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长江中游石笋年层厚度作为东亚夏季风强度代用指标的研究 被引量:30
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作者 刘浴辉 胡超涌 +2 位作者 黄俊华 谢树成 陈正洪 《第四纪研究》 CAS CSCD 北大核心 2005年第2期228-234,共7页
利用Olympus偏光显微镜,直接在光学薄片上对长江中游和尚洞HS 4石笋进行微层计数,并测量微层厚度。微层计数结果与其对应的U Th定年结果相吻合,证明该支石笋微层为年层;统计分析说明,该石笋的年层厚度变化响应近百年来东亚夏季风强度变... 利用Olympus偏光显微镜,直接在光学薄片上对长江中游和尚洞HS 4石笋进行微层计数,并测量微层厚度。微层计数结果与其对应的U Th定年结果相吻合,证明该支石笋微层为年层;统计分析说明,该石笋的年层厚度变化响应近百年来东亚夏季风强度变化,两者呈负相关,说明长江中游石笋生长受东亚夏季风制约。因而,长江中游石笋年层厚度可以作为高分辨率的东亚夏季风强度代用指标。 展开更多
关键词 石笋 年层厚度 东亚夏季风 长江中游
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湖北神农架石笋年纹层与氧碳同位素关系 被引量:3
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作者 梁燕 孔兴功 汪永进 《中国岩溶》 CAS CSCD 北大核心 2008年第4期371-376,共6页
基于湖北神农架青天洞石笋U系测年和年纹层统计结果,分别建立了末次盛冰期(17474±174~16105±151aB.P.)和全新世大暖期(6935.4±33.8~6137±48aB.P.)长达1000余年的两个石笋年纹层生长序列。全新世大暖期年纹层平均... 基于湖北神农架青天洞石笋U系测年和年纹层统计结果,分别建立了末次盛冰期(17474±174~16105±151aB.P.)和全新世大暖期(6935.4±33.8~6137±48aB.P.)长达1000余年的两个石笋年纹层生长序列。全新世大暖期年纹层平均厚度(265μm)约为末次盛冰期(102μm)的2.5倍,说明在间冰期东亚季风增强时石笋沉积速率较大,冰期时则相反。两支分辨率为4~8年的石笋年纹层厚度与δ13C变化曲线对比显示:在百年尺度上,石笋年纹层厚度与δ13C变化曲线均呈良好的相关性(相关系数分别为-0.53和-0.60),说明两指标可能受洞穴上覆土壤带CO2产率这一主控因素的影响。当上覆土壤层生物活动增强,CO2分压较高时,导致石笋δ13C值偏负、生长速率增大。然而,在相同尺度上,两支石笋δ18O变化与对应的δ13C及年纹层厚度之间的相关性较弱,反映研究地点上覆土壤层CO2产率对东亚夏季风强弱变化响应关系比较复杂。 展开更多
关键词 石笋 厚度 碳同位素 生长速率 湖北神农架
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Variation in the permafrost active layer over the Tibetan Plateau during 1980–2020 被引量:1
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作者 Jinglong Huang Chaofan Li +2 位作者 Binghao Jia Chujie Gao Ruichao Li 《Atmospheric and Oceanic Science Letters》 CSCD 2024年第5期34-39,共6页
The active layer,acting as an intermediary of water and heat exchange between permafrost and atmosphere,greatly influences biogeochemical cycles in permafrost areas and is notably sensitive to climate fluctuations.Uti... The active layer,acting as an intermediary of water and heat exchange between permafrost and atmosphere,greatly influences biogeochemical cycles in permafrost areas and is notably sensitive to climate fluctuations.Utilizing the Chinese Meteorological Forcing Dataset to drive the Community Land Model,version 5.0,this study simulates the spatial and temporal characteristics of active layer thickness(ALT)on the Tibetan Plateau(TP)from 1980 to 2020.Results show that the ALT,primarily observed in the central and western parts of the TP where there are insufficient station observations,exhibits significant interdecadal changes after 2000.The average thickness on the TP decreases from 2.54 m during 1980–1999 to 2.28 m during 2000–2020.This change is mainly observed in the western permafrost region,displaying a sharp regional inconsistency compared to the eastern region.A persistent increasing trend of ALT is found in the eastern permafrost region,rather than an interdecadal change.The aforementioned changes in ALT are closely tied to the variations in the surrounding atmospheric environment,particularly air temperature.Additionally,the area of the active layer on the TP displays a profound interdecadal change around 2000,arising from the permafrost thawing and forming.It consistently decreases before 2000 but barely changes after 2000.The regional variation in the permafrost active layer over the TP revealed in this study indicates a complex response of the contemporary climate under global warming. 展开更多
