Glacier meltwater in the Bogda region is a crucial water source for the Turpan-Hami Basin. In this study, we use three mass balance models with varying complexity to reconstruct the annual mass balance of glaciers in the Bogda region from 2000 to 2021. The performance of these models is validated using geodetic mass change data, MODIS albedo, and specific mass balance observations. All three independent model sets agree that glaciers in the Bogda region experienced a relatively stable negative mass balance between 2000 and 2021. The average annual mass balance was-0.48 m w.e., and the corresponding average meltwater runoff was 1.45 x 108 m3, accounting for 35.12 % of the total streamflow from 2000 to 2018. The primary driver of glacier melt in the region is incoming shortwave radiation (SWnet), with melt being the dominant mass loss process. After 2010, both the mass loss rate and meltwater runoff remained stable, due to the relatively low proportion of snowfall in the melt-season precipitation. Projections under three Shared Socioeconomic Pathways (SSPs) scenarios indicate that glacier mass in the Bogda region will decrease by 35.93 f 8.09 m w.e. (SSP 1-2.6), 41.73 f 8.13 m w.e. (SSP 2-4.5), and 49.79 f 8.26 m w.e. (SSP 5-8.5) by the end of the 21st century. As a result, glacier meltwater runoff will continue to decline.

Glaciers are a critical freshwater resource in the arid northwest of China, where vulnerability to glacier change is closely linked to regional water security, ecological stability, and socio-economic development. Using remote sensing imagery, reanalysis of meteorological data, and socio-economic statistics, we construct an Exposure-Sensitivity-Adaptive Capacity (ESA) assessment framework and corresponding indicator system to evaluate glacier change vulnerability in the Chinese Altai Mountains. We analyze its spatiotemporal patterns from 2000 to 2020 and apply an obstacle model to identify key factors impeding vulnerability reduction. Our results indicate that vulnerability to glacier change increased consistently during 2000–2020, with notable spatial heterogeneity: lower vulnerability in the southwestern and central areas, and higher vulnerability in the northern and eastern regions. As socio-economic conditions improved over this period, the primary obstacles to reducing vulnerability shifted from factors related to adaptive capacity and sensitivity—such as urban fixed-asset investment and total grain output—to those associated with exposure. By 2020, vulnerability was driven mainly by glacier change dynamics, regional development, and growing population pressure. To regulate regional vulnerability, we propose several mitigation pathways, including increasing urban fixed-asset investment, improving water use efficiency, managing population growth, engaging in climate change mitigation initiatives, and implementing direct glacier protection measures.

The increasing frequency of extreme climate events has drawn widespread attention, particularly regarding their impacts on glacier ablation. As the only glacier in the Sawir Mountains with long-term monitoring, the Muz Taw Glacier provides continuous records and serves as an important reference for glaciers in the regions of high latitude and low altitude. Using RClimDex model combination with measurements, ERA5-Land reanalysis, and multi-source remote sensing data, this study analyzed the evolution of extreme climate events in this typical glacier area from 2000 to 2024. Over the past 25 years, all extreme temperature indices show rapid warming in the glacier area, accompanied by differences in temporal pattern, with nighttime warming faster than daytime, and warming magnitude during the non-ablation period exceeding that during the ablation period. Except for R1Xday and R5Xday, extreme precipitation indices showed increasing duration and cumulative intensity, with greater intensity during the ablation period. The stronger correlation between extreme temperature indices and glacier albedo with mass balance suggests that rising extreme warm events and declining albedo contribute to the accelerated glacier mass loss. Particularly in 2024, the Muz Taw Glacier experienced the highest temperature and the greatest amount of mass loss ever recorded.

