Optimal measurement of ice-sheet deformation from surface-marker arrays

• Main Author: Macayeal, D. R.
• Format: Other/Unknown Material
• Language: unknown
• Published: 1983
• Subjects: GEOPHYSICS; Ross Ice Shelf; Ice Sheet; Ice Shelf
• Online Access: http://hdl.handle.net/2060/19840024879

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 1/(L delta t square root of N), where L is the stake separation, delta 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 revisiting 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 are obtained from 12 stakes after only 4 days of deformation. It is possible for the least squares procedure to aid airborne photogrammetric surveys because reducing the time interval between survey and re-survey permits better surface feature recognition.