Assessment of Snow Cover Vulnerability over the Qinghai-Tibetan Plateau

由在 Qinghai 西藏的高原(QTP ) 上从 98 个气象学的车站使用每日的空气温度和降水数据，和每日的降雪的天气现象数据，这份报纸在温暖状况的当前的气候状况和未来气候下面在 QTP 上在降雪和积累的雪上执行在风险评估。当降雨，降雪，或积累的雪天气现象发生时，批评价值为当前的气候条件基于每日的空气温度和降水被决定。0 潣摮瑩潩敮 ? 湩畤瑳祲愠摮愠慮祬敺 ? 桴 ? 湥楶潲浮湥慴? 敢敮楦獴漠 ? 捡散敬慲楴杮琠敨瀠慨敳漭瑵漠 ? 的空气温度 ?? 木′湩 ?

Sensitivity of the Number of Snow Cover Days to Surface Air Temperature over the Qinghai-Tibetan Plateau

基于雪盖子天(NSCD ) 的数字并且一致为时期的表面空气温度数据 19512004，这研究在 Qinghai 西藏的高原(QTP ) 上在 NSCD 的敏感上执行定量分析到表面空气温度。结果证明在当前的气候下面的极端敏感和敏感比在 QTP 的中央区域在边是更高的。在那里存在在车站举起和批评温度，敏感在到达极值之间的强壮的否定关联。在举起和极端敏感之间的否定关联不象以前的一样强壮。当前，在许多车站的 climatological 温度不到达批评阶段。在这些车站的敏感将在温暖的气候的当前的背景下面变得更大，它意味着 NSCD 将对表面空气温度更敏感。引证妈， L. ， D。Qin， L。Bian，等， 2010：到在 Qinghai 西藏的高原上的表面空气温度的雪盖子天的数字的敏感。副词。Clim。变化物件， 1， doi：10.3724/SP .J.1248.2010.00076。

Changes in Mean and Extreme Temperature and Precipitation over the Arid Region of Northwestern China： Observation and Projection

This paper reports a comprehensive study on the observed and projected spatiotemporal changes in mean and extreme climate over the arid region of northwestern China, based on gridded observation data and CMIP5 simulations under the RCP4.5 and RCP8.5 scenarios. The observational results reveal an increase in annual mean temperature since 1961, largely attributable to the increase in minimum temperature. The annual mean precipitation also exhibits a significant increasing tendency. The precipitation amount in the most recent decade was greater than in any preceding decade since 1961. Seasonally,the greatest increase in temperature and precipitation appears in winter and in summer, respectively. Widespread significant changes in temperature-related extremes are consistent with warming, with decreases in cold extremes and increases in warm extremes. The warming of the coldest night is greater than that of the warmest day, and changes in cold and warm nights are more evident than for cold and warm days. Extreme precipitation and wet days exhibit an increasing trend, and the maximum number of consecutive dry days shows a tendency toward shorter duration. Multi-model ensemble mean projections indicate an overall continual increase in temperature and precipitation during the 21 st century. Decreases in cold extremes, increases in warm extremes, intensification of extreme precipitation, increases in wet days, and decreases in consecutive dry days, are expected under both emissions scenarios, with larger changes corresponding to stronger radiative forcing.

Temporal-spatial characteristics of observed key parameters of snow cover in China during 1957-2009