Understanding regional glacier mass changes is essential for addressing local water resource challenges. However, regional glacier mass changes estimate has been hampered by glacier mass balance monitoring limitations. Here, we present glacier mass balance simulations for the recent historical period (2000-2021) and future projections throughout the 21st century (2022-2100) under Shared Socioeconomic Pathways (SSPs) for six basins in the Tianshan Mountains. The evolution of glacier meltwater runoff and its contribution to total river runoff were also analyzed. We show that, during 2000-2021, the mean annual glacier mass balance was -0.42 f 0.04 m w.e. a- 1, while glacier meltwater runoff was 36.26 f 9.57 & times; 108 m3 a- 1. Glacier meltwater contributed approximately 31.45% of total river runoff. By the end of the 21st century, mean annual mass balance is projected to range from -0.47 f 0.26 m w.e. a- 1 to -0.72 f 0.24 m w.e. a- 1 under SSP 1-2.6 and SSP 5-8.5, corresponding to cumulative mass balances of -37.27 f 12.16 m w.e. and -56.54 f 12.54 m w.e., respectively. This implies a total glacier mass loss of 53%-77% by 2100. Glacier meltwater runoff is projected to increase until approximately 2050 and then gradually decline, indicating a weakening role of glaciers in regulating water resources. Accounting for debris cover reduces simulated glacier mass loss by 5%-22%, whereas neglecting proglacial lakes leads to an underestimation of mass loss by 5%. These results improve our understanding of glacier responses to climate change and provide a scientific basis for sustainable water resource management in the Tianshan Mountains.

The scarcity of observational data on the mass balance of glaciershas hindered an accurate understanding of how glaciers respond to climate. The Muz Taw Glacier, the only glacier in the Sawir Mountains that is subject to long-term monitoring, serves as a reference glacier for this study. We utilized the COSIPY model and integrated both in-situ and geodetic data on glacier mass balance to reconstruct the mass balance of Muz Taw Glacier from 2000 to 2023. Over the past 24 years, the cumulative mass balance was found to be 18.5550 m w.e., with an average annual mass balance of 0.7731 m w.e. Changes in mass balance can be categorized into two distinct phases: remarkable mass loss from 2000 to 2008, exhibiting an average annual value of 0.7973 m w.e.; followed by another comparable period from 2009 to 2017 with an average annual value of 0.8045 m w.e. A notable deceleration in mass loss occurred between 2018 and 2023, during which the average annual loss decreased to 0.6896 m w.e. Throughout 2000-2023, Muz Taw Glacier experienced persistent mass loss influenced by multiple factors as revealed through energy budget analysis: net radiation represented 5%, while precipitation heat flux had a negligible contribution (1%). The uncertainty analysis indicates that our reconstructed sequence of mass balance is reliable. Furthermore, climate response analysis suggests that summer temperature emerges as the predominant factor governing changes in glacial dynamics. When compared with other monitored glaciers located within adjacent westerly-dominated regions, it appears that the mass loss rate of Muz Taw Glacier has been slowing down since 2018. This study investigates the interaction between glacier and climate using a full component glacier energy mass balance model. It helps

The debris-covered glaciers are extensively distributed in the Mt. Tomor of the Tien Shan. Conducting comparative studies between debris-covered and debris-free zones is crucial for understanding the varying responses of glaciers to climate change, and furthermore can enhance the accuracy of simulating the mass balance of debris-covered glaciers. Driven by the meteorological data, this study modelled the energy flux and melt characteristics in debris-covered and debris-free zones of Qingbingtan Glacier No. 72 in Mt. Tomor, Tien Shan using the Debris Energy-Balance model (DEB) and Coupled Snowpack and Ice surface energy and mass-balance model in Python (COSIPY), respectively. The results demonstrated that the simulated melt in the debris-covered zone (R2 = 0.92) and the debris-free zone (R2 = 0.79) was highly consistent with the measured values. The annual average melt in the debris-covered zone calculated by the DEB model was − 1.53 m w.e., while the value in the debris-free zone calculated using the COSIPY model was − 2.31 m w.e. from 2000 to 2023 for the point scale at the same altitude. The presence of debris resulted in a significant 33

