Urumqi Glacier Research Articles

Impact of Elevation-Dependent Warming on Runoff Changes in the Headwater Region of Urumqi River Basin

Warming in mountainous areas has obvious elevation dependence (warming rate increases with elevation), which deeply impacts runoff change in mountainous areas. This study analysed the influence of elevation-dependent warming on runoff in the headwater region of the Urumqi River Basin (URB) based on meteorological data, remote sensing images, and runoff data. Results indicated a significant warming rate in the URB from 1960 to 2019 (0.362 °C/decade; p < 0.01). The temperature increased with an obvious elevation-dependent warming in the URB, especially during winter. Glaciers sharply retreated in the headwater region of the URB under regional warming, and remote-based results showed that glacier areas decreased by 29.45 km2 (−57.81%) from the 1960s to 2017. The response of glacier mass balance and meltwater runoff to temperature change has a lag of 3 years in the headwater region of the URB. The elevation-dependent warming of temperature changes significantly impacted glacial meltwater runoff in the URB (R2 = 0.49). Rising temperatures altered the glacial meltwater runoff, and the maximum annual runoff of the Urumqi Glacier No. 1 meltwater runoff increased 78.6% in 1990–2017 compared to 1960–1990. During the period of 1960–1996, the total glacial meltwater runoff amounted to 26.9 × 108 m3, accounting for 33.4% of the total runoff during this period, whereas the total glacial meltwater runoff accounted for 51.1% of the total runoff in 1996–2006. Therefore, these results provide a useful reference for exploring runoff changes in mountainous watersheds in the context of elevation-dependent warming.

Evolution and origin of global glaciers and their impacts on the environment

Glacier is one of the most important freshwater resources. However, the situation of glaciers is changed nowadays because of global warming. This study aimed at two types of glaciers, and analyzed their evolution, origin and impacts on the environment. As for typical melting glaciers, the Vatnajokull glacier and Urumqi Glacier No.1, Tianshan Mountains gradually melt over time. Their causes are related to atmospheric River events, black carbon pollutants, ice recycling, global warming, and human activities. The impacts of glacier retreat mainly include sea-level rise and can alleviate global warming and cause surface deformation. However, there are some “weird” glaciers because they are expanded in the past few years rather than shrinking. Those glaciers are highly concentrated in the Karakoram, Pamir Mountains, Svalbard, the Canadian Arctic islands, Alaska, and Iceland, which are called surged-type glaciers. Hydrological control, thermal regime, deformable bed hypothesis, and critical mass are reasons for glacier expansion. There is no clear and unified opinion on the advantages or disadvantages of glacier expansion.

Multi-Temporal Variations in Surface Albedo on Urumqi Glacier No.1 in Tien Shan, under Arid and Semi-Arid Environment

Surface albedo exerts substantial control over the energy available for glacier melting. For Urumqi Glacier No.1 in the Tien Shan Mountains, China, represented as a “summer accumulation” glacier, the variations in albedo driven by surface processes are complex and still poorly understood. In this study, we examined the interannual trends in ablation-period albedo from 2000 to 2021 using MOD10A1 products, evaluated the variation in bare-ice albedo retrieved from 13 end-of-summer Landsat images obtained between 2002 and 2019, and investigated the seasonal variation and diurnal cycle of surface albedo collected near the equilibrium line of the glacier by an AWS from September 2018 to August 2021. During the period of 2000–2021, the average ablation-period albedo presented a slight but not statistically significant downward trend, with a total decrease of 1.87%. Specifically, the decrease in glacier albedo was quicker in July than that in August, and there was a slight increase in May and June. The blackening phenomenon was shown on the east branch glacier, but not on the west branch glacier. For seasonal variability, a bimodal pattern was demonstrated, different from the unimodal seasonal variation in other midlatitude glaciers. The albedo peaks occurred in December and April or May. Under clear sky conditions, the diurnal cycle presented three patterns: a symmetric pattern, an asymmetric pattern, and a progressive decreasing pattern. Air temperature and solid precipitation are the main drivers of variations in glacier albedo, but in different periods of the ablation season, two climate variables affect albedo to varying degrees. The effect of surface albedo reduction enhanced glacier melting by about 20% over the past 20 years. The short-term increase in albedo caused by summer snowfall can considerably reduce glacier melting by as much as 80% in June.

