近600年来北极与中国气候变化的对比

A compilation of paleoclimate records from lake sediments, trees, ice cores, and historical documents provide a view of China and Arctic environmental changes in the last 600 years. Many of these changes have also been identified in sedimentary and geochemical signatures in deep-sea sediment cores from the North Atlantic Ocean, Arctic and Greenland and ice cores from the Qinghai-Tibet Plateau, confirming the linkage of environmental changes of different time scales between the Arctic and China. It is shown that the changes of precipitation, temperature and sea ice cover in Arctic were correlated with climate changes in China. This paper also developed a comparative research on the climate changes between Arctic and China both during the Little Ice Age (LIA) and the instrumental observation period. Cycles and trend of temperature variations during LIA and temperature and precipitation during the instrumental observation period are performed. We found some similarities and differences of environmental changes between Arctic and China.     

Source and environmental significance of oxalate in Laohugou Glacier No. 12, Qilian Mountains,Western China

Retrieval of oxalate from snow and ice provides information on past environmental changes. In recent years, records of organic acids in middle-and low-latitude glaciers have attracted the attention of researchers globally. In this study, we analyzed oxalates in an ice core from Laohugou Glacier No. 12 on the Qilian Mountains at an elevation of 5,040 m a.s.l. in2006. Average oxalate concentration was 18.5±2.4 ng/g over the prior 46 years. Oxalate values showed a significantly increasing trend since 1985. From 1985 to 1995, oxalate concentrations had large fluctuations, peaking in about 1987 and exhibiting a slightly decreasing trend since 1995. The result shows that the abrupt increase of oxalate concentration in the ice core since the mid-1980 s reflects atmospheric environmental pollution by human and industrial activities.     

Quantifying temporal changes in Tornionjoki river ice breakup dates and spring temperatures in Lapland since 1802

Cryophenological records （i.e. observational series of freeze and breakup dates of ice） are of great importance when assessing the environmental variations in cold regions. Here we employed the extraordinarily long observational records of river ice breakup dates and air temperatures in northern Fennoscandia to examine their interrelations since 1802. Historical observations, along with modern data, comprise the informational setting for this analysis carried out using t-test. Temperature history of April-May season was used as cli- matic counterpart for the breakup timings. Both records （temperature and breakup） showed seven sub-periods during which their local means were distinctly different relative to preced- ing and subsequent sub-periods. The starting and ending years of these sub-periods oc- curred in temporal agreement. The main findings of this study are summarized as follows： （1） the synchrony between the temperature and river ice breakup records ruled out the possibility that the changes would have occurred due to quality of the historical series （i.e. inhomoge- neity problems often linked to historical time-series）; （2） the studied records agreed to show lower spring temperatures and later river ice breakups during the 19th century, in comparison to the 20th century conditions, evidencing the prevalence of cooler spring temperatures in the study region, in agreement with the concept of the Little Ice Age （1570-1900） climate in North-West Europe; （3） the most recent sub-period demonstrate the highest spring tem- peratures with concomitantly earliest river ice breakups, showing the relative warmth of the current springtime climate in the study region in the context of the past two centuries; （4） the effects of anthropogenic changes in the river environment （e.g. construction and demolition of dams） during the 20th century should be considered for non-climatic variations in the breakup records; （5） this study emphasizes the importance of multi-centurial （i.e. historical） cryo- phenological information for highly interesting viewpoints of climate and environmental his- tory.     

Atmospheric Methane in Ice Cores

<正> The reconstruction of air trapped in ice cores provides us the most di-rect information about atmospheric CH_4 variations in the past history.Ice corerecords from the“Three Poles(Antarctica,Greenland and Tibetan Plateau)”re-veal the detailed fluctuations of atmospheric CH_4 concentration with time and areallowed to quantify the CH_4 differences among latitudes.These data are indis-pensably in the farther study of the relationship between greenhouse gases andclimatic change,and of the past changes in terrestrial CH_4 emissions.Ice coresreconstruction indicates that atmospheric CH_4 concentration has increased quicklysince industrialization,and the present day's level of atmospheric CH_4(1800 pp-by)is unprecedented during the past Glacial-Interglacial climate cycles.     

