Comparison of historical and recent accumulation rates on Abramov Glacier, Pamir Alay

Kronenberg, Marlene; Machguth, Horst; Eichler, Anja; Schwikowski, Margit; Hoelzle, Martin

doi:10.1017/jog.2020.103

Cited by 15 publications

(21 citation statements)

References 62 publications

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“…Despite non-significant precipitation trends for the entire Pamir (Pohl et al, 2017), the Pamir-Alay received an increase in winter precipitation since 1950 (Haag et al, 2019;Kronenberg et al, 2021). Winter precipitation changes, however, play a subordinate role for the glacier mass balance of the Pamir-Alay, whereas spring and summer changes dominate (Fig.…”

Section: Analysis I: Har Dataset and Mb Barandunetalmentioning

confidence: 98%

Central Asia's spatiotemporal glacier response ambiguity due to data inconsistencies and regional simplifications

Barandun¹,

Pohl²

2022

Preprint

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Abstract. Glacier evolution across Tien Shan and Pamir is heterogeneous in space and time. This heterogeneity is believed to be mainly driven by contrasting climatic settings and changing atmospheric conditions. However, a systematic and consistent region-wide analysis of the climatic and static morphological drivers remains limited to date. Meteorological reanalysis and remote sensing products, and novel approaches to derive region-wide annual mass balance time series, all provide the basis to investigate the drivers behind the observed heterogeneous glacier response. Here, we investigate the consistency of interpretations derived from available datasets through correlation analyses between climatic and static drivers with mass balance estimates in Tien Shan and Pamir. Our results show that even supposedly similar datasets lead to different and partly contradicting assumptions on dominant drivers of mass balance variability. Only when considering all glaciers in the Pamir and Tien Shan together, we find a similar picture of dominant meteorological drivers over space. Using either existing mountain subdivisions or glacier subdivisions based on mass balance variability, no consistencies can be found. Within different mass balance and meteorological datasets the results suggest very different drivers. This conclusion is even more prominent in the temporal correlation analysis where contradicting patterns of dominant drivers result from presumably similar meteorological datasets. Clear non-climatic drivers could not be identified. Even with newly available mass balance and meteorological data, a knowledge gap about the main mechanisms behind the heterogeneous glacier response in Central Asia remains. The results highlight that apparent but false consistencies across studies using a single dataset might largely relate to the chosen dataset rather than to the processes or involved environmental variables. As long as no glaciological, meteorological, or hydrological in situ observation network provides data for direct calibration and validation of extensive datasets, we cannot predict a realistic improvement in our understanding of the changing cryosphere at regional scale for Tien Shan and Pamir.

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Section: Analysis I: Har Dataset and Mb Barandunetalmentioning

confidence: 98%

Central Asia's spatiotemporal glacier response ambiguity due to data inconsistencies and regional simplifications

Barandun¹,

Pohl²

2022

Preprint

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“…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.…”

Section: Limitationsmentioning

confidence: 99%

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

et al. 2022

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Mass balance measurements for Golubin glacier in Northern Tien Shan, Kyrgyzstan, have been discontinuous over the last century, with significant data gaps. We provide a unique over 100-year-long mass balance series on daily resolution. We applied a temperature index model calibrated with glaciological measurements and validated with secular mass balances derived from independent length change observations. A comparison with other recent geodetic studies reveals good agreement. Golubin lost −0.16 ± 0.45 m w.e. a−1 from 1900/1901 to 2020/2021. From the long-term mass balance time series, we identify a shift to a more negative/less positive regime with time, with a steepening of the ablation and accumulation gradients, especially for the past two decades. We observe a parallel shift of the mass balance gradient accompanied by a rotation of the ablation gradient due to increased ablation at the glacier tongue and accumulation above the equilibrium line altitude. This tendency is believed to intensify in the future, affecting glaciers’ mass balance sensitivity to changes in atmospheric conditions and year-to-year variability and resulting in irregular melt water release feeding the rivers that provide water to Bishkek. These kinds of datasets are sparse for Tien Shan and, yet, indispensable to enhancing our understanding of glacier changes in High Mountain Asia.

