Under Rayleigh equilibrium condition, stable isotopic ratio in residual water increases with the decrease of the residual water proportion f exponentially, and the fractionation rate of stable isotopes is inversely pr...Under Rayleigh equilibrium condition, stable isotopic ratio in residual water increases with the decrease of the residual water proportion f exponentially, and the fractionation rate of stable isotopes is inversely proportional to temperature. However, under kinetic evaporation condition, the fi＇actionation of stable isotopes is not only related to the phase temperature but also influenced by the atmospheric humidity and the mass exchange between liquid and vapor phases. The ratio 6 in residual water will not change with f after undergoing evaporation of a long time for great relative humidity. The rate that the evaporating water body reaches isotopic steady state is mainly dependent on the relative humidity in atmosphere. The analysis shows that the actual mean linear variety rates, about -30.0, of the δ^18O in residual water versus the residual water proportion at Nagqu and Amdo stations are consistent with the simulated process under temperature of 20℃ and relative humidity of 50%. The distillation line simulated under Rayleigh equilibrium condition is analogous to the global meteoric water line （MWL） as the temperature is about 20℃. Under non-equilibrium condition, the slope and constant values of distillation line are directly proportional to temperature and relative humidity. According to the basic data, the simulated distillation line is very consistent with the actual distillation line of Qinghai Lake.展开更多
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, Yangcu...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.展开更多
A 6-m ice core was recovered in 2004 from the Naimona＇Nyi Glacier, the middle Himalayas. Empirical orthogonal function （EOF） analysis on the major ion reveals that EOF1 represents the variations of majority of ions...A 6-m ice core was recovered in 2004 from the Naimona＇Nyi Glacier, the middle Himalayas. Empirical orthogonal function （EOF） analysis on the major ion reveals that EOF1 represents the variations of majority of ions which may be originated from crustal aerosols. Comparing the calcium concentrations from the Naimona＇Nyi with these from Dasuopu, East Rongbuk and Guliya ice cores, it is observed that calcium, a good indicator of the input of crustal aerosol in snow, concentrates mostly in the Guliya ice core located on the northern Tibetan Plateau, and gradually decreases from west to east in the Himalayas.展开更多
This paper calculated and evaluated the area and ice volume changes of Kangwure Glacier in Mt.Xixiabangma,middle of Himalayas in the past 3 decades,based on the field survey of glacier boundary position by differentia...This paper calculated and evaluated the area and ice volume changes of Kangwure Glacier in Mt.Xixiabangma,middle of Himalayas in the past 3 decades,based on the field survey of glacier boundary position by differential GPS and glacier depth by Ground Penetrating Radar(GPR),together with the topographic map and remote sense data.The studied data showed that the Kangwure Glacier has experienced significant mass deficit since the 1970s,with 34.2%of area loss,48.2%ofice volume loss and 7.5 m of average thickness decrease.This result revealed that the ice volume loss of Himalayan glaciers was more serious than expected.Analysis of meteorological data from two weather stations in the region of Mt.Xixiabangma,shows that the air temperature of this region has risen from the middle of the 20th century to the beginning of the 21st century.Significant retreat of Himalayas glacier driven by climatic warming will have a remarkable impact on hydrology and ecosystem.展开更多
Based on summer observations of stable isotope of precipitation at Muztagata,western China,during 2002―2003,this paper presents the relationship betweenδ18O in precipitation and air temperature,and discusses the eff...Based on summer observations of stable isotope of precipitation at Muztagata,western China,during 2002―2003,this paper presents the relationship betweenδ18O in precipitation and air temperature,and discusses the effect of moisture transport onδ18O in precipitation.Results show that air temperature correlates positively withδ18O in precipitation,and the temperature effect controls theδ18O of precipitation in this area.The Muztagata region exhibits highδ18O values in summer precipi-tation,similar to those shown at stations in adjacent regions.According to the results of our model set up to trace the moisture trajectories,the westerlies and local moisture circulation contribute to varia-tions of oxygen isotopes in precipitation.In addition,the impacts of the moisture transport distance,the moisture transport level,and the incursion of the polar air mass also influence the variations ofδ18O in precipitation.The moisture origins and transport mechanisms also contribute to the variation ofδ18O in precipitation at Muztagata.展开更多
