## 4 Results  
### Sea Ice Motions from Maximum Cross-Correlation Approach  
Among the MS bands of the KOMPSAT images, a common band of least saturated, preserving surface texture details of sea ice, was selected. Few saturated pixels in the red band exist only in the KOMPSAT-2 image acquired on 14 August 2014; therefore, the red band was used for further analyses. Hereafter, images denote the red band image. The cross-correlation coefficient was measured in whole image pairs of both spatial resolutions using the MCC approach. The histograms of the cross-correlation coefficient showed typical bimodal distribution for both resolutions, discriminating precise sea ice motion from errors that generally originate from matched blocks in a not overlapped image area (Figure 4). Around the predefined threshold value (i.e., cross-correlation coefficient = 0.6), a low amplitude of the histogram indicated that a possible few motion vectors with a higher cross-correlation coefficient than the threshold value existed in the dataset of the spatial resolution of 4 m (Figure 4a), while a more distinct bimodal distribution of the histograms was revealed in the dataset of the spatial resolution of 15 m. After applying outlier removal to remove the few remaining outlier motion vectors in the pairs of the dataset of the spatial resolution of 4 m, well-aligned continuous dense motion vectors without erroneous magnitudes or directions in overlapped areas were retrieved. The dense distributions of the moving distance and direction (i.e., the magnitude and direction of the motion vectors) from the image pairs of the 4 m spatial resolution revealed spatial patterns reflecting characteristics of sea ice motion (Figure 5). Figure 4: The histogram of the cross-correlation coefficient: (**a**) the image pairs of the spatial resolution of 4 m; and (**b**) the image pairs of the spatial resolution of 15 m.  
Figure 5: \(Cont\). Small vacant spaces in the motion vector fields appeared during the cross-correlation coefficient thresholding caused by free drifted isolated floes, which are seasonal characteristics of sea ice that especially appear in summer that decrease the cross-correlation between sequential images (Figure 6). Figure 5: An example of the results from sea ice motion measurement using the KOMPSAT-2 image acquired on 14 August 2014 (i.e., prior image) and the KOMPSAT-3 image acquired on 14 August 2014 (i.e., posterior image), resampled to the spatial resolutions of 4 m: (**a**) magnitudes of the sea ice motion vectors; (**b**) directions (headings) of the sea ice motion vectors, measured counterclockwise from east; (**c**) cross-correlation coefficient of each image block; (**d**) sea ice coverage of each image block in the prior image; and (**e**) entropy of each image block in the prior image, plotted only for the image blocks after applying the cross-correlation coefficient threshold and outlier removal. Wind is one of the main factors that controls sea ice motion [43]; therefore, wind direction and speed were measured in the IBRV Araon every second during the image acquisition period (Figure 7). Although the distance between the IBRV Araon and the ITP80 increased from 57.7 km at the acquisition time of image A to 258.7 km at the acquisition time of image D as time passed, the direction of sea ice motion generally corresponds to the wind records of a mainly southward direction. For the dataset spatially resampled to 15 m, the motion vectors with cross-correlation coefficients higher than the threshold value showed a well-aligned motion field without additional removal of erroneous magnitudes or directions of the motion vectors (Figure 8). Increased sea ice coverage and decreased entropy compared with the same image pair of the spatial resolution of 4 m were observable, and these trends were the same with the other image pairs. Slightly more discrete colors of the motion vectors were revealed in Figure 8a when compared with Figure 5a.