COSMIC掩星资料同化对台风“天兔”预报影响的试验

台风数值预报的关键之一在于给定准确的模式初始场。本文使用气象、电离层和气候星座观测系统(COSMIC)的卫星资料,通过资料同化技术改善数值天气预报模式的初始场,进而评估数据同化技术对台风(或热带气旋)预报的改善效果。使用我国自主研发的数值天气预报模式,对1319号台风“天兔”进行模拟试验,对温度场、湿度场、涡度散度场及假相当位温场进行诊断分析。试验结果表明,与同化常规探空资料相比,COSMIC资料的同化可减小模式预报台风路径误差,台风附近降水落区更为集中。研究评估了掩星资料同化对模式的改进作用,并能为台风预报技术和防灾减灾提供参考。     

Laboratory study on cement admixed marine silt bricks

For the purpose of efficient utilization of sediments dredged from harbor, a new method was proposed in this study. Marine silt bricks were made by mixing sediments with cement and gypsum, placing it in a cubic mold with 240 mm in length, 115 mm in width, and 53 mm in height, and curing for certain days. To investigate the effects of cement and initial water content of soil on the mechanical behavior of marine silt bricks, unconfined compressive and flexural strength tests were carried out. Given the same curing time and cement content, the higher the initial water content, the lower the compressive and flexural strength. After 60 days of curing, the compressive strength of marine silt bricks with cement content = 20% and water content = LL (liquid limit) reached approximately 5 MPa. The flexural strength was relatively low. The flexural strength of marine silt bricks with 20% cement and water content = LL was around 1.5 MPa. The compressive and flexural strength decreased with the increase of water/cement ratio. As for the curing time, longer curing time had a positive impact on the compressive strength. The ratio of flexural to compressive strength varied slightly in the range of 0.4–0.5.     

Mapping soil organic carbon stocks of northeastern China using expert knowledge and GIS-based methods

The main aim of this paper was to calculate soil organic carbon stock (SOCS) with consideration of the pedogenetic horizons using expert knowledge and GIS-based methods in northeastern China. A novel prediction process was presented and was referred to as model-then-calculate with respect to the variable thicknesses of soil horizons (MCV). The model-then-calculate with fixed-thickness (MCF), soil profile statistics (SPS), pedological professional knowledge-based (PKB) and vegetation type-based (Veg) methods were carried out for comparison. With respect to the similar pedological information, nine common layers from topsoil to bedrock were grouped in the MCV. Validation results suggested that the MCV method generated better performance than the other methods considered. For the comparison of polygon based approaches, the Veg method generated better accuracy than both SPS and PKB, as limited soil data were incorporated. Additional prediction of the pedogenetic horizons within MCV benefitted the regional SOCS estimation and provided information for future soil classification and understanding of soil functions. The intermediate product, that is, horizon thickness maps were fluctuant enough and reflected many details in space. The linear mixed model indicated that mean annual air temperature (MAAT) was the most important predictor for the SOCS simulation. The minimal residual of the linear mixed models was achieved in the vegetation type-based model, whereas the maximal residual was fitted in the soil type-based model. About 95% of SOCS could be found in Argosols, Cambosols and Isohumosols. The largest SOCS was found in the croplands with vegetation of Triticum aestivum L., Sorghum bicolor (L.) Moench, Glycine max (L.) Merr., Zea mays L. and Setaria italica (L.) P. Beauv.     

西北地区东部夏季水汽输送特征及其与降水的关系

采用ERA Interim 再分析资料和160 站逐月站点降水资料,运用经验正交函数（EOF）分析、合成分析等方法揭示了西北东部3 个分区的水汽输送的区域气候特征、与降水EOF气候模态相对应的整层水汽输送特征以及降水偏多（少）年的水汽输送异常特征。结果表明：西北地区东部夏季经向水汽输送的大值区处于900 hPa~800 hPa 高度上;纬向水汽输送大值位于700 hPa~500 hPa 高度上。对西北东部降水做EOF 分析,第一模态为全区一致型,与降水相对应的西风影响区主要盛行西风水汽输送,季风边缘区的南部盛行西南风水汽输送;第二模态为东南-西北型,东风、东北风水汽输送流入西北东部地区;第三模态为东北－西南型,西风和西北风水汽输送将水汽带到西风影响区内。     

中晚全新世毛乌素沙地东南部气候变化过程

位于中国北方半干旱区的毛乌素沙地对气候变化响应敏感,是研究气候变化的理想区域。通过对毛乌素沙地东南部锦界剖面磁化率、有机质含量、CaCO₃含量的分析,重建了7.5 ka BP以来的气候变化过程。结果显示：中晚全新世毛乌素沙地东南部环境与气候变化可分为3个阶段：7.5～4.6 ka BP,夏季风占主导,气候暖湿,与全新世大暖期对应;4.6～3.3 ka BP,气候突变为干冷并波动频繁;3.3～2.5 ka BP气候以干冷为主。另外,存在5次千年尺度的干旱事件：7.0～6.8 ka BP、6.6～5.7 ka BP、4.6～4.1 ka BP、3.7～3.5 ka BP、3.3～2.5 ka BP。研究区气候变化与全球具有较好的一致性。     