The cryosphere has an important impact on regional water resources and ecosystems in the Chinese AltaiMountains and its piedmont zone. Using the latest remote-sensing datasets of cryosphere changes and combiningwith in-situ observation data from glacier monitoring stations and snow cover surveys, the main cryosphereelements including glaciers, snow cover, and permafrost are investigated with emphasis on their changes since2000 and the current situation. Their water resource effects are also discussed. The results indicate that althoughthe glaciers in the region have experienced continuous and intensive melting, mass loss has slowed because bothglacier area shrinkage and thickness reduction were larger during 2000–2010 than during 2010–2021. Snowcoverwater equivalent (w.e.) has increased due to obvious increases in snow depth, although snow-coverarea has decreased slightly. Permafrost has been degrading. Overall, cryosphere contributions to the regionalwater resource are approximately 40.9% since 2000, among which snow-cover melting is the largest, contributing37.1% to water resources in the Irtysh River Basin and significantly more in the mountainous sub-basinswith increased snowfall. Glacier melting contributes 2.9%~3.4%, lower than earlier estimations of 3.4%~3.6% for the late 20th century. Permafrost thaw caused by active layer thickening contributes approximately0.59%. Meteorological data shows a warming and wetting trend, but summer temperature has a much lowerincrease rate and a slowing increase trend after 2013. Moreover, snowfall frequency has increased. In the future,glacier water resource contribution will continue to decrease, but the water resource effects of snow-covermelting and permafrost degradation would increase.

萨吾尔山是中国西部14座冰川分布的山系之一，横跨中国和哈萨克斯坦两国，尽管冰川规模不大，但因二元政治主体割裂了科学研究的完整性，同时萨吾尔山冰川水资源对于新疆阿勒泰地区吉木乃县可持续发展具有重要意义，为此结合航摄地形图、Landsat及Sentinel卫星遥感影像，并参考已有冰川编目和Google Earth高分辨率历史图像等数据资料，在野外台站现场观测验证基础上对萨吾尔山冰川当前现状和过去30多年间的变化进行了详细研究。结果表明：（1）截止2022年，萨吾尔山共分布冰川31条，总面积11.47 km2，新疆吉木乃县境内的木斯岛冰川为最大规模冰川，面积2.95 km2，其余90%的冰川其面积不足1 km2。（2）过去30多年来，萨吾尔山冰川变化的总体趋势是冰川分裂、面积减小和末端后退持续增加。冰川数量从12条分裂成31条，1989—2022年冰川面积减少8.11 km2，退缩率达41.42%，冰川末端退缩11.30 m。气温升高、冰川反照率降低和冰川破碎程度加大是引起萨吾尔山冰川退缩的主要原因。（3）相较于我国其他13座高大山系，萨吾尔山在过去半个多世纪中冰川面积相对退缩幅度最大。未来在全球气候变暖背景下萨吾尔山冰川极大可能会基本消融殆尽，这对本就干旱贫水的吉木乃县可持续发展将产生重要影响，需提早统筹谋划以应对未来的水资源危机。

AbstractWater scarcity is a critical threat in arid regions in China due to dry climate and rising human water demand. The sustainability of a recent wetter trend and its impact on future water security remain uncertain. This case study focuses on a hotspot region, the North Slope of the Tianshan Mountains (NSTM), to assess water scarcity in the coming decades (2030–2050) under two climate scenarios. To this end, we developed an integrated agro‐hydrological model to simulate historical and future hydrological processes and crop water dynamics in arid regions. Our results indicate nonsignificant increases in precipitation (around 3%) and evident rising temperatures (0.9–1.5°C) in the NSTM compared to the present‐day (2011–2020) climate. This translates to a projected increase in water availability (5.6%–11.2%) during 2030–2050, with slightly larger increases (6.3%–14%) in glacier runoff. However, the spatial mismatch between precipitation increases and water demand makes this potential gain largely offset by rising irrigation water demand (over 7%) if cropland remains constant from 2020 onwards. As a result, the current annual water deficit (3.3 km3) is likely to increase by 5%–11%, with 32% of NSTM basins facing persistent water scarcity. Most croplands are at high risk of groundwater depletion and 17%–34% of basins will experience intensified water scarcity. These findings highlight the urgent need for comprehensive water management strategies, including improved irrigation efficiency and exploration of alternative water sources, to ensure water security and sustainable development in arid China facing a changing climate.