On the importance of subsurface heat flux for estimating the mass balance of alpine glaciers

Glaciers, as massive freshwater reservoirs, support the planet's living systems and have an impact on our daily lives, even for communities living far away. Ongoing and future climate change is predicted to have strong impacts on the mass balance of alpine glacier around the world. To understand the relationship between climate and glacier dynamics, a range of mass balance models are currently used. Most of these models however, ignore subsurface heat fluxes as a component of glacier mass balance. Here, we set out to investigate the importance of subsurface heat flux for the mass balance of an alpine glacier using a surface energy mass balance model (SEM) coupled with a multilayer subsurface heat conduction model (MSHCM) that resolves the subsurface glacier temperature. As a case study, we investigate the Urumqi Glacier No.1 in the Tianshan Mountains (NW China), which has a long and continuous time series of surface and subsurface glacier temperature measurements. We evaluate the results of both glacier temperature models (SEM and MSHCM) using these in situ observations and investigate the sensitivity of mass balance to five meteorological factors: air temperature, precipitation, incoming shortwave radiation, relative humidity, and wind speed. The mass balance of the glacier was simulated first by including the influence of subsurface heat flux, and second, the subsurface heat flux was neglected. Observed and simulated mass balance and the englacial temperature were found to be reasonably close in both cases. Furthermore, the mass balance was simulated with a zero surface temperature assumption, which resulted in a 6% overestimation of the summer ablation. We concluded that the mass balance of Urumqi Glacier No.1 was most sensitive to variations in temperature, followed by precipitation. Furthermore, our results show that subsurface heat flux in the ablation area can generally be neglected in estimating the mass balance of alpine glaciers during ablation season.

Light-Absorbing Impurities on Urumqi Glacier No.1 in Eastern Tien Shan: Concentrations and Implications for Radiative Forcing Estimates During the Ablation Period

Light-absorbing impurities (LAIs) in surface snow and snow pits together with LAIs’ concentrations and their impacts on albedo reduction and sequent radiative forcing (RF) have been investigated in the past. Here, we focused on temporal–spatial distributions of LAIs, especially on the albedo reduction and radiative forcing caused by the LAIs in Urumqi Glacier No.1. Various snow samples, including fresh snow, aged snow, and granular ice were collected between 3,770 and 4,105 m a.s.l of Urumqi Glacier No.1 during the snowmelt season of 2015. For the surface snow samples, BC and OC concentrations were 582 and 1,590 ng g−1, respectively. Mineral dust (MD) concentrations were 110 μg g−1. Due to the different ablation status of the glacier surface, LAIs accumulate at the lower altitude of the glacier. The estimation by the Snow, Ice, and Aerosol Radiative (SNICAR) model indicated that BC and MD could reduce the albedo by 12.8 and 10.3% in fresh snow, aged snow by 23.3 and 5.9%, and granular ice by 22.4 and 26.7%, respectively. The RF of MD was higher than that of BC in fresh snow and granular ice, whereas the RF of BC exceeded MD in aged snow. These findings suggested that BC was the main forcing factor in snow melting and dust was the main forcing factor in accelerating glacier melt.

Elevation change of the Urumqi Glacier No.1 derived from Sentinel-1A data

Elevation change of the Urumqi Glacier No.1 derived from Sentinel-1A data

Seasonal Surface Change of Urumqi Glacier No. 1, Eastern Tien Shan, China, Revealed by Repeated High-Resolution UAV Photogrammetry

