Comment on tc-2021-380

Tobias Zolles

doi:10.5194/tc-2021-380-rc1

Abstract

Several regional studies identified heterogeneous mass changes in western High Mountain Asia over the last decade. Causes for these mass change patterns are still not fully understood. Modelling the physical interactions between glacier surface and atmosphere over several decades can provide insight into relevant processes. Such model applications, however, have data needs which are usually not met in these data scarce regions. Unique glaciological and meteorological data exist for the Abramov glacier in the Pamir Alay range. In this study, we use weather station measurements in combination with downscaled reanalysis data to force a coupled surface energy balance–multilayer subsurface model for Abramov glacier for 52 years. Available in situ data are used for model calibration and validation. We find an overall negative mass balance of −0.27m w.e. a−1 for 1968/1969–2019/2020 and a loss of firn pore space causing a reduction of internal accumulation. Despite increasing air temperatures, we do not find an acceleration of glacier-wide mass loss over time. Such an acceleration is compensated by increasing precipitation rates (+0.0022 m w.e. a−1, significant at a 90 % confidence level). Our results indicate a significant correlation between annual mass balance and precipitation (R2 = 0.72).

Highlights

IntroductionHeterogeneous mass changes of glaciers in High Mountain Asia (HMA) during the last decade have been detected by several regional studies (e.g. Kääb et al, 2012; Brun et al, 2017; Shean et al, 2020; Jakob et al, 2021)
We find an overall negative mass balance of -0.27 m w.e. a−1 for 1968/1969-2019/2020 and a loss of firn pore space causing a reduction of internal accumulation
Heterogeneous mass changes of glaciers in High Mountain Asia (HMA) during the last decade have been detected by several regional studies (e.g. Kääb et al, 2012; Brun et al, 2017; Shean et al, 2020; Jakob et al, 2021)

Summary

Introduction

Heterogeneous mass changes of glaciers in High Mountain Asia (HMA) during the last decade have been detected by several regional studies (e.g. Kääb et al, 2012; Brun et al, 2017; Shean et al, 2020; Jakob et al, 2021). Based on regional climate model data, glacier modelling 20 and moisture tracking, De Kok et al (2020) conclude that changes in irrigation patterns and climate are responsible for the identified mass balance patterns in HMA. Including in situ data and investigating processes at a local scale over several decades can be helpful in better understanding the influence of atmospheric conditions on glacier mass changes (Mölg et al, 2012; Zhu et al, 2020). 30 Several studies have applied energy balance models coupled to multi-layer snow models to simulate refreezing processes within the snow and firn as well as heat conduction which are relevant for the glacier mass and energy balance (e.g. Reijmer and Hock, 2008; Huintjes et al, 2015b).

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