Glacial changes are crucial to regional water resources and ecosystems in the Sawir Mountains. However, glacial changes, including the mass balance and glacial meltwater of the Sawir Mountains, have sparsely been reported. Three model calibration strategies were constructed including a regression model based on albedo and in-situ mass balance of Muz Taw Glacier (A-Ms), regression model based on albedo and geodetic mass balance of valley, cirque, and hanging glaciers (A-Mr), and degree-day model (DDM) to obtain a reliable glacier mass balance in the Sawir Mountains and provide the latest understanding in the contribution of glacial meltwater runoff to regional water resources. The results indicated that the glacial albedo reduction was significant from 2000 to 2020 for the entire Sawir Mountains, with a rate of 0.015 (10a)- 1, and the spatial pattern was higher in the east compared to the west. Second, the three strategies all indicated that the glacier mass balance has been continuously negative during the past 20 periods, and the average annual glacier mass balance was -1.01 m w.e. Third, the average annual glacial meltwater runoff in the Sawir Mountains from 2000 to 2020 was 22 x 106 m3, and its

Study region: The headwaters of Urumqi River basin located in eastern Tien Shan Study focus: Glacier shrinkage in recent decades has caused the volume and timing of glacier-fed streamflow to change, which in turn has significantly impacted the water supply and ecological system in the vast arid land in Central Asia and drawn wide public attention. Based on a glaciohydrologic degree-day model, the runoff mechanisms and processes of the glacier-fed catchment are revealed. New hydrological insights for the region: The study found that about 51 % glacier coverage of the Urumqi Glacier No.1 catchment (UG1C) generates approximately 76 % glacier runoff, indicating that glacier melt comprises a significant water resource in the region. The different ways that the glacier melts in response to temperature versus precipitation on a daily scale by changing glacier mass balance can effectively stabilize streamflow, showing a strong capacity of the glacier to naturally adjust streamflow beneficially to water utilization by those downstream. Based on the sensitivity of modelled runoff to glacier change by comparing simulations using constant glacier cover that accommodated dynamic changes in glacier area, we found that the maximum volume of ice melt runoff during the past four decades appeared during the period 1996-2019, most likely around 2010.

The cryosphere has an important impact on regional water resources and ecosystems in the Chinese Altai Mountains and its piedmont zone. Using the latest remote-sensing datasets of cryosphere changes and combining with in-situ observation data from glacier monitoring stations and snow cover surveys, the main cryosphere elements including glaciers, snow cover, and permafrost are investigated with emphasis on their changes since 2000 and the current situation. Their water resource effects are also discussed. The results indicate that although the glaciers in the region have experienced continuous and intensive melting, mass loss has slowed because both glacier area shrinkage and thickness reduction were larger during 2000-2010 than during 2010-2021. Snow cover water equivalent (w.e.) has increased due to obvious increases in snow depth, although snow-cover area has decreased slightly. Permafrost has been degrading. Overall, cryosphere contributions to the regional water resource are approximately 40.9% since 2000, among which snow-cover melting is the largest, contributing 37.1% to water resources in the Irtysh River Basin and significantly more in the mountainous sub-basins with increased snowfall. Glacier melting contributes 2.9%-3.4%, lower than earlier estimations of 3.4%-3.6% for the late 20th century. Permafrost thaw caused by active layer thickening contributes approximately 0.59%. Meteorological data shows a warming and wetting trend, but summer temperature has a much lower increase rate and a slowing increase trend after 2013. Moreover, snowfall frequency has increased. In the future, glacier water resource contribution will continue to decrease, but the water resource effects of snow-cover melting and permafrost degradation would increase.

