Brief communication: Updated GAMDAM glacier inventory over high-mountain Asia

Akiko Sakai

doi:10.5194/tc-13-2043-2019

Abstract

Abstract. The original Glacier Area Mapping for Discharge from the Asian Mountains (GAMDAM) glacier inventory was the first methodologically consistent dataset for high-mountain Asia. Nonetheless, the GAMDAM inventory underestimated glacier area, as it did not include steep ice- and snow-covered slopes or shaded components. During revision of the inventory, Landsat imagery free of shadow, cloud, and seasonal snow cover was selected for the period 1990–2010, after which >90 % of the glacier area was delineated. The updated GAMDAM inventory, comprised of 453 Landsat images, includes 134 770 glaciers with a total area of 100 693±11 790 km2.

Highlights

Glaciers in high-mountain Asia (HMA) play a significant role as a water resource for people living downstream (Immerzeel et al, 2010; Bolch et al, 2012)
Recent analysis of surface elevation change has revealed that glaciers in HMA exhibit contrasting behaviour (Brun et al, 2017; Gardner et al, 2013; Kääb et al, 2012, 2015): those in the Himalaya and the eastern Nyainqêntanglha Mountains are shrinking rapidly, while the Karakoram and West Kunlun glaciers are in balance or show a slight mass gain
Focusing on the steep snow-covered headwalls of the Khumbu Glacier, the image displayed in Fig. S1b exhibits the least seasonal snow cover and provides the sharpest boundaries among the four additional images, and this was utilized in the GGI18

Summary

Introduction

Glaciers in high-mountain Asia (HMA) play a significant role as a water resource for people living downstream (Immerzeel et al, 2010; Bolch et al, 2012). A recent climate analysis for those areas demonstrated that the Karakoram and West Kunlun regions are relatively stable under global warming conditions, being less sensitive to temperature change (Sakai and Fujita, 2017). This assessment of both glacier volume and climatic conditions is based on a large-scale glacier inventory, highlighting the need for accurate, high-quality coverage of the entire HMA region. Precise glacier inventories are needed for modelling total glacier volume (Frey et al, 2014; Farinotti et al, 2019), deriving volume change from altimetry and digital elevation maps (DEMs, e.g. Brun et al, 2017) and surfaceflow velocity (Dehecq et al, 2019), establishing changes in snow cover and albedo (Naegeli et al, 2019), catchmentand regional-scale hydrologic modelling (e.g. Immerzeel et al, 2010), projecting future glacier configuration (Huss and Hock, 2015; Shannon et al, 2019), and assessing uncertainty in estimates of glacier-surface elevation change (e.g. Nuimura et al, 2012; Bolch et al, 2017)

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Results

Conclusion