共查询到19条相似文献，搜索用时 187 毫秒
1.
青藏高原中部降水稳定同位素变化与季风活动 总被引：14，自引：2，他引：14
根据1998年夏季中日GAME／Tibet项目在青藏高原中部进行的降水中稳定同位素研究结果以及相关的气象观测资料，分析了青藏高原中部夏季降水中δ^18O的变化规律。研究结果发现，青藏高原中部夏季降水中δ^18O的波动与大规模天气活动有关，而不是地方性的气象条件。该地区降水中δ^18O对水汽来源的变化以及水汽的输送过程十分敏感。夏季伴随西南季风进入高原南部的水汽形成的降水中δ^18O较低，而且季风活动越强，降水中δ^18O也越来低。从青藏高原北部而来的水汽或地方蒸发水汽形成的降水，其δ^18O值较高。 相似文献
2.
为研究伊犁谷地降水同位素特征及陆地内循环对其的影响,为流域水循环研究提供科学依据,于2016年在伊宁、尼勒克和新源气象站采集降水同位素样品。采用回归对照法,讨论降水氘氧稳定同位素的影响因素。研究表明,研究区大气降水线方程为δD=7.96δ^18O+10.37,与全球大气降水线较接近,水汽主要由西风带输送;氘氧同位素夏季富集冬季贫化而氘盈余无规律变化,由于降水过程不仅受温度效应,还受到水汽陆地再循环影响。冬夏季样品在D-^18O关系图中分布特征,证明冬夏影响降水同位素本地水循环因素不同,夏季以云下蒸发为主。根据对氘过量计算的夏季降水雨滴蒸发分数为4.1%~16.2%,再次证明夏季云下蒸发效应明显,而在冬季云下蒸发效应几乎不会发生。 相似文献
3.
重要海-气-天文事件与新德里季风降水中δ18O的关系 总被引：5，自引：2，他引：3
通过分析西南季风区印度新德里站夏季降水资料发现, 降水中δ18O变化趋势大致与太阳黑子变化趋势一致, 是温度效应的具体体现. 温度和降水的耦合导致温度和降水量的比值(T/P)与δ18O具有显著的正相关关系; ENSO与δ18O的遥相关关系是热带印度洋和太平洋海气耦合作用的结果, 是降水量效应的反映. 在500 hPa高度, 云滴的蒸发以及与下层向上层传输的季风水汽之间发生稳定同位素交换, 可能是导致500 hPa高度风的速率与δ18O正相关的主要原因, 温度效应及降水量效应对这一关系的形成起促进作用. 相似文献
4.
为了探讨连续降水过程中水汽输送的变化,应用NCEP/NCAR资料、HYSPLIT后向轨迹模拟及降水稳定同位素资料对北京22场连续降水的水汽输送差异进行了研究。结果表明:连续降水的水汽输送可分为西向水汽输送、远洋水汽输送、近海水汽输送、远源大陆水汽输送和局地大陆水汽输送5种类型,并以近海水汽输送和西向水汽输送为主（降水量占比60.8%）。不同水汽输送类型下降水δ18O的差异主要受水汽源区同位素富集程度及水汽输送途中降水过程的影响,降水氘盈余的变化反映出二次蒸发的影响及水汽源区大气相对湿度的差异。14场连续降水的水汽输送类型发生了变化,且降水δ18O值的变化能够较好地指示水汽输送类型的变化。该结果说明降水同位素特征能够为识别水汽输送类型提供有效信息。 相似文献
5.
水汽输送对雅鲁藏布江流域降水中稳定同位素的影响 总被引：1，自引：0，他引：1
利用NCEP/NCAR全球大气再分析格点资料和2005年西藏雅鲁藏布江流域4个站点（拉孜、奴各沙、羊村和奴下）降水中δ18O数据，分析了雅鲁藏布江流域降水中δ18O变化同水汽输送通量的关系。从空间上来看，雅鲁藏布江流域降水中δ18O同水汽输送通量呈明显的正相关，从下游至上游，随着水汽输送通量的减少，降水中的δ18O逐渐降低；从时间上来看，春季水汽通量较小，降水中的δ18O较高，而在夏季，水汽通量大，降水中的δ18O较低。在此基础上，又利用NCEP/NCAR气象数据建立水汽追踪模型，以羊村站为例对雅鲁藏布江流域降水的水汽输送过程进行了追踪模拟，并讨论了降水中δ18O变化同水汽源地以及输送过程的关系。结果发现，在季风降水之前的春季，降水中较高的δ18O主要受西风带水汽输送以及当地蒸发水汽的影响；在季风期间，降水中较低的δ18O主要受来自印度洋暖湿水汽输送的影响。
相似文献
6.