The seasonal surface changes of glaciers in Tien Shan have seen little prior investigation despite the increase in geodetic studies of multi-year changes. In this study, we analyzed the potential of an Unmanned Aerial Vehicle (UAV) to analyze seasonal surface change processes of the Urumqi Glacier No. 1 in eastern Tien Shan. We carried out UAV surveys at the beginning and the end of the ablation period in 2018. The high-precision evolution of surface elevation, geodetic mass changes, surface velocity, and terminus change in the surveyed ablation area were correspondingly derived in combination with ground measurements, including stake/snow-pit observation and GPS measurement. The derived mean elevation change in the surveyed ablation area was −1.64 m, corresponding to the geodetic mass balance of approximately −1.39 m w.e. during the ablation period in 2018. The mean surface velocity was 3.3 m/yr and characterized by the spatial change of the velocity, which was less in the East Branch than in the West Branch. The UAV survey results were a little less than those from the ground measurements, and the correlation coefficient was 0.88 for the surface elevation change and 0.87 for surface displacement. The relative error of the glacier terminus change was 4.5% for the East Branch and 6.2% for the West Branch. These results show that UAV photogrammetry is ideal for assessing seasonal glacier surface changes and has a potential application in the monitoring of detailed glacier changes.

Retrieving and Verifying Three-Dimensional Surface Motion Displacement of Mountain Glacier from Sentinel-1 Imagery Using Optimized Method

The time series study of glacier movement is of special importance for rational management of freshwater resources, studying glacier evolution, understanding mechanism of glacier movement, and assessing disasters caused by glacier movement. In this paper, we put forward an optimization scheme for the shortcomings in the calculation method of using remote sensing to invert the three-dimensional (3D) surface motion displacement of glacier. The optimized method consists of Offset Tracking method, Optimizing the offset tracking results by means of iterative filtering, OT-SBAS technology and Conversion of 3D surface motion displacement of glacier. The Urumqi Glacier No. 1 was selected to test the optimized method. The 3D surface motion displacement of Urumqi Glacier No. 1 was retrieved by using the optimized method based on the ascending and descending Sentinel-1 datasets from 19 April to 29 August 2018. The distribution of 3D surface velocity of the Urumqi Glacier No. 1 was obtained in time series, and the accuracy of the inversion results was evaluated by using the field measurement data. The results show that the accuracies of the inverted displacements of east branch of Urumqi Glacier No. 1 (UG1E) were about 0.062, 0.063, and 0.152 m in the east, north and vertical directions, and these values for the west branch (UG1W) were 0.015, 0.020 and 0.026 m, respectively. It is indicated that using Sentinel-1 ascending and descending data and using the optimized method to retrieve the 3D surface motion displacement of glacier should satisfy the requirements of inversing the 3D surface motion displacement of high-latitude mountain glaciers in China.

An application of three different field methods to monitor changes in Urumqi Glacier No. 1, Chinese Tien Shan, during 2012–18

AbstractThis study deploys RTK-GNSS in 2012, TLS in 2015 and UAV in 2018 to monitor the changes of Urumqi Glacier No. 1 (UG1), eastern Tien Shan, and analyzes the feasibility of three technologies in monitoring the mountain glaciers. DEM differencing shows that UG1 has experienced a pronounced thinning and mass loss for the period of 2012–18. The glacier surface elevation change of −0.83 ± 0.57 m w.e. a−1 has been recorded for 2012–15, whereas the changes of glacier tongue surface elevation in 2015–18 and 2012–18 were −2.03 ± 0.95 and −1.34 ± 0.88 m w.e. a−1, respectively. The glacier area shrunk by 0.07 ± 0.07 × 10−3 km2 and the terminus retreat rate was 6.28 ± 0.83 m a−1 during 2012–18. The good agreement between the glaciological and geodetic specific mass-balances is promising, showing the combination of the three technologies is suitable to monitor glacier mass change. We recommend application of the three technologies to assess each other in different locations of the glacier, e.g. RTK-GNSS base stations, ground control points, glacier tongue and terminus, in order to avoid the inherent limitations of each technology and to provide reliable data for the future studies of mountain glacier changes in western China.

