On the use of iterative re-weighting least-squares and outlier detection for empirically modelling rates of vertical displacement |
| |
Authors: | E Rangelova G Fotopoulos M G Sideris |
| |
Institution: | (1) Department of Geomatics Engineering, Schulich School of Engineering, University of Calgary, 2500 University Dr NW, Calgary, AB, Canada, T2N 1N4;(2) Department of Civil Engineering, Faculty of Applied Sciences and Engineering, University of Toronto, 35 St. George Street, Toronto, ON, Canada, M5S 1A4 |
| |
Abstract: | The proper identification and removal of outliers in the combination of rates of vertical displacements derived from GPS,
tide gauges/satellite altimetry, and GRACE observations is presented. Outlier detection is a necessary pre-screening procedure
in order to ensure reliable estimates of stochastic properties of the observations in the combined least-squares adjustment
(via rescaling of covariance matrices) and to ensure that the final vertical motion model is not corrupted and/or distorted
by erroneous data. Results from this study indicate that typical data snooping methods are inadequate in dealing with these
heterogeneous data sets and their stochastic properties. Using simulated vertical displacement rates, it is demonstrated that
a large variety of outliers (random scattered and adjacent, as well as jointly influential) can be dealt with if an iterative
re-weighting least-squares adjustment is combined with a robust median estimator. Moreover, robust estimators are efficient
in areas weakly constrained by the data, where even high quality observations may appear to be erroneous if their estimates
are largely influenced by outliers. Four combined models for the vertical motion in the region of the Great Lakes are presented.
The computed vertical displacements vary between − 2 mm/year (subsidence) along the southern shores and 3 mm/year (uplift)
along the northern shores. The derived models provide reliable empirical constraints and error bounds for postglacial rebound
models in the region. |
| |
Keywords: | Outlier detection Robust estimation Vertical crustal displacement Postglacial rebound GRACE |
本文献已被 SpringerLink 等数据库收录! |
|