Two of the most important climate interactions between the ocean and atmosphere are the Asian monsoon in the Indian Ocean and El Niň o\|Southern Oscillation (ENSO) in the Pacific Ocean. Previous analyses have various...Two of the most important climate interactions between the ocean and atmosphere are the Asian monsoon in the Indian Ocean and El Niň o\|Southern Oscillation (ENSO) in the Pacific Ocean. Previous analyses have variously concluded either that the Asian monsoon affects the ENSO or that the converse is true. But previous research about the relation between ENSO and Asian monsoon was focused on tropic or low\|latitude ocean. There was litter research on this relation in mid\|latitude continent.Dasuopu glacier is located in middle Himalayas (85 43°E, 28 23°N) at an altitude over 7000m . In 1996 and 1997, a collaboration between China and American scientists had a series of ice core drilling performed down to the bed of Dasuopu glacier. The core analysis now is still in progress. Here a record of oxygen isotopic composition and accumulation of the ice core provides a record of relation between ENSO phenomenon and the Asian monsoon.The growth rate of the core averages over 1m per year, which provides a high resolution to date layer. There is a strong seasonal cycle in δ 18 O, thus we used the seasonal δ 18 O cycle to count annual layers in the core. According to previous studying, we assigned the high δ 18 O extremes to winter. The complete δ 18 O time series indicates a increasing trend since 1980.The δ 18 O in the core correlate strongly with observed sea surface temperature (SST) over the last decade years. Thus, the δ 18 O in the ice core at the location of south Tibetan Plateau is a relatively simple proxy for SST, which is very different from that at the location of north Plateau where δ 18 O proxy for local temperature. Furthermore, the δ 18 O in the core is also corresponds with an index of monsoon strength, which demonstrates that the ice core successfully captures the large\|scale aspects of Asian monsoon behavior.Generally, negative δ 18 O anomalies in the core correspond with weak monsoons, warm SST and El Niň o, on the other hand, positive anomalies correlate with strong monsoons, cool SST and La Niň o. These imply interaction between the tropics and mid\|latitudes, channeled through the monsoon system.展开更多
In 1996,two shallow ice cores were drilled at 7100m ASL. on the Dasuopu Glacier in the Xixiabangma in the middle Himalayas.Analytical results i ndicated that Cl\+- and Na\++ concentrations showed seasonal variations,a...In 1996,two shallow ice cores were drilled at 7100m ASL. on the Dasuopu Glacier in the Xixiabangma in the middle Himalayas.Analytical results i ndicated that Cl\+- and Na\++ concentrations showed seasonal variations,and there was a very good relation between them,which reflects that the moisture at the drilling site mainly came from oceans.An interesting phenomenon was that the changes in the ratio of Cl\+- to Na\++ in these cores might be associated with Indian summer monsoon rainfall in recent years (Fig.1).展开更多
A close correlation between δ 18O in the shallow ice core in Dasuopu Glacier of the Tibetan Plateau and large scale SST is found. The marked correlated regions are mainly distributed in the ocean currents of the Ocea...A close correlation between δ 18O in the shallow ice core in Dasuopu Glacier of the Tibetan Plateau and large scale SST is found. The marked correlated regions are mainly distributed in the ocean currents of the Oceans. The SST in different sea regions influences the precipitation and vapor origin of Dasuopu Glacier by way of its actions on atmospheric circulation. When the circulation situation favoring the transportation of oceanic vapor towards the glaciers of the southern Plateau appears, the δ18O in precipitation decreases, when that infavoring the transportation of oceanic vapor but favoring the transportation of the inland vapor towards the glaciers appears. the δ 18O in precipitation increases. Among various SST and circulation factors influencing δi8O in the ice core, the mean SST anomalies in the region A5 of the Northern Pacific Current and the position of the north boundary of Subtropical high over the South China Ocean have the important impact on the δ 18O in Dasuopu Glacier during midwinter,the mean SST anomalies in the region B of the Northern Pacific Current, the center position of the arctic vortex over the Northern Hemisphere and the strength of the arctic vortex over the Pacific have the important impact on the δ 18O in the Dasuopu Glacier during midsummer. The variations of these factors restrict the magnitude of δ 18O in the ice core, and their influence all have the omen.展开更多
