δ~(18)O, δD and d-excess signatures of ground ice in permafrost in the Beiluhe Basin on the Qinghai-Tibet Plateau,China

In this paper, stable isotope(δ~(18)O, δD) investigations were completed in ground ice from a deep borehole in the Beiluhe Basin on northern Qinghai-Tibet Plateau to unravel the isotopic variations of ground ice and their possible source water. The δ~(18)O and δD of ground ice show distinctive characteristics compared with precipitation and surface water. The near-surface ground ice is highly enriched in heavier isotopes(δ~(18)O and δD), which were gradually depleted from top to bottom along the profile. It is suggestive of different origin and ice formation process. According to isotopic variations, the ice profile was divided into three sections: the near-surface ground ice at 2.5 m is frozen by the active-layer water which suffered evaporation. It is possible that ground ice between 3 and 4.2 m is recharged by the infiltration of snowmelt. From 5 to 6 m, the ground ice show complex origin and formation processes. Isotopic variations from 6 to 11.1 m and 20.55 m indicate different replenishment water. The calculated slope of freezing line(S=6.4) is larger than the experimental value(5.76), and is suggestive of complex origin and formation process of ground ice.     

Intercomparison of stable isotopes in precipitation simulated by GCMs with GNIP survey over East Asia

Using the isotope enabled ECHAM4, GISS E and HadCM3 GCMs, the spatial distribution of mean δ¹⁸O in precipitation, mean seasonality and the correlations of δ¹⁸O in precipitation with temperature and precipitation amount are analyzed. The simulated results are in agreement with stable isotopic features by GNIP observations. Over East Asia, the distribution of δ¹⁸O in precipitation is of marked latitude effect and altitude effect. The latitude effect is covered by the continent effect in some regions. The largest seasonality of δ¹⁸O in precipitation appears in eastern Siberia controlled by cold high pressure, and the smallest seasonality is in the western Pacific controlled by the subtropical high. Relatively weak seasonality appears in middle latitudes where oceanic and continental air masses frequently interact. However, three GCMs show significant systematic lower δ¹⁸O for inland mid-high latitudes than GNIP data, which is related to the used isotopic scheme in GCMs. Temperature effect occurs mainly in inland mid-high latitudes. The higher the latitude and the closer the distance to inland is, then the stronger the temperature effect. Amount effect occurs mainly in low-mid latitudes and monsoon areas, with the strongest effect in low-latitude coasts or islands. However, three GCMs provide virtually non-existent amount effect in arid regions over Central Asia. The enrichment action of stable isotopes in falling raindrops under a cloud base, which is enlarged by these modes, is responsible for such a result. A significant difference between spatial distributions of δ¹⁸O statistics by GCMs simulations and by GNIP observations is that the standard deviation of GCMs statistics is greater than that of GNIP statistics. In contrast, by comparing parallel time series at a single station, the standard deviations of GCMs simulations are smaller than that of GNIP observations.     

Amount and temperature effects responsible for ecipitation isotope variation in the southern slope of Himalayas