The lapse rate of water isotopes is used in the study of the hydrologic cycle as well as in the estimation of uplift of the Tibetan Plateau.The greater elevation contrast in the Southern Himalayas allows for a detaile...The lapse rate of water isotopes is used in the study of the hydrologic cycle as well as in the estimation of uplift of the Tibetan Plateau.The greater elevation contrast in the Southern Himalayas allows for a detailed discussion about this lapse rate.We analyze variations of 18δO in precipitation and river water between 1320 m and 6700 m elevations in the Southern Himalayas,and calculate the specific lapse rate of water 18δO.The results show that the multi-year average lapse rate in precipitation over this region is 0.15‰/100 m.The one-year average lapse rate is 0.17‰/100 m from three sites along the Southern Himalayas.The two results agree,but are much lower than the global average of 0.28‰/100 m.This work also shows that there is a difference in precipitation 18δO lapse rate between the monsoon and non-monsoon seasons.The calculated precipitation lapse rate is much lower than that in surface water.展开更多
A Muztagata ice core recovered at 7010 m altitude in East Pamirs provides a Pb concentration record from 1955 to 2000. The result reveals in- creasing Pb concentrations from 1955 to 1993, with two Pb concentration pea...A Muztagata ice core recovered at 7010 m altitude in East Pamirs provides a Pb concentration record from 1955 to 2000. The result reveals in- creasing Pb concentrations from 1955 to 1993, with two Pb concentration peaks in 1980 and 1993. After 1993, Pb concentrations in ice core show an obvi- ously declining trend. Analysis shows that the lead in the Muztagata ice core mainly came from anthropo- genic emissions from countries in Central Asia, while the local emission had little contribution.展开更多
Given the potential use of stable isotope in the paleoclimate reconstruction from lacustrine records as well as in the local hydrology cycle, it is crucial to understand the processes of stable isotope evolution in ca...Given the potential use of stable isotope in the paleoclimate reconstruction from lacustrine records as well as in the local hydrology cycle, it is crucial to understand the processes of stable isotope evolution in catchment in the Tibetan Plateau region. Here we present a detailed study on the water oxygen isotope based on 2 years observation including precipitation, river water and lake water in the Yamzho Lake, south of the Tibetan Plateau. Temporal variation of local precipitation δ18O shows an apparent "monsoon cycle". In monsoon season, δ18O in waters is lower. In non-monsoon season, δ18O in precipitation and lake water is higher and higher river δ18O exists in spring, probably reflecting the effect of land surface evaporation, together with the higher δ18O values in spring precipitation. It is also found that the surface lake water δ18O varies seasonally and annually. The lower lake water δ18O in the late summer is apparently related to the summer monsoon precipitation. The mean δ18O value of lake water in 2007 is 1.2‰ higher than that in 2004, probably due to the less monsoon precipitation in summer of 2007, as can be confirmed from the precipitation data at the Langkazi meteorological data. It is also found that an obvious shift of vertical lake water δ18O reflects the fast mixture of lake water. δ18O values of lake water are over 10‰ higher than those of precipitation and river water in this region due to the evaporation fractionation. The modeled results show that the evaporation process of the lake water is sensitive to relative humidity, and the present lake water δ18O reflects a relative humidity of 51% in the Yamzho Lake. It shows that the lake will take 30.5 years to reach present lake water δ18O given a large shift in the input water δ18O. The modeled results also reveal that surface lake water temperature and inflow δ18O have slight effect on the isotopic balance process of lake water in the Yamzho Lake.展开更多
Precipitation δ 18O at Yushu, eastern Tibetan Plateau, shows strong fluctuation and lack of clear seasonality. The seasonal pattern of precipitation stable isotope at Yushu is apparently different from either that of...Precipitation δ 18O at Yushu, eastern Tibetan Plateau, shows strong fluctuation and lack of clear seasonality. The seasonal pattern of precipitation stable isotope at Yushu is apparently different from either that of the southwest monsoon region to the south or that of the inland region to the north. This different seasonal pattern probably reflects the shift of different moisture sources. In this paper, we present the spatial comparison of the seasonal patterns of precipitation δ 18O, and calculate the moisture transport flux by using the NCAR/NCEP reanalysis data. This allows us to discuss the relation between moisture transport flux and precipitation δ 18O. This study shows that both the southwest monsoon from south and inland air mass transport from north affected the seasonal precipitation δ 18O at Yushu, eastern Tibetan Plateau. Southwest monsoon brings the main part of the moisture, but southwest transport flux is weaker than in the southern part of the Tibetan Plateau. However, contribution of the inland moisture from north or local evaporation moisture is enhanced. The combined effect is the strong fluctuation of summer precipitation δ 18O at Yushu and comparatively poor seasonality.展开更多
