Multi-decadal variations in glacier flow velocity and the influencing factors of Urumqi Glacier No.1 in Tianshan Mountains, Northwest China

Urumqi Glacier No. 1 is a representative glacier in the inland areas of Central Asia and is the only Chinese reference glacier in the World Glacier Monitoring Service. In this study, we explored multi-decadal variations in the flow velocity of the glacier and the influencing factors based on continuous field observations and path coefficient analysis. Results show that the glacier flow velocity decreased from 5.5 m/a in 1980/1981 to 3.3 m/a in 2010/2011. The annual variation in the direction of glacier flow velocity in the western branch and eastern branch was less than 1°–3°, and the change of glacier flow velocity in the western branch was more dramatic than that in the eastern branch. Glacier flow velocity was influenced by glacier morphology（including glacier area, glacier length, and ice thickness）, glacier mass balance and local climate conditions（air temperature and precipitation）, the glacier morphology being the leading factor. The long-term flow velocity data set of Urumqi Glacier No. 1 contributes to a better understanding of glacier dynamics within the context of climatic warming.

Chemical Characteristics and Environmental Significance of Fresh Snow Deposition on Urumqi Glacier No.1 of Tianshan Mountains, China

Ice and snow chemistry of alpine glaciers is crucial for the research of regional atmospheric environment change. Fresh snow samples were weekly collected from Urumqi Glacier No.1 in the Tianshan Mountains, Xin- jiang, China, and the chemical characteristics and seasonal variations of major ions, mineral dust, δ18O and trace metals were measured. Results show that the concentrations of major ions in the snow are Ca2+ > SO42-> NH4+ > NO3-> Cl-> Na+ > Mg2+ > K+, in which Ca2+ is the dominant cation, and SO42-is the dominant anion. All major ions have close positive correlations with each other except NO3-. δ18O shows positive correlation with air temperature change during the study period. Mineral dust particle and major ionic concentrations in fresh snow have obvious seasonal change, with high concentration in spring but low concentration in summer and autumn, which indicates that the chemical mass input from Asian dust activity to snow is very significant. Temporal changes of trace metals in fresh snow, e.g., Cd, Pb, Zn, Al, Fe, have shown that human-induced pollution of central Asian region also has large contribution to the snow chemistry on alpine glaciers of the Tianshan Mountains.

Sensitivity of mountain runoff to climate change for Urumqi and Kaidu rivers originating from the Tianshan Mountains

The mountain watersheds of Kaidu River and Urumqi River, which separately originate from the south and north-side of the Tianshan Mountains in Xinjiang, are selected as the study area. The characteristics and trends on variation of temperature, precipitation and runoff, and the correlativity between temperature, precipitation, and runoffwere analyzed based on the past 40 years of observational data from the correlative hydrological and weather stations in the study areas. Various weather scene combinations are assumed and the response models of runoff to climate change are established in order to evaluate the sensitivity of runoff to climate change in the study areas based on the foregoing analysis, Results show that all variations of temperature, precipitation, and runoff overall present an oscillating and increasing trend since the 1960s and this increase are quite evident after 1990. There is a markedly positive correlation between mountain runoff, temperature, and precipitation while there are obvious regional differences of responding degree to precipitation and temperature between mountain runoff of Ummqi River and Kaidu River Basins Also, mountain runoff of Urumqi River Basin is more sensitive to precipitation change than that of Kaidu River Basin, and mountain runoff of Kaidu River Basin is more sensitive to temperature change than that of Ummqi River Basin.

Effect of topography on the changes of Urumqi Glacier No.1 in the Chinese Tianshan Mountains