中国冰川研究进展

Glacier inventory compilation during the past 20 years and modifications of that for the Eastern Pamir and Banggong Lake indicate that there are 46,342 modern glaciers with a total area and volume of 59415 km^2 and 5601 km^3 respectively in China. These glaciers can be classified into maritime and continental (including sub-continental and extremely continental) types. Researches show that glaciers in China have been retreating since the Little Ice Age and the mass wastage was accelerated during the past 30 to 40 years. Being an important part of glaciological studies in China,ice core climatic and environmental studies on Tibetan Plateau and in the Antarctica have provided abundant, high resolution information about past climatic and environmental evolution over the Tibetan Plateau and Antarctica. Except for different parameters recorded in ice cores relating to climate and environment changes on Tibetan Plateau, records from ice cores extracted from different glaciers show that the discrepancies in climatic and environmental changes on the north and south parts of the plateau may be the consequence of different influencing effects from terrestrial and solar sources.Glaciological and meteorological phenomena imply that Lambert Glacier valley is an important boundary of climate in the east Antarctica, which is thought to be connected with cyclonic activities and Circum-polar Waves over the Antarctica.     

Analyses of structure of planetary boundary layer in ice camp over Arctic ocean

The vertical structure of Planetary boundary layer over Arctic floating ice is presented by using about 50 atmospheric profiles and relevant data sounded at an ice station over Arctic Ocean from 22 August to 3 September,2003.It shows that the height of the convective boundary layer in day is greater than that of the stability boundary layer in night.The boundary layer can be described as vertical structures of stability,instability and multipling The interaction between relative warm and wet down draft air from up level and cool air of surface layer is significant,which causes stronger wind shear,temperature and humidity inversion with typical wind shear of 10 m/s/100 m,intensity of temperature inversion of 8 ℃/100 m.While the larger pack ice is broken by such process,new ice free area in the high latitudes of arctic ocean.The interactions between air/ice/water are enhanced.The fact helps to understanding characteristics of atmospheric boundary layer and its effect in Arctic floating ice region.     

塔里木河流域径流变化趋势及其对气候变化的响应

This paper has studied the change of streamflow and the impact of climatic variability conditions on regional hydrological cycle in the headwater of the Tarim River Basin. This study investigates possible causes of observed trends in streamflow in an environment which is highly variable in terms of atmospheric conditions, and where snow and ice melt play an important role in the natural hydrological regime. The discharge trends of three head streams have a significant increase trend from 1957 to 2002 with the Mann-Kendall test. Complex time-frequency distributions in the streamflow regime are demonstrated especially by Morlet wavelet analysis over 40 years. The purpose is to ascertain the nature of climatic factors spatial and temporal distribution, involved the use of EOF （Empirical Orthogonal Function） to compare the dominant temperature, precipitation and evaporation patterns from normally climatic records over the Tarim＇s headwater basin. It shows that the first principal component was dominated since the 1990s for temperature and precipitation, which identifies the significant ascending trend of spatial and temporal pattern characteristics under the condition of the global warming. An exponential correlation is highlighted between surface air temperature and mean river discharge monthly, so the regional runoff increases by 10%-16% when surface air temperature rises by 1 ℃. Results suggest that headwater basins are the most vulnerable environments from the point of view of climate change, because their watershed properties promote runoff feeding by glacier and snow melt water and their fundamental vulnerability to temperature changes affects rainfall, snowfall, and glacier and ice melt.     