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“…This is a good approximation for the cold and dry accumulation area (the part of the accumulation area without substantial melt). However, the T ma has been proven to be a major underestimate for the infiltration congelation/recrystallisation zone, which is the part of the accumulation area where snowmelt occurs and where the meltwater refreezes again (Shumskiy, 1955;Hooke, 1976;Maohuan et al, 1982;Maohuan, 1990;Arkhipov et al, 2004;van Pelt et al, 2016;Zekollari et al, 2017;Kronenberg et al, 2021). Latent heat released through water percolation and refreezing in firn induces warming (Shumskiy, 1955;Maohuan, 1990;Huybrechts et al, 1991;van Pelt et al, 2016;Zekollari et al, 2017).…”

Section: Surface Boundary Conditionsmentioning

confidence: 99%

“…Using ground-penetrating radar (GPR) measurements, other studies revealed the presence of cold and temperate layers on the Sary-Tor glacier (Petrakov et al, 2014); the Tuyuksu glacier (Nosenko et al, 2016); and the Abramov glacier, located in the nearby Pamir Alay (Kislov et al, 1977). According to measurements on the Abramov glacier, the Ürümqi glacier, and the Tuyuksu glacier, temperate ice was present near the surface of the lower part of the accumulation area (Kronenberg et al, 2021) and over a large area at the base (Nosenko et al, 2016). The latter was corroborated by larger summer velocities compared to winter velocities, indicating that basal sliding was occurring on the Ürümqi glacier in the Chinese Tien Shan (Maohuan et al, 1989;Maohuan, 1992).…”

Section: Introductionmentioning

confidence: 99%

Thermal regime of the Grigoriev ice cap and the Sary-Tor glacier in the inner Tien Shan, Kyrgyzstan

Tricht

Huybrechts²

2022

The Cryosphere

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Abstract. The thermal regime of glaciers and ice caps represents the internal distribution of ice temperatures. An accurate knowledge of the thermal regime of glaciers and ice caps is important to understand their dynamics and response to climate change and to model their evolution. Although the assumption is that most ice masses in the Tien Shan are polythermal, this has not been examined in appropriate detail so far. In this research, we investigate the thermal regime of the Grigoriev ice cap and the Sary-Tor glacier, both located in the inner Tien Shan in Kyrgyzstan, using a 3D higher-order thermomechanical ice flow model. Input data and boundary conditions are inferred from a surface energy mass balance model, a historical air temperature and precipitation series, ice thickness measurements and reconstructions, and digital elevation models. Calibration and validation of the englacial temperatures are performed using historical borehole measurements on the Grigoriev ice cap and radar measurements for the Sary-Tor glacier. The results of this study reveal a polythermal structure of the Sary-Tor glacier and a cold structure of the Grigoriev ice cap. The difference is related to the larger amount of snow (insulation) and refreezing meltwater (release of latent heat) for the Sary-Tor glacier, resulting in higher surface layer temperature, especially in the accumulation area, which is subsequently advected downstream. Further, ice velocities are much lower for the Grigoriev ice cap, with consequent lower horizontal advection rates. A detailed analysis concerning the influence of temperature and precipitation changes at the surface reveals that the thermal structure of both ice bodies is not constant over time, with recent climate change causing increasing ice temperatures in higher areas. The selected ice masses are representative examples of the (inner) Tien Shan glaciers and ice caps. Therefore, our findings and the calibrated parameters can be generalised, allowing improved understanding of the dynamics and future evolution of other glaciers and ice caps in the region.

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Comparison of historical and recent accumulation rates on Abramov Glacier, Pamir Alay

Cited by 15 publications

References 62 publications

Central Asia's spatiotemporal glacier response ambiguity due to data inconsistencies and regional simplifications

Central Asia's spatiotemporal glacier response ambiguity due to data inconsistencies and regional simplifications

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

Thermal regime of the Grigoriev ice cap and the Sary-Tor glacier in the inner Tien Shan, Kyrgyzstan

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