Expeditions to Muztagata(in the eastern Pamirs)during the summer seasons of2002 and 2003 collected precipitation samples and measured their oxygen isotopes.Theδ^(18)O inprecipitation displays a wide range,varying fro...Expeditions to Muztagata(in the eastern Pamirs)during the summer seasons of2002 and 2003 collected precipitation samples and measured their oxygen isotopes.Theδ^(18)O inprecipitation displays a wide range,varying from-17.40per thousand to+1.33per thousand inJune—September 2002 and from-22.31per thousand to+4.59per thousand in May—August 2003.Theδ^(18)O in precipitation correlates with the initial temperature of precipitation during theobserving periods.The positive correlation betweenδ^(18)O and temperature suggests thatδ^(18)Ocan be used as an indicator of temperature in this region.Theδ^(18)O values in fresh-snow samplescollected from two snow events at different elevations on the Muztagata Glacier show a strong''altitude effect'',with a ratio of nearly-0.40per thousand per 100 m from 5500 m to 7450 m.展开更多
The local meteoric water line (MWL) has been established from north to south of the Tibetan Plateau based on the measured results of δD and δ18O in precipitation and river water, and the relationship between MWL and...The local meteoric water line (MWL) has been established from north to south of the Tibetan Plateau based on the measured results of δD and δ18O in precipitation and river water, and the relationship between MWL and moisture origins discussed. The spatial and seasonal variations ofd in precipitation and river water on the Tibetan Plateau have been studied. Results show that the spatial and seasonal variations ofd between north and south of the Tanggula Mountains are related to different moisture origins and water recycling.展开更多
High resolutionδ^(18)O and methane records over the last 2ka have been reconstructed from Dasuopu ice core recovered from the Himalayas.Analysis shows that theδ^(18)O record correlates well with the Northern Hemisph...High resolutionδ^(18)O and methane records over the last 2ka have been reconstructed from Dasuopu ice core recovered from the Himalayas.Analysis shows that theδ^(18)O record correlates well with the Northern Hemispheric temperature,Dunde ice core record,and with temperature record in eastern China.The warming trend detected inδ^(18)O record from the last century is similar to that during the Medieval warm period.There is a dramatic increasing in methane concentration in the Dasuopu ice core,which reached 1031 nmol?mol-1 in 1997.Moreover,methane concentration in the Dasuopu ice core is about 15%-20%higher than that in Antarctica and Greenland.There is a positive correlation between methane concentration andδ^(18)O in Dasuopu ice core.展开更多
Atmospheric water vapor samples were col-lected in the Nagqu River Basin in the middle of Tibetan Plateau between August and October in 2004. Results show that there exist some fluctuations of the δ 18O of atmospheri...Atmospheric water vapor samples were col-lected in the Nagqu River Basin in the middle of Tibetan Plateau between August and October in 2004. Results show that there exist some fluctuations of the δ 18O of atmospheric water vapor, especially before and after the monsoon’s end. Moreover, the variety trend of the δ 18O of atmospheric water vapor inverse correlates with that of dew point. Precipitation events make an important effect upon the variation of δ 18O of atmospheric water vapor. During the whole sampling pe-riod, the δ 18O values of atmospheric water vapor are low while precipitation events occurred. The moisture origins also contribute to the variation of δ 18O of atmospheric water vapor. The oceanic moisture transported by the southwest monsoon results in lower δ18O of atmospheric water vapor in the Nagqu River Basin. Compared with the influence of the oceanic moisture, the δ 18O values, however, appear high re-sulting from the effect of the continental air mass in this re-gion.展开更多