广州大气降水中δ^18O与气象要素及季风活动之间的关系 总被引：1，自引：0，他引：1
根据2004年5月至2005年6月广州日大气降水中δ18O资料和GNIP提供的广州、香港多年月平均降水中δ D、δ18O资料, 研究了天气尺度下广州大气降水中δ18O与降水量、水汽压、气温和露点温度等气象要素之间的关系, 并就季风活动对本地降水中δ18O的影响作了初步分析. 结果表明: 在天气尺度下, 广州大气降水中δ18O与降水量、水汽压、气温和露点温度均存在显著的负相关关系, 同温度露点差存在显著的正相关关系, 表明广州大气降水中δ18O变化具有显著的降水量效应和湿度效应. 夏季风期间季风活动对天气尺度下降水中δ18O的变化具有显著影响, 使得天气尺度下大气降水中δ18O变化有时并不遵循降水量效应. 从多年气候平均状况来看, 广州、香港降水中δ18O的季节变化同亚洲夏季风的爆发和推进演变过程较为相似, 在夏季风活跃的时期, 大气降水中δ18O值也较低, 反映了季风降水再循环活动对降水中稳定同位素含量具有显著影响. 相似文献
7.
天山乌鲁木齐河流域山区降水δ18O和δD 特征及水汽来源分析 总被引：1，自引：0，他引：1
依据乌鲁木齐河流域山区3个站点实测次降水δ18O和δD数据以及气象观测资料,结合临近GNIP(Global Network of Isotopes in Precipitation)站点数据,对其降水δ18O和δD特征及水汽来源进行了分析。结果表明,大气降水中δ18O值波动范围大,但呈现明显的季节性变化:冬季降水δ18O较低,夏季降水δ18O较高。受流域山区气候和地理条件影响,从上游到下游各站点大气降水线截距和斜率均呈现逐渐减小趋势。大气降水中δ18O和δD与日均气温存在密切正相关关系,且温度与δ18O之间的相关性优于δD。降水中d-excess值也表现出季节性变化,冬季降水d-excess值高于夏季降水。利用HYSPLIT 4.0气团轨迹模型,得出夏季水汽主要来源西风环流输送,冬季受西风环流和极地气团共同影响。 相似文献
8.
黑河上游降水同位素特征及其水汽来源分析 总被引：2，自引：0，他引：2
为了加深对黑河上游水循环过程的理解, 以研究区5个站点2015年8月至2016年8月的降水同位素实测数据和气象数据为基础, 除对降水同位素特征进行分析外, 主要利用TrajStat软件中的后向轨迹计算模块与潜在源贡献因子分析（PSCF）方法, 对研究区降水的水汽来源进行了分析, 并结合水汽通量等方法进行了补充分析。结果表明： 降水同位素呈夏高冬低趋势, 大气水线斜率（8.02）和截距（11.02）均高于全球大气水线的斜率（8.00）和截距（10.00）, 存在温度效应（δ18O=0.43x-10.82, r=0.54, P<0.0001）, 不存在降水量效应（δ18O=-0.05x-7.81, r=0.03, P<0.0001）; 研究区降水受多种水汽影响, 西风水汽影响最大。夏季除受西风水汽影响外, 还受东南季风水汽影响显著且水汽来源复杂; 研究区夏季的潜在蒸发源地集中在一些相对湿度和蒸发量较大的地区, 如祁连山区、 河西地区、 柴达木盆地北部、 青藏高原东南部及酒泉地区西南部等; 当降水量小、 温度高时, 持续性降水的大气水线方程的斜率和截距较小, 暴雨稳定同位素值较贫化, 受东南季风水汽影响最大, 其次是北方和西风水汽, 多种水汽辐合是暴雨事件发生的必要条件。 相似文献
9.
