Sand Research.

For many years, I have been involved in the study of the physics of wind blown sand. This work is carried out in close collaboration with Keld Rømer Rasmussen from the Department of Earth Sciences, University of Aarhus. The main aim of the research has been to investigate and model the basic processes, but also to solve related statistical problems. We have always tried to ensure a fruitful mixture of theoretical work and experiments in the field as well as in the two windtunnels at Aarhus University. Applications of the research range from geomorphological processes to the desertification problems in the arid areas of the world.

My publications about sand and related subjects:

The vertical variation of particle speed and flux density in aeolian saltation: measurement and modeling. Co-author: K.R. Rasmussen. J. Geophys. Res., 113 2008, F02S12, doi:10.1029/2007JF000774.
On the size distribution of sand. Preprint 2006-3, Dept. of Applied Mathematics and Statistics, University of Copenhagen. postscript pdf
Dynamics of particles in aeolian saltation. Co-author: K.R. Rasmussen. In Garcia-Rojo, R., Herrmann, H.J. and McNamara, S. (eds.): Powders and Grains 2005, Vol. 2, Balkema, Rotterdam, 2005, 967 - 972. pdf
Probabilistic modeling of bed-load composition. Co-authors: I. McEwan, J. Heald, S. Tait, G. Cunningham, D. Goring and B.B. Willetts. J. of Hydr. Eng., 130, 2004, 129 - 139. ps pdf
On the rate of aeolian sand transport. Geomorphology 59, 2004, 53 - 62.
On the rate of aeolian sand transport. In Moctar, A.O.E. (ed.): Formation et Migration des Dunes, 2001, 56-60. Universite de Nouakchott. ps pdf
Aeolian mass transport near the saltation threshold. Co-author: K.R. Rasmussen. Earth Surface Processes and Landforms, 24, 1999, 1-10.
On the effect of time variability of the wind on rates of aeolian sand transport. Aarhus Geoscience, 7, 1997, 73-77. pdf
On the effect of mid-air collisions on aeolian saltation. Co-author: I. McEwan. Sedimentology, 43, 1996, 65-76.
Stochastic models of sand transport by wind and two related estimation problems. Internat. Statist. Rev., 61, 1993, 245-255.
A statistical model for the streamwise component of a turbulent velocity field. Co-authors: O.E. Barndorff-Nielsen and J.L. Jensen. Annales Geophysicae, 11, 1993, 99-103.
Methodology of sieving small samples and calibration of sieve sets. Co-authors: K. Dalsgaard and J.L. Jensen. In J.P.M. Syvitsky (ed.): Principles, Methods, and Application of Particle Size Analysis, Cambridge University Press, Cambridge, 1991, 64-75.
A review of recent progress in our understanding of aeolian sediment transport. Co-authors: R.S. Anderson and B.B. Willetts. Acta Mechanica, [Suppl] 1, 1991, 1-19.
An analytic model of wind-blown sand transport. Acta Mechanica, [Suppl] 1, 1991, 67-81.
On the temporal-spatial variation of sediment size distributions. Co-author: O.E. Barndorff-Nielsen. Acta Mechanica, [Suppl] 2, 1991, 23-35.
Parametric modelling of turbulence. Co-authors: O.E. Barndorff-Nielsen and J.L. Jensen. Phil. Trans. R. Soc. Lond., A 332, 1990, 439-455.
Radioactive tracer studies of grain progress in aeolian sand transport. A statistical analysis. Research Report 141, 1988, Department of Theoretical Statistics, University of Aarhus, 38 p.
Sand transport studies in a wind tunnel using radioactive grains. Report on a pilot experiment. Co-authors: O.E. Barndorff-Nielsen, J.L. Jensen, H.L. Nielsen and K.R. Rasmussen. Research Report 140, 1988, Department of Theoretical Statistics, University of Aarhus, 28 p.
Estimation of some aeolian saltation transport parameters from transport rate profiles. Proceedings of the International Workshop on the Physics of Blown Sand, 141-190. Memoirs No. 8, 1986, Department of Theoretical Statistics, University of Aarhus. pdf file
Measurement of saltation and wind strength on beaches. Co-authors: K.R. Rasmussen and B.B. Willetts. Proceedings of the International Workshop on the Physics of Blown Sand, 301-325. Memoirs No. 8, 1986, Department of Theoretical Statistics, University of Aarhus.
Laboratory studies of flow over dunes. Co-authors: K.R. Rasmussen and H. Tsoar. Proceedings of the International Workshop on the Physics of Blown Sand, 327-349. Memoirs No. 8, 1986 Department of Theoretical Statistics, University of Aarhus.
Windtunnel tracer studies of grain progress. Co-authors: O.E. Barndorff-Nielsen, J.L. Jensen, H.L. Nielsen and K.R. Rasmussen. Proceedings of the International Workshop on the Physics of Blown Sand, 243-251. Memoirs No. 8, 1986, Department of Theoretical Statistics, University of Aarhus.
Estimation of some aeolian saltation transport parameters: A reanalysis of Williams' data. Co-author: J.L. Jensen. Sedimentology, 33, 1986, 547-558.
The fascination of sand. Co-authors: O.E. Barndorff-Nielsen, P. Blæsild and J.L. Jensen. In A.C. Atkinson and S.E. Fienberg (eds.): A Celebration of Statistics, Springer-Verlag, New York, 1985, 57-87.
The Hanstholm experiment 1982. Sand grain saltation on a beach. Co-authors: J.L. Jensen, K. Rømer Rasmussen and B.B. Willetts. Research Report 125, 1984, Department of Theoretical Statistics, University of Aarhus, 66 p.
On the mathematical modelling of aeolian saltation. Co-author: J.L. Jensen. In B.M. Sumer and A. Müller (eds.): Mechanics of Sediment Transport, Balkema, Rotterdam, 1982, 65-72.
On the relation between size and distance travelled for winddriven sand grains - results and discussion of a pilot experiment using coloured sand. Co-authors: O.E. Barndorff-Nielsen and J.L. Jensen. In B.M. Sumer and A. Müller (eds.): Mechanics of Sediment Transport, Balkema, Rotterdam, 1982, 55-64.

Barchan dunes of dark sand in the Nili Patera region of Syrtis Major, Mars. The shapes of these dunes indicate that wind has been steadily transporting the dark sand from the right/upper right toward the lower left. This picture was taken on the first day of the MGS Mapping Phase during the second week of March 1999. It shows an area 2.1 kilometers wide at the full commanded resolution of 3 meters per pixel. Illumination is from the upper left. Photo Credit: NASA/JPL/Malin Space Science Systems.

Danish dunes