|
| Title: |
Dating annual layers of a shallow Antarctic ice core with an optical scanner |
| Author: |
McGwire, K.C., McConnell, J.R., Alley, R.B., Banta, J.R., Hargreaves, G.M. and Taylor, K.C. |
| URL: |
http://www.igsoc.org/journal/54/188/j08j041.pdf
|
| Periodical: |
Journal of Glaciology |
| Volume: |
54 |
| Issue: |
188 |
| Abstract: |
This study tests novel methods for automatically identifying annual layers
in a shallow Antarctic ice core (WDC05Q) using images that were collected
with an optical scanner at the U. S. National Ice Core Laboratory. A new
method of optimized variance maximization (OVM) modeled the density-related
changes in annual layer thickness directly from image variance. This was
done by using multi-objective complex (MOCOM) parameter optimization to
drive a low-pass filtering scheme. The OVM-derived changes in annual layer
thickness corresponded well with the results of an independent
glaciochemical interpretation of the core. Individual annual cycles in
image brightness were then identified by using OVM results to apply a
depth-varying low-pass filter and fitting a second-order polynomial to a
locally detrended neighborhood. The resulting map of annual cycles agreed
to within 1% of the overall annual count of the glaciochemical
interpretation. Agreement on the presence of specific annual layer features
was 96%. It was also shown that the MOCOM parameter optimization could
calibrate the image-based results to directly match the date of a specific
volcanic marker. |
| Year: |
2008 |
| Copyright: |
The Journal of Glaciology is a publication of the International Glaciological Society. All rights reserved. No part of this publication may be reproduced in any material form (including photocopying or storage in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright owner except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency, 90 Tottenham Court Road, London W1T 4LP, United Kingdom (Fax: +44-20-7631-5555; E-mail: info@cla.co.uk). Applications for the copyright owner's written permission to reproduce any part of this publication should be addressed to the publisher. Abstracts of articles in the Journal of Glaciology may be reprinted by abstracting journals.
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This site is administered by the WAIS Divide Ice Core Project Science Coordination Office (Desert Research Institute and University of New Hampshire). This material is based on work supported by the National Science Foundation under award OPP-0440817 to the Desert Research Institute, Nevada System of Higher Education. Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.