Oxygen stable isotope of atmospheric water vapor is widely used to study the modern process of cli-mate.Atmospheric water vapor samples were collected at Dlingha,northeast of Tibetan Plateau during the period from Jul...Oxygen stable isotope of atmospheric water vapor is widely used to study the modern process of cli-mate.Atmospheric water vapor samples were collected at Dlingha,northeast of Tibetan Plateau during the period from July 2005 to February 2006.The variation ofδ18O and the relationships betweenδ18O and both the temperature and specific humidity are analyzed in this paper.Results show that the sea-sonal variation ofδ18O of atmospheric water vapor at Delingha is remarkable with higherδ18O in summer and lowerδ18O in winter.The temporal variation of vaporδ18O shows obvious fluctuations,with magnitude of over 37‰.The daily variation of theδ18O is highly correlated with air temperature.The relationship betweenδ18O and atmospheric water vapor content is complex.Study shows thatδ18O of atmospheric water vapor is positively correlated with specific humidity in winter in seasonal scale and inversely correlated with specific humidity in summer rainy period.Theδ18O values of at-mospheric water vapor are lower than those of precipitation at Delingha,and the average difference is 10.7‰.Variations ofδ18O of atmospheric water vapor is also found to be affected by precipitation events,The model results show that the precipitation effect could have caused the vaporδ18O in the raining season to lower by 7%in average in July and August.展开更多
A 16.8 m firn core of middle Himalayas was recovered on the col of Dasuopu glacier in August 2006,being 7000 m above sea level.A total of 317 samples were measured for stable oxygen isotope ratios(δ18O)and major ion ...A 16.8 m firn core of middle Himalayas was recovered on the col of Dasuopu glacier in August 2006,being 7000 m above sea level.A total of 317 samples were measured for stable oxygen isotope ratios(δ18O)and major ion concentrations(Na+,NH4+,K+,Mg2+,Ca2+,Cl?,SO42?,and NO3?).The firn core dating and seasonal partitioning were carried out based on the marked seasonal variations along the stable oxygen isotopes and crustal species(Ca2+,Mg2+)profiles.The multi-parameters and high-resolution glaciochemical data set of Dasuopu firn core recorded the detailed chemical characteristics of pre-cipitation in high-elevation region,middle Himalayas,since 1991 A.D.,which mainly originated from the crustal and anthropogenic sources,while the sea-salt contribution was minor.The seasonal variability of major ion concentrations was dominated by the seasonal alternation of the prevalent air mass,at-mospheric circulation situation and precipitation regime.Linear regression analysis indicated that most of the variance in annual ionic fluxes can be explained by a linear dependence on snow accumu-lation rate.展开更多
基金N ational N atural Science Foundation of China, N o.40271025 the N ational H igh Technology Research andD evelopm ent Program of China (863 Program ), N o.2002A A 135360+1 种基金 the Program of Education D epartm ent ofH unan Province,N o.03C210the CA S Tianshan G laciologicalStation Foundation,N o.TZ2000-02
文摘Under Rayleigh equilibrium condition, stable isotopic ratio in residual water increases with the decrease of the residual water proportion f exponentially, and the fractionation rate of stable isotopes is inversely proportional to temperature. However, under kinetic evaporation condition, the fi＇actionation of stable isotopes is not only related to the phase temperature but also influenced by the atmospheric humidity and the mass exchange between liquid and vapor phases. The ratio 6 in residual water will not change with f after undergoing evaporation of a long time for great relative humidity. The rate that the evaporating water body reaches isotopic steady state is mainly dependent on the relative humidity in atmosphere. The analysis shows that the actual mean linear variety rates, about -30.0, of the δ^18O in residual water versus the residual water proportion at Nagqu and Amdo stations are consistent with the simulated process under temperature of 20℃ and relative humidity of 50%. The distillation line simulated under Rayleigh equilibrium condition is analogous to the global meteoric water line （MWL） as the temperature is about 20℃. Under non-equilibrium condition, the slope and constant values of distillation line are directly proportional to temperature and relative humidity. According to the basic data, the simulated distillation line is very consistent with the actual distillation line of Qinghai Lake.
基金National Natural Science Foundation of China, No.40121101 No.40671043+2 种基金 No.40571039 National Basic Research Program of China, No.2005CB422002 Knowledge Innovation Program of the Chinese Academy of Sciences, No.KZCX3- SW-339
文摘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.
基金National Natural Science Foundation of China, No.40121101 Knowledge Innovation Project of Chinese Academy of Sciences, No.KZCX3-SW-339
文摘A 6-m ice core was recovered in 2004 from the Naimona＇Nyi Glacier, the middle Himalayas. Empirical orthogonal function （EOF） analysis on the major ion reveals that EOF1 represents the variations of majority of ions which may be originated from crustal aerosols. Comparing the calcium concentrations from the Naimona＇Nyi with these from Dasuopu, East Rongbuk and Guliya ice cores, it is observed that calcium, a good indicator of the input of crustal aerosol in snow, concentrates mostly in the Guliya ice core located on the northern Tibetan Plateau, and gradually decreases from west to east in the Himalayas.
