Understanding changes in runoff due to climate variations in glacier-dominated headwaters is key to managing water resources and dryland watersheds effectively and rationally. The continuous glacier shrinkage caused by climate warming has significantly impacted the water supply and ecological systems in the vast arid regions of Central Asia, attracting extensive public concern. The study results indicate an increase in total runoff at the Urumqi River source region during both the baseline (1997–2016) and mid-century (2040–2059) periods, encompassing rain, glacier meltwater, and snowmelt components. Compared to the baseline period, the temperature increases by the mid-century under the three climate scenarios (SSP1−26, SSP2−45, and SSP5−85) range from 0.98 to 1.48 °C. In this region, during the period from 1997 to 2016, glacier meltwater was the dominant component of runoff, comprising 42.10–43.79% of the total, followed by snowmelt at 29.64–30.40% and rainfall contributions of 26.56–27.49%. Additionally, glacier storage in this typical catchment responds quickly to temperature fluctuations, significantly impacting runoff. The Urumqi River source region’s runoff exhibits heightened sensitivity to these temperature shifts compared to precipitation effects. We hypothesized three glacier coverage scenarios: unchanged at 100% glaciation, reduced by half to 50%, and fully retreated to 0% glaciation. Analysis of these scenarios demonstrated that glaciers are pivotal in runoff formation. Under the SSP1−26, SSP2−45, and SSP5−85 climate scenarios, glaciers contributed additional runoff increases of 51.61%, 57.64%, and 62.07%, respectively. Generally, glaciers play a critical role in supplying water in dry areas. Thus, accurately forecasting future water resource shifts in high-altitude glacier regions is crucial for downstream water resource management and utilization.

As a heavily glaciated region, the Eastern Pamir plays a crucial role in regional water supply. However, considerable ambiguity surrounds the distribution of glacier ice thickness and the details of ice volume. Accurate data at the local scale are largely insufficient. In this study, ground-penetrating radar (GPR) was applied to assess the ice thickness at Muztagh Glacier No.16 (MG16) in Muztagh Ata, Eastern Pamir, for the first time, detailing findings from four distinct profiles, bridging the gap in regional measurements. We utilized a total of five different methods based on basic shear stress, surface velocity, and mass conservation, aimed at accurately delineating the ice volume and distribution for MG16. Verification was conducted using measured data, and an aggregated model outcome provided a unified view of ice distribution. The different models showed good agreement with the measurements, but there were differences in the unmeasured areas. The composite findings indicated the maximum ice thickness of MG16 stands at 115.87 ± 4.55 m, with an ice volume calculated at 0.27 ± 0.04 km3. This result is relatively low compared to the findings of other studies, which lies in the fact that the GPR measurements somewhat constrain the model. However, the model parameters remain the primary source of uncertainty. The results from this study can be used to enhance water resource assessments for future glacier change models.

Study regionThe Urumqi River basin located in eastern Tien Shan in Central AisaStudy focusGlacier runoff plays a pivotal role in water resources and stabilizing streamflow in mountainous regions. To assess the characteristics of glacier ice melt runoff in sub-basins within a single basin, three sub-basins with glacier ratios varying from 4% to 46% in the Urumqi River basin are investigated. Through the simulation by HBV light model on the basis of the observed meteorological and hydrological data. The characteristics and behaviour of glacier ice melt runoff in the three sub-basins are analysed.New hydrological insights for the regionIt was found that both the contribution ratios of ice melt runoff and glacier runoff increase linearly with the increasing glacier ratio for the three catchments, rather than logarithmically or exponentially as observed in previous studies. This is due to the relatively high contributions of ice melt and glacier runoff to river flow in a catchment characterized by high elevation and extensive glacier coverage (Catchment 1), resulting from the coincidence of summer precipitation maxima with snow and ice melt in this region. The coefficient of variations (CV) of river flow tends to decrease with the decreasing glacier ratio in sub-basins in the Urumqi River basin, indicating that river flow becomes more stable as it flows farther from the headwater in the Urumqi River basin. The lowest glacierized Catchment 3 exhibited the minimum CV value, demonstrating a stable outflow.

基于全球开放冰川模型(OGGM),结合第六次气候模式比较计划(CMIP6),在5种气候模式(BCC-CSM2-MR、CESM2、CESM2-WACCM、FGOALS-f3-L、NorESM2-MM)模拟的 3 种气候情景(SSP1-2.6、SSP2-4.5、SSP5-8.5)下,系统分析了萨吾尔山冰川2020-2100年间面积和储量的变化.结果显示,3种气候情景下,萨吾尔山冰川面积和储量都呈现退缩趋势,其中SSP5-8.5气候情景下的冰川面积和储量损失最大,对应面积和储量变化为-0.154 km2·a-1和-5.11×106 m3·a-1,其次是SSP2-4.5,对应面积和储量变化为-0.150 km2·a-1和-5.05×106 m3·a-1,SSP1-2.6气候情景下面积和储量损失最小,面积和储量变化为-0.139 km2·a-1和-4.93×106 m3·a-1.萨吾尔山中国境内冰川面积和储量变化要大于哈萨克斯坦境内,其中冰川面积变化基本符合从相对平稳到快速变化,最后再放缓的过程,但是储量变化相对平缓.2020-2050年间,萨吾尔山冰川主要以冰川减薄为主;2050-2100年间,该地区冰川主要以冰川面积退缩为主.截至2060年,萨吾尔山47.8%的冰川将会退缩,该比例在2080年将上升至78.2%.

