Measuring and inferring the ice thickness distribution of four glaciers in the Tien Shan, Kyrgyzstan

Abstract

Glaciers in the Tien Shan mountains contribute considerably to the fresh water used for irrigation, households and energy supply in the dry lowland areas of Kyrgyzstan and its neighbouring countries. To date, reconstructions of the current ice volume and ice thickness distribution remain scarce, and accurate data are largely lacking at the local scale. Here, we present a detailed ice thickness distribution of Ashu-Tor, Bordu, Golubin and Kara-Batkak glaciers derived from radio-echo sounding measurements and modelling. All the ice thickness measurements are used to calibrate three individual models to estimate the ice thickness in inaccessible areas. A cross-validation between modelled and measured ice thickness for a subset of the data is performed to attribute a weight to every model and to assemble a final composite ice thickness distribution for every glacier. Results reveal the thickest ice on Ashu-Tor glacier with values up to 201 ± 12 m. The ice thickness measurements and distributions are also compared with estimates composed without the use of in situ data. These estimates approach the total ice volume well, but local ice thicknesses vary substantially.

Influence of glacier inventories on ice thickness estimates and future glacier change projections in the Tian Shan range, Central Asia

“…In this approach, the ice thickness ( h ) along the central flow lines can be calculated with Eqn (2) (Li and others, 2012). where is the ice density, is the gravity acceleration, f = 0.8 (Linsbauer and others, 2012; Frey and others, 2014; Van Tricht and others, 2021) is the shape factor, τ (in Pa) is the basal shear stress and α is the surface slope along the central flowlines computed with the topography data. The flowline slope is smoothed with a 1D Gaussian filter of kernel size 1.…”

“…Despite the importance of glaciers in the Tian Shan, few studies have specifically investigated ice thickness of all the glaciers in this region. Previous studies have either considered this region in the context of glaciers worldwide (Huss and Farinotti, 2012; Farinotti and others, 2019), or investigated several individual glaciers (Li and others, 2012; Pieczonka and others, 2018; Van Tricht and others, 2021). Due to the limited availability of measured glacier thickness and because global studies have different research aims, considerable uncertainty remains at the regional scale (Helfricht and others, 2019; Pelto and others, 2020).…”

Reconstructed Centennial Mass Balance Change for Golubin Glacier, Northern Tien Shan

“…The dynamic response time t resp is calculated following Jóhannesson et al [31], where h max is a characteristic ice thickness usually taken at the equilibrium line, where ice depths are near maximum. We used a maximum ice thickness h max of 154 ± 11 m [32] and b t of −3.5 m, based on the glaciological surveys of the recent monitoring [25].…”

“…A main limitation of this study is the lack of glacier thickness adjustment over the calculation time. Recent observations and new datasets documenting glacier thickness changes for this region (e.g., [32]) in combination with reinvestigated historical datasets (e.g., [56,57]) are valuable to improve glacier mass balance change assessments over long periods of time in the future.…”

Ice Thickness Measurement and Volume Modeling of Muztagh Ata Glacier No.16, Eastern Pamir

“…Various methods can be used to measure ice thickness, including radio echo sounding [6,7], drilling [8], seismic surveys [9], and gravity measurements [10][11][12][13]. Given the substantial electrical resistivity of glacier ice and the pronounced contrast in electromagnetic impedance between ice and bedrock, ground-penetrating radar (GPR) technology is frequently employed to assess ice thickness [14][15][16][17].…”