, P., 2010. Reanalysis of multi-temporal aerial images of Storglaciären, Sweden (1959-1999) – Part 1: Determination of length, area and volume changes. The Cryosphere. 4, 333–343. doi:10.5194/tc-4-333-2010. [Open Access journal].
Jansson, P. &: Pettersson, R., 2007. Spatial and temporal characteristics of a long mass balance record, Storglaciären, Sweden. Arct. Ant. Alp. Res. 39 (3), 432–437. doi:10.1657/1523-0430(06-041)[jansson]2.0.co;2.
Jansson, P., Linderholm, H.W., Pettersson, R., Karlin, T. & Mörth, C.-M., 2007. Assessing the possibility to couple chemical signals in winter snow on Storglaciären to atmospheric climatology. Ann. Glaciol. 46, 335–341.
Linderholm, H.W. & Jansson, P., 2007. Reconstruction of Storglaciären glacier mass balance from 1500 AD using tree-ring data. Ann. Glaciol. 46, 261–267.
Linderholm, H.W., Jansson, P. & Chen, D., 2006. A high-resolution reconstruction of Storglaciären mass balance back to 1780/81 using tree-ring data and circulation indices. Quat. Res. doi:10.1016/j.ypres.2006.08.005.
Holmlund, P., Jansson, P. & Pettersson, R., 2005. A re-analysis of the 58 year mass balance record of Storglaciären, Sweden. Ann. Glaciol. 42: 389-394.
Jansson, P. & Linderholm, H., 2005. Assessment of combined glacier and tree-ring studies to constrain latitudinal climate forcing of Scandinavian glacier mass balances. Ann. Glaciol. 42: 303-310.
Jansson, P., Rosqvist, G. & Schneider, T., 2005. Glacier fluctuations, suspended sediment flux and glacio-lacustrine sediments. Geogr. Ann. 87A (1): 37-50.
Jansson, P., Hock, R. & Schneider, T., 2003. The concept of glacier storage - A review. J. Hydrol. 282 (1-4): 116-129.
Albrecht, O., Jansson, P. & Blatter, H., 2000. Modelling glacier response to measured mass balance. Ann. Glaciol. 31: 91-96.
Jansson, P., 1999. Effect of uncertainties in measured variables on the calculated mass balance of Storglaciären. Geogr. Ann. 81A (4): 633-642.
Fountain, A., Jansson, P., Dyurgerov, M. & Kaser, G., 1999. Methods of mass balance measurements on modelling, Workshop in Tarfala, Sweden, 1998. Geogr. Ann. 81A (4): 461-465.
Holmlund, P. & Jansson, P., 1999. The Tarfala mass balance program. Geogr. Ann. 81A (4): 621-631.