Ekman模型时间变化风应力系数的伴随参数估计     

李国庆  高艳秋  张继才 《海洋与湖沼》2019,50(5):979-993

本文基于时间分布参数设置,利用伴随同化方法,反演了Ekman模型中随时间变化的风应力拖曳系数,并在孪生实验和实际实验中对该方法进行了验证。在孪生实验中,研究了参数反演结果对不同影响因素的响应,包括:风速分布、风应力系数分布、风应力系数初始猜测值、风应力系数独立变量个数、观测数据误差和观测的深度。孪生实验结果验证了伴随同化方法反演Ekman模型中时变风应力系数的有效性,具体包括如下五个方面结论:1)不同风速分布下均能成功反演出不同风应力拖曳系数分布; 2)反演结果对初始猜测值较为敏感,风应力系数初始猜测值越接近给定值,反演结果越好;3)风应力系数独立点个数的选取会显著影响反演结果,合理的选择有利于提高反演效率及减小观测数据误差;4)观测误差能够影响反演结果,观测数据误差在20%以下时能取得合理的反演结果; 5)反演结果对观测数据的表层和次表层流速更为敏感,这是由Ekman流的物理性质决定的。实际实验,利用百慕大锚系试验平台的风速和流速数据,去除周期性潮流和地转流成分后得到Ekman流成分,并作为观测输入到该同化模型,反演出了适用于该区域和该时段的随时间变化的风应力系数。通过比较模拟流速和观测流速,证明利用伴随同化方法能从实测数据中反演出合理的时变风应力系数,对于海洋模型风应力系数的确定是一项有益的尝试。  相似文献   

Phase equilibria modelling and LASS monazite petrochronology: P–T–t constraints on the evolution of the Priest River core complex,northern Idaho          下载免费PDF全文

L. M. Stevens  J. A. Baldwin  J. M. Cottle  A. R. C. Kylander‐Clark 《Journal of Metamorphic Geology》2015,33(4):385-411

Phase equilibria modelling, laser‐ablation split‐stream (LASS)‐ICP‐MS petrochronology and garnet trace‐element geochemistry are integrated to constrain the P–T–t history of the footwall of the Priest River metamorphic core complex, northern Idaho. Metapelitic, migmatitic gneisses of the Hauser Lake Gneiss contain the peak assemblage garnet + sillimanite + biotite ± muscovite + plagioclase + K‐feldspar ± rutile ± ilmenite + quartz. Interpreted P–T paths predict maximum pressures and peak metamorphic temperatures of ~9.6–10.3 kbar and ~785–790 °C. Monazite and xenotime ²⁰⁸Pb/²³²Th dates from porphyroblast inclusions indicate that metamorphism occurred at c. 74–54 Ma. Dates from HREE‐depleted monazite formed during prograde growth constrain peak metamorphism at c. 64 Ma near the centre of the complex, while dates from HREE‐enriched monazite constrain the timing of garnet breakdown during near‐isothermal decompression at c. 60–57 Ma. Near‐isothermal decompression to ~5.0–4.4 kbar was followed by cooling and further decompression. The youngest, HREE‐enriched monazite records leucosome crystallization at mid‐crustal levels c. 54–44 Ma. The northernmost sample records regional metamorphism during the emplacement of the Selkirk igneous complex (c. 94–81 Ma), Cretaceous–Tertiary metamorphism and limited Eocene exhumation. Similarities between the Priest River complex and other complexes of the northern North American Cordillera suggest shared regional metamorphic and exhumation histories; however, in contrast to complexes to the north, the Priest River contains less partial melt and no evidence for diapiric exhumation. Improved constraints on metamorphism, deformation, anatexis and exhumation provide greater insight into the initiation and evolution of metamorphic core complexes in the northern Cordillera, and in similar tectonic settings elsewhere.  相似文献   

Energy flux partitioning and evapotranspiration in a sub‐alpine spruce forest ecosystem          下载免费PDF全文

Zhu Gaofeng  Lu Ling  Su Yonghong  Wang Xufeng  Cui Xia  Ma Jinzhu  He Jianhua  Zhang Kun  Li Changbin 《水文研究》2014,28(19):5093-5104