Distribution features of stable oxygen isotopes in the typical monsoon temperate-glacier region, Mountain Yulong in China

During the summers of 1999 and 2000, sampling was carried out in Mt. Yulong, for the investigation of the spatial distribution of oxygen stable isotope in the atmospheric glacial hydro system and similar results obtained in the two years have confirmed our conclusion. There is an evident negative correlation between stable isotopic composition and air temperature precipitation amount, suggesting that there exits a strong "precipitation amount effect" in this typical monsoon temperate glacier region. There are marked differences between the δ 18 O values in winter accumulated snow, glacial meltwater, summer precipitation and glacier feeding stream. Under the control of varied climatic conditions, spatial and temporal variations of above glacial hydro mediums are apparent. Isotopic depletion or fractionation and ionic changes had occurred during the phase change and transformation processes of snow ice, ice meltwater, flowing of runoff and contact with bedrock. The variation of stable isotope in a runoff can reflect not only its own flowing process but also its different feeding sources.     

Streamflow trends and hydrological response to climatic change in Tarim headwater basin

This paper has studied the change of streamflow and the impact of climatic vari-ability conditions on regional hydrological cycle in the headwater of the Tarim River Basin. This study investigates possible causes of observed trends in streamflow in an environment which is highly variable in terms of atmospheric conditions, and where snow and ice melt play an important role in the natural hydrological regime. The discharge trends of three head streams have a significant increase trend from 1957 to 2002 with the Mann–Kendall test. Complex time-frequency distributions in the streamflow regime are demonstrated especially by Morlet wavelet analysis over 40 years. The purpose is to ascertain the nature of climatic factors spatial and temporal distribution, involved the use of EOF (Empirical Orthogonal Function) to compare the dominant temperature, precipitation and evaporation patterns from normally climatic records over the Tarim’s headwater basin. It shows that the first principal component was dominated since the 1990s for temperature and precipitation, which identifies the significant ascending trend of spatial and temporal pattern characteristics under the con-dition of the global warming. An exponential correlation is highlighted between surface air temperature and mean river discharge monthly, so the regional runoff increases by 10%–16% when surface air temperature rises by 1℃. Results suggest that headwater basins are the most vulnerable environments from the point of view of climate change, because their wa-tershed properties promote runoff feeding by glacier and snow melt water and their funda-mental vulnerability to temperature changes affects rainfall, snowfall, and glacier and ice melt.     

Analysis and discussion of different methods of artificial ice-high specimen preparation

Because ice-high foundation soil is widely distributed in permafrost regions,the correct preparation of ice-high specimens is of critical interest in engineering design for foundation stability.Past research has shown that the uniaxial compression strength of ice-high frozen soils changes as the ice or total water content increases; the differences of different methods of specimen preparation are analyzed here and the advantages and disadvantages of them are presented.It is confirmed that the role of crushed ice is significantly different from that of naturally frozen ice in frozen soils,and the size and amount of crushed ice will influence the strength and deformation mechanism of frozen soils.Therefore,it is strongly recommended that when a ice-high specimen is artificially prepared,the ice should be frozen through natural means and not be replaced with crushed ice.     

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.     

Discussion on possibilities of taking ground ice in permafrost as water sources on the Qinghai-Tibet Plateau during climate warming

Large amounts of ground ice are born with permafrost on the Qinghai-Tibet Plateau.Degradation of permafrost resulted from the climate warming will inevitably lead to melting of ground ice.The water released from the melting ground ice enters hydrologic cycles at various levels,and changes regional hydrologic regimes to various degrees.Due to difficulties in monitoring the perma-frost-degradation-release-water process,direct and reliable evidence is few.The accumulative effect of releasing water,however,is remarkable in the macro-scale hydrologic process.On the basis of the monitoring results of water-levels changes in some lakes on the Qinghai-Tibet Plateau,and combined with the previous results of the hydrologic changing trends at the regional scale,the authors preliminarily discussed the possibilities of the degrading permafrost on the Qinghai-Tibet Plateau as a potential water source during climate warming.     

