Assessment of Changes in Mass Balance of the Tuyuksu Group of Glaciers, Northern Tien Shan, Between 1958 and 2016 Using Ground-Based Observations and Pléiades Satellite Imagery

Abstract

Continuous measurements of glaciological mass balance have been conducted at the Central Tuyuksu glacier, Tuyuksu group of glaciers, Ile Alatau, northern Tien Shan since 1957, showing that cumulative mass balance was negative since the 1970s. Geodetic mass balance was calculated for the 1958-1998 and 1998-2016 periods using multitemporal digital elevation models derived from the historic photogrammetric surveys from 1958 and 1998 and the high-resolution Pléiades satellite stereo imagery from 2016. The geodetic measurements revealed a mean surface lowering of 23.2 ± 2.2 m (0.40 ± 0.04 m a −1 ) and a reduction in volume of (67.7 ± 6.7) × 10 6 m 3 in 1958-2016 at the Central Tuyuksu glacier, yielding a geodetic mass balance of −21.8 ± 2.6 m w.e. Similar trends were observed at other glaciers of the Tuyuksu group, which lost in total 83.4 × 10 6 m 3 of ice. The mass balance annual rates have not changed significantly from 1958-1998 (−0.39 ± 0.05 m w.e. a −1 ) to 1998-2016 (−0.35 ± 0.18 m w.e. a −1 ) at the Central Tuyuksu and at other glaciers of the Tuyuksu group whose maximum elevations exceed 4,000 m a.s.l. While glacier thinning intensified in the ablation zone and affected a larger area in 1998-2016, extending to 3,600-3,700 m a.s.l., the accumulation increased at higher elevations in 1998-2016. Geodetic mass balance was more negative in 1998-2016 than in 1958-1998 at the smaller glaciers with lower maximum elevations. At the Central Tuyuksu, the geodetic mass balance was in close agreement with the glaciological mass balance, particularly in 1958-1998 when the difference between the geodetic and the cumulative glaciological mass balance values did not exceed 5%. During 1998During -2016, this difference increased to 14%, with the glaciological method producing a more negative mass balance. This discrepancy

Reanalysing the 2007–19 glaciological mass-balance series of Mera Glacier, Nepal, Central Himalaya, using geodetic mass balance

“…Our study corroborates the tendency for glaciological mass-balance estimates world-wide to have a positive bias with roughly two-thirds of reanalyses producing more negative geodetic mass balances (e.g., Huss and others, 2009; Andreassen and others, 2016; Klug and others, 2018; O'Neel and others, 2019). The reasons for this bias remain often speculative and are mainly attributed to insufficient or erroneous accumulation measurements and a nonrepresentative spatial distribution of the point mass-balance measurements (Huss and others, 2009; Andreassen and others, 2016; Kapitsa and others, 2020). This bias is therefore expected to be smallest when the density and the spatial coverage of the measurement sites are highest and when the accumulation is lowest, such as for small to medium, easily accessible glaciers with limited turnover and during a period of considerable mass loss (Andreassen and others, 2016).…”

Increased mass loss of glaciers in Volcán Domuyo (Argentinian Andes) between 1962 and 2020, revealed by aerial photos and satellite stereo imagery

“…Even without GCPs, Pléiades-derived DEMs are located within ~10 m (90% circular error) and have an altimetric precision of ~1 m (Berthier and others, 2014). They have been already used to derive glacier elevation changes in diverse-glacierized regions worldwide (Kutuzov and others, 2019; Abermann and others, 2020; Andreassen and others, 2020; Kapitsa and others, 2020; Denzinger and others, 2021).…”

Review

“…but both geodetic data and in-situ measurements of Tuyuksu glacier clearly highlight negative mass balance Kapitsa et al (2020) and WGMS data. As already mentioned above Lahaul-Spiti has also more negative values in other studies.…”