Punktmasseschätzungen auf Grönland aus GRACE [article]

Jing Xia, Universität Stuttgart, Universität Stuttgart
In this study the mass changes of ice over Greenland is calculated by the transformation of gravity changes. An inversion is carried out by the least squares method. The observation time range is from April 2002 to March 2007 including 57 epochs. If the spherical harmonic series are expanded to degree 30 and the regularization factor is set to 10e-43, it is the optimal case to estimate the mass change as well as the volume change of the ice. In this case, the ice loss rate of Greenland is
more » ... Greenland is calculated as -227qkm/year. It is noticed that the result is not strongly influenced, if the spherical harmonic series are expanded to the degree higher than 30. After the comparison between two kinds of mass point distribution (first case: mass points distribute over the whole Greenland; second case: mass points distribute only on the east coast of the Greenland), it is indicated that the ice disappearance of the east coast accounts for about 70% over the whole Greenland. When the mass points are used for the whole island, the ice loss rate is -227qkm/year; when the mass points are used for the east coast, the ice loss rate is -221qkm/year. In order to determine the regularization parameter, the L-curve-criterion is utilized. The parameter influences the mass change strongly. Using the L-Curve-Criterion is the point with the largest curve investigated. The appropriate regularization parameter will be chosen for the optimal estimation.
doi:10.18419/opus-3785 fatcat:k7uzkqm5fbf4vfn5rhpkepwize