北阿尔金地区古元古代岩体LA-ICP-MS锆石U-Pb年龄及其地质意义

北阿尔金是塔里木克拉通变质基底的主要出露区之一。对该区具有侵入接触关系的正长花岗岩和花岗片麻岩进行了LA-ICP-MS锆石U-Pb定年研究。正长花岗岩中的锆石多呈椭圆状,具有振荡环带结构,部分颗粒中可见老锆石残核,Th/U值较高,亏损轻稀土元素,富集重稀土元素,具有负Eu异常和正Ce异常的特点,表明该组锆石为岩浆成因。定年结果获得1903±13Ma和2506±55Ma两组年龄加权平均值,前者代表岩体的结晶年龄,后者为捕获锆石年龄,结合区域年代学资料,认为正长花岗岩岩浆侵入过程中可能捕获了太古宇米兰群的古老基底锆石。花岗片麻岩中16个测点的锆石~(207)Pb/~(206)Pb年龄集中于1802±28Ma,代表了岩体侵位时代,其余5个测点的锆石~(207)Pb/~(206)Pb年龄为1911~1951Ma,说明岩浆侵位过程中捕获了部分正长花岗岩的物质。区域地质与同位素年代学研究表明,北阿尔金地区广泛存在2.0~1.8Ga的构造-热事件。获得的花岗质岩石的1.9~1.8Ga的年龄结果,直接证实了北阿尔金存在约1.9Ga的岩浆作用,可能为古元古代Columbia超大陆汇聚事件在该地区的响应,为探讨塔里木板块前寒武纪构造-热事件演化历史提供了新资料。古元古代末期约1.8Ga的花岗片麻岩,代表了后造山伸展阶段的岩浆活动。     

Developing a small lake: The case of Palakpakin Lake,San Pablo City,Philippines

This study assesses the development issues of Palakpakin Lake. Premised on the scarcity of development studies on lakes (as the field is dominated by limnology and aquaculture studies) and small-lake studies (as the field is heavily concentrated on big-lake studies), the article argues that the lake has long been wanting of development initiatives from its administrative agencies. It further contends that the Laguna Lake Development Authority and the City Government of San Pablo must now act to promote development of the lake; specifically, by modifying their model-template approach, by formulating a zoning-development plan, and by fostering ecotourism. These basic actions are necessary in managing, developing and conserving the natural resource, as well as in preparing, informing and precipitating other actions on the lake.     

用连续GPS与远震体波联合反演2015年尼泊尔中部M_S8.1地震破裂过程

由于印度-欧亚板块碰撞,位于板块边界带的喜马拉雅地区大震频繁,但对其活动性的认识仍十分有限.2015年4月25日尼泊尔中东部地区时隔80年再次发生8级地震,为研究板缘地震提供了一次难得机遇.本文用西藏和尼泊尔的GPS连续观测数据和全球分布的远震地震波记录联合反演此次特大地震的破裂过程,结果显示此次地震发生在印度板块与青藏高原接触边界面——喜马拉雅主滑脱断层上.北倾11°、近东西(295°)走向的断层面破裂约100km长(博卡拉到加德满都),130km宽(从加德满都深入我国西藏吉隆县),破裂以逆冲滑动为主,平均幅度达到2.4m,释放的地震矩高达9.4×1020 N·m.反演结果还显示,震源体主要破裂分布深度范围为5~25km,应无地表破裂,属于一次盲地震.基于GPS资料推测的地壳现今运动速率及1833年地震的震源位置,我们推测地震在此次地震破裂区域复发的周期可能为150~200a,而极震区以南的深部滑脱断层仍保持闭锁,未来仍有导致灾害性大震的可能性.     

城市轨道交通不动产产籍信息数据库设计

近些年来,城市轨道交通的快速发展形成了大量的不动产产籍信息,这些信息涉及城市轨道交通全生命周期,时间跨度大、专业种类多、信息涵盖内容广、管理难度大。本文介绍了城市轨道交通不动产产籍信息涉及的种类,并根据信息特征设计了城市轨道交通不动产产籍信息数据库。     

significance of high-resolution loess stratification based on grain size and magnetic susceptibility analysis to paleo-earthquake study: a case study of dongyugou loess section,at hongtong,shanxi province

As an important technology to paleoseismologic research, trenching has been used to identify paleo-earthquakes recorded in strata, combined with dating technology. However, there have been some bigger uncertainties and limitations. For instance, subtle strata in loess sediment cannot be interpreted only by naked-eye, which seriously affects identifying paleo-earthquake horizon and time. Therefore, how to improve the accuracy and reduce the uncertainty of paleo-earthquake identification is the important problem we are currently facing. Dongyugou loess section, located in the northeastern corner of Linfen Basin, Shanxi Province, cuts across the Huoshan piedmont fault. The section exposes not only the well-developed loess sequence, but also several obvious faulting events. Thus, this loess section is a better site to make a high resolution study to improve the accuracy and reduce the uncertainty of paleo-earthquake identification. Based on the high-resolution grain size and magnetic susceptibility analysis, and associated with visual interpretation by naked-eye, we made a high-resolution stratification of Dongyugou loess section, including high-resolution thickness of each stratum and its upper and bottom boundaries. Based on the high-resolution stratification and their comparison between two fault walls, we identified three earthquake events, which occurred after formation of u5-7, u4 and u2, corresponding to their stratification depth of 7.1m, 4.7m and 2.9m in hanging wall. Based on results of OSL dating and average sedimentation rate of hanging wall, we estimated that the three events occurred around 45.8ka(between (48.1±1.5)～(43.2±2.5)ka), 32.8ka(between (35.0±2.4)～(30.6±1.3)ka) and 23.3ka(between (26.4±0.8)～(20.9±0.7)ka). According to the thickness difference of three loess-paleosol sedimentary cycles between two fault walls, we calculated the coseismic vertical displacements of the three events as 0.5m, 0.4 and 1.3m, respectively. Compared with other segments of the Huoshan piedmont fault zone, we found the southernmost segment is the weakest, with longer recurrence interval of about 11ka and lower vertical slip rate of 0.048mm/a. The high-accuracy grain size and magnetic susceptibility analysis offers an effective method for reducing the uncertainties of the paleo-earthquake research in loess area.