Using observed snow cover data from Chinese meteorological stations, this study indicated that annual mean snow depth, Snow Water Equivalent (SWE), and snow density during 1957-2009 were 0.49 cm, 0.7 mm, and 0.14 g/cm 3 over China as a whole, respectively. On average, they were all the smallest in the Qinghai-Tibetan Plateau (QTP), and were greater in northwestern China (NW). Spatially, the regions with greater annual mean snow depth and SWE were located in northeastern China including eastern Inner Mongolia (NE), northern Xinjiang municipality, and a small fraction of southwestern QTP. Annual mean snow density was below 0.14 g/cm 3 in most of China, and was higher in the QTP, NE, and NW. The trend analyses revealed that both annual mean snow depth and SWE presented increasing trends in NE, NW, the QTP, and China as a whole during 1957-2009. Although the trend in China as a whole was not significant, the amplitude of variation became increasingly greater in the second half of the 20th century. Spatially, the statistically significant (95%-level) positive trends for annual mean snow depth were located in western and northern NE, northwestern Xinjiang municipality, and northeastern QTP. The distribution of positive and negative trends for annual mean SWE were similar to that of snow depth in position, but not in range. The range with positive trends of SWE was not as large as that of snow depth, but the range with negative trends was larger.

Key Issues on Cryospheric Changes,Trends and Their Impacts

根据在世界上在中国和 cryospheric 科学的当前的地位分析 cryospheric 研究的重要性，这篇论文在中国处理关键问题和现在的 cryospheric 科学的主要内容。当前处理的关键问题是：我) 响应在水资源评价的气候变化和规模变换的冰河的不同类型的机制；ii ) 在冻结的土壤和植被之间的水和热交换当模特儿；iii ) 在象结合气候一样的 cryosphere 的物理过程的 parameterization 当模特儿。为了获得这些的完整的澄清，给问题调音，下列三个方面的工作应该被加亮，即， cryospheric 过程和回答到气候变化， cryospheric 变化的影响，和改编为 cryospheric 变化的策略。引证 Qin， D. ，和丁·伊， 2010：在 cryospheric 变化，趋势和他们的影响上给问题调音。副词。Clim。变化物件， 1， doi：10.3724/SP .J.1248.2010.00001。

From highly polluted inland city of China to"Lanzhou Blue":The air-pollution characteristics

Air quality was improved considerably and the so-called"Lanzhou Blue"appeared frequently in Lanzhou due to implementation of some strict emission-control measures in recent years.To better understand whether the concentration of each air pollutant had decreased significantly and then give some suggestions as to urban air-quality improvement in the near future,the variations of the Air Quality Index(AQI)and six criterion air pollutants(PM_(2.5),PM_(10),CO,SO_2,NO_2,and O_3)at five state-controlled monitoring sites of Lanzhou were studied from 2013 to 2016.The AQI,PM_(2.5),PM_(10),and SO_2 gradually decreased from 2013 to 2016,while CO and NO_2 concentrations had slightly increasing trends,especially in urban areas,due to the large number of motor vehicles,which had an annual growth rate of 30.87%.The variations of the air pollutants in the no-domestic-heating season were more significant than those in the domestic-heating season.The increase of ozone concentration for the domestic-heating season at a background station was the most significant among the five monitoring sites.The vehicle-exhaust and ozone pollution was increasingly severe with the rapid increase in the number of motor vehicles.The particulate-matter pollution became slight in the formerly highly polluted Lanzhou City.Some synergetic measures in urban and rural areas of Lanzhou should be taken by the local government in the near future to control fine particulate-matter(PM_(2.5))and ozone pollution.

Accumulation and geochemical evidence for the Little Ice Age episode in eastern Antarctica

Data on accumulation and concentration of chemical compounds recorded in an essentially unexplored area(Dome Argus)of the Indian Ocean sector of eastern Antarctica during the past 2,680 years(680 B.C. to 1999 A.D.) are presented. During the first 1, 700 years(680 B. C. to 1000 A. D.), the accumulation data shows a slightly decreasing trend, while chemical ions appear to be stable, representing a stable climatic condition. An intensive increasing trend of the accumulation occurred during the 12^(th) to 14^(th) century. The period from 15^(th) to 19^(th) century was characterized by a rapid reducing accumulation and concentrations of volatile compounds suffering post-depositional loss linked to sparse precipitation amount,which was temporally consistent with the Little Ice Age(LIA) episode. Comparison between observed accumulation rates with other eastern Antarctic ice cores show a consistent decreasing trend during LIA, while sea salt and dust-originated ions increased due to sea ice extent and intensified atmospheric transportation. Distribution of volcanic originated sulfate over the Antarctic continent show a significant change during the 15^(th) century, coincident with the onset of the LIA. These results are important for the assessment of Antarctic continent mass balance and associated interpretation of the Dome A deep ice core records.