Black carbon and dust in the Third Pole glaciers: Revaluated concentrations, mass absorption cross-sections and contributions to glacier ablation

In snow and ice, light-absorbing particles (LAPs), such as black carbon (BC) and dust, accelerate the melting of Third Pole glaciers (TPGs). In this study, we revaluated LAP concentrations in the snow pits of TPGs (SP-TPGs), measured LAP mass absorption cross-sections (MACs), and simulated their effects on glacier darkening and melting based on the Spectral Albedo Model for Dirty Snow and a surface energy and mass balance model. The results indicated that because of their short distances to emission sources, the average BC concentrations measured in snow pits in the periphery of Third Pole were much higher than those measured in the inland Tibetan Plateau, and the average dust concentrations generally decreased from north to south. The average MACs of BC in the SP-TPGs varied from 3.1 to 7.7 m2 g−1 at 550 nm, most of the average spectral values were comparable in the visible and near-infrared bands to those calculated by Mie theory, except those in Urumqi Glacier No. 1 (UR), Syek Zapadniy Glacier (SZ), and Laohugou Glacier No.12 (LH), while the average spectral MACs of dust in the SP-TPGs were considerably smaller in magnitude than most of the variations measured in other regions. Compared with the pure snow surfaces, BC and dust played comparable roles in reducing albedo in UR, SZ, LH, and Renlongba Glacier, whereas BC was the most prominent absorber in the other glaciers. The combined effect of BC and dust accelerated melting by 30.4–345.9 mm w.e. (19.7–45.3% of the total mass balance) through surface albedo darkening (0.06–0.17) and increased radiation absorption (25.8–65.7 W m−2) within one month of the ablation season. This study provides a new data set of LAP concentrations and MACs and helps to clarify the roles of these factors in the cryospheric environment of the Third Pole.

Characteristics and controls of vegetation and diversity changes monitored with an unmanned aerial vehicle (UAV) in the foreland of the Urumqi Glacier No. 1, Tianshan, China

Exposed surfaces following glacial retreat are ideal field laboratories for studying primary vegetation succession. Many related studies based on ground sampling methods have been performed worldwide in proglacial zones, but studies on species diversity and vegetation succession using aerial photography have been rare. In this study, we investigated soil organic carbon (SOC), total nitrogen (TN), plant species diversity, and fractional vegetation cover (FVC) along a chronosequence within the foreland of Urumqi Glacier No. 1 by combining field sampling and aerial photography. We then analysed soil development and vegetation succession along distance (distance from glacier terminus) and time (terrain age) gradients as well as the relationships between topographic and environmental variables (aspect, slope, SOC, and TN), distance, time, and species distributions. The results indicated that: (1) plant diversity and FVC showed increasing trends with increases in distance and terrain age, whereas soil nutrient content varied nonlinearly; (2) Silene gonosperma, Leontopodium leontopodioides, and Saussurea gnaphalodes were the dominant species in the early, transient, and later succession stages, respectively. Cancrinia chrysocephala occurred in all stages and had a high abundance in the early and later stages; and (3) the relationships of FVC with soil nutrient content were nonlinear. Moreover, distance and site age played important roles in species distribution. These findings confirm that distance and terrain age positively affect vegetation succession. The increase in FVC facilitated the accumulation of soil nutrition, but this trend was affected by the rapid growth of plants. Caryophyllaceae and Asteraceae were the most common plants during the succession stages, and the former tended to colonise in the early succession stage. We conclude that the UAV-based method exhibits a high application potential for assessing vegetation dynamics in glacier forelands, which has a significance for long-term and repeated monitoring on the process of vegetation colonisation and succession in deglaciated areas.

60-year changes and mechanisms of Urumqi Glacier No. 1 in the eastern Tianshan of China, Central Asia

60-year changes and mechanisms of Urumqi Glacier No. 1 in the eastern Tianshan of China, Central Asia

The quantification of major soluble ions in glacial ice in the ablation area of Urumqi Glacier No.1, Tienshan Mountains in China

The quantification of major soluble ions in glacial ice in the ablation area of Urumqi Glacier No.1, Tienshan Mountains in China

Template matching for simple waveforms with low signal-to-noise ratio and its application to icequake detection*

Template matching is a useful method to detect seismic events through waveform similarity between two signals. The traditional template matching method works well in detecting small tectonic earthquakes. However, the method has some difficulty when the signals have relatively low signal-to-noise ratios (SNRs) and simple shapes, e. g. a sinusoidal function. In this study, we modify the traditional template matching approach for this situation. We first construct a virtual three-component seismic station using vertical-component waveforms recorded by three stations. Next, we select a template event from the virtual station, and apply the traditional template matching. We then verify this method by detecting icequakes with simple waveforms on the Urumqi Glacier No. 1 and compare the results with those from the short-term-averages over long-term-average (STA/LTA), the REST method, and traditional template matching method. It can be concluded that the modified template matching method using virtual stations has some advantages for seismic data with low SNRs.

