Optimal Measurement of Ice-Sheet deformation from Surface-Marker Arrays

• Published in: Journal of Glaciology
• Main Author: MacAyeal, D.R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1985
• Subjects: Earth-Surface Processes; Ross Ice Shelf; Ice Sheet; Ice Shelf; Journal of Glaciology
• Online Access: http://dx.doi.org/10.1017/s0022143000004998; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000004998

Abstract Surface strain-rate is best observed by fitting a strain-rate ellipsoid to the measured movement of a stake network, or other collection of surface features, using a least-squares procedure. Error of the resulting fit varies as (L Δ t√n) -1 where L is the stake separation, Δ t is the time period between initial and final stake survey, and n is the number of stakes in the network. This relation suggests that, if n is sufficiently high, the traditional practice of re-visiting stake-network sites on successive field seasons may be replaced by a less costly single-year operation. A demonstration using Ross Ice Shelf data shows that reasonably accurate measurements can be obtained from 12 stakes after only four days of deformation. The least-squares procedure may also aid airborne photogrammetric surveys in that reducing the time interval between survey and re-survey could permit better surface-feature recognition.