基金supported by the National Basic Research Program of China(2005CB422004 and 2009CB723901)the Knowledge Innovation Program of the Chinese Academy of Sciences(ZCX2-YW-146)the National Natural Science Foundation of China-Projects of International Cooperation(40810019001)and the National Natural Science Foundation of China(40771048)
文摘This paper calculated and evaluated the area and ice volume changes of Kangwure Glacier in Mt.Xixiabangma,middle of Himalayas in the past 3 decades,based on the field survey of glacier boundary position by differential GPS and glacier depth by Ground Penetrating Radar(GPR),together with the topographic map and remote sense data.The studied data showed that the Kangwure Glacier has experienced significant mass deficit since the 1970s,with 34.2%of area loss,48.2%ofice volume loss and 7.5 m of average thickness decrease.This result revealed that the ice volume loss of Himalayan glaciers was more serious than expected.Analysis of meteorological data from two weather stations in the region of Mt.Xixiabangma,shows that the air temperature of this region has risen from the middle of the 20th century to the beginning of the 21st century.Significant retreat of Himalayas glacier driven by climatic warming will have a remarkable impact on hydrology and ecosystem.
基金supported by the National Natural Science Foundation of China(Grant No.40121101,40571039)the Chinese Academy of Sciences(Grant No.KZCX3-SW-339)+1 种基金the Ministry of Science and Technology of the People's Republic of China(Grant No.2005CB422004)the National Natural Science Foundation of China(Grant No.40271025).
文摘Based on summer observations of stable isotope of precipitation at Muztagata,western China,during 2002―2003,this paper presents the relationship betweenδ18O in precipitation and air temperature,and discusses the effect of moisture transport onδ18O in precipitation.Results show that air temperature correlates positively withδ18O in precipitation,and the temperature effect controls theδ18O of precipitation in this area.The Muztagata region exhibits highδ18O values in summer precipi-tation,similar to those shown at stations in adjacent regions.According to the results of our model set up to trace the moisture trajectories,the westerlies and local moisture circulation contribute to varia-tions of oxygen isotopes in precipitation.In addition,the impacts of the moisture transport distance,the moisture transport level,and the incursion of the polar air mass also influence the variations ofδ18O in precipitation.The moisture origins and transport mechanisms also contribute to the variation ofδ18O in precipitation at Muztagata.
基金supported by the National Basic Research Program of China (2010CB951702)the National Natural Science Foundation of China (41025002)the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-Q09-03 and KZCX2-YW-GJ05)
文摘The lapse rate of water isotopes is used in the study of the hydrologic cycle as well as in the estimation of uplift of the Tibetan Plateau.The greater elevation contrast in the Southern Himalayas allows for a detailed discussion about this lapse rate.We analyze variations of 18δO in precipitation and river water between 1320 m and 6700 m elevations in the Southern Himalayas,and calculate the specific lapse rate of water 18δO.The results show that the multi-year average lapse rate in precipitation over this region is 0.15‰/100 m.The one-year average lapse rate is 0.17‰/100 m from three sites along the Southern Himalayas.The two results agree,but are much lower than the global average of 0.28‰/100 m.This work also shows that there is a difference in precipitation 18δO lapse rate between the monsoon and non-monsoon seasons.The calculated precipitation lapse rate is much lower than that in surface water.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 40121101, 90102005）the Chinese Academy of Sciences （Grant No. KZCX3-SW-339）National Basic Research Program of China （Grant No. 2005CB422004）.
文摘A Muztagata ice core recovered at 7010 m altitude in East Pamirs provides a Pb concentration record from 1955 to 2000. The result reveals in- creasing Pb concentrations from 1955 to 1993, with two Pb concentration peaks in 1980 and 1993. After 1993, Pb concentrations in ice core show an obvi- ously declining trend. Analysis shows that the lead in the Muztagata ice core mainly came from anthropo- genic emissions from countries in Central Asia, while the local emission had little contribution.
