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91.
Expeditions to Muztagata (in the eastern Pamirs) during the summer seasons of 2002 and 2003 collected precipitation samples and measured their oxygen isotopes. The δ18O in precipitation displays a wide range, varying from -17.40‰ to +1.33‰ in June-September 2002 and from -22.31‰ to +4.59‰ in May-August 2003. The δ18O in precipitation correlates with the initial temperature of precipitation during the observing periods. The positive correlation between δ18O and tem- perature suggests that δ18O can be used as an indicator of temperature in this region. The δ18O values in fresh-snow samples collected from two snow events at different elevations on the Muztagata Glacier show a strong "altitude effect", with a ratio of nearly -0.40‰ per 100 m from 5500 m to 7450 m. 相似文献
92.
LIU Zhongfang TIAN Lide YAO Tandong GONG Tongliang YIN Changliang YU Wusheng 《地理学报》2007,17(3):317-326
This paper reveals the temporal and spatial variations of stable isotope in precipita-tion of the Yarlung Zangbo River Basin based on the variations of δ18O in precipitation at four stations (Lhaze, Nugesha, Yangcun and Nuxia) in 2005. The results show that δ18O of pre-cipitation has distinct seasonal changes in the Yarlung Zangbo River Basin. The higher value of δ18O 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, 18O of precipitation is gradually depleted. Thus, δ18O of precipitation decreases gradually from the downstream to the upstream, and the lapse rate of δ18O in precipitation is approximately 0.34‰/100m and 0.7‰/100km for the two reasons. During monsoon precipitation, spatial variation of δ18O in precipitation is dominated by the amount effect in the large scale synoptic condition. 相似文献
93.
94.
1 Introduction The TP is a spectacular field laboratory for analyzing fundamental processes of geodynamics and environmental change as well as their interrelationships (Kutzbach et al., 1993). Being the largest and highest continental plateau with a mean … 相似文献
95.
This paper reveals the temporal and spatial variations of stable isotope in precipita-tion of the Yarlung Zangbo River Basin based on the variations of δ18O in precipitation at four stations (Lhaze,Nugesha,Yangcun and Nuxia) in 2005. The results show that δ18O of pre-cipitation has distinct seasonal changes in the Yarlung Zangbo River Basin. The higher value of δ18O 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,18O of precipitation is gradually depleted. Thus,δ18O of precipitation decreases gradually from the downstream to the upstream,and the lapse rate of δ18O in precipitation is approximately 0.34‰/100m and 0.7‰/100km for the two reasons. During monsoon precipitation,spatial variation of δ18O in precipitation is dominated by the amount effect in the large scale synoptic condition. 相似文献
96.
古里雅冰芯中钙离子含量及与气候变化关系 总被引:3,自引:0,他引:3
通过对古里雅冰帽中Ca2+含量变化的分析揭示:1)古里雅冰帽中的Ca2+主要来自它周围较近的地表矿物中的可溶性Ca(HCO3)2对同一根冰芯而言,Ca2+含量较高,反映出当时该冰川作用区较干旱,反之则较湿润;3)冰芯中的Ca2+含量,呈上升状态反映出当时的气候环境往干旱方向发展.而呈下降趋势则有两种可能:一种是气候环境较湿润;另一种是长期或重度干旱造成究竟是何种原因,可结合其它方法,如PH值、电导率、SO2-4等进行综合判断得出结论此点对于利用冰芯寻找古气候中的长期或重度干旱的年代尤为重要 相似文献
97.
希夏邦马峰冰川粒雪中环境季节变化记录研究 总被引:9,自引:0,他引:9
在希夏邦马峰达索普冰川海技7000m冰雪平台钻取14m粒雪芯一支。通过对粒雪芯中δ^18O和主要离子浓度的季节变化分析,认识希夏邦马峰地区大气环境的季节变化特征。相关分析和经验正交函数(EOF)分析结果表明,达索普粒雪芯内的δ^18O与Ca^2+、Mg^2+、SO4^2-、NO3^-和NH4^+浓度之间正相关显著,而与Na^+、Cl^-和K^+浓度之间的关系不明显。EOF1代表了以尘埃来源为主的离 相似文献
98.