Topography plays an important role in determining the glacier changes.However,topography has often been oversimplified in the studies of the glacier changes.No systematic studies have been conducted to evaluate the relationship between the glacier changes and topographic features.The present study provided a detailed insight into the changes in the two branches(east branch and west branch)of Urumqi Glacier No.1 in the Chinese Tianshan Mountains since 1993 and systematically discussed the effect of topography on the glacier parameters.This study analyzed comprehensive recently observed data(from 1992/1993 to 2018/2019),including mass balance,ice thickness,surface elevation,ice velocity,terminus,and area,and then determined the differences in the changes of the two branches and explored the effect of topography on the glacier changes.We also applied a topographic solar radiation model to analyze the influence of topography on the incoming shortwave radiation(SW_(in))across the entire glacier,focusing on the difference in the SW_(in) between the two branches.The glacier mass balance of the east branch was more negative than that of the west branch from 1992/1993 to 2018/2019,and this was mainly attributed to the lower average altitude of the east branch.Compared with the west branch,the decrease rate of the ice velocity was lower in the east branch owing to its relatively increased slope.The narrow shape of the west branch and its southeast aspect in the earlier period resulted in a larger glacier terminus retreat of the west branch.The spatial variability of the SW_(in) across the glacier surface became much larger as altitude increased.The SW_(in) received by the east branch was slightly larger than that received by the west branch,and the northern aspect could receive more SW_(in),leading to glacier melting.In the future,the difference of the glacier changes between the two branches will continue to exist due to their topographic differences.This work is fundamental to understanding how topographic features affect the glacier changes,and provides information for building different types of relationship between the glacier area and ice volume to promote further studies on the basin-scale glacier classification.

The processes and characteristics of mass balance on the Urumqi Glacier No. 1 during 1958-2009

As a solid reservoir, a glacier can regulate regional water resources. The annual net mass balance directly reflects the fluctuation of the glacier and climate variability. Based on 51 years of mass balance observation data, the mass balance of Tianshan Mountains Urumqi Glacier No. 1 experienced a nine times positive balance fluctuation and nine times negative balance fluctuation. There were 35 and 16 negative and positive balance years, respectively. From 1996/97 to 2008/09, 12 consecutive negative balance years were observed at Tianshan Mountains Urumqi Glacier No. 1. These results demon- strate that the Urumqi Glacier No. 1 is experiencing a strong negative balance, and the strongest negative balance, -931 mm w.e. （mm water equivalent）, during the observation period occurred in 2008. In addition, the cumulative mass balance reached 13,709 mm w.e. in 2008. However, in 2009, the mass balance was positive at 63 mm w.e. The equilibrium-line al- titude changes with the fluctuation in the mass balance, and the effective mass balance gradient is 7.4 mrn/m. In this paper, the headwaters of the Urumqi River were analyzed using meteorological data from 1958 to 2009, including the average seasonal temperature and precipitation. The results showed that the main factor associated with the mass balance variation of Glacier No. 1 is the fluctuation in the summer air temperature, followed by changes in the precipitation.

Hydrological processes of glacier and snow melting and runoff in the Urumqi River source region, eastern Tianshan Mountains, China

Hydrological processes were compared, with and without the influence of precipita- tion on discharge, to identify the differences between glacierized and non-glacierized catchments in the Urumqi River source region, on the northern slope of the eastern Tianshan Mountains, during the melting season （May-September） in 2011. The study was based on hydrological data observed at 10-min intervals, meteorological data observed at 15-min intervals, and glacier melting and snow observations from the Empty Cirque, Zongkong, and Urumqi Glacier No.1 gauging stations. The results indicated that the discharge differed markedly among the three gauging stations. The daily discharge was more than the nightly discharge at the Glacier No.1 gauging station, which contrasted with the patterns observed at the Zongkong and Empty Cirque gauging stations. There was a clear daily variation in the discharge at the three gauging stations, with differences in the magnitude and duration of the peak discharge. When precipitation was not considered, the time-lags between the maximum discharge and the highest temperature were 1-3 h, 10-16 h, and 5-11 h at the Glacier No.l, Empty Cirque, and Zongkong gauging stations, respectively. When precipitation was taken into consideration, the corresponding time-lags were 0-1 h, 13 h, and 6-7 h, respectively. Therefore, the duration from the generation of discharge to confluence was the shortest in the glacierized catchment and the longest in the catchment where was mainly covered by snow. It was also shown that the hydrological process from the generation of discharge to confluence shortened when precipitation was considered. The factors influencing changes in the discharge among the three gauging stations were different. For Glacier No.1 station, the discharge was mainly controlled by heat conditions in the glacierized region, and the discharge displayed an accelerated growth when the temperature exceeded 5℃ in the melt season. It was found that the englacial and subglacial drainage channel of Glacier No.1 had become simpler during the past 20 years. Its weaker retardance and storage of glacier melting water resulted in rapid discharge confluence. It was also shown that the discharge curve and the time-lag between the maximum discharge and the highest temperature could be used to reveal the evolution of the drainage system and the process of glacier and snow melting at different levels of glacier coverage.