关键词 Active layer thickness PERMAFROST Tibetan plateau Climatological characteristics
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过去800年中国西南水文气候变化及其动力学机制
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作者 赵彬 崔英方 +2 位作者 孔兴功 赵侃 汪永进 《高校地质学报》 CAS 2024年第6期747-755,共9页
中国西南地区不同时间尺度水文气候变化及其驱动机制仍不明确,主要原因可能与长时间序列高分辨率水文记录的稀少有关。文章基于贵州董哥洞石笋年纹层厚度序列,重建了过去800年(1180~1969 AD)年分辨率精确时标的区域水文变化历史。与北... 中国西南地区不同时间尺度水文气候变化及其驱动机制仍不明确,主要原因可能与长时间序列高分辨率水文记录的稀少有关。文章基于贵州董哥洞石笋年纹层厚度序列,重建了过去800年(1180~1969 AD)年分辨率精确时标的区域水文变化历史。与北半球温度记录对比结果表明:两者在百年尺度演变特征上具有很好的相似性,并在小冰期存在显著干旱事件(~1540~1630 AD)。同时,西南区域水文重建和南美秘鲁水文记录高度相似且呈现反相位关系,支持北半球温度通过调制热带辐合带(ITCZ)经向移动影响低纬水文变化的观点。数学分析结果显示区域水文变化具有显著的~3年和~7年周期特征(贡献率约为44%),可能与ENSO年际变化有关。同时,区域水文变率从中世纪暖期到小冰期转换过程中逐步减小,在小冰期北半球温度最低阶段(~1540~1630 AD)达到最小,随后逐步增大,现代暖期(1850 AD以来)达到最大,这一特征和ENSO变率重建结果基本一致。这些发现表明区域水文气候的年际变化主要受热带太平洋海表温异常的影响,其变率演化可能受长期温度背景状况的调制。该研究支持全球持续变暖情景下,ENSO变率和低纬水文变率增大,极端气候事件(旱涝)发生频率和变化幅度增加的观点。 展开更多
关键词 中国西南 石笋 年层厚度 水文气候 北半球温度 ENSO
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末次盛冰期南京降水记录中ENSO的演化 被引量:1
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作者 夏志锋 汪永进 吴江滢 《南京师大学报(自然科学版)》 CAS CSCD 北大核心 2006年第1期106-110,共5页
基于南京葫芦洞一支石笋TIMS-U系测年和纹层计数的交叉定年。获得丁末次盛冰期在24170~21222aBP时段石笋年纹层厚度的时间序列,主要反映了夏季风降水变率.小波分析揭示末次盛冰期连续3ka夏季风降水记录中厄尔尼诺一南方涛动(ENSO)... 基于南京葫芦洞一支石笋TIMS-U系测年和纹层计数的交叉定年。获得丁末次盛冰期在24170~21222aBP时段石笋年纹层厚度的时间序列,主要反映了夏季风降水变率.小波分析揭示末次盛冰期连续3ka夏季风降水记录中厄尔尼诺一南方涛动(ENSO)周期和强度随时间的演化特征,该记录表明ENSO在末次盛冰期并非一直存在,有着高发期和平缓期。其爆发的频率和强度逐渐减弱。支持ENSO演化的“冰期阻尼效应”假说. 展开更多
关键词 末次盛冰期 石笋厚度 ENSO演化 小波分析
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Changes in the Thermal and Hydraulic Regime within the Active Layer in the Qinghai-Tibet Plateau 被引量:7
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作者 XIE Changwei ZHAO Lin +1 位作者 WU Tonghua DONG Xicheng 《Journal of Mountain Science》 SCIE CSCD 2012年第4期483-491,共9页
The change trends of air temperature,precipitation and evaporation from 1999 to 2008 shows that the climate in the Qinghai-Tibet Plateau permafrost region had become warmer.The analysis of the systematic active-layer ... The change trends of air temperature,precipitation and evaporation from 1999 to 2008 shows that the climate in the Qinghai-Tibet Plateau permafrost region had become warmer.The analysis of the systematic active-layer data monitoring network along the Qinghai-Tibet Highway indicated that the active-layer thickness had been increasing and the soil temperature was rising.The soil temperature was rising in winter but not at the end of spring or during the entire summer.With thickening and warming of the active layer,the liquid water content of the active layer had an obvious downward migration and liquid water content in the top horizons decreased,but in the deeper horizons it increased. 展开更多
关键词 Soil temperature Water content Activelayer PERMAFROST Qinghai-Tibet Plateau (QTP)
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CAROTID INTIMA- MEDIA THICKNESS AND THE ASSOCIATION WITH CARDIOVASCULAR RISK FACTORS IN THE ELDERLY 被引量:1
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作者 叶平 王节 +1 位作者 尚延忠 朱平 《Chinese Medical Sciences Journal》 CAS CSCD 2001年第1期15-18,共4页