Characterization of contemporary aeolian dust deposition on mountain glaciers of western China

From 2008 to 2010,a total of 15 snow pit samples were collected from 13 mountain glaciers in western China.In this study these samples are used to determine the spatial distribution of insoluble particle concentrations and dust deposition fluxes in western China.The results show that the mass concentrations of insoluble particles exhibit high spatial variation and strongly decrease(by a factor of approximately 50) from the north(Tienshan Mountains) to the south(Himalayas).However,the insoluble particles concentrations at the southeastern Tibetan Plateau(TP) sites are also high and approximately 30 times greater than those in the Himalayas.The spatial distribution of the dust flux is similar to that of the mass concentrations;however,the high dust deposition rate in the southeastern TP is very significant as a result of the extensive snow accumulation(precipitation) in this region.The average sizes of the insoluble particles at each site generally exhibit bimodal distributions with peaks at approximately 5 μm and 10 μm,which can be explained as resulting from dust emissions from regional and local sources,respectively.The enrichment factors for most of the elements measured in insoluble particles are less than 10 at all of the study sites,indicating primarily crustal sources.However,the sites located in the peripheral mountains of western China,such as the Tienshan Mountains and the Himalayas,are characterized by high levels of certain enrichment elements(e.g.,Cu,Zn,Cr,and V) indicative of sources related to the long-range transport of pollutants.

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.

Spatiotemporal variability in tree ring's δ^(13)C of Picea crassifolia in the Qilian Mountains:climatic significance and responses to rising CO_2

The carbon isotopic composition (δ13C) of tree rings was used to assess changes in intrinsic water-use efficiency (Wi) 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 Wi 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 Wi 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.

Snow water equivalent over Eurasia in the next 50 years projected by aggregated CMIP3 models

Based on remote sensing snow water equivalent(SWE) data,the simulated SWE in 20C3M experiments from 14 models attending the third phase of the Coupled Models for Inter-comparison Project(CMIP3) was first evaluated by computing the different percentage,spatial correlation coefficient,and standard deviation of biases during 1979-2000.Then,the diagnosed ten models that performed better simulation in Eurasian SWE were aggregated by arithmetic mean to project the changes of Eurasian SWE in 2002-2060.Results show that SWE will decrease significantly for Eurasia as a whole in the next 50 years.Spatially,significant decreasing trends dominate Eurasia except for significant increase in the northeastern part.Seasonally,decreasing proportion will be greatest in summer indicating that snow cover in warmer seasons is more sensitive to climate warming.However,absolute decreasing trends are not the greatest in winter,but in spring.This is caused by the greater magnitude of negative trends,but smaller positive trends in spring than in winter.The changing characteristics of increasing in eastern Eurasia and decreasing in western Eurasia and over the Qinghai-Tibetan Plateau favor the viewpoint that there will be more rainfall in North China and less in the middle and lower reaches of the Yangtze River in summer.Additionally,the decreasing rate and extent with significant decreasing trends under SRES A2 are greater than those under SRES B1,indicating that the emission of greenhouse gases(GHG) will speed up the decreasing rate of snow cover both temporally and spatially.It is crucial to control the discharge of GHG emissions for mitigating the disappearance of snow cover over Eurasia.