Zhongfang Liu Lide Tian Tandong Yao Wusheng Yu 《Theoretical and Applied Climatology》2010,99(1-2):95-104
The stable isotopic composition of precipitation in different regions reflects climatic factors such as temperature, precipitation, moisture sources, and transport process. However, the isotopic variation in the region is usually much complicated due to the combined influences of these factors. A good understanding of climatic controls on the isotopic composition of precipitation can contribute to the study on isotopic tracer for climate and hydrology. To investigate the isotopic variation of precipitation and its climatic controls in the middle of the Tibetan Plateau, a monitoring station for stable isotope in precipitation has been established in Nagqu region, central Tibetan Plateau. We obtained 79 daily samples at Nagqu Meteorological Station in 2000. The observed δ 18O in precipitation showed a distinctly seasonal pattern with higher values in spring and winter and lower values in summer, despite of individually low values in winter due to extremely low temperature. To further understand this pattern, we evaluated the influence of temperature, precipitation, moisture sources, and moisture transport process on precipitation δ 18O. A multiple linear regression model represents quantitatively the dependence of precipitation δ 18O on precipitation and temperature: δ 18Oppt?=??0.30P???0.11T???14.8 (R 2?=?0.13, n?=?79, P?=?0.005), which indicates δ 18O values in precipitation are more dependent on precipitation amount than on temperature. In contrast, when the temperature is low enough (<2°C), δ 18O values in precipitation are mainly dependent on temperature: δ 18Oppt?=?0.53T???10.2 (R 2?=?0.44, n?=?19, P?=?0.002). The variation of δ 18O in precipitation is also closely related to moisture origins and transport trajectories. A model is set up to trace the trajectories for air masses arriving in the observed region, and the results demonstrated that humid marine air masses from the Indian Ocean generally have significantly lower δ 18O values than dry continental air masses from the north or local re-evaporation. During monsoon precipitation, the distance and depth of moisture transport as well as convective precipitation all lead to the large variability of δ 18O in precipitation. 相似文献
99.
Progress on observation of cryospheric components and climate-related studies in China 总被引:1,自引:0,他引:1
Systematic studies on the cryosphere in China started in the late 1950s. Significant achievements have been made by continuous investigation of glacier inventories, frozen ground observations, paleo-climate analyses of ice cores, process studies and the modeling of cryopsheric/atmospheric interactions. The general facts and understanding of these changes include: (1) Solid precipitation, including the number of days with frost and hail storms, shows a decreasing tendency over the past half century. (2) In most areas glaciers are retreating or have completely vanished (〉80%), some glaciers are still advancing (5%-20% depending upon time period). The annual glacial melt water has been increasing since the 1980s. This increased supply of melt water to river runoff in Northwest China is about a 10%-13%. (3) The long-term variability of snow cover in western China is characterized by a large inter-annual variation superimposed on a small increasing trend. Snow cover variability in the Qinghai-Xizang Plateau (QXP) is influenced by the Indian monsoon, and conversely impacts monsoon onset and strength and eventually the drought and flood events in middle-low reaches of Yangtze River. (4) Frozen ground, including permafrost, is decaying both in QXP and in Northeast China. The most significant changes occurred in the regions with thickest seasonal frozen ground (SFG), i.e., inland QXP, then northeastern and northwestern QXP. The cold season air temperature is the main factor controlling SFG change. The increase of ground surface temperatures is more significant than air temperature. (5) The sea ice coverage over the Bohai Sea and Yellow Sea has deceased since the 1980s. (6) River ice duration and ice thickness is also decreasing in northern China.
In 2001, the Chinese National Committee of World Climate Research Program/Climate and Cyosphere (WCRP/CliC) (CNC-CliC) was organized to strengthen research on climate and cryosphere in China. Future monitoring of the cryosphe 相似文献
In 2001, the Chinese National Committee of World Climate Research Program/Climate and Cyosphere (WCRP/CliC) (CNC-CliC) was organized to strengthen research on climate and cryosphere in China. Future monitoring of the cryosphe 相似文献
100.