通过现代观测来检验湖面蒸发对中国干旱、半干旱区湖泊水位变化的影响(英文)

Qinghai Lake and Zhuye Lake, ~400 km apart, are located in the northwest margin of the Asian summer monsoon. Water of these two lakes mostly comes from the middle and eastern parts of the Qilian Mountains. Previous studies show that the Holocene climate changes of the two lakes implied from lake records are different. Whether lake evaporation plays a role in asynchronous Holocene climate changes is important to understand the lake records. In this paper, we used modern observations beside Qinghai Lake and Zhuye Lake to test the impact factors for lake evaporation. Pan evaporation near the two lakes is mainly related to relative humidity, temperature, vapor pressure and sunshine duration. But tem-perature has different impacts to lake evaporation of the two lakes, which can affect Holocene millennial-scale lake level changes. In addition, differences in relative humidity on the millen-nial-scale would be more significant, which also can contribute to asynchronous lake records.     

Variability of atmospheric freezing level height derived from radiosonde data in China during 1958–2005 and its impact to cryosphere changes

Atmospheric air temperature data from 92 stations in China’s radiosonde network were used to analyze changes in the freezing level height (FLH), glacier snow line, and ice edge from 1958–2005 (48 years) and to examine the impact of these changes on the cryosphere. In general, the FLH, glacier snow line, and ice edge exhibited latitudinal zonation, declining from south to north. Trends in the FLH, glacier snow line, and ice edge showed spatial heterogeneity during the study period, with prevailing upward trends. Temporally, the FLH, glacier snow line, and ice edge trends differed on various time scales.     

祁连山老虎沟冰芯记录的高山区大气降水变化（英文）

The net accumulation record of ice core is one of the most reliable indicators for reconstructing precipitation changes in high mountains.A 20.12 m ice core was drilled in 2006 from the accumulation zone of Laohugou Glacier No.12 in the northeastern Tibetan Plateau,China.We obtained the precipitation from the ice core net accumulation during 1960-2006,and found out the relationship between Laohugou ice core record and other data from surrounding sites of the northeastern Tibetan Plateau.Results showed that during 1960-2006,the precipitation in the high mountains showed firstly an increasing trend,while during 1980 to 2006 it showed an obvious decreasing trend.Reconstructed precipitation change in the Laohugou glacier basin was consistent with the measured data from the nearby weather stations in the lower mountain of Subei,and the correlation coefficient was 0.619(P<0.001).However,the precipitation in the high mountain was about 3 times more than that of the lower mountain.The precipitation in Laohugou Glacier No.12 of the western Qilian Mountains corresponded well to the net accumulation of Dunde ice core during the same period,tree-ring reconstructed precipitation,the measured data of multiple meteorological stations in the northeastern Tibetan Plateau,and also the changes of adjacent PDSI drought index.Precipitation changes of the Laohugou glacier basin and other sites of the northeastern Tibetan Plateau had significantly positive correlation with ENSO,which implied that the regional alpine precipitation change was very likely to be influenced by ENSO.     

The coupled characteristics of the physical process between sea ice of two poles and Tibetan land surface

In order to discuss the characteristics of sea ice change of strong signal area on Antarctic and Arctic and the correlation between the thermal state on the land surface of Tibetan Plateau and the atmosphere circulation of North Hemisphere or the climate changes in China, and to study the feedback mechanism among “three-pole” factors, the earlier stage “three-pole” strong signal characteristics by using statistic methods such as teleconnection,which affect the regional climate changes in China and East Asia. The cross-correlation feature and coupling effect between ice caps of North and South pole and water-thermal state on Tibetan Plateau surface are discussed as well. The contribution of three-pole's earlier stage factors to China's summer climate change and the influence of its dynamic structure are compared here. The formation mechanisms of global climate change and regional climate change of China are investigated from the aspect of qualitative correlation mode of global sea-land-air-ice.     