南极科考断面水汽同位素观测与模拟及其反映的水循环信息 总被引：1，自引：0，他引：1
大气水汽同位素实时监测为水循环和区域大气环流分析提供了新的定量化方法. 依托雪龙号考察船, 利用水同位素激光光谱仪(PICARRO L1102-i)完成了38° N~69° S海表大气水汽氢氧稳定同位素的观测, 结合表层海水和GNIP降水同位素分析了多相水同位素纬向特征. 结果表明: 水汽、降水和表层海水同位素比率(δ18O, δD)随纬度呈明显的递变性规律, 赤道最低, 副热带升高, 而在南极大陆外围高纬区域则急剧降低;过量氘(d-excess)变化与此相反, 反映出副热带下沉气流对同位素富集影响以及高纬度极地气团经过洋面时过饱和分馏的剧烈变化. 实测水汽同位素与LMDZ4-iso和ECHAM5-wiso模型对比表明了模拟结果较好, 根据模拟进一步分析了南极内陆Dome A水汽同位素反映的水汽源区. 结果显示, 除了中纬度印度洋海区之外, 中低纬东太平洋海域也是冰盖内陆的重要水汽源区. 相似文献
10.
了解沙漠降水稳定同位素特征,有助于研究干旱区水循环过程.根据2015-2016年取自巴丹吉林沙漠4个站点的降水样品,分析了δ2H、δ18O的时空分布特征及影响因素;借助后向气团轨迹模型分析了降水水汽来源;采用氘盈余模型计算了水汽再循环比.结果显示,降水δ2H、δ18O均表现出季节效应,夏高冬低;沙漠腹地较外围山区δ2H、δ18O偏正,d-excess偏负,反映出腹地降水的蒸发程度更高.年内降水主要来自西风水汽,夏季部分受东南季风影响.沙漠湖泊区再循环比为10.3%~10.9%,略大于山区的8.5%;再循环水汽在总蒸发量中占比11.1%,反映出沙漠强烈的蒸发对本地降水的贡献较为有限. 相似文献
11.
12.
青藏高原及其毗邻地区降水中稳定同位素成分的经向变化 总被引：8，自引：6，他引：2
分析了从南亚经青藏高原到毗邻的我国西北地区一个经向剖面上降水中稳定同位素成分的时空分布以及与温度、降水量、水汽来源的关系.在青藏高原南部和南亚,温度效应均不存在.在所统计的站点中,大约一半的取样站具有降水量效应,但降水中稳定同位素比率的季节变化并不与降水量强度的变化相一致.在季节变化中,δ18O的最大值往往出现在雨季到来之前的春季,最小值则出现在雨季后期或雨季结束的秋季.在青藏高原中、北部和毗邻的我国西北地区,各取样站均具有显著的温度效应,且降水中δ18O的季节变化与温度的季节变化几乎一致.说明在这些地区,温度是制约降水中稳定同位素变化的主要影响因子.由于来自源区水汽的直接凝结,南亚地区降水中平均稳定同位素成分相对较重.稳定同位素比率的季节差异较小;从青藏高原南坡的坚景到唐古拉山,由于翻越喜马拉雅山时水汽受强烈的洗涤作用,降水中稳定同位素比率急剧减小,达经向分布中δ18O的最低值段;从31°N到青藏高原北部,降水中稳定同位素比率随纬度而增大,并最终过渡到与我国西北地区降水中稳定同位素比率的变化型相类似. 相似文献
13.