The time series of accumulation in recent 300 years correlated well with solar activity in Dasuopu ice core. Results of spectrum analysis on the accumulation time series of the Dasuopu ice core shows that there are so...The time series of accumulation in recent 300 years correlated well with solar activity in Dasuopu ice core. Results of spectrum analysis on the accumulation time series of the Dasuopu ice core shows that there are some periods that coincide with the periods of solar activity. By comparing the long-time change trend of the accumulation in the Dasuopu ice core with various kinds of indexes of solar activity intensity, a negative correlation is found between the trend and solar activity.展开更多
Three ice cores distributed across Dasuopu glacier in Himalayas were recovered. A 400-year net annual accumulation record reconstructed from one of the cores reflects the major precipitation trend in the central Himal...Three ice cores distributed across Dasuopu glacier in Himalayas were recovered. A 400-year net annual accumulation record reconstructed from one of the cores reflects the major precipitation trend in the central Himalayas. This record is related closely to the Indian monsoon precipitation. Wavelet and moving T-test were applied to the 400-year-long Dasuopu accumulation record, and significant staggered variability and abrupt change of the record on interannual to centennial time scales are identified. Finally the possible reason for abrupt change of the accumulation record is discussed.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
The concentrations of CH4 in the atmosphere over the past 2000 years have been deduced by extracting and analyzing the air in bubbles embedded in the Dasuopu ice core, Qing-hai-Tibetan Plateau. Upon analyzing 57 ice c...The concentrations of CH4 in the atmosphere over the past 2000 years have been deduced by extracting and analyzing the air in bubbles embedded in the Dasuopu ice core, Qing-hai-Tibetan Plateau. Upon analyzing 57 ice core samples we found that the concentration of CH4 200 years ago and earlier was 0.85 μ mol· mol-1 or about 40% of present atmospheric CH4 levels over Qinghai-Tibetan Plateau. A rapid and significant increase of atmospheric CH4 started about 200–250 a ago. For a given age before 19th century, the Dasuopu CH4 concentrations were about 15%-20% higher than those in Antarctic and Greenland references. It was also found that the Dasuopu CH4 concentrations changed more frequently, and its fluctuations could reflect the temperature change sensitively.展开更多
To better understand ultra-high-altitude climate characteristics and their changes, an automatic weather station was installed on August 4, 2005 on the Mt. Xixiabangma Dasuopu glacier (28°23.04′N, 85°43.72...To better understand ultra-high-altitude climate characteristics and their changes, an automatic weather station was installed on August 4, 2005 on the Mt. Xixiabangma Dasuopu glacier (28°23.04′N, 85°43.72′E, 6900 m a.s.l.) in the middle of the Himalayas. Mountain weather conditions were observed continuously and automatically. This paper is the first to publish meteorological data for a whole year for a high-elevation region, and analyze wind direction, wind speed, air temperature, air pressure and humidity. Analysis of the observation data reveals that this region was strongly influenced by the westerly jet from October 10, 2005 to April 21, 2006 and by the Indian monsoon from May to September. The seasonal transitions of the westerly jet were characterized by changes in meteorological elements. In winter, influenced by the westerly jet, the wind speed in the study region was very high and fluctuated violently, gale days were frequent, temperature and air pressure fluctuated dramatically, the diurnal range of temperature decreased and the diurnal range of air pressure increased, relative humidity and specific humidity declined sharply, and air was dry. In summer, influenced by the Indian monsoon, the relative humidity and specific humidity were high. In addition, we analyzed reanalysis data for the location of the automatic weather station. The results confirmed that this region was strongly affected by the westerly jet from October 10, 2005 to April 21, 2006 and the observations that the seasonal transitions of the westerly jet were characterized by changes in meteorological elements.展开更多