Seasonal variation of stable isotopes in precipitation of Kathmandu Valley on the southern slope of Himalaya was carried out to understand the controlling mechanism of amount and temperature effect on the basis of one year stable isotope data from 2010 to 2011. Highly depleted isotope values in major rainy period are obtained just after the onset of precipitation in summer, which accounts for "amount effect" due to saturation isotopic compositions in high moisture condition, whereas, the higher values in winter are indicative to regional vapors (temperature effect) recycling of various sources. An abrupt depletion of isotope values in mid- June, indicates the onset date of monsoon precipitation, by the replacement of winter air mass with southern monsoon. Thus, precipitation isotopes are a tool revealing the onset date of summer monsoon and temporal features of variability, in local and regional monsoons precipitations. A comparison of long term monthly values of δ¹⁸O, temperature, and precipitation with GNIP δ¹⁸O data shows the temporal variations of stable isotopes are mostly controlled by amount and temperature effects. During summer monsoon, the amount effects are stronger for high values of precipitation (R=0.7) and altitude effect appears for low moisture in late rainy season, thus from December to June (winter to pre-monsoon) the controlling features of isotopes remains under the temperature effect. A temporal rate of temperature effect is derived as 0.04‰ per year which indicates a dry signal of atmospheric condition and a temperature relation δ¹⁸O=(0.371±0.08)T+(0.156±0.05) is obtained from this analysis. The meteoric water lines of Kathmandu before and after monsoon onset of 2011, are found as δD=(4.36±0.3)δ¹⁸O+(15.66±1.2) and δD=(6.91±0.2)δ¹⁸O?(7.92±2.26) from lab samples result, and δD=9.2δ¹⁸O+11.725 and δD=8.53δ18O+16.65 from GNIP data, which lacks the consistency both for slopes and intercepts values for the study period. The mean lapse rate values of δ¹⁸O and δD from GNIP data are obtained as ?0.002‰/m and ?0.015 ‰/m, which indicate the altitudinal effects in regional precipitation of the southern slope of Himalayas. This study estimates new stable isotopes data in recent precipitation using simple methodology which can be important for regional precipitation monitoring systems, environmental change and paleo-climatic studies.     

Study of temperature and precipitation change in upstream mountain area of the Hexi inland river basin since 1960s

All rivers in the Hexi inland region of Gansu Province, China, originate from the northern slope of the Qilian Mountains. They are located in the southern portion of the region and respectively belong to the three large river systems from east to west, the Shiyang, Heihe and Shule river basins. These rivers are supplied by precipitation, snowmelt and ice-melt runoff from the Qilian Mountain area. Therefore, changes of precipitation and temperature in the upstream watersheds of these rivers have an important effect on changes of mountainous runoff and reasonable utilization of water resources in this region. For this reason, the Qilian Mountain area, upstream watersheds and runoff forming areas of these rivers are chosen as the study area. The change characteristics and variation trend of temperature and precipitation in this area under the backdrop of global warming are analyzed based on observational data of relational weather and hydrologic stations in the area. Results show that temperatures in the upriver mountain areas of these three large river basins have been increasing, although the increasing degree is differentially affected by global warming. The rising extent of annual and seasonal temperatures in the upstream mountain area of the Shule river basin located in the western Qilian Mountains, were all largest over the past 50 years. Precipitation in the upstream mountain areas of Hexi region’ three river basins located respectively in the western, middle and eastern Qilian Mountains have been presenting an increasing trend to varying degrees as a whole for more than 50 years. This means that climate in the upstream mountain areas of Hexi region’ three river basins are becoming increasingly warmer and moister over the past 50 years, which will be very good for the ecological environment and agricultural production in the region.     

Spatial and temporal distribution of precipitation based on corrected TRMM data around the Hexi Corridor, China

Accurate rainfall distribution is difficult to acquire based on limited meteorological stations, especially in remote areas like high mountains and deserts. The Hexi Corridor and its adjacent regions （including the Qilian Mountains and the Alxa Plateau） are typical districts where there are only 30 available rain gauges. Tropical Rainfall Measuring Mission （TRMM） data provide a possible solution. After precision analysis of monthly 0.25 degree resolution TRMM 3B43 data from 1998 to 2012, we find that the correlations between TRMM 3B43 estimates and rain gauge precipitation are significant overall and in each station around the Hexi Corridor; however, the biases of annual precipitation differ in different stations and are seriously overestimated in most of the sites. Thus, Inverse Distance Weighting （IDW） interpolation method was used to rectify TRMM data based on the difference between TRMM 3B43 estimates and rain gauge observations. The results show that rectified TRMM data present more details than rain gauges in remote areas where there are few stations, alt- hough they show high coherence of distribution. Precipitation decreases from southeast to northwest on an annual and seasonal scale. There are three rainfall centers （〉500 mm） including Menyuan, Qilian and Toson Lake, and two low rain- fall centers （〈50 mm） including Dunhuang and Ejin Banner. Meanwhile, precipitation in most of the study area presents an increasing trend; especially in northern Qilian Mountains （〉5 mm/a）, Badain Jaran Desert （〉2 mm/a）, Toson Lake （〉20 mm/a） and Qingtu Lake （〉20 ram/a） which shows a significant increasing trend, while precipitation in Hala Lake （〈-2 mm/a） and Tengger Desert （〈-3 mm/a） demonstrates a decreasing trend.     

