Seasonal δ 18O variation in water on the southeast Tibetan Plateau has been studied, showing the consistent variation pattern of δ 18O with altitude indicative of relevant atmospheric circulation processes. Study sh...Seasonal δ 18O variation in water on the southeast Tibetan Plateau has been studied, showing the consistent variation pattern of δ 18O with altitude indicative of relevant atmospheric circulation processes. Study shows a similar variation pattern of fixed-site river water δ 18O with that of the precipitation δ 18O in southeast Tibet. δ 18O in regional rivers in southeast Tibet demonstrates a gradual depletion with increasing altitude, though the rates vary seasonally. The most depleted river 18O occurs during the monsoon period, with the lowest δ 18O/altitude lapse rate. The river 18O during the westerly period is also depleted, together with low δ 18O/altitude lapse rate. The pre-monsoon rivers witness the most enriched 18O with least significant correlation coefficient with the linear regression, whilst the postmonsoon rivers witness the largest δ 18O/altitude lapse rate. Different coherence of seasonal δ 18O variation with the altitude effect is attributed to different moisture supplies. Though sampling numbers vary with seasons, the δ 18O-H linear correlation coefficients all reach the 0.05 confidence level, thus witnessing the variation features of δ 18O in seasonal river water due to the influence of atmospheric general circulation and land surface processes revealed from the altitudinal lapse rates.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
The altitude effect of δ18O is essential for the study of the paleo-elevation reconstruction and possible to be solved through modern process studies. This study presents new δ18O results from southeast Tibetan Plat...The altitude effect of δ18O is essential for the study of the paleo-elevation reconstruction and possible to be solved through modern process studies. This study presents new δ18O results from southeast Tibetan Plateau along two transects, the Zayu transect and the Lhasa-Nyang transect, with δ18O data from June to September representative of monsoon period and δ18O data during the rest of the year of non-monsoon period. Altitude effect outweighs the longitude and latitude effects in determining regional δ18O variation spatially. Relevant δ18O data from previous studies in the nearby region have also been combined to comprehensively understand the influence of different moisture sources on δ18O from local scale to regional scale. The δ18O in surface water in the southeast Tibetan Plateau and its nearby regions influenced by the Indian summer monsoon shows that single dominant moisture source or simple moisture sources lead to smaller altitudinal lapse rate, whilst growing contributions from local convection to precipitation enlarge δ18O-altitude rate. It thereupon reveals the significance of the Indian summer monsoon to the altitude effect of δ18O in surface water, and the complicated effect of local convection or westerlies evolution to the variation of altitudinal lapse rate. Paleo-monsoon evolution therefore should be considered when altitude effect is applied to paleo-elevation reconstruction for the Tibetan Plateau.展开更多
基金Supported by the National Natural Science Foundation of China (Grant Nos. 40571039, 40701037 and 40830638) and group program of Chinese Academy of Sciences
文摘Seasonal δ 18O variation in water on the southeast Tibetan Plateau has been studied, showing the consistent variation pattern of δ 18O with altitude indicative of relevant atmospheric circulation processes. Study shows a similar variation pattern of fixed-site river water δ 18O with that of the precipitation δ 18O in southeast Tibet. δ 18O in regional rivers in southeast Tibet demonstrates a gradual depletion with increasing altitude, though the rates vary seasonally. The most depleted river 18O occurs during the monsoon period, with the lowest δ 18O/altitude lapse rate. The river 18O during the westerly period is also depleted, together with low δ 18O/altitude lapse rate. The pre-monsoon rivers witness the most enriched 18O with least significant correlation coefficient with the linear regression, whilst the postmonsoon rivers witness the largest δ 18O/altitude lapse rate. Different coherence of seasonal δ 18O variation with the altitude effect is attributed to different moisture supplies. Though sampling numbers vary with seasons, the δ 18O-H linear correlation coefficients all reach the 0.05 confidence level, thus witnessing the variation features of δ 18O in seasonal river water due to the influence of atmospheric general circulation and land surface processes revealed from the altitudinal lapse rates.
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supported by Knowledge Innovation Program of the Chinese Academy of Sciences (Grant Nos. KZCX2-YW-Q09-06 andKZCX2-YW-T11)National Natural Science Foundation of China(Grant Nos. 40830638 and 41101021)
文摘The altitude effect of δ18O is essential for the study of the paleo-elevation reconstruction and possible to be solved through modern process studies. This study presents new δ18O results from southeast Tibetan Plateau along two transects, the Zayu transect and the Lhasa-Nyang transect, with δ18O data from June to September representative of monsoon period and δ18O data during the rest of the year of non-monsoon period. Altitude effect outweighs the longitude and latitude effects in determining regional δ18O variation spatially. Relevant δ18O data from previous studies in the nearby region have also been combined to comprehensively understand the influence of different moisture sources on δ18O from local scale to regional scale. The δ18O in surface water in the southeast Tibetan Plateau and its nearby regions influenced by the Indian summer monsoon shows that single dominant moisture source or simple moisture sources lead to smaller altitudinal lapse rate, whilst growing contributions from local convection to precipitation enlarge δ18O-altitude rate. It thereupon reveals the significance of the Indian summer monsoon to the altitude effect of δ18O in surface water, and the complicated effect of local convection or westerlies evolution to the variation of altitudinal lapse rate. Paleo-monsoon evolution therefore should be considered when altitude effect is applied to paleo-elevation reconstruction for the Tibetan Plateau.
