The University of Southampton
University of Southampton Institutional Repository

A densely sampled core and climate variable aliasing

A densely sampled core and climate variable aliasing
A densely sampled core and climate variable aliasing
Undersampled records are susceptible to aliasing, in which a high frequency appears incorrectly as a lower one. We study the sampling requirements in a core taken from Rockall Trough using bulk density, P-wave velocity, and magnetic susceptibility as measured on an automated system. At 2-cm spacing (approximately 33 years in this core), all variables show a characteristic red-noise behavior, but with a spectral slope that is sufficiently weak so that significant aliasing appears to be present. P-wave velocity shows the largest potential corruption, probably owing to the weaker spatial averaging present in the sensor. Approximately 50% of the apparent low-frequency energy is aliased in all variables at some frequencies in both quiet and active regions of the record. In this core, a sampling interval of 0.2 cm appears to be "safe" in both active and quiet portions of the core, aliasing little or no energy, except in the P-wave record. For cores of different duration, sampling interval, and measurement type, the considerations will be identical, the importance of the problem depending directly upon the shape of the overall spectrum describing the entire frequency (wavenumber) range of physical variability.
0276-0460
64-71
Wunsch, C.
cc7ca024-feaa-4733-9c9c-8dd935befc6c
Gunn, D.E.
31b09ec5-5838-4c52-8954-a880f9c6cb7b
Wunsch, C.
cc7ca024-feaa-4733-9c9c-8dd935befc6c
Gunn, D.E.
31b09ec5-5838-4c52-8954-a880f9c6cb7b

Wunsch, C. and Gunn, D.E. (2003) A densely sampled core and climate variable aliasing. Geo-Marine Letters, 23 (1), 64-71. (doi:10.1007/s00367-003-0125-2).

Record type: Article

Abstract

Undersampled records are susceptible to aliasing, in which a high frequency appears incorrectly as a lower one. We study the sampling requirements in a core taken from Rockall Trough using bulk density, P-wave velocity, and magnetic susceptibility as measured on an automated system. At 2-cm spacing (approximately 33 years in this core), all variables show a characteristic red-noise behavior, but with a spectral slope that is sufficiently weak so that significant aliasing appears to be present. P-wave velocity shows the largest potential corruption, probably owing to the weaker spatial averaging present in the sensor. Approximately 50% of the apparent low-frequency energy is aliased in all variables at some frequencies in both quiet and active regions of the record. In this core, a sampling interval of 0.2 cm appears to be "safe" in both active and quiet portions of the core, aliasing little or no energy, except in the P-wave record. For cores of different duration, sampling interval, and measurement type, the considerations will be identical, the importance of the problem depending directly upon the shape of the overall spectrum describing the entire frequency (wavenumber) range of physical variability.

This record has no associated files available for download.

More information

Published date: 2003

Identifiers

Local EPrints ID: 1234
URI: http://eprints.soton.ac.uk/id/eprint/1234
ISSN: 0276-0460
PURE UUID: d9842271-9836-480a-8340-57cc0f638bd6

Catalogue record

Date deposited: 06 Apr 2004
Last modified: 15 Mar 2024 04:42

Export record

Altmetrics

Contributors

Author: C. Wunsch
Author: D.E. Gunn

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×