Temporal and spatial changes of temperature and precipitation in Hexi Corridor during 1955–2011

This study is focused on the northwestern part of Gansu Province, namely the Hexi Corridor. The aim is to address the question of whether any trend in the annual and monthly series of temperature and precipitation during the period 1955-2011 appears at the scale of this region. The temperature and precipitation variation and abrupt change were examined by means of linear regression, five-year moving average, non-parameter Mann-Kendall test, accumulated variance analysis and Pettitt test method. Conclusions provide evidence of warming and wetting across the Hexi Corridor. The mean annual temperature in Hexi Corridor increased significantly in recent 57 years, and the increasing rate was 0.27℃/10a. The abrupt change phenomenon of the annual temperature was detected mainly in 1986. The seasonal average temperature in this region exhibited an evident upward trend and the uptrend rate for the standard value of winter temperature indicated the largerst of four seasons. The annual precipitation in the Hexi Corridor area displayed an obviously increasing trend and the uptrend rate was 3.95 mm/10a. However, the annual precipitation in each basin of the Hexi Corridor area did not passed the significance test. The rainy season precipitation fluctuating as same as the annual one presented insignificant uptrend. No consistent abrupt change was detected in precipitation in this study area, but the rainy season precipitation abrupt change was mainly observed in 1968.     

西北地区山区融雪期气候变化对径流量的影响(英文)

Water resources in the arid land of Northwest China mainly derive from snow and glacier melt water in mountainous areas. So the study on onset, cessation, length, tempera-ture and precipitation of snowmelt period is of great significance for allocating limited water resources reasonably and taking scientific water resources management measures. Using daily mean temperature and precipitation from 8 mountainous weather stations over the pe-riod 1960?2010 in the arid land of Northwest China, this paper analyzes climate change of snowmelt period and its spatial variations and explores the sensitivity of runoff to length, temperature and precipitation of snowmelt period. The results show that mean onset of snowmelt period has shifted 15.33 days earlier while mean ending date has moved 9.19 days later. Onset of snowmelt period in southern Tianshan Mountains moved 20.01 days earlier while that in northern Qilian Mountains moved only 10.16 days earlier. Mean precipitation and air temperature increased by 47.3 mm and 0.857℃ in the mountainous areas of Northwest China, respectively. The precipitation of snowmelt period increased the fastest, which is ob-served in southern Tianshan Mountains, up to 65 mm, and the precipitation and temperature in northern Kunlun Mountains increased the slowest, an increase of 25 mm and 0.617℃, respectively, while the temperature in northern Qilian Mountains increased the fastest, in-creasing by 1.05℃. The annual runoff is also sensitive to the variations of precipitation and temperature of snowmelt period, because variation of precipitation induces annual runoff change by 7.69% while change of snowmelt period temperature results in annual runoff change by 14.15%.     

Temperature and precipitation changes in Extensive Hexi Region,China, 1960–2011

Global climate change has been evident in many places worldwide. This study provides a better understanding of the variability and changes in frequency, intensity, and duration of temperature, precipitation, and climate extremes in the Extensive Hexi Region, based on meteorological data from 26 stations. The analysis of average, maximum, and minimum temperatures revealed that statistically significant warming occurred from 1960 to 2011. All temperature extremes displayed trends consistent with warming, with the exception of coldest-night temperature(TNn) and coldest-day temperature(TXn), which were particularly evident in high-altitude areas and at night. Amount of precipitation and number of rainy days slowly increased with no significant regional trends, mainly occurring in the Qilian Mountains and Hexi Corridor. The significance of changes in precipitation extremes during 1960–2011 was high, but the regional trends of maximum 5-day precipitation(RX5day), the average precipitation on wet days(SDII), and consecutive wet days(CWD) were not significant. The variations in the studied parameters indicate an increase in both the extremity and strength of precipitation events, particularly in higher-altitude regions. Furthermore, the contribution from very wet precipitation(R95) and extremely wet precipitation(R99) to total precipitation also increased between 1960 and 2011. The assessment of these changes in temperature and precipitation may help in developing better management practices for water resources. Future studies in the region should focus on the impact of these changes on runoffs and glaciers.     

