MEASUREMENT PROCEDURE OF SINGLE-GRAIN APATITE(U-Th)/He DATING AND ITS VALIDATION BY DURANGO APATITE STANDARD          下载免费PDF全文

WANG Ying  ZHENG De-wen  WU Ying  LI You-juan  WANG Yi-zhou 《地震地质》2017,39(6):1143-1157

(U-Th)/He isotopic dating has been developed very quickly in recent years, due to the recognition that the thermal history of rock at low temperature can be effective revealed by such dating method. In particular, He closure temperature in apatite (40~80℃) is very low, so apatite (U-Th)/He ages can reflect the thermal history information of the low-temperature stage, and have a good application prospect in the field of low-temperature thermal chronology. However, because of many influence factors and complicated measurement procedures, the development of apatite He dating in China remains in its early stage. In this study, a measurement procedure was established at the (U-Th)/He dating laboratory of Institute of Geology, China Earthquake Administration. We measured the daughter isotopic helium by diode laser heating four batches of a total seventy-five grains of Durango apatite in an Alphachron helium mass spectrometry system. Then the apatite grains were dissolved to precisely measure the concentration of parent nuclides (U, Th)using the solution isotope dilution method through an automatic sampling ICP-MS (Agilent 7900). Results show that the Th/U values of Durango apatite grains were in the range of 17.23 to 23.60, while all the 75ages were in the range of 28.61 to 34.51Ma with an average of (31.71±1.55)Ma (1σ), which are consistent with the international calibrated ages.  相似文献   

Application of lagged correlations between solar cycles and hydrosphere components towards sub-decadal forecasts of streamflows in the Western USA     

Michael G. Wallace 《水文科学杂志》2019,64(2):137-164

Trade winds localized within the Western Equatorial Pacific express lagged and statistically significant correlations to sunspot numbers as well as to streamflow in rivers of the Southern Rocky Mountains. Both correlation sets were integrated in a linear regression analysis to produce relatively accurate sub-decadal streamflow forecasts for an annual and a 5-year average. In comparison to the autocorrelation technique, the prototyped method yielded the highest correlations, the highest goodness-of-fit scores, and the lowest root mean squared errors, for both the 5-year average and the annual average assignments. Of all of the cases examined, the highest Kolmogorov-Smirnov test scores between observation and prediction were found for the single solar-based forecast 5 years in advance for the 60-month average streamflow of the Animas River in New Mexico.  相似文献   

地表热通量对陕南强降水的影响   总被引：8，自引：0，他引：8  

毕宝贵  刘月巍  李泽椿 《地理研究》2005,24(5):681-691

通过对2002年6月8～9日陕南大暴雨天气过程中地表感热和潜热通量的数值模拟表明:地表感热、潜热通量和温度的区域性分布与高原东部特殊的地形分布有关,地表热通量和温度的等值线与地形等高线大致平行,平原低洼地区和山脉所在地特征明显,从而可以说明地形热力状况在陕西强降水中发挥重要作用;地表潜热作用大于地表感热,去掉地表潜热的作用后,模式对降水的模拟结果与实况偏差较大;地表感热使山脊降水减少,使平原、山谷降水增加,这与夜间的山谷风环流密不可分。  相似文献   

膨润土热传导性能的温度效应     

徐云山  孙德安  曾召田  吕海波 《岩土力学》2020,41(1):39-45

以高庙子（GMZ07）和美国怀俄明州（MX80）钠基膨润土为研究对象,采用热探针法研究温度对压实膨润土试样热传导性能的影响。在保持干密度和含水率不变的情况下,使用KD2 Pro型热特性分析仪测定不同温度（5～90 ℃）试样的热传导系数,并对部分试样进行压汞试验。试验结果表明：GMZ07和MX80膨润土的热传导系数均随着温度的增大而增大,在90 ℃时最高可达5 ℃的1.2～1.5倍,主要原因是温度引起的水汽潜热传输促进了试样内部的热传导;当试样温度高于60 ℃时,温度对热传导系数的影响较低于60 ℃时更显著;含水率不为0时,两种膨润土热传导系数的温度效应均随干密度的增大而减小;干试样的热传导系数几乎不随温度发生变化,这与水汽潜热传输的强化机制有关。热传导系数温度效应的机制可理解为：热传导系数取决于试样内部可供潜热传输的水分和传热通道数。  相似文献   