Abstract Physical interactions between glacier surfaces and atmosphere are crucial to understanding the mechanism and process of glacier ablation but poorly constrained based on measured meteorological data from monitoring glaciers. We investigate how climatic regimes influence glacier mass loss in High Mountain Asia (HMA) from the perspective of glacier energy and mass balance for 30 glaciers with meteorological and mass-balance observations and project their volume loss under various shared socioeconomic pathways (SSPs) by the end of the 21st century. Our study shows that net shortwave (SWnet; 92.7%) and longwave (LWnet; 82.0%) radiation in the monsoon-dominated glaciers during the melt season are 1.08 times higher than those in the westerlies-dominated glaciers. Turbulent fluxes are similar in both regions, so that SWnet and LWnet determine the energy supply and expenditure in the two regions, respectively. Driven by such an energy balance context, melt (94.3%) in monsoon-dominated glaciers is 1.38 times greater than in westerlies-dominated glaciers, while snowfall in monsoon-dominated glaciers decreases, which jointly determines the difference in mass loss between the two regions. Additionally, sublimation and refreezing are the crucial factors contributing to mass balance, but their impact on mass balance is small. Volume-loss differences of approximately 15% also exist between the two regions under three shared socioeconomic pathways (SSPs).

As a particular type of alpine glacier, debris-covered glaciers are essential for local water resources and glacial disaster warnings. The Eastern Tomur Peak Region (EPTR) is the most concentrated glacier in Tien Shan Mountain, China, where the glaciers have not been studied in detail. This paper evaluates the delineation accuracy of Landsat8 OLI, Sentinel-1A, and GF images for debris-covered glaciers in the EPTR. Each image uses the most advanced delineation method for itself to minimize the error of inherent resolutions. The results show that the accuracy of these images for delineating debris-covered glaciers is very high, and the F1 scores are expressed as 96.73%, 93.55%, and 95.81%, respectively. Therefore, Landsat images were selected to analyze the area change of EPTR from 2000 to 2022 over a 5-year time scale. The results indicate that glaciers of the EPTR decreased by 19.05 km2 from 2000 to 2020, accounting for 1.9% (0.08% a−1), and debris increased by 10.8%, which validates the opinion that the presence of debris inhibits glacier melting. The most varied time was 2010–2022, but it was much less than other Tien Shan regions. The lower glacier ablation rate in this area results from the combined effect of decreased bare ice and increased debris. The main reason for the change in debris-covered glaciers is the increase in temperature.

Rayleigh lidar data in 2013–2015 is used to describe the characteristics of gravity wave potential energy density in the mesosphere above Golmud (36.25° N, 94.54° E) of the Tibetan Plateau. In this study, the vertical profiles of the atmospheric gravity wave potential energy density between 50–80 km above the region are presented, including the potential energy mass density Epm and the potential energy volume density Epv. It shows the mathematical characteristics of the atmospheric gravity wave potential energy density vertical distribution, which also indicate the gravity waves are obviously dissipated in the lower mesosphere and close to conservative growth in the upper mesosphere (the turning point is around 61 km). A total of 1174 h of data covers seasonal changes, which reveals the seasonal characteristics of the potential energy density. The Epm increases faster with altitude in summer than others. All seasons of the potential energy density profiles show that gravity waves are dissipated in the lower mesosphere, among which spring and winter are the most severe and summer is weakest. The Epm is higher in spring and winter below 55 km. Above 55 km, it is the maximum in winter, followed by summer. Then, the AGWs activities between the location with mid–latitudes and different longitudes are compared and discussed.

Two years of observational data from the 532 nm Rayleigh lidar were used to study the vertical profile characteristics of atmospheric gravity wave potential energy density (GWPED) between 40–80 km above Jiuquan (40° N, 95° E) for the first time. The atmospheric gravity waves (AGWs) characteristics are presented in terms of the atmospheric relative temperature perturbation, along with the estimated annual and seasonal GWPED with high spatial and temporal resolution (0.5 km and 1 h). The annual potential energy mass density Epm and volume density Epv vertical profiles show that the GWPED in the upper mesosphere is close to the adiabatic growth rate. The seasonal vertical profiles result shows that Epm is higher in autumn–winter than in spring–summer in all the observed altitudes. The GWPED approaches adiabatic growth above 61 and 65 km in spring–summer and autumn–winter, respectively. The AGWs severely dissipate below the turning altitudes and transfer energy into the background atmosphere. The GWPED scale heights show that the AGWs dissipation rate of spring–summer is close to that of autumn–winter. Furthermore, based on the wind data from SD–WACCM, the influence of critical level filtering on AGWs is discussed. It plays an important role in affecting the seasonal variation in GWPED.

A vehicle-mounted sodium fluorescence scattering Doppler lidar and a vehicle-mounted 532 nm Rayleigh scattering Doppler lidar have been developed for wind and temperature observations in near space region. Three-frequency-ratio Doppler measurement method was used to obtain wind and temperature from 80 km to 100 km in the sodium fluorescence scattering Doppler lidar. And Iodine absorption line edge technique was employed to measure wind speed below 70 km, integration method was used to measure temperature below 80 km in the 532 nm Rayleigh scattering Doppler lidar. When the range resolution was 1 km and the temporal resolution was 1 h, the uncertainties of measured temperature and wind speed were about 0.2 K and 0.4 m/s at 40 km, 1.5 K and 5.5 m/s at 70 km, 0.3 K and 1.0 m/s at 92 km. The two lidars have carried out long-term observations in Beijing, Qinghai, Gansu. The data are used for near space environmental characteristics researches.