近50年气候变化背景下中国西部冰川面积状况分析(英文)

Based on the glacier area variation records in the typical regions of China moni-tored by remote sensing, as well as the meteorological data of air temperature and precipitation from 139 stations and the 0℃ isotherm height from 28 stations, the glacier area shrinkage in China and its climatic background in the past half century was discussed. The initial glacier area calculated in this study was 23,982 km2 in the 1960s/1970s, but the present area was only 21,893 km2 in the 2000s. The area-weighted shrinking rate of glacier was 10.1%, and the interpolated annual percentage of area changes (APAC) of glacier was 0.3% a-1 since 1960. The high APAC was found at the Ili River Basin and the Junggar Interior Basin around the Tianshan Mountains, the Ob River Basin around the Altay Mountains, the Hexi Interior Basin around the Qilian Mountains, etc. The retreat of glacier was affected by the climatic background, and the influence on glacier of the slight-increased precipitation was counteracted by the significant warming in summer.     

Glacier area shrinkage in China and its climatic background during the past half century

Based on the glacier area variation records in the typical regions of China monitored by remote sensing, as well as the meteorological data of air temperature and precipitation from 139 stations and the 0℃ isotherm height from 28 stations, the glacier area shrinkage in China and its climatic background in the past half century was discussed. The initial glacier area calculated in this study was 23,982 km2 in the 1960s/1970s, but the present area was only 21,893 km2 in the 2000s. The area-weighted shrinking rate of glacier was 10.1%, and the interpolated annual percentage of area changes (APAC) of glacier was 0.3% a-1 since 1960. The high APAC was found at the Ili River Basin and the Junggar Interior Basin around the Tianshan Mountains, the Ob River Basin around the Altay Mountains, the Hexi Interior Basin around the Qilian Mountains, etc. The retreat of glacier was affected by the climatic background, and the influence on glacier of the slight-increased precipitation was counteracted by the significant warming in summer.     

Spatiotemporal variability in tree ring’s δ13C of Picea crassifolia in the Qilian Mountains: climatic significance and responses to rising CO2

The carbon isotopic composition (δ¹³C) of tree rings was used to assess changes in intrinsic water-use efficiency (W_i) to increasing atmospheric CO₂ and climate change during the period of 1891–2003. Five Qinghai spruce (Picea crassifolia) stands were selected in the Qilian Mountains, growing along a precipitation gradient. All five δ¹³C were correlated to each other, but two sites (DDS and CLS), which are far from the main body of the mountains, show relative weak connections to other sites. Although trees at all sites had improved their W_i in response to increasing atmospheric CO₂ concentration, spruce growing in the regions far away from the main body of the mountains were less sensitive to improved W_i than those of other sites. Based on the correlation between carbon isotope discrimination (Δ) and Palmer Drought Severity Index (PDSI), the drought history covering the period of 1891–2003 was reconstructed in the study region. The two most severe drought epochs of the late 1920s and the last decade were caused by reduced precipitation and climate warming, respectively. Our results will be useful in assessing any further spatial climate-related bioclimatic information.     

Elemental composition and its environmental significance for the varicolored hills in the northern foothills of the Qilian Mountains of Sunan Yugur Autonomous County, China

The varicolored hills in the northern foothills of the Qilian Mountains of northern China, in the Hexi Corridor of Gansu Province's Sunan Yugur Autonomous County, have given this region a unique geomor...     