Modeling of Mass Balance Variability and Its Impact on Water Discharge from the Urumqi Glacier No. 1 Catchment, Tian Shan, China

Originating in the Tian Shan mountains, Urumqi River plays a key role in terms of water supply to downstream areas. In its headwaters, Urumqi Glacier No. 1 (UG1) is the largest glacier contributing to water discharge. Assessing its response to the changing climatic conditions in the area is of major importance to quantify future water availability. We here apply COSIPY, a COupled Snowpack and Ice surface energy and mass balance model in PYthon, to UG1, implementing a new albedo parameterization which integrates site-specific bare-ice albedo values on a pixel-by-pixel basis observed by remote sensing. We assess model performance threefold: quantitatively based on long-term measurement data of (1) surface mass balance (SMB) and (2) water discharge as well as qualitatively (3) comparing simulated snow line altitudes to such imated on the basis of time-lapse photography. Comparison of the modeled SMB with annually-averaged data from ablation stakes reveals that COSIPY including the new albedo parameterization accounts for 57.6% of the variance observed in the measurements. The original albedo parameterization performs only slightly inferior (57.1%). Glacier-wide comparison between modeled and glaciological SMB shows high agreement. In terms of discharge prediction, COSIPY reproduces onset and duration of the discharge season well. Estimated discharge from the whole catchment shows shortcomings in exactly matching the measured times series, but interannual variability is captured.

A long glacier mass balance record analysis in Chinese Urumqi Glacier No. 1 and the relationships with changes in large-scale circulations

The 57 years of annual and seasonal mass balance records from observed mass balance made by the Tienshan Glaciological Station on Urumqi Glacier No. 1 (UG 1), Tienshan Mountains, showed a detailed understanding of the spatial and temporal variability that reflect changes in the UG1 at regional scales. Glacier mass balances of UG1 showed negatively decreasing and accelerated mass loss since 1960. There were 42 negative mass balance years and 15 positive mass balance years during 1960–2016. The abrupt change analysis showed from the year of 1993 with a shift to more negative balance. UG 1 is in the anomalous anticyclone edge zone, and this has facilitated the inter-decadal increase in summer precipitation over the Tienshan Mountains. Judged from the values of correlation coefficients and spatial distribution of all the stations in Xinjiang, mass balance change of UG1 appears to be controlled mainly through air temperature variations. While analysis shows that high correlation of mass balances of UG1 with EA/WR which indicated that the mass balance variability of UG1 is closely related to global climate phenomena.

A Test Study of an Energy and Mass Balance Model Application to a Site on Urumqi Glacier No. 1, Chinese Tian Shan

In this study, energy and mass balance is quantified using an energy balance model to represent the glacier melt of Urumqi Glacier No. 1, Chinese Tian Shan. Based on data from an Automatic Weather Station (4025 m a.s.l) and the mass balance field survey data nearby on the East Branch of the glacier, the “COupled Snowpack and Ice surface energy and Mass balance model” (COSIMA) was used to derive energy and mass balance simulations during the ablation season of 2018. Results show that the modeled cumulative mass balance (−0.67 ± 0.03 m w.e.) agrees well with the in-situ measurements (−0.64 ± 0.16 m w.e.) (r2 = 0.96) with the relative difference within 5% during the study period. The correlation coefficient between modeled and observed surface temperatures is 0.88 for daily means. The main source of melt energy at the glacier surface is net shortwave radiation (84%) and sensible heat flux (16%). The energy expenditures are from net longwave radiation (55%), heat flux for snow/ice melting (32%), latent heat flux of sublimation and evaporation (7%), and subsurface heat flux (6%). The sensitivity testing of mass balance shows that mass balance is more sensitive to temperature increase and precipitation decrease than temperature decrease and precipitation increase.