长白山针阔混交林秋季净生态系统水气交换量     

温学发  于贵瑞  孙晓敏  Li Qingkang  REN Chuanyou  HAN Shijie 《地理学报(英文版)》2003,13(4):463-468

Water vapour and CO2 fluxes were measured by the eddy-covariance technique above a mixed needle and broad-leaved forest with affiliated meteorological measurements in Changbai Mountain as part of China‘s FLUX projects since late August in 2002. Net water vapour exchange and environmental control over the forest were examined from September 1 to October 31 in 2002. To quantify the seasonal dynamics, the transition period was separated into leafed, leaf falling and leafless stages according to the development of leaf area. The results showed that (a) seasonal variation of water vapour exchange was mainly controlled by net radiation (Rn) which could account for 78.5%, 63.4% and 56.6% for leafed, leaf falling and leafless stages, respectively, while other environmental factors‘ effects varied evidently; (b) magnitude of water vapour flux decreased remarkably during autumn and daily mean of water vapour exchange was 24.2 mg m^-2 s^-1 (100%), 14.8 mg m^-2 s^-1 (61.2%) and 10.3 mg m^-2 s^-1 (42.6%) for leafed, leaf falling and leafless stage, respectively; and (c) the budget of water vapour exchange during autumn was estimated to be 87.1 kg H2O m2, with a mean of 1427.2 g H2O d^-1 varying markedly from 3104.0 to 227.5 g H2O m^-2d^-1.  相似文献   

初始外围尺度与加热对台风次眼墙形成的影响北大核心          下载免费PDF全文

林超然  谈哲敏 《气象科学》2022,42(4):427-439

台风次眼墙位于主眼墙外侧,由次对流环和低层切向风次极大值两个基本结构组成。本文通过一系列理想数值试验讨论了不同初始涡旋外围风场结构对次眼墙形成的影响作用以及关键动力学过程。结果表明,次眼墙形成的时间和位置与初始涡旋外围尺度显著相关:随着外围尺度递减,台风从形成完整双眼墙、伪双眼墙到没有双眼墙逐步过渡,次眼墙形成时间推迟且位置更加靠近台风中心。动力学分析发现,初始外围尺度可控制外雨带分布,雨带的非绝热加热主导了主眼墙外围边界层径向入流和绝对涡度径向输送的分布和大小。绝对涡度径向输送和摩擦耗散的相对大小及位置决定了次眼墙低层切向风次极大值出现的可能性和位置。动量强迫对低层切向风次极大值的大小仍有贡献。  相似文献   

台风“摩羯”和“利奇马”经渤海强度变化特征分析          下载免费PDF全文

朱男男  左涛  苏杭 《气象科技》2022,50(2):214-223

利用FY 4水汽云图、NCEP/FNL资料、自动站资料和ERA Interim海温资料，分析入海增强台风“摩羯”（1814）和入海减弱台风“利奇马”（1909）经过渤海强度变化特征。结论如下：台风“摩羯”中心入海增强过程伴随着中高层冷空气侵入，冷空气深入“摩羯”云系中心，台风强度减弱并逐渐消亡。台风“利奇马”入海前冷空气已经侵入台风中心，台风入海后强度减弱,暖心结构变得不对称，低层有清晰的斜压特征。“摩羯”入海前渤海上空为强辐散区，“利奇马”入海前渤海上空为弱辐合场，北上前进方向出现高空辐散有利于台风加强。台风登陆前垂直风切变与台风强度反位相分布，北上后台风垂直风切变与台风强度同位相分布。“摩羯”入海后水汽通道出现断裂，其入海增强更多依赖于热力条件和动力条件。“利奇马”水汽通量和水汽通量散度源于自身环流的贡献。台风“摩羯”入海后潜热加热率激增，“利奇马”低层维持弱潜热加热直至台风消亡。  相似文献   

