Glacier boundaries (1975-2020) and elevation change (2000-2020) of the Peruvian Cordilleras Vilcanota, Vilcabamba, and Urubamba

• Main Authors: Taylor, Liam, Quincey, Duncan, Smith, Mark, Potter, Emily, Castro, Joshua, Fyffe, Catriona
• Format: Dataset
• Language: English
• Published: NERC EDS UK Polar Data Centre 2022
• Subjects: "EARTH SCIENCE","CRYOSPHERE","GLACIERS/ICE SHEETS","GLACIER ELEVATION/ICE SHEET ELEVATION"; "EARTH SCIENCE","CRYOSPHERE","GLACIERS/ICE SHEETS","GLACIER MASS BALANCE/ICE SHEET MASS BALANCE"; "EARTH SCIENCE","CRYOSPHERE","GLACIERS/ICE SHEETS","GLACIER THICKNESS/ICE SHEET THICKNESS"; "EARTH SCIENCE","CRYOSPHERE","SNOW/ICE","ICE EXTENT"; ASTER; Landsat; Peru; mass balance; tropical glaciers; Ice Sheet
• Online Access: https://dx.doi.org/10.5285/d4dedc2d-1f7f-45c8-8b04-41b8b099cef9; https://data.bas.ac.uk/full-record.php?id=GB/NERC/BAS/PDC/01603

This dataset contains glacier boundaries from 1975 to 2020 and elevation change data from 2000 to 2020 over the Cordilleras Vilcanota, Vilcabamba, and Urubamba, Peru. Glacier boundary data were analysed in Google Earth Engine from the Landsat archive and quantifies rate of change in ice extent over recent decades. Elevation change data were analysed in Google Earth Engine from the ASTER archive and quantifies change in ice thickness over decadal intervals from 2000 to 2020. Data are available as shapefiles (.shp) and GeoTIFFs (.tif). Summary data are available as CSVs (.csv). This work was funded by NERC SPHERES Doctoral Training Partnership (NE/L002574/1) and NERC Newton Fund (PEGASUS) (NE/S013318/1). : Glacier Boundaries Landsat-2 scenes were used to manually delineate glacier outlines for the 1970s. All other glacier outlines were produced from full-archive Landsat-5 (1984 - 2012) and Landsat-8 (2013 - 2020) imagery using a Normalised Difference Snow / Water Index (NDSI, NDWI) in Google Earth Engine. A cloud-free composite was produced for each year by extracting the median pixel value from the driest months (August to December) to minimise snow and cloud cover. Due to heavy cloud in these regions, there are some years within the time series with no usable imagery. Elevation Change All L1A ASTER tiles collected over these regions in the 20-year timespan from 1st January 2000 to 31st December 2020 were used to derive DEMs and co-registered to off-ice areas using the method of Nuth and Kääb (2011). DEMs were clipped to the range of elevation of the cordilleras, ± 100m of the median to remove erroneous values. A single value per pixel per year was extracted from all DEM tiles by collecting the median value. Using these single values per year, a linear fit through the surface elevation was then calculated over three time periods: 2000 - 2010; 2010 - 2020; and 2000 - 2020 to represent elevation change per year during these intervals. : ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) L1A (AST_L1A) Landsat-2 MSS L1TP Landsat-5 TM Collection 1 Tier 1 TOA Reflectance (Google Earth Engine) Landsat-8 Level 2 Collection 2 Tier 1 (Google Earth Engine) : All 1984 - 2020 glacier boundaries have an accuracy of 5%, with the 1975 Landsat-2 scenes at 11% owing to larger pixel sizes in the original dataset Volume change error is calculated as a median of off-ice areas within a 2 km buffer of glaciers and this error carried forward to calculate mass (following Brun et al. 2017) and mass balance.