Fig. 2

The time-series summer HiRISE images in the same scale of four areas show an example of yearly cycle variations of RSL across different MYs. The (a) and (b) panels correspond to Palikir crater, (c) and (d) to Raga. Red arrows in the first column mark features as references to indicate the area variation of the RSL. The time-series variations in the total areas of detected RSL are shown in (e) for Palikir and (f) for Raga across MY 32 to MY 36. The software ArcGIS 10.6 (https://www.esri.com/) was used to create the maps in (a–d).