黔东南暴雨气候特征及其地形影响

利用1960~2000年贵州省黔东南地区降水观测资料,统计分析黔东南地区暴雨时空分布特征,进一步揭示其活动规律及主要影响因素。结果表明:黔东南地区暴雨有显著年代际变化特征,存在准15年的周期变化,并与贵州降水和长江中下游降水呈同位相;存在两个暴雨多发中心,夜间暴雨较多。黔东南暴雨地域分布极为复杂,局地性暴雨较多,这与黔东南特殊地形有着密切关系,地形因素是影响黔东南地区暴雨的重要原因,对形成上述特征的气候学成因做了初步讨论。     

Tectonic Features of the M_S8.0 Wenchuan Earthquake and Its Aftershocks

The M8.0 Wenchuan earthquake occurred on the Longmenshan fault zone. Based on field investigation of the surface rupture and focal mechanism study of the aftershocks, we discuss the geological relationship of the main, secondary and triggered ruptures. The main rupture is about 200km long and can be divided into the south part and the north part. The south part consists of two parallel fault zones characterized by reverse faulting, with several parallel secondary ruptures on the hanging wall of the main fault, and the north part is a single main fault zone characterized by lateral strike-slip and reverse faulting. Compared to a 300km long aftershock distribution, the surface rupture only occupies 200km, and the remaining 100km on the northeast of the main rupture was triggered by aftershocks. Study on the ruptures of this earthquake will be useful for studying the earthquake risk evolution on the Longmenshan fault system.     

科里奥利力对断层作用的统计研究

首先给出了分解到已知断层面法向和切向上的断层错动科里奥利应力(简称为科里奥利法向应力和切向应力)表达式,然后从哈佛大学矩心矩张量目录中选取主余震资料进行分析,按断层分类研究了科里奥利法向应力和主震震级与其最大余震震级差及主震地震矩与余震地震矩总和之差的折合矩震级间的关系.研究结果显示:地震断层错动过程中虽然产生了使断层两盘相互拉离(或挤压)的科里奥利法向应力,它降低(或增加)了断层错动时断层面上的摩擦阻力,但是应力量值太小(科里奥利法向应力估计最大不到0.1MPa,即不到一个大气压),不足以对断层错动及主震能量释放产生影响,从而影响余震的最大震级和总体水平.     

我国全新世泥炭α纤维素稳定碳同位素记录的对比与分析

泥炭是古气候研究的宝贵材料,α纤维素稳定碳同位素（δ¹³C_cell）是泥炭古气候研究的常用代用指标。我国已有数个地点报道了全新世泥炭全样或单种植物δ¹³C_cell记录,对这些记录的古气候解译存在明显冲突。结合相应的孢粉和植物残体证据,对这些记录进行综合对比,结果发现：高山草地植被带和内陆干旱区荒漠草原植被带当中的泥炭地,全新世期间的原地植物种属构成相对稳定且未发生显著变化,因此其δ¹³C_cell记录具有较为明显的长期变化趋势,其古气候解译也更为可靠;森林植被带和林草交互带当中的泥炭地,全新世期间的原地植物种属构成发生过显著变化（如木本植物入侵）,这可能是造成其全新世δ¹³C_cell记录长期趋势不明显或其古气候指示意义复杂难解的主要原因。这些结果显示了泥炭地的原地植物种属构成,对相应δ¹³C_cell记录的古气候解译的重要影响。同时也表明,无论是泥炭δ¹³C_cell研究地点的选择,还是泥炭δ¹³C_cell记录的古气候解译,都需重视其来源植物种属构成和变化。对于全新世泥炭δ¹³C_cell古气候研究,建议开展针对性的现代过程研究,尤其是优势泥炭植物种属的δ¹³C_cell在时间序列上的现代过程研究,以提供可靠的古气候解译基础。

     

Influencing factors for formation of urban and rural spatial structure in metropolis fringe area—Taking Shuangliu County of Chengdu in China as a case