Variations in the equilibrium line altitude of Urumqi Glacier No.1,Tianshan Mountains,over the past 50 years

The glacier ELA is one of the important parameters reflecting climate change.Based on observations of the equilibrium line altitude(ELA) of Urumqi Glacier No.1 in the Tianshan Mountains,we established a statistical model between ELA and its major influencing factors,warm season air temperature(air temperature averages for May,June,July and August) and annual precipitation.Result showed that,warm season air temperature was the leading climatic factor influencing ELA variations.The glacier ELA ascends(descends) 61.7 m when warm season air temperature increases(decreases) by 1°C,and ascends(descends) 13.1 m when cold season precipitation decreases(increases) by 10%.In the period 1959-2008,the glacier ELA showed a general increasing trend,ascending108 m and reaching its highest altitude in 2008 at 4168 m a.s.l.,close to the glacier summit.If future climate is similar to that in the past 50 years,the ELA of Urumqi Glacier No.1 will still ascend with a speed of 2.16 m/a.However,If future climate is similar to that in the period 2000-2008,the ELA will still ascend with a speed of 6.5 m/a before it is stable.As a result of ELA variation,the accumulation area ratio(AAR) of the glacier showed a decreasing trend during the past 50 years.

Features and significance of the Yudai porphyry copper deposit in the Kalatag district,eastern Tianshan,NW China

1 Introduction The eastern Tianshan region covers around 60000 km2in area and is located in the eastern part of Xinjiang.The district contains various types mineral commodities including Cu,Ni,Au,Fe,Pb and Zn(Wang et al.,2006).The Dannanhu belt in eastern part of the area is interpreted as a volcanic arc and forms an important mineralized zone bordered by the Turpan-Hami Basin to the north and Kanggur back-arc basin to the south.

乌鲁木齐米东区社区获得性病毒性肺炎患儿的病原体检测与流行病学情况分析

目的探讨与分析乌鲁木齐米东区社区获得性病毒性肺炎患儿的病原体检出与流行病学情况,希望为预防社区获得性病毒性肺炎的发生提供参考。方法选择2023年3月—2023年5月在乌鲁木齐米东区人民医院诊治的90例社区获得性病毒性肺炎患儿作为本次课题研究的对象,采集所有患儿的鼻咽拭子,采用多病原核酸检测技术检测病原体状况。结果在90例患儿中,检出流感病毒A型阳性6例、流感病毒B型22例、副流感病毒1型2例、副流感病毒2型1例、鼻病毒25例、呼吸道合胞病毒15例、腺病毒10例、人类偏肺病毒3例、博卡病毒6例。检出混合感染9例,占比10.0%,其中2种病毒混合感染7例,3种病毒混合感染2例。不同性别人群的多病原核酸检测分布情况对比,差异无统计学意义(P>0.05);<1岁人群的鼻病毒、流感病毒B型检出率显著高于其他年龄段人群(P<0.05);冬季人群的流感病毒B型检出率显著高于其他季节,其他病毒在不同季节与年龄人群的分布情况对比,差异无统计学意义(P>0.05)。结论乌鲁木齐米东区社区获得性病毒性肺炎患儿的病原体以鼻病毒、流感病毒B型、呼吸道合胞病毒、腺病毒为主,可表现为混合感染,年龄、季节与鼻病毒、流感病毒B型感染的发生密切相关。

Glacier mass balance and its impacts on streamflow in a typical inland river basin in the Tianshan Mountains, northwestern China

Glaciers are known as natural ’’solid reservoirs’ ’, and they play a dual role between the composition of water resources and the river runoff regulation in arid and semi-arid areas of China. In this study, we used in situ observation data from Urumqi Glacier No. 1, Xinjiang Uygur Autonomous Region, in combination with meteorological data from stations and a digital elevation model, to develop a distributed degree-day model for glaciers in the Urumqi River Basin to simulate glacier mass balance processes and quantify their effect on streamflow during 1980–2020. The results indicate that the mass loss and the equilibrium line altitude(ELA) of glaciers in the last 41 years had an increasing trend, with the average mass balance and ELA being-0.85(±0.32) m w.e./a(meter water-equivalent per year) and 4188 m a.s.l., respectively. The glacier mass loss has increased significantly during 1999–2020, mostly due to the increase in temperature and the extension of ablation season. During 1980–2011, the average annual glacier meltwater runoff in the Urumqi River Basin was 0.48×108 m3, accounting for 18.56% of the total streamflow. We found that the annual streamflow in different catchments in the Urumqi River Basin had a strong response to the changes in glacier mass balance, especially from July to August, and the glacier meltwater runoff increased significantly. In summary, it is quite possible that the results of this research can provide a reference for the study of glacier water resources in glacier-recharged basins in arid and semi-arid areas.