基金Supported by the National Basic Research Program of China (Grant No. 2005CB422004)National Natural Science Foundation of China (Grant Nos. 40830638 and 40771048)
文摘Given the potential use of stable isotope in the paleoclimate reconstruction from lacustrine records as well as in the local hydrology cycle, it is crucial to understand the processes of stable isotope evolution in catchment in the Tibetan Plateau region. Here we present a detailed study on the water oxygen isotope based on 2 years observation including precipitation, river water and lake water in the Yamzho Lake, south of the Tibetan Plateau. Temporal variation of local precipitation δ18O shows an apparent "monsoon cycle". In monsoon season, δ18O in waters is lower. In non-monsoon season, δ18O in precipitation and lake water is higher and higher river δ18O exists in spring, probably reflecting the effect of land surface evaporation, together with the higher δ18O values in spring precipitation. It is also found that the surface lake water δ18O varies seasonally and annually. The lower lake water δ18O in the late summer is apparently related to the summer monsoon precipitation. The mean δ18O value of lake water in 2007 is 1.2‰ higher than that in 2004, probably due to the less monsoon precipitation in summer of 2007, as can be confirmed from the precipitation data at the Langkazi meteorological data. It is also found that an obvious shift of vertical lake water δ18O reflects the fast mixture of lake water. δ18O values of lake water are over 10‰ higher than those of precipitation and river water in this region due to the evaporation fractionation. The modeled results show that the evaporation process of the lake water is sensitive to relative humidity, and the present lake water δ18O reflects a relative humidity of 51% in the Yamzho Lake. It shows that the lake will take 30.5 years to reach present lake water δ18O given a large shift in the input water δ18O. The modeled results also reveal that surface lake water temperature and inflow δ18O have slight effect on the isotopic balance process of lake water in the Yamzho Lake.
基金the National Basic Research Program of China (Grant No.2005CB422002)National Natural Science Foundation of China (Grand Nos.40671043,40571039 and 40121101)
文摘Precipitation δ 18O at Yushu, eastern Tibetan Plateau, shows strong fluctuation and lack of clear seasonality. The seasonal pattern of precipitation stable isotope at Yushu is apparently different from either that of the southwest monsoon region to the south or that of the inland region to the north. This different seasonal pattern probably reflects the shift of different moisture sources. In this paper, we present the spatial comparison of the seasonal patterns of precipitation δ 18O, and calculate the moisture transport flux by using the NCAR/NCEP reanalysis data. This allows us to discuss the relation between moisture transport flux and precipitation δ 18O. This study shows that both the southwest monsoon from south and inland air mass transport from north affected the seasonal precipitation δ 18O at Yushu, eastern Tibetan Plateau. Southwest monsoon brings the main part of the moisture, but southwest transport flux is weaker than in the southern part of the Tibetan Plateau. However, contribution of the inland moisture from north or local evaporation moisture is enhanced. The combined effect is the strong fluctuation of summer precipitation δ 18O at Yushu and comparatively poor seasonality.
基金supported by the National Natural Science Foundation of China(Grant Nos.40121101 and 40571039)the Chinese Academy of Sciences(Grant No.KZCX3-SW-339)the Ministry of Science and Technology of the People's Republic of China(Grant No.2005CB422004).
文摘Expeditions to Muztagata(in the eastern Pamirs)during the summer seasons of2002 and 2003 collected precipitation samples and measured their oxygen isotopes.Theδ^(18)O inprecipitation displays a wide range,varying from-17.40per thousand to+1.33per thousand inJune—September 2002 and from-22.31per thousand to+4.59per thousand in May—August 2003.Theδ^(18)O in precipitation correlates with the initial temperature of precipitation during theobserving periods.The positive correlation betweenδ^(18)O and temperature suggests thatδ^(18)Ocan be used as an indicator of temperature in this region.Theδ^(18)O values in fresh-snow samplescollected from two snow events at different elevations on the Muztagata Glacier show a strong''altitude effect'',with a ratio of nearly-0.40per thousand per 100 m from 5500 m to 7450 m.
基金Acknowledgements This work was supported by the National Nature Science Foundation of China (Grant No.49671021)
文摘The local meteoric water line (MWL) has been established from north to south of the Tibetan Plateau based on the measured results of δD and δ18O in precipitation and river water, and the relationship between MWL and moisture origins discussed. The spatial and seasonal variations ofd in precipitation and river water on the Tibetan Plateau have been studied. Results show that the spatial and seasonal variations ofd between north and south of the Tanggula Mountains are related to different moisture origins and water recycling.
基金This work was supported by Ministry of Science and Technology of China(Grant No.G1998040811)Pre-Launching Project of 973+1 种基金Chinese Academy of Sciences(Grant No.KZCX2-301)Innovation Group Fund of the National Natural Science Fundation of China.