With rapid urbanization process, the pace of urban sprawl has been quickened and most metropolises have experienced expansions in leaps and bounds in suburbanization, which has greatly changed the urban and rural spatial structure of the metropolis fringe area. In this paper, Shuangliu County is taken as a case, since it is a typical fringe area of Chengdu Metropolis. Based on Landsat TM images of Chengdu City and Shuangliu County obtained in 1985, 2000 and 2004, characteristics of urban and rural spatial structure in Shuangliu County were analyzed, such as core-periphery spatial structure and some obvious integration trends. Then the influencing factors for the formation of urban and rural spatial structure were identified, including some natural, social, economic and political factors. According to the discussion of this paper, Shuangliu County is undergoing a key transition and reform period. Its formation of urban and rural spatial structure was affected not only by such common factors as the location, natural background, industrial transition, migration, etc., but also by some unique factors such as city planning and policy guidance, which played an important role in accelerating its uneven spatial structure. The understanding of the role of the influencing factors would be useful for carrying out spatial management and development planning of metropolis fringe area.     

苏北浅滩养殖筏架附生绿藻入海过程在黄海绿潮形成中的作用

本研究采用现场定量观测为主的研究方法,在2017年5月期间对苏北浅滩竹根沙收紫菜养殖筏架作业过程进行跟踪调查;对养殖筏架绠绳附生绿藻自然脱落和收筏架作业过程人为刮落附生绿藻,以及收筏架作业前后入海的漂浮绿藻生物量进行定量观测。结果表明:筏架绳附生绿藻自然脱落率低,为3.58%±0.78%;收筏架作业过程中绠绳上刮落绿藻生物量为(12±3)kg湿重/根,由此估算2017年整个苏北浅滩刮落的生物量估算可达到万吨湿重;收筏架作业后海域漂浮绿藻生物量是作业前的7.6倍。研究结果进一步明确了收筏架作业过程中人为刮落绿藻是目前筏架附生绿藻最主要的入海方式。刮落绿藻是海水中漂浮绿藻的主要来源,其生物量对南黄海绿潮的规模大小有重要的影响。研究结果为绿潮防控措施的制定和实施提供科学依据。     

Recent Progresses in Comparative Planetology——Summary of the Session of Comparative Planetology at the 3rd Conference of Earth System Sciences

Comparative planetology is an interdisciplinary science between Earth sciences and astronomy. It studies physical, chemical and dynamical properties of planets and satellites and their surface characteristics, interior structures and chemistry, magnetic field, climate and possible existence of life. Although the study of comparative planetary science is at its infancy stage in China, it is very encouraging to see that 25 papers were received by the session, which is much more than what we expected. It indicates that more and more scientists are interested in this research field. These papers can be classified into three categories: solar planets, extra-solar planets, and moon explorations. Scientists from both China and oversea reported their recent results.     

近50a察右中旗干旱变化主要特征分析

文章利用察右中旗1961-2010年4-9月降水量资料和1980-2010年土壤水分资料,根据农业气候学中的降水量、土壤水分、降水量距平百分率干旱指标,计算分析了察右中旗近50a来干旱特征。     

基于EnKF综合水头和浓度观测数据推估地下水流模型参数

地下水反应运移模型具有参数个数众多,观测数据类型多样的特点。为了探究不同类型观测数据在反应运移模拟数据同化中的数据价值,构建了三氯乙烯降解反应运移模型的理想算例,基于水头和浓度两种类型观测数据,采用集合卡尔曼滤波方法推估渗透系数和贮水系数的非均质空间分布,讨论了影响同化结果的因素。结果表明:与仅同化水头数据的结果相比,联合同化水头和浓度观测数据推估渗透系数场和贮水系数场时具有更高的精度,在观测数据拟合和模型预测方面也有更好的表现。与目前溶质运移模型、非饱和流模型等地下水模型中的研究结果相似,数据同化结果受样本数量,观测井的数量和位置的影响,合理优化布置监测井和选择样本数量可有效改善数据同化效果并提高计算效率。