To investigate the association of carotid arterial intima- media thickness (IMT) with principal cardiovascular risk factors in the elderly. Methods. Carotid arterial IMT was measured by high resolution B mode ultrasou... To investigate the association of carotid arterial intima- media thickness (IMT) with principal cardiovascular risk factors in the elderly. Methods. Carotid arterial IMT was measured by high resolution B mode ultrasound in 94 elderly subjects (old- aged group), and compared with subjects aged Results. In comparison with the middle- aged group, the prevalence of coronary heart disease, cerebral vascular disease, hypertension and diabetes mellitus was significantly higher, and serum cholesterol and systolic blood pressure were also significantly higher in old- aged group. Although there was no obvious difference in IMT between the two groups, carotid plaque and carotid wall thickening were more frequently found in old- aged group. Age, systolic blood pressure and serum cholesterol were shown as the independent determinants for carotid IMT in the total participants, whereas no such independent relation was found in old- aged group. Conclusion. Age is the major risk factor for carotid atherosclerosis in the elderly. In other words, the occurrence of carotid atherosclerosis is the result of advancing age combined with the effect of multiple cardiovascular risk factors. 展开更多
关键词 the elderly carotid artery ATHEROSCLEROSIS risk factors
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Modeling permafrost properties in the Qinghai-Xizang(Tibet) Plateau 被引量:7
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作者 HU GuoJie ZHAO Lin +8 位作者 WU XiaoDong LI Ren WU TongHua XIE ChangWei PANG QiangQiang XIAO Yao LI WangPing QIAO YongPing SHI JianZong 《Science China Earth Sciences》 SCIE EI CAS CSCD 2015年第12期2309-2326,共18页
Water and heat dynamics in the active layer at a monitoring site in the Tanggula Mountains, located in the permafrost region of the Qinghai-Xizang (Tibet) Plateau (QXP), were studied using the physical-process-bas... Water and heat dynamics in the active layer at a monitoring site in the Tanggula Mountains, located in the permafrost region of the Qinghai-Xizang (Tibet) Plateau (QXP), were studied using the physical-process-based COUPMODEL model, including the interaction between soil temperature and moisture under freeze-thaw cycles. Meteorological, ground temperature and moisture data from different depths within the active layer were used to calibrate and validate the model. The results indicate that the calibrated model satisfactorily simulates the soil temperatures from the top to the bottom of the soil layers as well as the moisture content of the active layer in permafrost regions. The simulated soil heat flux at depths of 0 to 20 cm was consistent with the monitoring data, and the simulations of the radiation balance components were reasonable. Energy consumed for phase change was estimated from the simulated ice content during the freeze/thaw processes from 2007 to 2008. Using this model, the active layer thickness and the energy consumed for phase change were predicted for future climate warming scenarioS. The model predicts an increase of the active layer thickness from the current 330 cm to approximately 350-390 cm as a result of a 1-2℃ warming. However, the effect active layer thickness of more precipitation is limited when the precipitation is increased by 20%-50%. The COUPMODEL provides a useful tool for predicting and understanding the fate of permafrost in the QXP under a warming climate. 展开更多
关键词 PERMAFROST COUPMODEL hydrothermal processes phase change soil temperature soil moisture
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