Inventory of glaciers in the Eastern Sayan on the basis of space surveys

Abstract

Small glaciers (areas smaller 1 km2) are the most numerous in most mountainous and glacial regions of the Earth, but their responses to the present-day climate change are still to be investigated. The paper presents results of the new inventory of small inter-continental glaciers located in the Eastern Sayan (South of Eastern Siberia). The previous (1950) glacier inventory was made from data of aerial photography carried out in the middle of the 20th century (USSR Glacier Inventory, KL 1950). A more complete inventory of the East Sayan glaciers for the state of 2000 (KL 2000) had been performed using the multichannel space images (Landsat Enhanced Thematic Mapper (ETM+) of 2000 and 2001, and the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM). In addition, some glaciers from the Inventory KL 1950 were re-mapped on the basis of the Landsat images (TM, ETM+, 1986-2011) for years 1950, 1990 and 2010. The glacier outlines, determined on the test site from images of medium (Landsat) and high (World View.1) satellite resolution, were compared that confirmed that errors of mapping of small glaciers did not exceed 15%. The KL 2000 contains data on 172 glaciers with a total area of 16.6±1.9 km2. Glacier sizes are from 0.02 to 1.37 km2. For 1950-2000, the total area of the East Sayan glaciers had decreased by 59% (0.40% per a year). In 1990-2000, the glaciers decreased the most rapidly (by an order of magnitude faster as compared to the period of 1950-1990.). In 2000-2010, the area of glaciation slightly increased (by 4%) owing to formation of very small glaciers (area smaller 0.5 km2). On the whole, changes in glacier areas in the years 1950-2010 are in the good agreement with changes in amounts of winter precipitation and summer temperatures. In addition to regional climatic factors, there are also some local factors related to the topography and microclimate of individual glaciers which do also influence on the dynamics of small glaciers.