大气水汽同位素组成的短期变异特征

Stable isotopes of atmospheric water vapor reveal rich information on water movement and phase changes in the atmosphere. Here we presented two nearly continuous time-series of δD and δ18O of atmospheric water vapor (δv) measured at hourly intervals in surface air in Beijing and above a winter wheat canopy in Shijiazhuang using in-situ meas-urement technique. During the precipitation events, the δv values in both Beijing and Shiji-azhuang were in the state of equilibrium with precipitation water, revealing the influence of precipitation processes. However, the δv departures from the equilibrium state were positively correlated with local relative humidity. Note that the δv tended to enrich in Beijing, but deplete in Shijiazhuang during the precipitation events, which mainly resulted from the influence of transpiration processes that enriched the δv in Shijiazhuang. On seasonal time-scale, the δv values were log-linear functions of water vapor mixing ratios in both Beijing and Shijiazhuang. The water vapor mixing ratio was an excellent predictor of the δv by the Rayleigh distillation mechanisms, indicating that air mass advection could also play an important role in deter-mining the δv. On a diurnal time-scale, the δv reached the minimum in the early afternoon hours in Beijing which was closely related to the atmospheric processes of boundary layer entrainment. During the peak of growing season of winter wheat, however, the δv reached the minimum in the early morning, and increased gradually through the daytime, and reached the maximum in the late afternoon, which was responsible by the interaction between boundary layer entrainment and the local atmospheric processes, such as transpiration and dew for-mation. This study has the implications for the important role of vegetation in determining the surface δv and highlights the need to conduct δv measurement on short-term (e.g. diurnal) time scales.     

Amount and temperature effects responsible for precipitation isotope variation in the southern slope of Himalayas

Seasonal variation of stable isotopes in precipitation of Kathmandu Valley on the southern slope of Himalaya was carried out to understand the controlling mechanism of amount and temperature effect on the basis of one year stable isotope data from 2010 to 2011. Highly depleted isotope values in major rainy period are obtained just after the onset of precipitation in summer, which accounts for "amount effect" due to saturation isotopic compositions in high moisture condition, whereas, the higher values in winter are indicative to regional vapors (temperature effect) recycling of various sources. An abrupt depletion of isotope values in mid-June, indicates the onset date of monsoon precipitation, by the replacement of winter air mass with southern monsoon. Thus, precipitation isotopes are a tool revealing the onset date of summer monsoon and temporal features of variability, in local and regional monsoons precipitations. A comparison of long term monthly values of δ 18 O, temperature, and precipitation with GNIP δ 18 O data shows the temporal variations of stable isotopes are mostly controlled by amount and temperature effects. During summer monsoon, the amount effects are stronger for high values of precipitation (R=0.7) and altitude effect appears for low moisture in late rainy season, thus from December to June (winter to pre-monsoon) the controlling features of isotopes remains under the temperature effect. A temporal rate of temperature effect is derived as 0.04‰ per year which indicates a dry signal of atmospheric condition and a temperature relation δ 18 O=(0.371±0.08)T+(0.156±0.05) is obtained from this analysis. The meteoric water lines of Kathmandu before and after monsoon onset of 2011, are found as δD=(4.36±0.3)δ 18 O+(15.66±1.2) and δD=(6.91±0.2)δ 18 O (7.92±2.26) from lab samples result, and δD=9.2δ 18 O+11.725 and δD=8.53δ 18 O+16.65 from GNIP data, which lacks the consistency both for slopes and intercepts values for the study period. The mean lapse rate values of δ 18 O and δD from GNIP data are obtained as 0.002‰/m and 0.015 ‰/m, which indicate the altitudinal effects in regional precipitation of the southern slope of Himalayas. This study estimates new stable isotopes data in recent precipitation using simple methodology which can be important for regional precipitation monitoring systems, environmental change and paleo-climatic studies.     