In this study, we examined the year 2011 characteristics of energy flux partitioning and evapotranspiration of a sub‐alpine spruce forest underlain by permafrost on the Qinghai–Tibet Plateau (QPT). Energy balance closure on a half‐hourly basis was H + λE = 0.81 × (R_n ? G ? S) + 3.48 (W m^?2) (r² = 0.83, n = 14938), where H, λE, R_n, G and S are the sensible heat, latent heat, net radiation, soil heat and air‐column heat storage fluxes, respectively. Maximum H was higher than maximum λE, and H dominated the energy budget at midday during the whole year, even in summer time. However, the rainfall events significantly affected energy flux partitioning and evapotranspiration. The mean value of evaporative fraction (Λ = λE/(λE + H)) during the growth period on zero precipitation days and non‐zero precipitation days was 0.40 and 0.61, respectively. The mean daily evapotranspiration of this sub‐alpine forest during summer time was 2.56 mm day^?1. The annual evapotranspiration and sublimation was 417 ± 8 mm year^?1, which was very similar to the annual precipitation of 428 mm. Sublimation accounted for 7.1% (30 ± 2 mm year^?1) of annual evapotranspiration and sublimation, indicating that the sublimation is not negligible in the annual water balance in sub‐alpine forests on the QPT. The low values of the Priestley–Taylor coefficient (α) and the very low value of the decoupling coefficient (Ω) during most of the growing season suggested low soil water content and conservative water loss in this sub‐alpine forest. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

转换波AVO近似及其在PP/PS联合反演中的应用(英文)     

王璞  胡天跃 《应用地球物理》2011,8(3):189-196

多分量勘探相比常规纵波勘探而言有许多的优势,PP/PS联合AVO分析和反演是强而有效的储层识别方法。在本文中,我们推导了更精确的转换波AVO反射系数公式;并在入射角小于30度时进行了进一步简化,其对于转换波AVO分析和反演而言更加简单有效。基于该近似,我们进行了PP/PS联合AVO反演。实际资料的实例表明,反演得到的纵横波速度比可很好地识别岩性及油气。反演得到的流体因子和泊松比等其他属性在储层处也显示出明显异常,效果显著。  相似文献   

Metamorphic veining and mass transfer in a chemically closed system: a case study in Alpine metabauxites (western Vanoise)   总被引：2，自引：0，他引：2  

B. GOFFÉ  F. BRUNET  C. POINSSOT  O. VIDAL  N. FINDLING  D. MENUT 《Journal of Metamorphic Geology》2011,29(3):275-300

In western Vanoise (French Alps), karstic pockets of Triassic‐to‐Jurassic metabauxites embedded in carbonate rocks and containing several generations of metamorphic veins were studied. During blueschist facies metamorphism, a cumulative amount of ～13 vol% of water is inferred to have been produced locally by successive dehydration reactions, and part of this fluid remained in the bauxitic lenses during most of the metamorphic cycle. Field and geochemical evidence show that these rocks have been isolated from large‐scale fluid flow (closed‐system behaviour). It is proposed that the internally derived fluid has promoted the opening of fluid‐filled open spaces (as attested by the euhedral habits of vein minerals) and served as medium for mass transfer from rock to vein. Indeed, the vein infill is obviously the result of chemical interactions, at the millimetre‐to‐centimetre scale, between the rock minerals and the locally produced aqueous fluid. Two vein types can be distinguished based on mineralogical and textural features: (i) some veins are filled with newly formed products of either prograde (chloritoid) or retrograde (chlorite) metamorphic reactions; in this case, fluid‐filled open spaces seem to offer energetically favourable nucleation/growth sites; (ii) the second vein type is infilled with cookeite or pyrophyllite, that were present in the host rock prior to the vein formation. In this closed chemical system, the components for the vein infill minerals have been transferred from rock to vein through the fluid, in a dissolution–transport–precipitation process, possibly stress‐assisted. These different vein generations all contain Al‐rich mineral infills, suggesting that Al was a mobile element (cm scale) during metamorphism. In these HP rocks, fluid flow may have been restricted, and if so mass transfer occurred by diffusion in an almost stagnant fluid. Metamorphic veins can be seen as witnesses of fluid and mass redistribution that partly accommodate the rock deformation (lateral segregation).  相似文献   

100MPa、800℃下Mo和W在流体／花岗质熔体相间分配的实验研究   总被引：3，自引：0，他引：3  

管申进  张辉  唐勇  张锦煦 《地球化学》2011,(6):516-524

利用“RQV-快速内冷淬火”（外加热冷封式）高温高压实验装置,在100MPa、800℃条件下,以东秦岭地区出露的高钾钙碱性岩浆岩（合峪花岗岩）为实验初始物,实验研究了Mo和W在花岗岩-H2O、花岗岩-NaCl（KCl）-H2O及花岗岩-NaF-H2O体系流体／熔体相间的分配行为。实验结果表明,Mo比W更倾向于分配进入流体相（DMo^流体/溶体〉〉DW^流体/溶体）,相对于纯水体系而言,流体介质中Cl和F的存在均有利于Mo和W向流体相迁移富集,随体系内Cl含量的不断增高,Mo和W的分配系数呈线性增大趋势,而在天然花岗岩可能含有的F含量范围之内,F含量的增高将阻碍Mo、W向流体相迁移,流体介质中Na／K（摩尔比）的变化对Mo和W的分配系数没有明显影响,表明体系碱质（Na或K）类型不是Mo和W在流体／熔体相间分配的主要影响因素。  相似文献   

