May-1 to June-2 is 32 days, 2 Landsat Cycles. my animations are ~always use the same path,row.
Excellent practice. Others, in their search for pairs of cloud-free days, may not realize why this is important in avoiding artifacts, so I chased down the accession numbers (which are unambiguous in the case of Landsat-8 dates) to confirm the path,row business and look at the centers of scene (nadirs directly below satellite) which can wander a bit even with the same path,row.
Here they are both favorably near to the fracture of interest (rather than on the image margins) but displaced southeasterly by 5.4 km. This has a minimal effect compared to unavoidable sun elevation differences (and so shading), here over 7º.
This is what made possible widespread co-registration of upstream glacier features above by simple pixel shifting without the need for non-linear warping. Warping is problematic for Zachariae, Petermann and Jakobshavn because there aren't any fixed points (rocks) in the interior and everything else is in non-uniform motion. This means correcting along the coastal direction only.
I have been wrestling with the same issue of best fixed reference frame on a 15-year time series at Petermann. This is another story of a warm ocean current melting the underside of an ice shelf underside so does not have the dynamic thinning/stretching, calving and grounding line migration issues of Zachariae but instead a tapering of velocities as the main ice stream brushes against the edge of a tributary glacier contribution, which in turn brushes against a later tributary, which in turn brushes against a third tributary, which in turn scrapes along the rock wall.
Here two old fractures have remained the same distance apart and can be taken as the fixed points for alignment and rescaling. It all bears an uncanny resemblance to the Transverse Range in California, rotated as the Pacific Plate grinds past the N American.
Entity ID: LC80110032015153LGN00
Coordinates: 79.11406,-25.93111
Acquisition Date: 02-JUN-15
Path: 11
Row: 3
Sun Elevation 32.227“
Entity ID: LC80110032015121LGN00
Coordinates: 79.1478,-26.11325
Acquisition Date: 01-MAY-15
Path: 11
Row: 3
Sun Elevation 25.123º
Distances, bearings, and google earth kml provided by
http://www.movable-type.co.uk/scripts/latlong.html