Classification of snow cover days in western China and comparison with satellite remote sensing data

The daily snow cover data from 232 meteorological stations to the west of 105°E in China for the period 1951–2004 were used to classify the snow cover and analyze decadal variations of snow cover types in western China, and comparison was made between the observational data and those retrieved from passive microwave remote sensing data (SMMR and SSM/I) in 1980–2004. The results show that stable snow-covered areas included northern Xinjiang, the Tianshan Mountains, and the eastern Tibetan Plateau with more than 60 snow cover days; no snow cover was found in the center of the southern Xinjiang Basin, the Sichuan Basin, and southern Yunnan. In addition to the above-mentioned, there were unstable snow-covered areas in western China. Furthermore, the snow cover types in northern Xinjiang, the Tianshan Mountains, the Hexi Corridor, and the vast areas from Chengdu to Kunming were unchanged. In the 1980s, the south-north dividing line between the major snow-covered area and snow-free area advanced to its most southern position. The snow cover days calculated from satellite remote sensing were generally longer than those from observational data in western China, mainly in the higher-altitude mountains, the Hexi Corridor, and the western Sichuan Plateau.     

乌鲁木齐河流域不同水体中的氧稳定同位素

The variations of the stable oxygen isotope in different water mediums in Urumqi River Basin, China, are analyzed. The stable oxygen isotope in precipitation has marked temperature effect either under synoptic or seasonal scale at the head of Urumqi River. The linear regression equations of δ^18O against temperature are δ^18O=-0.94T-12.38 and δ^18O=1.29T-13.05 under the two time scales, respectively. The relatively large δ^18O/temperature slopes show the strong sensitivity of δ^18O in precipitation to temperature variation at the head of Urumqi River. According to the analyses on the δ^18O in precipitation sampled at three stations with different altitudes along Urumqi River, altitude effect is notable in the drainage basin. The δ^18O/altitude gradients have distinct differences: the gradient from Urumqi to Yuejinqiao is merely -0.054‰/hm, but -0.192‰/hm from Yuejinqiao to Daxigou, almost increasing by 2.6 times over the former. No altitude effect is found in surface firn the east branch of Glacier No. 1 at the head of Urumqi River, showing that precipitation in the glacier is from the cloud cluster with the same condensation level. Influenced by strong ablation and evaporation, the δ^18O in surface firn increases with increasing altitude sometimes. Survey has found that the δ^18O in meltwater at the terminus of Glacier No. 1 and in stream water at Total Control have the similar change trend with the former all smaller than the latter, which displays the different runoff recharges, and all mirror the regime of temperature in the same term basicallv.     

近50年来祁连山冰川变化——基于中国第一、二次冰川编目数据（英文）

Glaciers are the most important fresh-water resources in arid and semi-arid regions of western China. According to the Second Chinese Glacier Inventory(SCGI), primarily compiled from Landsat TM/ETM+ images, the Qilian Mountains had 2684 glaciers covering an area of 1597.81±70.30 km~2 and an ice volume of ~84.48 km~3 from 2005 to 2010. While most glaciers are small(85.66% are 1.0 km~2), some larger ones(12.74% in the range 1.0–5.0 km~2) cover 42.44% of the total glacier area. The Laohugou Glacier No.12(20.42 km~2) located on the north slope of the Daxue Range is the only glacier 20 km~2 in the Qilian Mountains. Median glacier elevation was 4972.7 m and gradually increased from east to west. Glaciers in the Qilian Mountains are distributed in Gansu and Qinghai provinces, which have 1492 glaciers(760.96 km~2) and 1192 glaciers(836.85 km~2), respectively. The Shule River basin contains the most glaciers in both area and volume. However, the Heihe River, the second largest inland river in China, has the minimum average glacier area. A comparison of glaciers from the SCGI and revised glacier inventory based on topographic maps and aerial photos taken from 1956 to 1983 indicate that all glaciers have receded, which is consistent with other mountain and plateau areas in western China. In the past half-century, the area and volume of glaciers decreased by 420.81 km~2(–20.88%) and 21.63 km~3(–20.26%), respectively. Glaciers with areas 1.0 km~2 decreased the most in number and area recession. Due to glacier shrinkage, glaciers below 4000 m completely disappeared. Glacier changes in the Qilian Mountains presented a clear longitudinal zonality, i.e., the glaciers rapidly shrank in the east but slowly in the central-west. The primary cause of glacier recession was warming temperatures, which was slightly mitigated with increased precipitation.     