Recent change of the ice core accumulation rates on the Qinghai-Tibetan Plateau

Three ice cores recovered from the Himalayas (i.e. the East Rongbuk Glacier and the Far East Rongbuk Glacier at Mt. Qomolangma (Everest), and the Dasuopu Glacier at Xixiabangma) show a sharp decline in the accumulation rates since the 1950s, which is consistent with the precipitation fluctuation over India and the low northern latitude zone (5°-35癗). Correspondingly, an increasing trend is observed for the ice core accumulations from the central and northern Qinghai-Tibetan Plateau (i.e. the Xiao Dongkemadi Glacier in the central Tanggula Mountains, the Guliya Ice Cap in the western Kunlun Mountains, and the Dunde Ice Cap in the Qilian Mountains) since the 1950s, which is consistent with the precipitation fluctuation over the middle-high northern latitude zone (35°-70°N). However, the variation magnitude of the high-elevation ice core accumulations is more significant than that of precipitation at the low-eleva- tion places, suggesting its extra sensitivity of high-elevation areas to climatic change.

Global pollution shown by lead and cadmium contents in precipitation of polar regions and Qinghai-Tibetan Plateau

The analysis of the major ions, lead and cadmium has been performed for snow-pit samples collected from the Arctic, the Qinghai-Tibetan Plateau and the Antarctic Ice Sheet. These snow pits were excavated respectively from the snowpack in Canadian Northwest Territory (NWT) and the central Arctic, three glaciers on the Qinghai-Tibetan Plateau and surface snow along the route of the International Trans-Antarctic Expedition (ITAE). The source regions for the lead pollution of central Arctic have been identified by analyzing of stable lead isotopic ratios, meteorological and atmospheric chemistry studies. It shows that the central Arctic is still under intensive lead input, despite the fact that lead content in Greenland Ice Sheet displays a rapid decreasing since the 1970s due to US and some European countries’ campaigns to reduce lead-containing gasoline-additives. This is because there are multiple lead sources for the central Arctic, including the countries that have not performed gasoline-additives

Relative humidity reconstruction for northwestern China's Altay Mountains using tree-ring δ^(18)O

Relative humidity is an important factor in water and water vapor feedback cycles.In this study,we established a 222-year annual tree-ring δ^(18)O chronology for Siberian larch(Larix sibirica Ldb.)from the Altay Mountains in northwestern China.Climate response analyses revealed that the relative humidity was the primary factor limiting tree-ring δ^(18)O fractionation.Based on our analysis,tree-ring δ^(18)O can be used to reconstruct the July–August relative humidity based on both a reasonable mechanism of tree-ring δ^(18)O fractionation and a statistically significant regression model.We used this model to reconstruct variations in the July–August relative humidity,and the model explained 47.4% of the total variation in the measured relative humidity data from 1961 to 2011.The relative humidity in the study area increased from 1900 to the 1990s and decreased thereafter.Two regime-shift dry periods were detected during the study period(one from 1817 to 1830 and the other from 2004 to 2011).

The summer monsoon evolution recorded by carbon isotope of organic matter from the Yuanbao loess section during the Last Interglaciation

Based on the carbon isotope record of organic matter from the Yuanbao loess section, northwestern China, five enhanced summer monsoon events were observed at this area during the Last Interglaciation. Such events were also recorded by the paleosol layers, pollen assemblage and magnetic susceptibility. It is suggested that the enhanced summer monsoon leads to the shift of vegetation type, which results in the change of δ13C value of organic matter in the paleosol layer. It appears that the δ13C of organic matter is a good indicator for the summer monsoon variation. Among these five events, the first, second and the fifth reached their maximum smoothly, but the other two had experienced a less cold stage before reaching their peaks, which suggests that the mechanisms of such events may be different.

