We describe several new ice velocity maps produced by theGreenland Ice Mapping Project (GIMP) using Landsat 8 and Copernicus Sentinel1A/B data. We then focus on several sites where we analyse these data inconjunction with earlier data from this project, which extend back to theyear 2000. At Jakobshavn Isbræ and Køge Bugt, we find good agreement whencomparing results from different sensors. In a change from recent behaviour,Jakobshavn Isbræ began slowing substantially in 2017, with a midsummerpeak that was even slower than some previous winter minima. Over the lastdecade, we identify two major slowdown events at Køge Bugt that coincidewith short-term advances of the terminus. We also examined populations ofglaciers in north-west and south-west Greenland to produce a record of speed-upsince 2000. Collectively these glaciers continue to speed up, but there areregional differences in the timing of periods of peak speed-up. In addition,we computed trends in winter flow speed for much of the south-west margin ofthe ice sheet and find little in the way of statistically significant changesover the period covered by our data. Finally, although the consistency of thedata is generally good over time and across sensors, our analysisindicates that substantial differences can arise in regions with high strainrates (e.g. shear margins) where sensor resolution can become a factor. Forapplications such as constraining model inversions, users should factor inthe impact that the data's resolution has on their results.
展开▼