天山乌鲁木齐河源1号冰川表层雪微生物多样性分析

为探究天山乌鲁木齐河源1号冰川(简称“乌源1号冰川”)积雪微生物群落特征及其与气候环境的关系,采集该区域2021年春季(4月)海拔3549 m处(TSX1)以及夏季(6月)海拔3770 m处(TSX2)和海拔3800 m处(TSX3)表层雪样,针对细菌16S rDNA V3-V4区、古菌16S rDNA V4-V5区和真菌ITS2区分别进行高通量测序,分析雪样中细菌、古菌和真菌的多样性。结果表明:(1)乌源1号冰川表层雪微生物多样性具有季节性差异,细菌多样性春季较高夏季较低,而真菌多样性则相反。(2)在物种组成上,细菌优势门为Proteobacteria(58.13%~89.10%)和Bacteroidetes(4.24%~40.74%),优势属为Flavobacterium(2.32%~33.64%)和Polaromonas(0.01%~24.72%);古菌优势门为Thaumarchaeota(38.10%~97.55%),其次为Nanoarchaeaeota(0%~61.90%)和Euryarchaeota(0%~2.82%);真菌优势门为Ascomycota(7.06%~88.43%)和Monoblepharidomycota(36.21%~40.78%),优势属为Aspergillus(0.16%~81.04%)和Rhodotorula(0.02%~8.05%)。(3)网络互作分析表明,微生物网络互作以正相关连接为主(97.3%),负相关连接仅占2.7%,互作关系趋于合作关系。(4)乌源1号冰川表层雪中具有丰富的微生物,微生物群落的季节变化反映了微生物对不同季节大气环流的响应。

东天山卡拉塔格地区玉带铜矿床地质特征及成因

玉带铜矿床位于东天山大南湖—头苏泉岛弧带北缘的卡拉塔格地区,为近年来发现的中型铜矿床。通过野外地质调查和室内研究,对该矿床地质特征及成因进行探讨,发现矿床含矿地质建造为一套火山岩—火山碎屑岩,成矿地质体为石英闪长玢岩,矿体产于石英闪长玢岩体及其与围岩接触带,受断裂控制,主要呈脉状和透镜状。矿石类型以浸染状和细脉状为主,矿石组构以粒状结构,浸染状和细脉状构造为主,金属矿物主要为黄铜矿和黄铁矿,脉石矿物主要为石英,其次为绿泥石和绢云母。成矿过程可划分为石英—磁铁矿、钾长石—石英—黄铁矿、石英—黄铁矿—黄铜矿—辉钼矿和石英—碳酸盐—石膏4个阶段。矿区普遍发育钾化、硅化、绿泥石化、绿帘石化、绢云母化和碳酸盐化等蚀变,具带状分布特征,水平方向上由石英闪长玢岩中心向外可划分为钾化—硅化带、硅化—绢云母化带、泥化带和绿泥石—绿帘石化—碳酸盐化带;垂向上由石英闪长玢岩中心向外可划分为钾化—硅化带、硅化—绢云母化—黄铁矿化带和绿泥石—绿帘石化—碳酸盐化带。玉带铜矿床的成矿地质条件、矿体特征及围岩蚀变特征均与大南湖—头苏泉岛弧带斑岩型矿床一致,属于斑岩型铜矿床。

基于Landsat卫星遥感的2000年~2020年天山区植被覆盖时空变化研究

植被是对应一个区域生态系统十分重要的组成部分,是评价和反映区域的气候与环境情况情况的重要指标。利用2000年~2020年三期不同时相Landsat系数据提取NDVI,基于像元二分模型估算天山区植被覆盖度。结果表明:(1)过去21年,天山区整体分析,植被覆盖面积和覆盖度均呈减小趋势,其中总植被覆盖面积降幅较明显,2020年相比2000年,总植被覆盖面积减小57.91km^(2),降幅为42.33%,其余极高、中与低覆盖面积有所减小,高覆盖面积基本稳定,裸地或极低覆盖面积增加;(2)近21年,三个时期增加区合计面积都大于减小区总和面积,主要以轻微改善区域与轻微退化区面积为主,整体上分析,天山区植被覆盖度变化不仅有阶段性差异,还存在区域性差异;(3)近21年,林地、草地、水域与未利用土地面积降幅分别为100%、14.3%、5.2%和1000%,耕地和建设用地面积增幅分别为320.6%和46.9%。

