Spatial patterns in glacier characteristics and area changes from 1962 to 2006 in the Kanchenjunga–Sikkim area, eastern Himalaya

The region spans 27°04′52′′ to 28°08′26′′ N latitude and 88°00′57′′ to 88°55′50′′ E longitude. The relief in this area ranges from 300 m at the bottom of the valleys to 8598 m, with valley glaciers covering about 68% of the glacierized area, mountain glaciers covering 28%, and the remaining area consisting of cirque glaciers and aprons. The glacier ablation area is typically covered with heavy debris, originating from rockfall on the steep slopes, with a thickness of up to several meters at the glacier termini. The eastern part of the area constitutes the Sikkim province of India, while the western part is located in Nepal and encompasses the Tamor basin and parts of the Arun basin. The climate in this region is dominated by the South Asian summer monsoon circulation system, caused by the inflow of moist air from the Bay of Bengal to the Indian subcontinent during the summer. The Himalaya and Tibetan plateau are influenced by this system, resulting in significant precipitation and glacier mass balance changes. Glacier mapping from 2000 Landsat ASTER data revealed a total glacierized area of 1463 ± 89 km², with 569 ± 29 km² located in Sikkim and 494 ± 29 km² in eastern Nepal. Supraglacial debris covered 11% of the total glacierized area, and supraglacial lakes covered about 5.8% of the debris-covered glacier area. Glacier area loss from 1962 to 2000 was 0.50 ± 0.2% yr⁻¹, with little difference between Nepal (0.53 ± 0.2% yr⁻¹) and Sikkim (0.44 ± 0.2% yr⁻¹). Glacier area change was controlled mostly by glacier area, elevation, altitudinal range, and, to a lesser extent, slope and aspect. In the Kanchenjunga-Sikkim area, a glacier area loss of 0.23 ± 0.08% yr⁻¹ was estimated from 1962 to 2006 based on high-resolution imagery. Clean glaciers exhibited more area loss on average from 1962 to 2006 (34%) compared to debris-covered glaciers (22%). Glaciers in this region of the Himalaya are shrinking at similar rates to those reported for other parts of the Himalaya, but individual glacier rates of change vary across the study area with respect to topography, percent debris cover, or glacier elevations. The study aims to present the current glacier characteristics and glacier characteristics in a data-scarce area of the eastern Himalaya, based on an updated 2000 Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and Advanced Spaceborne Thermal Emission Radiometer (ASTER) inventory, along with topographic data from the Shuttle Radar Topography Mission (SRTM). The study also investigates spatial patterns in glacier surface area changes from 1962 to 2000 and 2006, and their dependence on topographic and climatic factors, with a particular emphasis on debris-covered glacier tongues.