Insights into mercury in glacier snow and its incorporation into meltwater runoff based on observations in the southern Tibetan Plateau

The Tibetan Plateau(TP) is recognized as "Water Tower of Asia". Yet our understanding of mechanisms influencing incorporation of mercury(Hg) into freshwater in mountain glaciers on the TP remains quite limited. Extensive sampling of environmental matrices(e.g., snow/ice)were conducted on the East Rongbuk glacier on Mt. Everest and Zhadang glacier on Mt.Nyainqentanglha for Hg speciation analysis. Speciated Hg behaved quite different during snowmelt: a preferential early release of DHg(dissolved Hg) was observed at the onset of snowmelt, whereas PHg(particulate-bound Hg) and THg(total Hg) become relatively enriched in snow and released later. Small fraction of Hg in snow was lost during a snowmelt day(18.9%–34.7%) with a large proportion(58.1%–87.3%) contributed by PHg decrease, indicating that the deposited Hg is most likely retained in glacier snow/ice. Furthermore, THg were positively correlated with PHg and crustal major ions(e.g., Ca^(2+), Mg^(2+)) during snowmelt, indicating that Hg is mainly migrated with particulates. The main pathway of Hg loss during snowmelt was most probably associated with release of PHg with meltwater, which was greatly influenced by ablation intensity of snow/ice. This should be paid particular concern as Hg preserved in mountain glaciers will mostly enter aquatic ecosystem as climate warms, impacting on downstream ecosystems adversely. Obvious decrease of THg during the downstream transport from glacier was observed with a large proportion contributed by PHg decrease. The main removal mechanism of Hg was associated with sedimentation of PHg during the transport process.

Organic acids:Differences in ice core records between Glacier 1,Tianshan,China and the polar areas

Formate (HCOO-), acetate (CH3COO-), oxalate (C2O42-) and pyruvate ((CO)C2O42-) are detected in a 14.08-m-long ice core recovered in Glacier 1 at the Urumqi riverhead, Tianshan, China, which is a mid-latitude alpine glacier (43°06′N, 86°49′E). the mean concentrations for the four organic acids in recent four decades are (102.8±147.3), (392.3±390.8), (6.9(+14.8) and (4.2±8.3) ng/g, respectively, with the ratio for HCOO-/CH3COO- of 0.34± 0.43. They represent the major acid components, and originate mainly from anthropogenic emission in the nearby industrial cities. Compared with Greenland and Antarctica, Glacier 1 is much higher in carboxylic acids, which were not subjected to long distance transportation as well as complicated atmospheric reactions. The alpine glacier can be, therefore, useful to reconstructing human pollution scenario to the regional atmosphere.

Spatial and temporal variability of marine-origin matter along a transect from Zhongshan Station to Dome A,Eastern Antarctica

The spatiotemporal distribution pattern of marine-origin matter on the Antarctica ice sheet was used to study variations in the source regions, transport mechanisms and postdepositional influences. We present data on sea salt ions, sulfur components and stable isotopes from surface and snow pit samples collected along the transect route from Zhongshan Station to Dome A during the austral summer in 2012–2013. A general decreasing trend in the accumulation, sea salt ions and sulfur components occurred with increasing distance from the coast and increasing elevation. However, different sources of the marine components, transport pathways and post-depositional influences were responsible for their different spatial distribution patterns. The marine ions in the coastal snow pit varied seasonally, with higher sea salt ion concentrations in the winter and lower concentrations in the summer; the opposite pattern was found for the sulfur compounds. The sea ice area surrounding Antarctica was the main source region for the deposited sea salt and the open sea water for the sulfur compounds. No significant trends in the marine-origin components were detected during the past 3 decades. Several periods of elevated deposition of sea salt ions were associated with lower temperatures(based on δD and δ18O) or intensified wind fields. In comparison to the sea salt ions, the sulfur concentrations exhibited the opposite distribution patterns and were associated with changes in the surrounding sea ice extent.

Main pollution sources of central Arctic revealed by lead and its isotopic ratios recorded in snow

The spatial distribution and environmental significance of Pb and its stable isotope ratios in central Arctic snow are discussed. The shear zone is a dividing line. The concentration of Pb in the south section is higher than that of the north section, and in the shear zone it is close to that of sea salt. Anthropogenic Pb by calculation is larger than 99%. Its main sources are polluted air masses origi nation from Europe and the midpart of Russia, as well as the western North America and far east Russia. This is also conformed by 206Pb/ 207Pb.