MacGregor, J.A., K. Matsuoka, M.R. Koutnik, E.D. Waddington, M. Studinger, and D.P. Winebrenner, Ann Glacol., 50(51), 25-34, 2009 [link to the full paper]

Radar layers in the ice sheets tell us about past snow falls.

Ice-penetrating radar detect reflectors in the ice sheets as well as their beds.  Such reflectors are well accepted as isochrones, which is composed of snow deposited to the ice-sheet surface in the same year.  Tracking such layers give us information about the snowfall (accumulation) history in the past, only if we successfully extract effects of ice deformation after the deposition.

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Conway, H., B. Smith, P. Vaswani, K. Matsuoka, E. Rignot, and P. Claus, Ann. Glaciol., 50 (51), 93-97, 2009 [Link to the full paper]

The long teil behind the single otter airplane is indeed the radar system.

We are proud of our science at the cutting edge, but our instruments do not look as fancy as you imagine….  We adapted our ground-based radar system to the use from an airplane with the minimum efforts: the transmitter was placed in an old shipping box and some more parts of the system are actually from dust-covered areas in the storage space…  We got great results with it. Read the rest of this entry »

Matsuoka, K., L. Wilen, S. P. Hurley, and C. F. Raymond, IEEE Trans. Geosci. Remote Sens., 47 (5), 1429-1443, doi 10.1109/TGRS.2008.2005201, 2009. [Link to the publisher’s site]

Effects of alignments of ice crystals dominates frequency dependnece of the radar returned power from the bed

Ice-core scientists make thin (< 1 mm) slices from ice cores to look crystal alignments of the ice core.  They change tilt and azimuthal angles of the slice under the natural light so that individual crystals show different colors in terms of angles and crystal alignments.  This technique has been used to determine alignments of ice crystals, which is related to the past deformation of the ice and current viscosity of the ice.

Radar scientists can do a similar survey using much longer wavelength (radio wave) for much thicker ice (actual ice sheet, rather than mm-thick samples).  However, we have a single spectrum (rather than white light) in general so the information that we can gain is less than the ice core studies. Read the rest of this entry »

MacGregor, J. A., K. Matsuoka, and M. Studinger , Earth Planet. Sci. Lett., 282, 222-233, 2009. [Link to the paper]

Our interpretation of the ice and subice structure over Lake Vostok

We identified the reflection cause of a very weak echo in the radar image over subglacial lake Vostok in East Antarctica.  Lake Vostok is the largest subglacial lake amongst more than 170 lakes identified so far.  An international team (mainly a collaboration between France, Russia, and US) drilled a deep ice core of roughly 3.5 km long which has been revealed a dynamics climate change in the past 420,000 years.  The ice thickness at the drilling site is about 300 m more than the length of the core: are there opportunity to reconstruct the climate record longer than we already have (420k years)?? Read the rest of this entry »

Matsuoka, K., A. Gades, H. Conway, G. Catania, and C. F. Raymond, Ann. Glaciol., 50 (51), 98-104, 2009. [Link to the full paper]

Satellite image showing micro topography of the ice streams, West Antarctica. Rectangles in the main map and inset show, respectively, our study area and the coverage of the main map.

This paper unlocks a three-dimensional ice structure beneath linear features observed from space using ground-based ice-penetrating radar.  Read the rest of this entry »