Simone Zonetti

SVALI post doc: From January 2014

Subject: Glacial isostatic adjustment (GIA)

Theme 1: Observing the present - baseline and changes

WP 1.1: Ice-volume/mass changes

GPS measurements in Iceland show accelerating crustal uplift rates during the last two decades in response to the downwasting of glaciers due to warming climate. The objective of the postdoctoral research project is to develop detailed numerical models of the glacial isostatic adjustment (GIA) signal in Iceland. In particular, new estimates of current surface deformation (from GPS and InSAR measurements), and new observations and simulations of ice volume changes will be used to refine numerical models of crustal structure and mantle dynamics in Iceland. In addition, the project aims to include results from ongoing work including: (i) extention of glaciation history back to the Little Ice Age; (ii) extraction of uplift rates from observations of sea-level; and (iii) analysis of gravity changes due to ice-mass variations. The GIA uplift signal is superimposed on seasonal variatiations due to the annual glacier mass-balance cycle as well as other causes for seasonal variations, tectonic signals related to various geophysical processes such as plate movements, earthquakes and eruptions, and corrupted by artificial shifts due to problems arising in the international base-station network and equipment malfunction as well as set-up changes. The GPS-signal needs to be decomposed into a (quasi) periodic seasonal component and a longer-term trend that provides a consistent estimate of the long-term GIA signal as well as a robust estimate of the amplitude and shape of the seasonal variation. This processing is accompanied by semi-automated detection of and correction for shifts in the GPS time-series that is essential to obtain accurate uplift rates. The derived seasonal component of the crustal movements provides constraints on the amplitude of the seasonal mass-balance cycle of Icelandic glaciers.

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