Glacier volume changes have remarkable impacts on regional water resources; however, their estimation uncertainties remain large. In this study, the surface elevations of seven glaciers at the headwaters of the Urumqi River exhibited obvious thinning at the rate of 0.32 m a-1 from 1964 to 2021. Correlations between the ice volume change (dV) derived from surface elevation conversion and the area change (dS) were established for valley, cirque, and hanging glaciers. The ice volumes of valley, cirque, and hanging glaciers in the Urumqi River Basin decreased by 0.99 km3, 0.18 km3, and 0.59 km3, respectively, and the total ice volume decreased by 1.76 km3 during 1964-2021. Ice volume losses are accelerating. The correlation between dV and dS for valley glaciers produced a large estimation difference for the ice volume change of Urumqi Glacier No. 1 (UG1) compared with the glaciological mass balance (15%), while the estimation differences of ice volume changes for the three types of glaciers in the Urumqi River Basin were within acceptable limits (10%) based on the geodetic results. This new method has vast potential in estimating ice volume changes at the basin or regional scale, or even across western China.

As an important part of the cryosphere, glaciers provide important freshwater for the arid region of western China and the glacier change vulnerability is closely related to regional socioeconomic development. Based on remote sensing images, reanalysis meteorological data, relevant socio-economic data, etc., this study constructed a framework and indicator system for evaluating the glacier change vulnerability in the Chinese Altai Mountains, analyzed the spatiotemporal changes pattern of glacier change vulnerability from 2000 to 2020, and discussed the factors affecting the glacier change vulnerability by using the obstacle degree model. The results showed that firstly the glacier change vulnerability in the Chinese Altai Mountains had decreased and then increased during the period 2000-2020, and the regional differences decreased slowly in the period 2000-2010 and increased in the period 2010-2020. Secondly, the glacier change vulnerability aggregation was high for the spatial scale, showing a distribution pattern of low vulnerability in the southwest and central regions, and high vulnerability in the northern and eastern regions. Thirdly, as the socio-economic conditions had been improving, the main factors hindered the reduction of glacier change vulnerability gradually shifted from the adaptability and sensitivity factors, such as the amount of urban fixed assets investment and total grain output, to those related to exposure. By 2020, glacier change and development were the main reasons for vulnerability.

As one of the major water supply systems for inland rivers, especially in arid and semi-arid regions, snow cover strongly affects hydrological cycles. In this study, remote sensing datasets combined with in-situ observation data from a route survey of snow cover were used to investigate the changes in snow cover parameters on the Chinese Altai Mountains from 2000 to 2022, and the responses of snow cover to climate and hydrology were also discussed. The annual snow cover frequency (SCF), snow cover area, snow depth (SD), and snow density were 45.03%, 2.27 × 104 km2, 23.4 cm, and ~0.21 g·cm−3, respectively. The snow water equivalent ranged from 0.58 km3 to 1.49 km3, with an average of 1.12 km3. Higher and lower SCF were mainly distributed at high elevations and on both sides of the Irtysh river. The maximum and minimum snow cover parameters occurred in the Burqin River Basin and the Lhaster River Basin. In years with high SCF, abnormal westerly airflow was favorable for water vapor transport to the Chinese Altai Mountains, resulting in strong snowfall, and vice versa in years with low SCF. There were significant seasonal differences in the impact of temperature and precipitation on regional SCF changes. The snowmelt runoff ratios were 11.2%, 25.30%, 8.04%, 30.22%, and 11.56% in the Irtysh, Kayit, Haba, Kelan, and Burqin River Basins. Snow meltwater has made a significant contribution to the hydrology of the Chinese Altai Mountains.