Climatic and environmental change in Yanchi Lake, Northwest China since the Late Glacial: A comprehensive analysis of lake sediments

Modern climate research has shown that the Asian summer monsoon water vapor transport is limited to the eastern part of the Qilian Mountains. On the Holocene millennial-scale, whether the northwest boundary of the summer monsoon varies according to climate change is a key scientific issue. Yanchi Lake is located in the northern Qilian Mountains and the middle of the Hexi Corridor, where the modern climate is less affected by the Asian summer monsoon. It is a key research area for examining the long-term variations of the Asian summer monsoon. Paleoclimatic data, including AMS ^14C dates of pollen concentrates and bulk organic carbon, lithology, grain-size, mineral composition and geochemical proxies were acquired from sediments of Yanchi Lake. The chronological results show that the lower part of the lacustrine section is formed mainly in the Late Glacial and early Holocene period, while the proxies＇ data indicate the lake expansion is associated with high content of mineral salts. The middle part of this section is formed during the transitional period of the early and middle Holocene. Affected by the reworking effect, the pollen concentrates AMS^14C dates from the middle part of the section are generally older than those from the lower part. Since the mid-Holocene, Yanchi Lake retreated significantly and the deposition rate dropped obvi- ously. The Yanchi Lake record is consistent with the Late Glacial and Holocene lake records in the Qinghai-Tibet Plateau and the climatic records in typical monsoon domain, which indicate the lake expansion and the strong Asian summer monsoon during the Late Glacial and early Holocene. The long-term monsoonal pattern is different from the lake evolution in Central Asia on the Holocene millennial-scale. This study proves the monsoon impacts on the northwestern margin of the summer monsoon, and also proves the fact that the northern boundary of the summer monsoon moves according to millennial-scale climate change.     

The impacts of climate change on hydrology in a typical glacier region—A case study in Hailuo Creek watershed of Mt. Gongga in China

The glaciers of the Hengduan Mountains play an important role in the hydrology processes of this region. In this study, the HBV Light model, which relies on a degree-day model to simulate glacier melting, was employed to simulate both glacier runoff and total runoff. The daily temperature and precipitation at the Hailuo Creek No. 1 Glacier from 1952 to 2009 were obtained from daily meteorological observed data at the glacier and from six national meteorological stations near the Hailuo Creek Basin. The daily air temperature, precipitation, runoff depth, and monthly potential evaporation in 1995, 1996, and 2002 were used to obtain a set of optimal parameters, and the annual total runoff and glacier runoff of the Hailuo Creek Glacier(1952–2009) were calculated using the HBV Light model. Results showed the average annual runoff in the Hailuo Creek Basin was 2,114 mm from 1952 to 2009, of which glacial melting accounted for about 1,078 mm. The river runoff in the Hailuo Creek catchment increased as a result of increased glacier runoff. Glacier runoff accounted for 51.1% of the Hailuo Creek stream flow in 1994 and increased to 72.6% in 2006. About 95% of the increased stream flow derived from the increased glacier runoff.     

Temporal and spatial variations of δ^18O in precipitation of the Yarlung Zangbo River Basin

This paper reveals the temporal and spatial variations of stable isotope in precipitation of the Yarlung Zangbo River Basin based on the variations of δ^18O in precipitation at four stations （Lhaze, Nugesha, Yangcun and Nuxia） in 2005. The results show that δ^18O of precipitation has distinct seasonal changes in the Yarlung Zangbo River Basin. The higher value of δ^18O occurs in spring prior to monsoon precipitation, and the lower value occurs during monsoon precipitation. From the spatial variations, with the altitude-effect and rainout process during moisture transport along the Yarlung Zangbo River Valley, δ^18O of precipitation is gradually depleted. Thus, δ^18O of precipitation decreases gradually from the downstream to the upstream, and the lapse rate of δ^18O in precipitation is approximately 0.34‰/100m and 0.7%J‰/100km for the two reasons. During monsoon precipitation, spatial variation of δ^18O in precipitation is dominated by the amount effect in the large scale synoptic condition.