福建锦城187Ma花岗岩的发现——对华南沿海早侏罗世构造演化的制约   总被引：7，自引：2，他引：5  

刘潜  于津海  苏斌  王勤  唐红峰  许海  崔翔 《岩石学报》2011,27(12):3575-3589

本文对福建沿海福清地区的锦城花岗岩和牛头尾花岗闪长岩进行了岩石地球化学、锆石U-Pb-Hf同位素分析.LA-ICP-MS锆石U-Pb定年结果显示锦城花岗岩的年龄为187±1Ma,为福建沿海首次发现的早侏罗世岩浆活动;牛头尾花岗岩形成时代为130±1Ma,代表燕山晚期(白垩纪)的一期岩浆活动.锦城花岗岩具有高5iO2、偏碱、高Fe2OT3等特征,为高钾钙碱性系列,岩石相对富集轻稀土,亏损Nb、Ta、Ti等高场强元素,富集Ba、Sr等大离子亲石元素,具高Rb/Sr( 1.31 ～ 1.93)比值及低Rb/Ba(0.26 ～0.29)、Eu/Eu*(0.30 ～0.56)、La/Yb(5.69 ～ 18.39),Sr/Y(2.24 ～2.29)比值,为典型的Ⅰ型花岗岩,且具有火山孤花岗岩的地球化学特征,很可能形成于与俯冲相关的构造背景.牛头尾花岗岩相比锦城花岗岩低SiO2,贫钾,而富镁、钙,属于花岗闪长岩.其更亏损Nb、Ta及富集Ba、Sr,具较低Rb/Sr(0.27)、Rb/Ba(0.09)比值和较高的Eu/Eu*(0.98)、La/Yb( 16.87),Sr/Y( 19.08)比值,同样为具有弧特征的钙碱性Ⅰ型花岗岩,也形成于与大洋俯冲有关的构造背景.锦城花岗岩和年头尾花岗闪长岩具有相似的锆石Hf同位素组成,εHf(t)分别为2.18～4.73和1.25 ～4.15,tDMC均为～ 1.0Ga,表明二者起源于相同的新元古代新生地壳.结合已有的资料,本次研究发现锦城花岗岩与南岭地区同时代岩浆岩( 194 ～ 172Ma)在成因上有密切的联系,暗示古太平洋板决的俯冲很可能自早侏罗世开始.这样,华南古特提斯构造域向古太平洋构造域的转换很可能发生在早侏罗世之前,大致在205 ～ 190Ma期间.  相似文献   

基于相关系数和Fisher最优分割法的汛期分期研究   总被引：1，自引：0，他引：1  

王双银  杨筱筱 《水文》2011,(4):1-5

从径流形成原理出发,提出了采用降雨径流相关系数作为汛期分期指标的基本思路。以陕西省石头河水库1954~2007年的日降水和日流量资料为基础,采用主成分分析法对影响时段径流的因素进行了分析,筛选出了影响不同时段径流量的主要因素,计算了主要影响因素与时段径流量的相关系数,采用Fisher最优分割法将石头河水库汛期划分为汛前过渡期(4月1日~5月20日)、前汛期(5月21日~7月10日)、主汛期(7月11日~8月10日)、后汛期(8月11日~9月20日)和汛后过渡期(9月21日~10月31日),并结合区域气候特点和实际发生的洪水对成果进行了合理性论证。该方法资料要求低,计算简便,具有一定的推广应用价值。  相似文献   

一种基于数据机制的DBM模型及其应用     

胡乃发  杨弘  尚尔君  王安志  金昌杰  关德新 《水文》2011,31(6):1-7

将DBM(Data Based Mechanistic)模型应用到辽东森林小流域——大湖沟,分别以其2006年6月和2007年7月数据构建研究区丰水期和枯水期的DBM模型,拟合效率系数分别为0.952 8和0.837 8,模型拟合效果在验证期的不同时段表现出明显的差异性。对丰水期模型参数用固定时间间隔法(FIS)进行时变性分析,发现参数b的取值随时间产生变化。对枯水期的二阶DBM模型进行快、慢流分解,得出了连续时间当量的快、慢流的平均滞后时间分别为5.3h和243.3h。  相似文献   

内蒙古东部额尔古纳地块古变质岩地球化学特征及成因环境探讨   总被引：2，自引：0，他引：2  

刘树杰  李玉龙  王德福 《吉林地质》2011,30(1):19-28

额尔古纳地块古老变质岩系重新厘定为古元古界兴华渡口群与风水山片麻杂岩.对兴华渡口群与风水山片麻杂岩的岩石学、岩石化学化学与地球化学特征进行了分析,论述了本区的变质作用特征,并对额尔古纳地块的基底构造背景及成因模式进行了探讨.  相似文献