A high-resolution 2ooo-year methane record has been constructed from an ice core recovered at 7200 m a.s.1, on the Dasuopu Glacier in the central Himalayas. This sub-tropical methane record reveals an increasing trend...A high-resolution 2ooo-year methane record has been constructed from an ice core recovered at 7200 m a.s.1, on the Dasuopu Glacier in the central Himalayas. This sub-tropical methane record reveals an increasing trend in the concentration of methane during the industrial era that is similar to observations from polar regions. However, we also observed the differences in the atmospheric methane mixing ratio between this monsoon record and those from polar regions during pre-industrial times. In the time interval o N 1850 A.D., the average methane concentration in the Dasuopu ice core was 782±40 ppbv and the maximum temporal variation exceeded 200 ppbv. The difference gradient of methane concentration in Dasuopu ice core with Greenland and Antarctica cores are 66±40 ppbv and 107±40 ppbv, respectively. This suggests that the tropical latitudes might have acted as a major global methane source in preindustrial times. In addition, the temporal fluctuation of the pre-industrial methane records suggests that monsoon evolution incorporated with high methane emission from south Asia might be responsible for the relatively high methane concentration observed in the Dasuopu ice core around A.D. 800 and A.D. 1600. These results provide a rough understanding of the contribution of tropical methane source to the global methane budget and also the relationship betweenatmospheric methane and climate change.展开更多
Ice formation was studied on the Dasuopu Glacier located in the Mount Xixabangma (28°23’ N, 85°43’E) in the Himalayas. Snow pits and shallow ice cores are analyzed to reveal ice formation process. The resu...Ice formation was studied on the Dasuopu Glacier located in the Mount Xixabangma (28°23’ N, 85°43’E) in the Himalayas. Snow pits and shallow ice cores are analyzed to reveal ice formation process. The results show that the ice formation process, or in other words, the process of densitification, on the col (7 000 m a.s.l. ) of the Dasuopu Glacier is a stable, slow and gradual process. The snow-ice transformation on the glacier is estimated to be 30—40 m below the surface. The temperature on the Dasuopu Glacier is very low (～ - 14℃ at 10 m) and similar to that in polar type ice cap. We,therefore, speculate that the process of snow-ice transformation is undertaken under snow pressure,and that there is a percolation zone on the Dasuopu Glacier. The high altitude of the col and monsoon snow fall accompnied by heavy cloud and high albedo favorite the percolation zone formation.展开更多
文摘Two of the most important climate interactions between the ocean and atmosphere are the Asian monsoon in the Indian Ocean and El Niň o\|Southern Oscillation (ENSO) in the Pacific Ocean. Previous analyses have variously concluded either that the Asian monsoon affects the ENSO or that the converse is true. But previous research about the relation between ENSO and Asian monsoon was focused on tropic or low\|latitude ocean. There was litter research on this relation in mid\|latitude continent.Dasuopu glacier is located in middle Himalayas (85 43°E, 28 23°N) at an altitude over 7000m . In 1996 and 1997, a collaboration between China and American scientists had a series of ice core drilling performed down to the bed of Dasuopu glacier. The core analysis now is still in progress. Here a record of oxygen isotopic composition and accumulation of the ice core provides a record of relation between ENSO phenomenon and the Asian monsoon.The growth rate of the core averages over 1m per year, which provides a high resolution to date layer. There is a strong seasonal cycle in δ 18 O, thus we used the seasonal δ 18 O cycle to count annual layers in the core. According to previous studying, we assigned the high δ 18 O extremes to winter. The complete δ 18 O time series indicates a increasing trend since 1980.The δ 18 O in the core correlate strongly with observed sea surface temperature (SST) over the last decade years. Thus, the δ 18 O in the ice core at the location of south Tibetan Plateau is a relatively simple proxy for SST, which is very different from that at the location of north Plateau where δ 18 O proxy for local temperature. Furthermore, the δ 18 O in the core is also corresponds with an index of monsoon strength, which demonstrates that the ice core successfully captures the large\|scale aspects of Asian monsoon behavior.Generally, negative δ 18 O anomalies in the core correspond with weak monsoons, warm SST and El Niň o, on the other hand, positive anomalies correlate with strong monsoons, cool SST and La Niň o. These imply interaction between the tropics and mid\|latitudes, channeled through the monsoon system.
