Annual variations in GPS-measured vertical displacements near Upernavik Isstrøm (Greenland) and contributions from surface mass loading: Annual GPS Verticals in Greenland

Lin Liu, Shfaqat Abbas Khan, Tonie van Dam, Joseph Ho Yin Ma, Michael Bevis

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Abstract

In response to present-day ice mass loss on and near the Greenland Ice Sheet, steady crustal uplifts have been observed from the network of Global Positioning System (GPS) stations mounted on bedrock. In addition to the secular uplift trends, the GPS time series also show prominent annual variability. Here we examine the annual changes of the vertical displacements measured at two GPS stations (SRMP and UPVK) near Upernavik Isstrøm in western Greenland. We model elastic loading displacements due to various surface mass loading including three non-ice components: atmospheric pressure, ocean bottom pressure, continental water storage, and one ice component, i.e., surface mass balance (SMB). We find that the contribution from atmospheric pressure changes can explain 46% and 78% of the annual amplitude observed in the GPS verticals at SRMP and UPVK, respectively. We also show that removing the predicted loading displacements due to SMB adversely increases the annual variance of the GPS residuals. However, using the GPS data alone, we cannot identify the exact cause(s) of this discrepancy because the annual loading displacements are sensitive to the SMB changes from over 85% of the ice sheet area. Alternatively, by differencing vertical displacements between the two stations, we find a good agreement between the modeled differential SMB loading displacements and the GPS residuals after removing non-ice components. Our study highlights the necessity of correcting for non-ice loading contributions in the GPS measurements of crustal deformation to infer ice mass changes in Greenland at annual periods.
Original languageEnglish
JournalJournal of Geophysical Research
Volume122
Issue number1
Pages (from-to)677–691
ISSN2169-9380
DOIs
Publication statusPublished - 2017

Cite this

@article{4be0e2893a7b44e6b207f116f61f386d,
title = "Annual variations in GPS-measured vertical displacements near Upernavik Isstr{\o}m (Greenland) and contributions from surface mass loading: Annual GPS Verticals in Greenland",
abstract = "In response to present-day ice mass loss on and near the Greenland Ice Sheet, steady crustal uplifts have been observed from the network of Global Positioning System (GPS) stations mounted on bedrock. In addition to the secular uplift trends, the GPS time series also show prominent annual variability. Here we examine the annual changes of the vertical displacements measured at two GPS stations (SRMP and UPVK) near Upernavik Isstr{\o}m in western Greenland. We model elastic loading displacements due to various surface mass loading including three non-ice components: atmospheric pressure, ocean bottom pressure, continental water storage, and one ice component, i.e., surface mass balance (SMB). We find that the contribution from atmospheric pressure changes can explain 46{\%} and 78{\%} of the annual amplitude observed in the GPS verticals at SRMP and UPVK, respectively. We also show that removing the predicted loading displacements due to SMB adversely increases the annual variance of the GPS residuals. However, using the GPS data alone, we cannot identify the exact cause(s) of this discrepancy because the annual loading displacements are sensitive to the SMB changes from over 85{\%} of the ice sheet area. Alternatively, by differencing vertical displacements between the two stations, we find a good agreement between the modeled differential SMB loading displacements and the GPS residuals after removing non-ice components. Our study highlights the necessity of correcting for non-ice loading contributions in the GPS measurements of crustal deformation to infer ice mass changes in Greenland at annual periods.",
author = "Lin Liu and Khan, {Shfaqat Abbas} and {van Dam}, Tonie and Ma, {Joseph Ho Yin} and Michael Bevis",
year = "2017",
doi = "10.1002/2016JB013494",
language = "English",
volume = "122",
pages = "677–691",
journal = "Journal of Geophysical Research",
issn = "0148-0227",
publisher = "American Geophysical Union",
number = "1",

}

Annual variations in GPS-measured vertical displacements near Upernavik Isstrøm (Greenland) and contributions from surface mass loading : Annual GPS Verticals in Greenland. / Liu, Lin; Khan, Shfaqat Abbas; van Dam, Tonie; Ma, Joseph Ho Yin; Bevis, Michael.

In: Journal of Geophysical Research, Vol. 122, No. 1, 2017, p. 677–691.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Annual variations in GPS-measured vertical displacements near Upernavik Isstrøm (Greenland) and contributions from surface mass loading

T2 - Annual GPS Verticals in Greenland

AU - Liu, Lin

AU - Khan, Shfaqat Abbas

AU - van Dam, Tonie

AU - Ma, Joseph Ho Yin

AU - Bevis, Michael

PY - 2017

Y1 - 2017

N2 - In response to present-day ice mass loss on and near the Greenland Ice Sheet, steady crustal uplifts have been observed from the network of Global Positioning System (GPS) stations mounted on bedrock. In addition to the secular uplift trends, the GPS time series also show prominent annual variability. Here we examine the annual changes of the vertical displacements measured at two GPS stations (SRMP and UPVK) near Upernavik Isstrøm in western Greenland. We model elastic loading displacements due to various surface mass loading including three non-ice components: atmospheric pressure, ocean bottom pressure, continental water storage, and one ice component, i.e., surface mass balance (SMB). We find that the contribution from atmospheric pressure changes can explain 46% and 78% of the annual amplitude observed in the GPS verticals at SRMP and UPVK, respectively. We also show that removing the predicted loading displacements due to SMB adversely increases the annual variance of the GPS residuals. However, using the GPS data alone, we cannot identify the exact cause(s) of this discrepancy because the annual loading displacements are sensitive to the SMB changes from over 85% of the ice sheet area. Alternatively, by differencing vertical displacements between the two stations, we find a good agreement between the modeled differential SMB loading displacements and the GPS residuals after removing non-ice components. Our study highlights the necessity of correcting for non-ice loading contributions in the GPS measurements of crustal deformation to infer ice mass changes in Greenland at annual periods.

AB - In response to present-day ice mass loss on and near the Greenland Ice Sheet, steady crustal uplifts have been observed from the network of Global Positioning System (GPS) stations mounted on bedrock. In addition to the secular uplift trends, the GPS time series also show prominent annual variability. Here we examine the annual changes of the vertical displacements measured at two GPS stations (SRMP and UPVK) near Upernavik Isstrøm in western Greenland. We model elastic loading displacements due to various surface mass loading including three non-ice components: atmospheric pressure, ocean bottom pressure, continental water storage, and one ice component, i.e., surface mass balance (SMB). We find that the contribution from atmospheric pressure changes can explain 46% and 78% of the annual amplitude observed in the GPS verticals at SRMP and UPVK, respectively. We also show that removing the predicted loading displacements due to SMB adversely increases the annual variance of the GPS residuals. However, using the GPS data alone, we cannot identify the exact cause(s) of this discrepancy because the annual loading displacements are sensitive to the SMB changes from over 85% of the ice sheet area. Alternatively, by differencing vertical displacements between the two stations, we find a good agreement between the modeled differential SMB loading displacements and the GPS residuals after removing non-ice components. Our study highlights the necessity of correcting for non-ice loading contributions in the GPS measurements of crustal deformation to infer ice mass changes in Greenland at annual periods.

U2 - 10.1002/2016JB013494

DO - 10.1002/2016JB013494

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VL - 122

SP - 677

EP - 691

JO - Journal of Geophysical Research

JF - Journal of Geophysical Research

SN - 0148-0227

IS - 1

ER -