中国西部汛期降水的时空演变分析

用中国西部１０省区（１１０°Ｅ以西）１３０个站的月降水资料，分析夏半年４—１０月的月降水相对系数、月际和年际标准差变化特征。结果表明，各地区受不同降水体系影响，降水在时空上的差异很大。天山北部主要受西风带降水体系影响，月际降水差异不大；西北地区受西太平洋副热带高压雨带影响，降水具有西进北抬尔后东退南辙的特征；高原季风雨带对四川西部、云南和西藏有明显影响，雨季从东南向西北开始，而结束与此相反。月际和年际标准差表明，在以南疆盆地为主的东北—西南一带地区的标准差为高值区，而该地区以东和以北地区的标准差呈逐渐减小趋势     

Rapid forecasting of urban flood inundation using multiple machine learning models

Natural Hazards - Urban flood inundation is worsening as the number of short-duration rainstorms increases, and it is difficult to accurately predict urban flood inundation over a long lead time;...     

NEW OBSERVATIONS ON THE MEIOTIC PROCESS IN THE MARINE DINOFLAGELLATE NOCTILUCA SCINTILIANS （NOCTILUCALES, DINOPHYCEAE）

The meiotic process in Noctiluca scintillans were observed under light microscope.Some abnormal cell divisions, incompletely separated “zoospores” and the changes of the zoospores are described in this paper. Together with the fmdings of field samplings and the previous results by other researchers, the process of meiosis in N. scintillans was supposed to be a pathway to reduce the extra high density of NH3-N within the cell in order to ensure normal population growth.     

重力不稳定性与亚洲内陆三角形地震区地球动力学特征

本文研究了亚洲内陆三角形地震区的岩石圈厚度、上地幔顶部Pn波速度、上地幔密度分布、地壳结构、现代构造运动及地震活动等特征。认为该区内存在着地幔分异物质多元底辟现象,致使岩石圈减薄及地壳增生变厚,而巨厚的地壳处于重力不稳定状态,地壳物质发生流变,该区内现代构造运动与地震活动均与此有关。作者认为,重力是导致本区上地幔及地壳发生构造运动的主要力源之一。     

The role of salinity in fluvio-deltaic morphodynamics: A long-term modelling study

Salinity difference between terrestrial river discharge and oceanic tidal water plays a role in modifying the local flow field and, as a consequence, estuarine morphodynamics. Although widely recognized, recent numerical studies exploring the long-term morphological evolution of river-influenced estuaries with two-dimensional, depth-averaged models have mostly neglected salinity. Using a three-dimensional morphodynamic model, we aim to gain more insight into the effect of salinity on the morphodynamics of fluvio-deltaic systems. Model results indicate that the resultant estuarine morphology established after 600 years differs remarkably when a salinity gradient is included. A fan-shaped river-mouth delta exhibits less seaward expansion and is cut through by narrower channels when salinity is included. The inclusion of salinity tends to generate estuarine circulation, which favours landward sediment transport and hence limits the growth of the delta while enhancing the development of intertidal areas. The formation of deltaic channel–shoal patterns resulting from morphodynamic evolution tends to strengthen salinity stratification, which is characterized by an increased gradient Richardson number. The direction of the depth-averaged residual sediment transport over a tide may be opposite to the direction of residual velocity, indicating the significant influence of baroclinic effects on the net sediment transport direction (and hence morphological change). The effect of salinity on morphological evolution becomes less profound when the strength of tidal or fluvial forcing is dominant over the other. The effects of sediment type and flocculation, which are particularly important when salinity gradients are present, are also discussed. Overall, this study highlights that neglecting salinity to simulate long-term estuarine morphodynamics requires more careful justification, particularly when the environment is characterized by fine sediment types (favouring suspended transport), and relatively large river discharge and estuarine depth (favouring baroclinic effects). © 2020 John Wiley & Sons, Ltd.     

JpGraph绘图类库在地震数据展示中的应用

天津市地震局在进行地震观测数据可视化发布工作中,采用PHP语言及JpGraph类库实现了前兆类观测数据在WEB页面中的图形化展示,扩展了PHP语言在行业数据发布与展示系统中的应用,本文主要阐述JpGraph类库的应用及在使用中遇到的问题.     