文摘In 1996,two shallow ice cores were drilled at 7100m ASL. on the Dasuopu Glacier in the Xixiabangma in the middle Himalayas.Analytical results i ndicated that Cl\+- and Na\++ concentrations showed seasonal variations,and there was a very good relation between them,which reflects that the moisture at the drilling site mainly came from oceans.An interesting phenomenon was that the changes in the ratio of Cl\+- to Na\++ in these cores might be associated with Indian summer monsoon rainfall in recent years (Fig.1).
文摘A close correlation between δ 18O in the shallow ice core in Dasuopu Glacier of the Tibetan Plateau and large scale SST is found. The marked correlated regions are mainly distributed in the ocean currents of the Oceans. The SST in different sea regions influences the precipitation and vapor origin of Dasuopu Glacier by way of its actions on atmospheric circulation. When the circulation situation favoring the transportation of oceanic vapor towards the glaciers of the southern Plateau appears, the δ18O in precipitation decreases, when that infavoring the transportation of oceanic vapor but favoring the transportation of the inland vapor towards the glaciers appears. the δ 18O in precipitation increases. Among various SST and circulation factors influencing δi8O in the ice core, the mean SST anomalies in the region A5 of the Northern Pacific Current and the position of the north boundary of Subtropical high over the South China Ocean have the important impact on the δ 18O in Dasuopu Glacier during midwinter,the mean SST anomalies in the region B of the Northern Pacific Current, the center position of the arctic vortex over the Northern Hemisphere and the strength of the arctic vortex over the Pacific have the important impact on the δ 18O in the Dasuopu Glacier during midsummer. The variations of these factors restrict the magnitude of δ 18O in the ice core, and their influence all have the omen.
文摘The time series of accumulation in recent 300 years correlated well with solar activity in Dasuopu ice core. Results of spectrum analysis on the accumulation time series of the Dasuopu ice core shows that there are some periods that coincide with the periods of solar activity. By comparing the long-time change trend of the accumulation in the Dasuopu ice core with various kinds of indexes of solar activity intensity, a negative correlation is found between the trend and solar activity.
基金This work was supported by Ministry of Science and Technology of China (Grant No. G1998040807) Chinese Academy of Sciences (Grant No. KZCX2-301)+1 种基金the National Natural Science Foundation of China (Grant Nos. 40101006 and 40171020) Innovation Fund of C
文摘Three ice cores distributed across Dasuopu glacier in Himalayas were recovered. A 400-year net annual accumulation record reconstructed from one of the cores reflects the major precipitation trend in the central Himalayas. This record is related closely to the Indian monsoon precipitation. Wavelet and moving T-test were applied to the 400-year-long Dasuopu accumulation record, and significant staggered variability and abrupt change of the record on interannual to centennial time scales are identified. Finally the possible reason for abrupt change of the accumulation record is discussed.
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the National Natural Science Foundation of China (Grant No.49671021), the National Key Project for Basic Research (Grant No. KZ951-A1-204), CAS Project for Tibetan Research Project (Grant No. KZ95-T-06) and Innovation Project of Cold and Arid Regions E
文摘The concentrations of CH4 in the atmosphere over the past 2000 years have been deduced by extracting and analyzing the air in bubbles embedded in the Dasuopu ice core, Qing-hai-Tibetan Plateau. Upon analyzing 57 ice core samples we found that the concentration of CH4 200 years ago and earlier was 0.85 μ mol· mol-1 or about 40% of present atmospheric CH4 levels over Qinghai-Tibetan Plateau. A rapid and significant increase of atmospheric CH4 started about 200–250 a ago. For a given age before 19th century, the Dasuopu CH4 concentrations were about 15%-20% higher than those in Antarctic and Greenland references. It was also found that the Dasuopu CH4 concentrations changed more frequently, and its fluctuations could reflect the temperature change sensitively.
