Grain-size evolution of polar firn: a new empirical grain growth parameterization based on X-ray microcomputer tomography measurements


Contact
Stefanie.Linow [ at ] awi.de

Abstract

Firn microstructure properties from six different sites in Greenland and Antarctica are investigated by means of X-ray microcomputer tomography. The optical effective radius is calculated from the specific surface area (SSA) and used as a measure of grain size. It is shown that the recently introduced spherical approximation of firn grains using the effective radius R_eff is representative of grain size in the microwave frequency region. The measured profiles show the well-known increase of grain size with depth at all sites, where the increase is largest at near-surface depths. A large variability in grain size on the decimeter-to-centimeter scale as a result of different grain properties of single layers is superimposed on the overall trend at each site. A simple empirical parameterization of grain-size evolution is developed which allows the rapid grain growth in the uppermost layers of the firn to be predicted. The growth is driven by strong seasonal and diurnal temperature gradients. The model can be used to simulate grain-size profiles required by models of firn/microwave interaction (e.g. for retrieval of accumulation rates from satellite microwave sensors) in a more realistic fashion.



Item Type
Article
Authors
Divisions
Primary Division
Programs
Primary Topic
Publication Status
Published
Eprint ID
31503
DOI 10.3189/2012JoG11J256

Cite as
Linow, S. , Hörhold, M. and Freitag, J. (2012): Grain-size evolution of polar firn: a new empirical grain growth parameterization based on X-ray microcomputer tomography measurements , Journal of Glaciology, 58 (212), pp. 1245-1252 . doi: 10.3189/2012JoG11J256


Share
Add to AnyAdd to TwitterAdd to FacebookAdd to LinkedinAdd to PinterestAdd to Email


Citation

Research Platforms
N/A

Campaigns
N/A


Actions
Edit Item Edit Item