Contribution of a pathway through the Arctic Ocean to the recent reduction in the ice cover

The sea ice cover in the Arctic Ocean has been reducing and hit the low record in the summer of 2007.The anomaly was extremely large in the Pacific sector. The sea level height in the Bering Sea vs.the Greenland Sea has been analyzed and compared with the current meter data through the Bering Strait.A recent peak existed as a consequence of atmospheric circulation and is considered to contribute to inflow of the Pacific Water into the Arctic Basin.The timing of the Pacific Water inflow matched with the sea ice reduction in the Pacific sector and suggests a significant increase in heat flux.This component should be included in the model prediction for answering the question when the Arctic sea ice becomes a seasonal ice cover.     

The role of Pacific water in the dramatic retreat of arctic sea ice during summer 2007

A model study is conducted to examine the role of Pacific water in the dramatic retreat of arctic sea ice during summer 2007.The model generally agrees with the observations in showing considerable seasonal and interannual variability of the Pacific water inflow at Bering Strait in response to changes in atmospheric circulation. During summer 2007 anomalously strong southerly winds over the Pacific sector of the Arctic Ocean strengthen the ocean circulation and bring more Pacific water into the Arctic than the recent(2000-2006) average.The simulated summer(3 months) 2007 mean Pacific water inflow at Bering Strait is 1.2 Sv,which is the highest in the past three decades of the simulation and is 20%higher than the recent average.Particularly ,the Pacific water inflow in September 2007 is about 0.5 Sv or 50%above the 2000-2006 average.The strengthened warm Pacific water inflow carries an additional 1.0×10~(20) Joules of heat into the Arctic,enough to melt an additional 0.5 m of ice over the whole Chukchi Sea.In the model the extra summer oceanic heat brought in by the Pacific water mainly stays in the Chukchi and Beaufort region,contributing to the warming of surface waters in that region.The heat is in constant contact with the ice cover in the region in July through September.Thus the Pacific water plays a role in ice melting in the Chukchi and Beaufort region all summer long in 2007,likely contributing to up to 0.5 m per month additional ice melting in some area of that region .     

2000-2011年可可西里地区主要湖泊冰情时空变化（英文）

Lake ice phenology,i.e.the timing of freeze-up and break-up and the duration of the ice cover,is regarded as an important indicator of changes in regional climate.Based on the boundary data of lakes,some moderate-high resolution remote sensing datasets including MODIS and Landsat TM/ETM+ images and the meteorological data,the spatial-temporal variations of lake ice phenology in the Hoh Xil region during the period 2000–2011 were analyzed by using RS and GIS technology.And the factors affecting the lake ice phenology were also identified.Some conclusions can be drawn as follows.(1) The time of freeze-up start(FUS) and freeze-up end(FUE) of lake ice appeared in the late October–early November,mid-November – early December,respectively.The duration of lake ice freeze-up was about half a month.The time of break-up start(BUS) and break-up end(BUE) of lake ice were relatively dispersed,and appeared in the early February – early June,early May – early June,respectively.The average ice duration(ID) and the complete ice duration(CID) of lakes were 196 days and 181 days,respectively.(2) The phenology of lake ice in the Hoh Xil region changed dramatically in the last 10 years.Specifically,the FUS and FUE time of lake ice showed an increasingly delaying trend.In contrast,the BUS and BUE time of lake ice presented an advance.This led to the reduction of the ID and CID of lake.The average rates of ID and CID were –2.21 d/a and –1.91 d/a,respectively.(3) The variations of phenology and evolution of lake ice were a result of local and climatic factors.The temperature,lake area,salinity and shape of the shoreline were the main factors affecting the phenology of lake ice.However,the other factors such as the thermal capacity and the geological structure of lake should not be ignored as well.(4) The spatial process of lake ice freeze-up was contrary to its break-up process.The type of lake ice extending from one side of lakeshore to the opposite side was the most in the Hoh Xil region.     

HISTORICAL VARIATIONS IN THE ADVANCE AND RETREAT OF THE BATURA GLACIER IN THE KARAKORAM MOUNTAINS

ABSTRACT According to repeated measurements at the fixed station, geomorphological in-vestigation, documentary records and recalls of the local residents, the Batura Glacier's terminus has undergone many changes during the- Quaternary and recent time.