Terrigenous plant wax inputs to the Arabian Sea: Implications for the reconstruction of winds associated with the Indian Monsoon 总被引：1，自引：0，他引：1
Kristina A. Dahl Delia W. Oppo Konrad A. Hughen Frank Sirocko 《Geochimica et cosmochimica acta》2005,69(10):2547-2558
We have determined the accumulation rates and carbon isotopic compositions (δ13C) of long-chain (C24-C32) terrigenous plant wax fatty acids in 19 surface sediment samples geographically distributed throughout the Arabian Sea in order to assess the relationship between plant wax inputs and the surrounding monsoon wind systems. Both the accumulation rate data and the δ13C data show that there are three primary eolian sources of plant waxes to the Arabian Sea: Africa, Asia, and the Arabian Peninsula. These sources correspond to the three major wind systems in this region: the summer (Southwest) monsoon, the winter (Northeast) monsoon, and the summer northwesterlies that blow over the Arabian Peninsula. In addition, plant waxes are fluvially supplied to the Gulf of Oman and the Eastern African margin by nearby rivers. Plant wax δ13C values reflect the vegetation types of the continental source regions. Greater than 75% of the waxes from Africa and Asia are derived from C4 plants. Waxes delivered by northwesterly winds reflect a greater influence (25-40%) of C3 vegetation, likely derived from the Mesopotamian region. These data agree well with previously published studies of eolian dust deposition, particularly of dolomite derived from the Arabian Peninsula and the Mesopotamian region, in surface sediments of the Arabian Sea. The west-to-east gradient of plant wax δ13C and dolomite accumulation rates are separately useful indicators of the relationship between the northwesterly winds and the winds of the Southwest monsoon. Combined, however, these two proxies could provide a powerful tool for the reconstruction of both southwest monsoon strength as well as Mesopotamian aridity. 相似文献
14.
U. R. Rao P. S. Desai P. C. Joshi P. C. Pandey B. S. Gohil B. Simon 《Journal of Earth System Science》1998,107(1):33-43
Detailed analysis of the surface winds over the Indian Ocean derived from ERS-1 scatterometer data during the years 1993 and
1994 has been used to understand and unambiguously identify the onset phase of south-west monsoon. Five day (pentad) averaged
wind vectors for the period April to June during both years have been examined to study the exact reversal of wind direction
as well as the increase in wind speed over the Arabian Sea in relation to the onset of monsoon over the Indian west coast
(Kerala). The related upper level humidity available from other satellites has also been analysed.
The results of our analysis clearly show a consistent dramatic reversal in wind direction over the western Arabian Sea three
weeks in advance of the onset of monsoon. The wind speed shows a large increase coinciding with the onset of monsoon. These
findings together show the dominant role of sea surface winds in establishing the monsoon circulation. The study confirms
that the cross equatorial current phenomenon becomes more important after the onset of monsoon. 相似文献
15.
A 30 ka paleo-climate record of the Boise area, Idaho, USA has been delineated using groundwater stable isotopic compositions. Groundwater ages are modern (cold batholith), 5-15 ka (thermal batholith) , 10-20 ka (frontal fault) , and 20-30 ka (Snake River plain thermal). The stable isotopic composition of groundwaters have been used as a surrogate for the stable isotopic composition of precipitation. Using δ2H and δ18O compositions, local groundwater lines (LGWL's) were defined for each system. Each LGWL has been evaluated with defined slopes of 6.94 and 8, respectively, and resulting deuterium excess values (d) were found for each groundwater system for each slope. Time dependent changes in moisture source humidity and temperature, and Boise area recharge temperatures, calculated from stable isotopic data and the deuterium excess factors, agree with previous paleo-climate studies. Results indicate that from the last glacial maximum to the present time the humidity over the ocean moisture source increased by 9%, sea surface temperature at the moisture source increased 6-7°C, and local Boise temperature increased by 4-5°C. A greater increase of temperature at the moisture source as compared to the Boise area may impart be due to a shift in the moisture source area. 相似文献
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17.
T. M. Balakrishnan Nair 《Journal of Earth System Science》2006,115(4):461-472
Particulate fluxes of aluminium, iron, magnesium and titanium were measured using six time-series sediment traps deployed
in the eastern, central and western Arabian Sea. Annual Al fluxes at shallow and deep trap depths were 0.47 and 0.46 g m-2 in the western Arabian Sea, and 0.33 and 0.47 g m-2 in the eastern Arabian Sea. There is a difference of about 0.9–1.8 g m-2y-1 in the lithogenic fluxes determined analytically (residue remaining after leaching out all biogenic particles) and estimated
from the Al fluxes in the western Arabian Sea. This arises due to higher fluxes of Mg (as dolomite) in the western Arabian
Sea (6–11 times higher than the eastern Arabian Sea). The estimated dolomite fluxes at the western Arabian Sea site range
from 0.9 to 1.35gm-2y-1. Fe fluxes in the Arabian Sea were less than that of the reported atmospheric fluxes without any evidence for the presence
of labile fraction/excess of Fe in the settling particles. More than 75% of Al, Fe, Ti and Mg fluxes occurred during the southwest
(SW) monsoon in the western Arabian Sea. In the eastern Arabian Sea, peak Al, Fe, Mg and Ti fluxes were recorded during both
the northeast (NE) and SW monsoons. During the SW monsoon, there exists a time lag of around one month between the increases
in lithogenic and dolomite fluxes. Total lithogenic fluxes increase when the southern branch of dust bearing northwesterlies
is dragged by the SW monsoon winds to the trap locations. However, the dolomite fluxes increase only when the northern branch
of the northwesterlies (which carries a huge amount of dolomite accounting 60% of the total dust load) is dragged, from further
north, by SW monsoon winds. The potential for the use of Mg/Fe ratio as a paleo-monsoonal proxy is examined. 相似文献
18.