Spatial distribution and potential sources of methanesulfonic acid in High Asia glaciers

As a receptor of atmospheric deposition, glaciers are considered an ideal archive in the study of climate change and geochemical cycles. The deposition of methanesulfonic acid (MSA) in the glaciers provides good opportunities to study the biogeochemical cycle of sulfur in the cryosphere. In the present work, snow samples were collected from six High Asia glaciers along a north-to-south transect to determine the spatial distribution of MSA and elucidate its potential sources. The median MSA concentration in the Urumqi Glacier No.1 of Tien Shan was 138.8 ng mL−1, which was distinctly higher than those observed in the Tibetan Plateau (TP) glaciers and polar regions. The levels of MSA in the interior TP glaciers were higher than those observed in the margins of northeastern and southeastern TP. Good correlations between MSA and K+ (r = 0.86, n = 30, α = 0.01), Mg2+ (r = 0.86), and NH4+ (r = 0.73) were observed in continental glaciers. Principal component analysis indicated that MSA may have terrigenous material inputs. At Yulong Snow Mountain, MSA was correlated with Na+ (r = 0.76, n = 8, α = 0.1), a sea-salt tracer ion, suggesting that MSA may be derived from marine environments. According to dimethyl sulfide (DMS) production and NH3 emissions in High Asia, we deduced that the high concentrations of MSA in continental glaciers are possibly related to the sources of hypersaline soil environments and animal husbandry in nomadic areas. This work is useful for further studies on regional sulfur cycling and the impacts of human activities on climate change.

New insights into particle-bound trace elements in surface snow, Eastern Tien Shan, China

Trace elements (TEs) in the insoluble particles of surface snow are less affected by melting processes and can be used as environmental proxies to reveal natural and anthropogenic emissions. Here the first comprehensive study of the 16 TEs (Al, As, Ba, Bi, Cr, Cu, Fe, Mn, Ni, Pb, Sn, Sr, Ti, U, V, and Zn) in insoluble particles (>0.45 μm) from surface snow samples collected at Urumqi Glacier No. 1 (UG1), Eastern Tien Shan, China, from February 2008 to January 2010 were presented. Results show that concentrations of most insoluble particulate TEs (TEs insol) in the snow were higher in summer while lower in winter, due to the increasing particle inputs and melting processes. The abundances of As, Cr, Cu, Ni, Pb, and Zn in some samples were higher than those in surrounding urban soils, which might due to these TEs have further anthropogenic input beyond the already contaminated re-suspended urban soil particles and TEs were mainly enriched in particles with small grain size. Based on enrichment factor (EF) and principal component analysis (PCA), our results suggest that eight TEs (Al, Fe, Ti, Ba, Mn, Sr, U, and V) mainly came from mineral dust, while the remaining eight TEs (As, Bi, Cr, Cu, Ni, Pb, Sn, and Zn) were affected by coal combustion, mining and smelting of non-ferrous metals, traffic emissions, and the steel industry. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model suggests that pollutants might originate from Xinjiang province, Kazakhstan, and Kyrgyzstan. Moreover, UG1 received more significant inputs of particle-bound pollutants in summer than in winter due to the stronger convection and the prevailing valley wind that transports pollutants from the city of Urumqi.

Effect of Simulated Warming on Microbial Community in Glacier Forefield

Glaciers are constantly retreating because of global warming. In this study, three soil samples along the forefield of Urumqi Glacier No. 1 were collected. The effects of warming on the microbial community in the glacier forefield were investigated through a 150-day laboratory experiment. In this experiment, two temperature treatments were performed at 5℃and 15℃. The results showed that with increasing deglaciation age, the concentrations of carbon and nitrogen increased and the abundance and alpha diversity of microbial communities increased in the original samples. The 150-day laboratory experiment indicated that warming insignificantly changed the copy number of archaea and bacteria. Furthermore, it changed the microbial community composition, and the changes varied in different sampling sites. Based on the analysis of abundant OTUs changing significantly with warming, the sampling sites with shorter deglaciation age had stronger response with warming, representing an increase in the abundance of genus Thiobacillus. Furthermore, these results revealed that warming caused different effects on microbes along glacier forefield and thus, it could provide important characteristics of the microbial community with warming in alpine glacier regions.