中国是中纬度山地冰川大国，冰川科学研究十分重要。冰川还是我国西部干旱区重要的水资源——我国及周边国家大江大河的源头，由冰川变化引发的水文、水资源变化对于我国西北干旱区山盆地理结构的生态系统具有决定性意义。中国科学院天山冰川观测试验站（以下简称“天山冰川站”）建立于中国冰川学开创之初的1959年，围绕乌鲁木齐河源1号冰川（以下简称“1号冰川”）的研究，对中国冰川科学理论的形成和发展起着关键性作用，亦是对国际冰川学的重要发展和贡献。以乌鲁木齐河山区流域综合观测试验为基础的水文学研究，奠定了我国内陆河流域水文研究基础。60年来，作为中国冰川学观测、试验、研究和人才培养的基地，对外开放交流的平台，天山冰川站在冰川物理学、冰川对气候变化的响应、冰川水文、雪冰物理化学过程、第四纪冰川、冰缘植被与生态等研究方向取得系统性创新成果，为中国的冰川学事业作出了卓越贡献。世界冰川监测服务中心（WGMS）将1号冰川列为全球10条重点观测研究的参照冰川之一，即作为中国和中亚干旱区的参照冰川，其长期、系统的观测研究成为许多国家冰川学研究的参照和典范。

Precipitation plays an important role in the process of water cycle and is a main driving force of terrestrial hydrological process.The change of precipitation form is an important part of understanding the evolution of land water cycle under the background of global warming， which is a hot and difficult issue for scholars at home and abroad.In our study， an observation comparison experiment of solid precipitation measurements with a PWS100 laser sensor and a Geonor T-200B at the terminus of Urumqi Glacier No.1， Tianshan Mountains from May 2018 to April 2020 was carried out.Three parts of results are obtained from this study.Firstly， the experiment site was dominated by solid precipitation particles， accounting for 63% of total precipitation particles.The liquid particles accounted for 37% of total precipitation particles.On the monthly scale， the number of particles from June to August was the largest， with 57% of liquid particles and 43% of solid particles.In the other months， the number of solid particles accounted for 96% of the total number of particles.Secondly， based on the proportion of precipitation particles in different temperature ranges， the precipitation types were divided with the temperature 6.5 ℃ as the critical value.The modified total precipitation accumulation of Geonor T-200B was 1202 mm， accounting for 67% of DFIR， which underestimated the precipitation， but the average relative capture rate was about 87%.Thirdly， the daily precipitation recorded PWS100 and Geonor T-200B was strong correlated and the annual amount of precipitation recorded by two instruments differed 71 mm.However， there was a small seasonal difference between two observed data sets.The amount of precipitation from PWS100 was 73 mm higher in June to August and 37 mm lower in September to May in the next year compared with the values recorded by Geonor T-200B.PWS100 observed large precipitation in summer with large precipitation and complex precipitation types， but less precipitation in winter.Moreover， PWS100 was not sensitive to small raindrops， which would lead to insufficient catch quantity.Therefore， it indicated that Geonor T-200B was more efficient than PWS100 in terms of catching solid precipitation.The results provide experimental basis for further research on the seasonal changes of mountainous runoff under the background of climatic warming.

The Mt.Tomur glaciers, in the Tian Shan mountains of Western China, are usually debris-covered, and due to climate change, glacial hazards are becoming more frequent in this region. However, no changes in the long-time series of glacier surface velocities have been observed in this region. Conducting field measurements in high-altitude mountains is relatively difficult, and consequently, the dynamics and driving factors are less studied. Here, image-correlation offset tracking using Landsat images was exploited to estimate the glacier surface velocity of glaciers in the Mt.Tomur region from 2000 to 2020 and to assess glacier ice thickness. The results show that the glacier surface velocity in the Mt.Tomur region showed a significant slowdown during 2000–2020, from 6.71 ± 0.66 m a−1 to 3.95 ± 0.66 m a−1, an overall decrease of 41.13%. The maximum glacier ice thickness in the Mt.Tomur region was estimated based on the ice flow principle being 171.27 ± 17.10 m, and the glacier average thickness is 50.00 ± 5.0 m. Glacier thickness at first increases with increasing altitude, showing more than 100 ± 10 m ice thickness between 3400 m and 4300 m, and then decreases with further increases in altitude. The reliability of the surface velocity and ice thickness obtained from remote sensing was proved using the measured surface velocity and ice thickness of Qingbingtan glacier No. 72 stall (the correlation coefficient R2 > 0.85). The debris cover has an overall mitigating effect on the ablation and movement rate of Qingbingtan Glacier No. 72; however, it has an accelerating effect on the ablation and movement rate of glacier No. 74.