利用稳定同位素大气水平衡模式（iAWBM）的模拟数据,分析了在不同的下垫面蒸发和不同的凝结分馏条件下降水中δ18O的时间变化、降水量效应、负温度效应和大气水线。并通过与长沙站5年实测数据的比较以及模拟试验结果之间的相互比较,揭示下垫面蒸发水汽中稳定同位素的季节性变化和云中稳定同位素分馏对降水中稳定同位素变化的可能影响,增进对季风区水稳定同位素效应的理解和认识。iAWBM给出的4个模拟试验均很好地再现了监测站降水中δ18O的时间变化,模拟出季风区降水中稳定同位素在暖半年被贫化、在冷半年被富集的基本特点。与平衡分馏相比,动力分馏下降水中稳定同位素被贫化的程度加强、季节差和离散程度减小;由下垫面蒸发水汽中稳定同位素δe季节性变化所引起的降水中稳定同位素的变化在不同季节完全相反：在长沙,暖半年降水中δ18O更低,冷半年降水中δ18O更高,使得降水中稳定同位素季节差和离散程度增大。4个模拟试验均很好地再现了季风区的降水量效应和负温度效应。与平衡分馏相比,动力分馏下模拟的降水量效应和负温度效应的斜率相对较小;δe季节性变化导致模拟的降水量效应和负温度效应的斜率增大。利用iAWBM,模拟出季风区湿热气候条件下的MWL。动力分馏以及δe季节变化均使模拟得到的MWL的斜率和截距减小。 相似文献
19.
The isotopic composition and parameters for deuterium excess of brines, which were sampled in the Si-chuan Basin, show obvious regularities of distribution. The brine isotopic composition shows distinct two systems of marine and terrestrial deposits, with the Middle Triassic strata as the boundary. Brine hydrogen isotopic composition of marine deposits is lower while oxygen isotopic composition is higher than that of the SMOW, respectively, indicating that the brines were derived from seawater with different evaporating degrees at different times. From the Sinian strata, up to the Cambrian, Permian Maokou Formation and the Triassic Jialingjiang Formation, the δD values of brines tend to become relatively positive with the strata becoming younger. Brines of terrestrial deposits are considered to have been derived from precipitation and their isotopic composition is close to the globe meteoric water line (GMWL). Brines of transitional deposits between marine and terrestrial ones (the Upper Triassic Xujiahe Formation) have δD and δ18O values falling between the two end members of marine deposit brines and precipitation, indicating that the brines are a mixture of precipitation and vaporing seawater. Water samples from the brine-bearing strata of different ages show various deuterium excesses (d) with an evident decreasing trend as the age of strata gets older and older. Brine-bearing strata of the Triassic Leikoupo-Jialingjiang Formation, the Permian Maokou Formation, the Cambrian and Sinian strata are all carbonate rocks which have experienced intensive water/rock reaction and the deuterium excess essentially changes with time. All brine-bearing-strata surrounding the basin or faults, as well as those brine wells exploited for resources, have been obviously influenced by the precipitation supply. Therefore, the deuterium excesses of their brines have increased to different extents, depending on the amount of involvement of meteoric water. The variation and distribution of d values of the brines from different Triassic strata are related to the embedded depth of the strata. The deuterium excesses of brines become lower with increasing burial depth of the strata. 相似文献