1991-2008年天山乌鲁木齐河源区多年冻土的变化

天山乌鲁木齐河源多年冻土变化的研究,对于揭示气候变暖背景下,天山多年冻土对气候变化的响应以及由多年冻土变化引起的植被土壤演化、水文变化具有重要意义.对1991以来河源区海拔3500m左右的气温、降水、地温观测数据进行综合分析,结果表明:河源区的活动层呈逐渐增厚趋势,最大活动层厚度出现在2007年,达到1.60m,较1992年增加了0.35m;多年冻土活动层的变化与河源区夏半年(5-10月)的水热状况密切相关,活动层厚度随融化指数、夏半年降水量的增加而增大.多年冻土年变化深度由1993年的10m增加到12m左右;年平均地温上升明显,由1993年的-1.6℃上升到2008年的-1.0℃.年变化层以下的温度,均有不同程度的上升,年均增温速率随深度的增加而减小,推断长期持续的气候变暖是导致乌鲁木齐河源区多年冻土升温的主要驱动力.估算2008年的多年冻土下限深度约为86.8m,较1992年减小了7.7m,河源区多年冻土很可能正在发生自下而上的迅速退化.

地球化学块体与大型矿集区的关系——以东天山为例

通过在东天山15万km2的战略性深穿透地球化学调查共圈出大于1000km2以上的地球化学块体18处,其中铜-铅-锌-银地球化学块体5处,铜地球化学块体3处,铜-镍地球化学块体1处,金的地球化学块体4处,铀的地球化学块体3处,铂-钯地球化学块体1处,钨地球化学块体1处。有6处地球化学块体与已知矿集区相对应,新圈定的地球化学块体12处,其中有3处发现了新的矿床。根据这些块体与矿集区的对比得出如下结论:所有的已知矿集区都位于地球化学块体的范围之内,地球化学块体为矿集区的形成提供了丰富的物质基础;有矿集区的存在一定有地球化学块体的存在,但反过来有地球化学块体的存在不一定有矿集区的存在,地球化学块体是客观存在的,而矿集区是已经发现了一系列矿床并勘探到一定程度才能称作矿集区,因此,地球化学块体内可能会存在潜在的矿集区,这为利用地球化学块体预测新的矿集区提供了依据。

夏干萨特树轮年表中降水信息的探讨与326年降水重建

夏干萨特位于新疆天山中段乌鲁木齐河山区 ,在此干旱、半干旱地区的森林下限所采集的天山云杉 (Picca schrenk-inna var. tianschanica)树轮样本建立的树轮宽度年表具有最大的平均敏感度和最大的标准差 ,说明该年表可能含有最多的降水信息。利用相关分析的方法计算了年轮宽度指数和气候要素间的相关关系 ,发现 5月份的降水与年表的相关最好。进一步计算了旬降水量与年表的相关关系 ,发现 5月下旬的降水与年表的单相关系数最高 ,5月下旬的降水是森林下限云杉生长的主要限制因子。这一结果具有明确的树木生理学意义。云杉直径生长主要在 5～ 8月份 ,其中 5～ 6月份形成大约一半的年轮。5月下旬位于年轮形成关键时段的中部 ,为轮宽形成的最活跃期。同时 5月下旬降水的大变率与夏干萨特年表的高敏感度相一致 ,从另一角度说明了 5月下旬降水作为森林下限天山云杉生长关键限制因子的适当性。重建了大西沟气象站 5月下旬 3 2 6a的降水并分析了其长期变化特征 ,发现 3 2 0多年来的 5月下旬降水分为 8个完整的干湿变化阶段 ,其中最干期出现在 1 70 1～ 1 72 2年 ,最湿期出现在 1 961～ 1 981年。降水序列具有显著的 64,3 2 ,2 2 ,1 4,5和 1 1 a变化周期 ,其中的 2 2 a及 1 1 a周期与太阳黑子的活动周期相一致。