基金supported by the National Natural Science Foundation of China (40830638)Projects of International Cooperation (40810019001)+1 种基金the Third Pole Environment Program (GJHZ0906)the CAS/SAFEA International Partnership Program for Creative Research Teams
文摘To better understand ultra-high-altitude climate characteristics and their changes, an automatic weather station was installed on August 4, 2005 on the Mt. Xixiabangma Dasuopu glacier (28°23.04′N, 85°43.72′E, 6900 m a.s.l.) in the middle of the Himalayas. Mountain weather conditions were observed continuously and automatically. This paper is the first to publish meteorological data for a whole year for a high-elevation region, and analyze wind direction, wind speed, air temperature, air pressure and humidity. Analysis of the observation data reveals that this region was strongly influenced by the westerly jet from October 10, 2005 to April 21, 2006 and by the Indian monsoon from May to September. The seasonal transitions of the westerly jet were characterized by changes in meteorological elements. In winter, influenced by the westerly jet, the wind speed in the study region was very high and fluctuated violently, gale days were frequent, temperature and air pressure fluctuated dramatically, the diurnal range of temperature decreased and the diurnal range of air pressure increased, relative humidity and specific humidity declined sharply, and air was dry. In summer, influenced by the Indian monsoon, the relative humidity and specific humidity were high. In addition, we analyzed reanalysis data for the location of the automatic weather station. The results confirmed that this region was strongly affected by the westerly jet from October 10, 2005 to April 21, 2006 and the observations that the seasonal transitions of the westerly jet were characterized by changes in meteorological elements.
基金supported by the National Natural Science Foundation of China (40671044)the Ministry of Science and Technology of China (2005CB422004)
文摘A high-resolution 2ooo-year methane record has been constructed from an ice core recovered at 7200 m a.s.1, on the Dasuopu Glacier in the central Himalayas. This sub-tropical methane record reveals an increasing trend in the concentration of methane during the industrial era that is similar to observations from polar regions. However, we also observed the differences in the atmospheric methane mixing ratio between this monsoon record and those from polar regions during pre-industrial times. In the time interval o N 1850 A.D., the average methane concentration in the Dasuopu ice core was 782±40 ppbv and the maximum temporal variation exceeded 200 ppbv. The difference gradient of methane concentration in Dasuopu ice core with Greenland and Antarctica cores are 66±40 ppbv and 107±40 ppbv, respectively. This suggests that the tropical latitudes might have acted as a major global methane source in preindustrial times. In addition, the temporal fluctuation of the pre-industrial methane records suggests that monsoon evolution incorporated with high methane emission from south Asia might be responsible for the relatively high methane concentration observed in the Dasuopu ice core around A.D. 800 and A.D. 1600. These results provide a rough understanding of the contribution of tropical methane source to the global methane budget and also the relationship betweenatmospheric methane and climate change.
文摘Ice formation was studied on the Dasuopu Glacier located in the Mount Xixabangma (28°23’ N, 85°43’E) in the Himalayas. Snow pits and shallow ice cores are analyzed to reveal ice formation process. The results show that the ice formation process, or in other words, the process of densitification, on the col (7 000 m a.s.l. ) of the Dasuopu Glacier is a stable, slow and gradual process. The snow-ice transformation on the glacier is estimated to be 30—40 m below the surface. The temperature on the Dasuopu Glacier is very low (～ - 14℃ at 10 m) and similar to that in polar type ice cap. We,therefore, speculate that the process of snow-ice transformation is undertaken under snow pressure,and that there is a percolation zone on the Dasuopu Glacier. The high altitude of the col and monsoon snow fall accompnied by heavy cloud and high albedo favorite the percolation zone formation.
