Ice sheet velocity x component (vx) in meters per year for 2021. Annual mosaics are produced from data with resolutions varying from a few hundred meters to 1.5km. The 2021 annual mosaic includes data collected between 2020-12-01 and 2021-11-30. Note that these data have been rounded to the nearest centimeter for QGreenland to save disk space. Please see the original data source for the un-modified and additional data: * x and y component velocity error estimates (ex, ey). * A temporal offset parameter (dT) that reports the difference in days between the date of each velocity estimate and the midpoint date of the corresponding measurement period. * Shapefile that indicates the source of the image pairs (SAR or Landsat 8) used to produce the mosaic. === Original Data Source === MEaSUREs Greenland Annual Ice Sheet Velocity Mosaics from SAR and Landsat, Version 4 This data set, part of the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) program, contains annual ice velocity mosaics for the Greenland Ice Sheet derived from Synthetic Aperture Radar (SAR) data obtained by the German Space Agency's TerraSAR-X/TanDEM-X (TSX/TDX) and the European Space Agency's Copernicus Sentinel-1A and -1B satellites, and from the US Geological Survey's Landsat 8 optical imagery for years 2015 to 2021. See Greenland Ice Mapping Project (GrIMP) website for related data: http://nsidc.org/data/measures/gimp. Citation: Joughin, I. (2022). MEaSUREs Greenland Annual Ice Sheet Velocity Mosaics from SAR and Landsat, Version 4 [Data Set]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/RS8GFZ848ZU9. [Accessed on: 2023-08-24] Citation URL: https://doi.org/10.5067/RS8GFZ848ZU9