天山南、北坡河流出山径流对气候变化的敏感性分析——以开都河与乌鲁木齐河出山径流为例

选取开都河与乌鲁木齐河山区流域为研究区域,利用有关水文气象台站1960～2005年的观测资料,对研究区域的气温、降水与出山径流的变化特征及趋势进行了分析,并根据研究区域气候变化的特征与趋势及出山径流与山区降水、气温之间的关系,假定不同的气候情景组合,建立山区径流对气候变化的响应模型,以揭示天山南、北坡河流出山径流对气候变化的响应及其差异。结果表明,开都河与乌鲁木齐河山区径流与气温、降水量均呈正相关关系,受山区降水、气温持续增加和上升的影响,出山径流总体呈上升趋势,1990年代以后的升幅尤为显著;相对而言,乌鲁木齐河山区径流对降水变化更为敏感,而开都河出山径流对气温变化的敏感性略甚于气温。

东天山卡拉塔格泥盆纪岩浆岩地球化学特征及成因

文中对卡拉塔格地区泥盆纪岩浆岩进行了系统的岩相学、岩石地球化学研究,探讨其成因及形成构造背景。卡拉塔格地区泥盆纪火山岩主要为安山岩,并被同期一套成分连续的侵入体,包括辉长岩、闪长岩、石英闪长岩、二长岩等侵入。其中,辉长岩为钙碱性-低钾系列准铝质岩石,具有较高的Al2O3含量(18.76%~19.06%)和Mg#(57.28~69.37),具有正Eu异常;闪长岩、石英闪长岩、二长岩和安山岩为钙碱性-高钾钙碱性系列的准铝质-弱过铝质岩石,也具有较高的Al_2O_3含量(15.02%～17.43%)和Mg#(53.67～72.91),具有较弱的Eu负异常或无Eu异常。这些岩浆岩都具有较低的初始Sr值(0.703 11～0.705 18)以及较高的ε值Nd(t)(5.36～7.72),均富集轻稀土和大离子亲石元素Rb、Ba、K等,亏损重稀土和高场强元素Ta、Nb、Ti等,都具有岛弧岩浆岩的特征。相似的岩石地球化学特征显示它们可能为同源岩浆活动的产物,可能是由俯冲洋壳形成的流体交代地幔楔岩石发生部分熔融而形成。泥盆纪岩浆岩形成于康古尔洋向卡拉麦里洋俯冲的岛弧背景。

乌鲁木齐城市活断层探测与地震危险性评价主要成果简介

以乌鲁木齐市建成区和规划区作为探测目标区,对区内的活动断层及其深部发震构造进行了系统的探测,对活动断层的危险性和危害性进行了初步评价。根据断层活动性鉴定,确定目标区内存在2组全新世活动断层,即王家沟断层组和九家湾断层组。前者为近EW向的北倾逆断层,后者为NE走向的北倾正断层。晚更新世活动断层为八钢-石化隐伏断层、西山断层、碗窑沟断层和白杨南沟断层。深部发震构造探测揭示出目标区所处的北天山山前薄皮推覆构造及其前缘逆断层-褶皱的清楚结构,结合流动地震观测和小震精确定位等,建立了目标区活动断层的发震构造模型。通过古地震探槽和地震活动性研究对目标区全新世活动断层和晚更新世活动断层的地震危险性进行了评价;并在此基础上对可能发生的直下型大地震所引起的强地震动进行了预测,对全新世活动断层可能产生的地表错动带和晚更新世活动断层可能引起的地表变形带进行了预测。

天山乌一号冰川物质平衡特征的统计分析

利用天山乌鲁木齐河源一号冰川物质平衡的多年观测资料,通过数学统计方法提取主成分,获得影响该冰川物质平衡的主要因素,通过成分矩阵的旋转获得表示冰川物质平衡特征的两个主因子,其中第一主因子为影响冰川物质平衡的常年因子,代表该冰川的多年持续变化方向与趋势,第二主因子为影响冰川物质平衡的年际因子,代表该冰川在平衡年内的物质平衡变化特征。常年因子的持续下降反映了冰川持续后退的现实,年际因子在上世纪80年代中期以后突然强劲上升,实际上是冰川物质平衡水平提高,平衡年内积累量和消融量都增加的表现,清晰地指示了西北地区气候由暖干向暖湿的转型。常年因子是冰川物质平衡变化的主导因子,控制了冰川变化的方向。常年因子具有较好的周期性,以6年周期最为明显,但其形成原因尚不明。年际因子周期性不明显,但可以看出其周期与太阳黑子变化具有相关性,同时受到常年因子的影响。