西北太平洋海气界面热通量时空分布特征研究   总被引：2，自引：0，他引：2       下载免费PDF全文

翟方国 《海洋科学》2009,33(7):37-42

基于第三版本HOAPs (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data)海表面温度、潜热通量、感热通量、海表面空气比湿以及海表面风场5个参量的18 a(1988～2005年)逐月平均资料,利用经验正交函数和奇异值分解方法分析了异常潜热和感热通量场在西北太平洋的时空分布特征及造成这种分布的主要影响因素.EOF的分析结果表明,异常潜热通量场主要体现为第一第二两个模态的变化,第一模态显示整个海域呈同相变化且在时间上呈准年周期变化,第二模态则描述了分别位于10°N,25°N和40°N的3个极值中心并伴随多年振荡,由因子载荷分布可知热带太平洋是第二模态的行为中心,因此该模态可能与ENSO事件相关.异常感热通量场则主要表现为第一模态的变化,在时间上呈准年周期变化并伴随有多年时间尺度的振荡.奇异值分解方法的分析结果表明异常海表面风场是异常潜热和感热通量场时空变化的重要影响因素.  相似文献   

同化MODIS温度产品估算地表水热通量   总被引：4，自引：0，他引：4       下载免费PDF全文

徐同仁  刘绍民  秦军  梁顺林 《遥感学报》2009,13(6):999-1019

基于集合卡尔曼滤波和通用陆面模型(CLM 1.0)发展了一个地表温度的同化系统。这个系统同化了MODIS温度产品, 并将MODIS的叶面积指数引入CLM模型中, 主要用于改进地表水热通量的估算精度。将CLM输出的地表温度与MODIS地表温度建立关系, 并作为同化系统的观测算子。将MODIS地表温度与实测地表温度进行了比较, 将其均方差(Root Mean Square Error, RMSE)作为观测误差。选取3个美国通量网站点(Blackhill、Bondville、Brookings)作为实验数据, 结果表明: 同化结果中地表温度、显热通量的估算精度均有提高。其中Blackhill站的估算精度改进最大, 均方差由81.5W·m-2减小到58.4W·m-2, Bondville站均方差由47.0W·m-2减小到31.8W·m-2, Brookings站均方差由46.5W·m-2减小到45.1W·m-2。潜热通量估算精度在Bondville站均方差由88.6W·m-2减小到57.7W·m-2, Blackhill站均方差由53.4W·m-2减小到47.2W·m-2。总之, 结合陆面过程模型同化MODIS温度产品估算地表水热通量是可行的。  相似文献   

2010年6月中旬浙闽赣地区暴雨特征和冰云热力效应的数值模拟分析          下载免费PDF全文

邢书强  李小凡 《气象科学》2021,41(4):427-440

以2010年6月19日发生在浙闽赣地区的一次强降水过程为例,利用中尺度WRF模式进行模拟,用模拟资料对该地区降水收支特征和冰云热力作用进行分析。依据局地水汽/热量变化项、水汽/热量辐合辐散项和云凝物辐合辐散项这3个因子可将降水分为8类,其中局地水汽变干和大气变暖、水汽辐合和热量辐散以及云凝物辐合时,降水强度(雨强)最强,而局地水汽变湿和大气变冷、水汽辐合和热量辐散以及云凝物辐合时,降水覆盖率最大。冰云热力效应包括辐射和潜热两部分。基准试验与敏感性试验对比分析表明冰云辐射减弱降水,而冰云潜热增强降水。热量收支对比分析发现冰云辐射造成辐射冷却的减弱在对流层中低层随高度增加,减弱大气不稳定和降水;而冰云潜热造成潜热增强在对流层中高层随高度减小,增强大气不稳定和降水。  相似文献