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941.
942.
重力异常平面图的区域划分是地球物理场及地质构造解释的重要参考,但对于大范围数据一直缺少自动化辅助划分方法。基于凝聚层次聚类算法,开展重力异常网格数据的自动化区域划分研究,以空间邻近性为限制条件,分析不同连接方法对模拟重力异常数据的聚类效果,最终选取以Ward法为连接方式的凝聚聚类法,对菲律宾海盆区域的简单布格重力异常数据进行应用实验,并与已有板块划分理论进行对比分析。结果表明:凝聚聚类算法能够根据重力异常数据的空间位置及其数值的大小进行较为合理的自动划分;对菲律宾海盆重力异常的聚类分析结果与已有的板块区划较为接近,能够反映出许多局部细节上的信息,有利于解释工作的开展。因此,聚类分析是研究地球物理场特征的有效辅助工具。 相似文献
943.
944.
为探讨大别造山带早期结晶基底物质组成及其演化特征,对大别造山带蕙兰山地区出露的黑云紫苏斜长片麻岩的岩石学、地球化学、锆石U-Pb年代学及Lu-Hf同位素组成进行研究,显示其原岩应为石英闪长岩,成岩时代为古元古代早期(2463±22 Ma),且经历了古元古代麻粒岩相变质作用,锆石Ti地质温度计显示其变质温度为767~827℃(平均799℃),变质时间为2002±11 Ma(MSWD=0.46)。岩石地球化学成分显示其SiO2含量为55.16%~57.10%,MgO为4.74%~5.89%,Mg#值为47.5~50.4,钙碱性系列,富Mg贫Si,稀土配分曲线呈现轻稀土相对富集的右倾分布特征((La/Yb)N=19.3~34.1),无明显Eu异常((Eu/Eu*)=0.9~1.2),且具较高的Sr、Ni、Cr含量,以及较低的YbN值及Y含量,与镁质闪长岩具相似特征;明显富集Rb、Ba、K等大离子亲石元素,相对亏损Nb、Ta、Zr、Hf等高场强元素;锆石Lu-Hf同位素显示具有较为均一... 相似文献
945.
通过利用CANDELS-EGS(Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey-Extended Groth Strip)场中HST WFC3(Hubble Space Telescope Wide Field Camera 3)F160W高分辨率的观测图像,研究了9个光谱红极亮红外星系的形态结构特征.发现这些星系的形态表现出多样性(从椭圆到多个亮核或弥散的结构),如:双核,气体桥,双不对称体,不规则或椭圆结构.为了定量地研究这些极亮红外星系的形态,测量了它们在静止光学波段的形态参数(基尼系数G和矩指数M20).与近邻极亮红外星系相比,高红移极亮红外星系的G偏小而M20偏大,表明这些星系的星族分布聚集度小且不对称性大.基于对样本中极亮红外星系2维面亮度轮廓的拟合,得到这些星系的有效半径分布在2.4 kpc到5.8 kpc之间,其平均值是(3.9±1.1)kpc.相比较于近邻相似质量的恒星形成星系来说,高红移极亮红外星系的平均大小要小1到2倍.在类似红移和红外光度条件下,得出的这些结果也与其它文献中给出的结论相一致. 相似文献
946.
KONG Xu LIN Lin LI Jin-rong ZHOU Xu ZOU Hu LI Hong-yu CHEN Fu-zhen DU Wei FAN Zhou MAO Ye-wei WANG Jing ZHU Yi-nan ZHOU Zhi-min 《Chinese Astronomy and Astrophysics》2014
In recent years the number of worldwide 8∼10 m-class ground-based telescopes is continually increased, the 4 m-diameter or smaller telescopes have become the small and medium-sized telescopes. In order to obtain some noticeable scientific results by using these existing small and medium-sized telescopes, we have to consider very carefully what we can do, and what we can not. For this reason, the Time Allocation Committee of the 2.16 m telescope of the National Astronomical observatories of China (NAOC) has decided to support some key projects since 2013. The long-term project “Spectroscopic Observations of the Star Formation Regions in Nearby Galaxies” proposed by us is one of three key projects, it is supported by the committee with 30 dark/grey nights in each of three years. 相似文献
947.
In this study,the Institute of Atmospheric Physics,Chinese Academy of Sciences-regional ensemble forecast system(IAP-REFS) described in Part I was further validated through a 65-day experiment using the summer season of 2010.The verification results show that IAP-REFS is skillful for quantitative precipitation forecasts(QPF) and probabilistic QPF,but it has a systematic bias in forecasting near-surface variables.Applying a 7-day running mean bias correction to the forecasts of near-surface variables remarkably improved the reliability of the forecasts.In this study,the perturbation extraction and inflation method(proposed with the single case study in Part I) was further applied to the full season with different inflation factors.This method increased the ensemble spread and improved the accuracy of forecasts of precipitation and near-surface variables.The seasonal mean profiles of the IAP-REFS ensemble indicate good spread among ensemble members and some model biases at certain vertical levels. 相似文献
948.
It is generally agreed that El Nino can be classified into East Pacific(EP)and Central Pacific(CP)types.Nevertheless,little is known about the relationship between these two types of El Ni?o and land surface climate elements.This study investigates the linkage between EP/CP El Ni?o and summer streamflow over the Yellow and Yangtze River basins and their possible mechanisms.Over the Yellow River basin,the anomalous streamflow always manifests as positive(negative)in EP(CP)years,with a correlation coefficient of 0.39(-0.37);while over the Yangtze River basin,the anomalous streamflow shows as positive in both EP and CP years,with correlation coefficients of 0.72 and 0.48,respectively.Analyses of the surface hydrological cycle indicate that the streamflow is more influenced by local evapotranspiration(ET)than precipitation over the Yellow River basin,while it is dominantly affected by precipitation over the Yangtze River basin.The different features over these two river basins can be explained by the anomalous atmospheric circulation,which is cyclonic(anticyclonic)north(south)of 30°N over East Asia.EP years are dominated by two anticyclones,which bring strong water vapor convergence and induce more precipitation but less ET,and subsequently increase streamflow and flooding risks.In CP years,especially over the Yellow River basin,two cyclones dominate and lead to water vapor divergence and reduce moisture arriving.Meanwhile,the ET enhances mainly due to local high surface air temperature,which further evaporates water from the soil.As a result,the streamflow decreases,which will then increase the drought risk. 相似文献
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950.