#Glims in validation plus#

GLIMS ingests snapshot glacier outlines from cooperative scientists who have generated remote sensing data of various spatial resolutions, most commonly from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), the Landsat Enhanced Thematic Mapper Plus (ETM+) or Thematic Mapper, aerial photographs, and topographic maps. Glacier outlines are available through the Global Land Ice Measurements from Space (GLIMS) web site ( ), now linked with the WGMS website.

#Glims in validation series#

These archived data include detailed digital glacier outlines and elevations, carefully compiled time series of measurements of glacier termini fluctuations and mass balance, and glacier photograph pairs showing changes through time. Together, in situ glacier measurements and satellite observations provide a wealth of glacier data contained in the archives of both the World Glacier Monitoring Service (WGMS), Zurich, Switzerland, and the National Snow and Ice Data Center (NSIDC), Boulder, USA. Satellite observations, such as those applied in this study, provide a more enhanced, comprehensive, and systematic approach to monitoring glacier areas at larger scales and higher temporal resolution. Perhaps the simplest method to monitor change of mountain glaciers is by recording the annual location of the glacier terminus. In order to better understand the role of glaciers in the global hydrologic cycle, an effort to complete a global inventory of glaciers was encouraged during the International Geophysical Year (1959) and again during the International Hydrological Decade (1965–1974). Recent studies show that changes in dust and carbonaceous particles during the last 200 years have been shortening snow cover duration, likely leading to glacier retreat and downwasting. As with the global record, temperature increases have been reported in the last decades in the mountains of the globe. Moreover, snow cover in the Northern Hemisphere has retreated since the late 1970s, consistent with warming and a positive snow-albedo feedback. There is now clear evidence that the vast majority of Earth's glaciers have been in retreat during the last 100–150 years. Global snow and ice covers have been in general retreat due to several forcings within the Anthropocene, the period of the modern global environment dominated by human activities. Comparisons of MODICE with GLIMS glacier outlines derived from SPOT, ASTER, and Landsat Thematic Mapper show strong agreement with the higher resolution outlines subject to uncertainties with spatial resolution, deep mountain shadows, and GLIMS interpretation errors. The end product of MODICE is a consistently derived map of annual minimum exposed snow and ice.

Here we present the MODIS Persistent Ice (MODICE) algorithm that leverages the time series of fractional snow and ice cover from the MODIS Snow Covered Area and Grain size (MODSCAG) algorithm. The Global Land Ice Measurements from Space (GLIMS) project has compiled digital glacier outlines and related metadata for the majority of the world's glaciers but inconsistency among product algorithms and time periods represented precludes the production of a consistently derived global data set. Global snow and ice have been diminishing during the Anthropocene but we still lack a complete mapping of annual minimum exposed snow and ice with a consistent, repeatable algorithm.