晋陕峡谷基座阶地沉积物释光测年方法的比较研究

黄河的系列阶地是其发育过程中最直接的遗迹记录,确定阶地的精确形成年代是研究其地貌演化最重要的关键问题之一。尽管以往对黄河阶地进行了大量的测年研究,尤其是光释光测年,但对各测年方法结果可靠性的比较相对较少。本研究选择黄河晋陕峡谷黑峪口地区的一个典型基座阶地,对其沉积物进行多方法的光释光测年研究,包括应用于细粒（FG）石英与粗粒（CG）石英的单片剂量再生法（OSL-SAR）和应用于粗粒钾长石的红外后多步高温红外法（MET-pIRIR）;同时,测定了现代黄河河流样品不同释光信号的残余剂量。结果表明,粗粒和细粒石英具有不同的光释光性质,细粒石英的光释光性质具有更多的快组分、更高的饱和剂量和热稳定性等使其更适合光释光OSL-SAR方法测年。尽管现代样品的细颗粒比粗颗粒有更大的光释光（SAR-OSL）残余剂量,但阶地样品的细颗粒SAR-OSL年龄与地层层序的一致性表明细颗粒的光释光年代是可靠的。现代样品粗颗粒石英的光释光信号晒退较彻底,但阶地样品的粗颗粒石英SAR-OSL年龄与地层的不一致性和其较大的离散性,表明其SAR-OSL年龄的可靠性不如细颗粒石英。根据细粒石英的SAR-OSL年龄,研究阶地的形成年龄为64.7±2.5 ka。现代样品中的MET-pIRIR和回授光释光信号（TT-OSL）晒退不彻底,阶地沉积物样品钾长石的MET-pIRIR年龄远高于其对应的石英SAR-OSL年龄,并大于其上覆马兰黄土的年代上限。本研究说明在进行其他黄河阶地释光测年时,应同时应用粗粒和细粒石英,通过分析其光释光性质和样品的地貌沉积过程来确定其可靠性。在对阶地沉积物应用石英的TT-OSL和钾长石MET-pIRIR方法测年时需要特别谨慎。

     

中国东北地区的构造格局与演化:从500Ma到180Ma

中国东北变质基底为由含矽线石榴片麻岩、角闪斜长片麻岩、石墨大理岩和各种长英质片麻岩组成的孔兹岩系。采自额尔古纳、兴安、佳木斯和兴凯地块的矽线石榴片麻岩样品的锆石U-Pb测年均指示高级变质发生在500Ma左右。来自松辽地块古生代沉积物碎屑锆石的证据也表明约500Ma构造岩浆事件的存在。跨越整个中国东北不同地块的泛非期高级变质岩形成了超过1 300km北西向展布的晚泛非期"中国东北孔兹岩带",以顺时针p/T轨迹的孔兹岩带与同期岩浆杂岩共同构成了一巨型的约500Ma前后的造山带,笔者这里命名为"中国东北早古生代造山带"。这证明了中国东北各地块在500Ma之前已经拼合,并与西伯利亚克拉通具有构造亲缘性,曾是晚泛非期(500 Ma)西伯利亚南缘Sayang-Baikal造山带的组成部分。450Ma之后,已经拼合的中国东北地块群从西伯利亚裂解,向南朝现今的中国东北漂移;230Ma前后,东北地块群沿索伦—西拉沐伦—长春缝合带与华北板块碰撞;210～180 Ma,由于太平洋板块的俯冲导致佳木斯地块与西部松辽地块最终拼贴,沿佳木斯—兴凯地块西缘和南缘形成一弧形高压带(包括佳木斯—兴凯地块西缘黑龙江蓝片岩带和佳木斯—兴凯地块南缘长春—延吉带),这里简称"吉林—黑龙江高压变质带",之后东北地区进入了环太平洋构造域演化阶段并持续至今。     

东亚夏季风石笋记录中缺失格陵兰间冰段25?

东亚季风是全球气候系统的重要组成部分[16]。了解北大西洋地区温度变化和东亚夏季风之间的关系对了解东亚季风的控制机制具有重要意义。葫芦洞和董哥洞石笋δ18O记录显示距今7510ka北大西洋地区千年尺度温度变化对东亚夏季风变化具有重要影响:较强的东亚夏季风与北大西洋地区较高气温对应,反之亦然[7,8]。但是,在此之前东亚夏季风变化与北大西洋地区温度变化之间是否具有类似的联系?到目前为止对这一问题尚没有明确的探讨。