Recently A. Sheperd and others used ERS-altimetry to measure
thickness changes of Pine Island Glacier (PIG), one of the
largest ice streams in the region. They observed a thinning of
10m at the grounding line from 1992 to 1999. To obtain a
complementary time series of long-term ice velcoity of Pine
Island Glacier we used a feature tracking method along the
central flowline. Input are pairs of SAR intensity images
separated by 2 months to two years. We observe a 10% increase of
ice flow on the lower glacier during 1992 and 2000 (see Figure
1). The velocity increase between 1992 and 2000 is significant
and cannot be attributed to seasonal variations. Our results are
consistent with the thinning observed by Sheperd and others. An
additional peculiarity of the motion field on the floating part
of PIG becomes apparent with differential radar interferometry
(D-InSAR) using ERS-tandem data. A single interferogram covers a
1-day period. The two differential interferograms shown in
Figure 2 were genetrated by differen