文摘High resolutionδ^(18)O and methane records over the last 2ka have been reconstructed from Dasuopu ice core recovered from the Himalayas.Analysis shows that theδ^(18)O record correlates well with the Northern Hemispheric temperature,Dunde ice core record,and with temperature record in eastern China.The warming trend detected inδ^(18)O record from the last century is similar to that during the Medieval warm period.There is a dramatic increasing in methane concentration in the Dasuopu ice core,which reached 1031 nmol?mol-1 in 1997.Moreover,methane concentration in the Dasuopu ice core is about 15%-20%higher than that in Antarctica and Greenland.There is a positive correlation between methane concentration andδ^(18)O in Dasuopu ice core.
基金This work was supported by the National Natural Science Foundation of China(Grant No.40271025)the Collective Innovation of the National Natural Science Foundation of China(Grant No.40121101)+1 种基金the Innovation Program of Chinese Academy of Sciences(Grant No.KZCX3-SW-339)Ministry of Science and Technology of China(Grant No.2001CCB711001).
文摘Atmospheric water vapor samples were col-lected in the Nagqu River Basin in the middle of Tibetan Plateau between August and October in 2004. Results show that there exist some fluctuations of the δ 18O of atmospheric water vapor, especially before and after the monsoon’s end. Moreover, the variety trend of the δ 18O of atmospheric water vapor inverse correlates with that of dew point. Precipitation events make an important effect upon the variation of δ 18O of atmospheric water vapor. During the whole sampling pe-riod, the δ 18O values of atmospheric water vapor are low while precipitation events occurred. The moisture origins also contribute to the variation of δ 18O of atmospheric water vapor. The oceanic moisture transported by the southwest monsoon results in lower δ18O of atmospheric water vapor in the Nagqu River Basin. Compared with the influence of the oceanic moisture, the δ 18O values, however, appear high re-sulting from the effect of the continental air mass in this re-gion.
基金the National Natural Science Foundation of China(Grant Nos.40671043,40571039 and 40771048)National Basic Research Program of China(Grant No.2005CB422002)
文摘Oxygen stable isotope of atmospheric water vapor is widely used to study the modern process of cli-mate.Atmospheric water vapor samples were collected at Dlingha,northeast of Tibetan Plateau during the period from July 2005 to February 2006.The variation ofδ18O and the relationships betweenδ18O and both the temperature and specific humidity are analyzed in this paper.Results show that the sea-sonal variation ofδ18O of atmospheric water vapor at Delingha is remarkable with higherδ18O in summer and lowerδ18O in winter.The temporal variation of vaporδ18O shows obvious fluctuations,with magnitude of over 37‰.The daily variation of theδ18O is highly correlated with air temperature.The relationship betweenδ18O and atmospheric water vapor content is complex.Study shows thatδ18O of atmospheric water vapor is positively correlated with specific humidity in winter in seasonal scale and inversely correlated with specific humidity in summer rainy period.Theδ18O values of at-mospheric water vapor are lower than those of precipitation at Delingha,and the average difference is 10.7‰.Variations ofδ18O of atmospheric water vapor is also found to be affected by precipitation events,The model results show that the precipitation effect could have caused the vaporδ18O in the raining season to lower by 7%in average in July and August.
基金the National Basic Research Program of China(Grant No.2005CB422004)the National Natural Science Foundation of China(Grant Nos.40571039 and 40121101)
文摘A 16.8 m firn core of middle Himalayas was recovered on the col of Dasuopu glacier in August 2006,being 7000 m above sea level.A total of 317 samples were measured for stable oxygen isotope ratios(δ18O)and major ion concentrations(Na+,NH4+,K+,Mg2+,Ca2+,Cl?,SO42?,and NO3?).The firn core dating and seasonal partitioning were carried out based on the marked seasonal variations along the stable oxygen isotopes and crustal species(Ca2+,Mg2+)profiles.The multi-parameters and high-resolution glaciochemical data set of Dasuopu firn core recorded the detailed chemical characteristics of pre-cipitation in high-elevation region,middle Himalayas,since 1991 A.D.,which mainly originated from the crustal and anthropogenic sources,while the sea-salt contribution was minor.The seasonal variability of major ion concentrations was dominated by the seasonal alternation of the prevalent air mass,at-mospheric circulation situation and precipitation regime.Linear regression analysis indicated that most of the variance in annual ionic fluxes can be explained by a linear dependence on snow accumu-lation rate.
