## 3 Results
Figure 5 presents the temporal variation of the velocity anomaly in A and B at the centers of the dotted circles shown in the sub-images of Figure 4. The amplitude of velocity anomaly for A is \(\sim\)1 cm/day, which is smaller value than that of B with \(\sim\)5 cm/day. Considering the range direction (from satellite to target) and the ice flow direction, a positive anomaly value means either acceleration of horizontal ice flow or inflation (uprising) of ice surface, or a mixture of both. Similarly, negative anomalies mean either slow-down in horizontal flow or vertical depression (subsidence) of ice surface, or a mixture of both. It is worth noting that the velocity anomalies are the ice velocity difference from the master DInSAR pair [20100616-20100617], and the negative values do not represent the reversal of directions of the actual horizontal flow or vertical motion, if any. Figure 6 shows the enlarged surface features and bed topography of Campbell Glacier along the profile lines. Figure 6a is an optical image in Google Earth, showing that transverse crevasses begin to develop from anomaly B, while there are no crevasses in A or upstream. Figure 6b is the DInSAR image based on which the profile line along the valley is drawn alongside with a survey line. Figure 6c is an example of DInSAR image showing two anomalies A and B, a hinge line, and two possible grounding lines to be determined later from a radargram. Figure 6d is the IPR-derived bed topography generated in this study, and (e) is the Bedmap2 bed topography for comparison. The IPR bed topography has a better resolution of \(\sim\)88 m than that of Bedmap2 with 1 km pixel spacing. Figure 4: (**a**–**j**) A series of DInSAR images of Campbell Glacier near the anomalies A and B. One color cycle represents 2\(\pi\) phase. The dotted circles A and B were drawn based on (**e**) and their locations are identical at each image for comparison. Figure 5: LOS velocity anomaly in A and B of Campbell Glacier, relative to the DInSAR pair [20100616_20100617]. The anomaly A has higher variation of LOS velocity than B. Figure 7 shows the profiles of the ice body along the IPR survey line. Figure 7a is along the survey line intersecting the center of anomaly A, but it slightly touches anomaly B. IPR surface profile matches almost exactly with TanDEM-X DEM, while there is a large discrepancy with Bedmap2 surface elevation of up to 200 m. IPR-derived surface elevation is about 100 m higher than Bedmap2 in the beginning of the profile, gradually crosses at a distance of 18 km, and lower than Bedmap2 by a maximum of 200 m. This is not a temporal change of ice elevation but is thought to be an error in Bedmap2, because IPR and TanDEM-X match very well even though they were obtained completely independently. The radargram in Figure 7b supports the credibility of IPR bed topography because a large bed hill observed in Bedmap2 at a distance of 6-12 km does not appear in the radargram. Moreover, the resolution along the IRP survey line is about 7 m, far better than Bedmap2 bed data with 1 km pixel spacing. The hydraulic head at the bed shows gradual ice flow,  
Figure 6: Surface and bed images of Campbell Glacier: **(a)** Google Earth image; **(b)** DInSAR image; **(c)** DDInSAR image; **(d)** IRP-derived bed topography; and **(e)** Bedmap2-derived bed topography. The yellow profile line is along the fastest ice-velocity in the glacier valley, while the blue line is one of the IPR survey line that crosses the anomalies A and B depicted as circles. The white box is the extent of Figure 4.  
but it has a hill to prevent flow at a distance of 25 km, as shown Figure 7a. The flow should divert from the survey line to overcome the bed hill in Figure 7a. A radargram in Figure 7b shows a very bright feature in anomaly A. This region has a flat bed and hydraulic head, suggesting a possible water reservoir at the ice bed in A. The bight radar reflection of A is very similar to the one in the hinge zone, defined from grounding line to hinge line, as shown in Figure 7b.