To get a better overview of atmosphere-driven mass changes at Urumqi Glacier No.1, Chinese Tien Shan, the surface energy budget and mass balance is modeled by linking the COupled Snowpack and Ice surface energy and MAss balance model (COSIMA) with in-situ measured meteorological records for the ablation period in 2018. The COSIMA is calibrated by manual optimization and the modeled results agree well with the in-situ surface temperature, snow height and seasonal mass balance. Our results reveal that Urumqi Glacier No.1 experienced a significant mass loss, with an average value of − 0.77 m w.e. over the ablation period 2018. The surface energy budget components can be classified into two categories: radiation (shortwave and longwave) and turbulent fluxes. Surface melt and solid precipitation were dominated components of mass balance. The COSIMA can reproduce the glaciological mass balance compared with other models. Sensitivity analysis showed that the mass balance was more sensitive to the temperature than precipitation, and mass loss caused by temperature increase of 1 K needed to be compensated by at least 40% precipitation increase. Air temperature during the ablation period was more important than annual precipitation in controlling mass balance changes on Urumqi Glacier No. 1. These findings will enhance our understanding of the mechanisms underlying mass balance processes of ablation period and their contribution to the acceleration of glacier retreat in Tien Shan.

As a key component of the hydrological cycle, knowledge and comprehension of precipitation formation and evolution are of leading significance. This study investigates the statistical characteristics of raindrop size distribution for heavy precipitation events with observations collected by a Present Weather Sensor (PWS100) disdrometer located in the alpine area of eastern Tianshan, China. The characteristics are quantified based on heavy rain, heavy snow, and hail precipitation events classified using the rainfall intensity and the precipitation-related weather codes (US National Weather Service). On average, the heavy precipitation events in the headwaters of the Urumqi River are dominated by medium-sized (2–4 mm) raindrops. As well, we investigate mass-weighted mean diameter–normalized intercept parameter scatterplots, which demonstrate that the heavy precipitation events in alpine regions of the Tianshan Mountains can be identified as maritime-like clusters. The concentration of raindrops in heavy precipitation is the highest overall, while the concentration of raindrops in heavy snow is the lowest when the diameter is lower than 1.3 mm. The power–law relationships of radar reflectivity (Z) and rain rate (R) [Z = ARb] for the heavy rain, heavy snow, and hail precipitation events are also calculated. The Z–R relationship of heavy rain and heavy snow in this work has a lower coefficient value of A (10 and 228.7, respectively) and a higher index value of b (2.6 and 2.1, respectively), and the hail events are the opposite (A = 551.5, b = 1.3), compared to the empirical relation (Z = 300R1.4). Furthermore, the possible thermodynamics and general atmospheric circulation that cause the distinctions in the raindrop size distribution characteristics between alpine areas and other parts of the Tianshan Mountains are also debated in this work. The headwaters of the Urumqi River in alpine areas have relatively colder and wetter surroundings in the near-surface layer than the foothills of the Tianshan Mountains during the precipitation process. Meanwhile, a lower temperature, a higher relative humidity, a more efficient collision coalescence mechanism, and glacier local microclimate effects (temperature jump, inverse glacier temperature, glacier wind) at the headwaters of the Urumqi River during the precipitation process are probably partly responsible for more medium- and large-size drops in the mountains.