Statistical relationship between solar wind conditions and geomagnetic storms in 1998-2008

Applying ACE data and pressure-corrected Dst index (Dst*), annual distributions of solar wind structures detected at L1 point (the first Lagrangian point between solar-terrestrial interval) and correlations between solar wind structures and geomagnetic storms in 1998-2008 have been studied. It was found that, within the Earth's upstream solar wind, the dominant feature was interplanetary coronal mass ejections (ICMEs), primarily magnetic clouds, during solar maximum period but corotating interaction regions (CIRs) at solar minimum. During rising and declining phases, solar wind features became unstable for the complicated solar corona transition processes between the maximum and minimum phases, and there was a high CIR occurrence rate in 2003, the early period of the declining phase, for the Earth's upstream solar wind was dominated by high-speed southern coronal-hole outflows at that time. The occurrence rate of sector boundary crossing (SBC) events was evidently higher at the late half of declining phase and minimum period. ICMEs mainly centered on the maximum period but CIRs on all the declining phase. The occurrence rate of ICMEs was 1.3 times of that of CIRs, and more than half of ICMEs were magnetic clouds (MCs). Half of magnetic clouds could drive interplanetary shock and played a crucial role for geomagnetic storms generation, especially intense storms (Dst*≤100 nT), in which 45% were jointly induced by sheath region and driving MC structure. Sixty percent of intense storms were totally induced by shock-driving MCs; moreover, 74% of intense storms were driven by magnetic clouds, 81% of them driven by ICMEs. Shock-driving MC was the most geoeffective interplanetary source for four fifths of it able to lead to storms and more than one-third to intense storms. The rest of intense storms (19%) were induced just by 3% of all detected CIRs, and most of CIRs (53%) were corresponding to nearly 40% moderate and small storms (−100 nT<Dst*≤−30 nT). The true sector boundary crossing (SBC) events actually had no obvious geoeffectiveness, just 6% of them corresponding to small storms.     

3D Coronal Structures and Magnetic Field During the Total Solar Eclipse of 29 March 2006

The good quality of the observing sequence of about 60 photographs of the white-light corona taken during the total solar eclipse observations on 29 March 2006, in Al Sallum, Egypt, enable us to use a new method of image processing for enhancement of the fine structure of coronal phenomena. We present selected magnetic-field lines derived for different parameters of the extrapolation model. The coincidence of the observed coronal white-light fine structures and the computed field-line positions provides a 3D causal relationship between coronal structures and the coronal magnetic field.     

Impact of terrain heterogeneity on near-surface turbulence structure

This study investigates the impact of terrain heterogeneity on local turbulence measurements using 18 months of turbulence data taken on a 30 m tower at the SIRTA mixed land-use observatory under varying stability conditions and fetch configurations. These measurements show that turbulence variables such as the turbulent kinetic energy or momentum fluxes are strongly dependent on the upstream complexity of the terrain (presence of trees or buildings, open field). However, using a detection technique based on wavelet transforms which permits the isolation of the large-scale coherent structures from small-scale background fluctuations, the study shows that, for all stability conditions, whatever the upstream complexity of the terrain, the coherent structures display universal properties which are independent of the terrain nature: the frequency of occurrence, time duration of the coherent structures, the time separation between coherent structures and the relative contribution of the coherent structures to the total fluxes (momentum and heat) appear to be independent of the upstream roughness. This is an important result since coherent structures are known to transport a large portion of the total energy. This study extends to all stability conditions a numerical study by Fesquet et al. [Fesquet, C., Dupont, S., Drobinski, P., Barthlott, C., Dubos, T., 2008. Impact of terrain heterogeneities on coherent structures properties: experimental and numerical approaches. In: 18th Symposium on Boundary Layers and Turbulence. No. 11B.1. Stockholm, Sweden., Fesquet, C., Dupont, S., Drobinski, P., Dubos, T., Barthlott, C., in press. Impact of terrain heterogeneity on coherent structure properties: numerical approach. Bound.-Layer Meteorol.] conducted in neutral conditions which shows that a reason for such behavior is that the production of local active turbulence in an internal boundary layer associated with coherent structure originating from the outer layer and impinging onto the ground is not sensitive to the nature of the terrain.     

台风莫拉克登陆期间的中尺度波动特征分析

利用波作用理论对台风莫拉克登陆期间的降水进行诊断分析。结果表明:波作用密度异常能在一定程度上指示暴雨雨区发展移动,其异常值的空间分布能够反映雨区上空动力场和热力场的典型垂直结构特征。台风内中尺度波动与暴雨落区宏观上具有一定联系。为了详细研究台风内部的波动特征,利用WRF(Weather Research and Forecasting model)模式模拟的高分辨率资料对台风登陆过程中波动特征进行分析,低波数波动的传播主导强对流的非对称分布,2波在登陆初期对对流分布起着关键作用,中尺度波动中同时存在涡旋罗斯贝波以及重力惯性波的特征,对登陆期间涡旋混合的现象有重要作用。     

松辽盆地十屋断陷反转构造与油气聚集

晚期强烈构造反转是十屋断陷构造发育的一个重要特色。本文以高分辨率三维地震资料为基础,结合相干技术和三维可视化技术等先进地震资料处理和解释技术,对研究区反转构造进行了精细构造解释和研究。将研究区反转构造划分为四个反转构造带,在对反转构造样式再认识的基础上在十屋乃至松辽地区新发现了欺压式断层和截断型反转构造两种反转构造样式。进而将反转构造样式除坳陷层滑脱褶皱外,依据反转过程中形成的逆断层与早期伸展断层的组合关系归纳为五种类型:复活型、前展型、后展型、欺压型、截断型。并对反转构造与油气聚集之间的关系作了深入探讨,研究认为区内反转构造具有十分有利的成藏条件且四个反转构造带具有不同的圈闭类型和油气聚集特点。初步建立了十屋断陷基于反转构造的油气成藏模式,为进一步油气勘探提供了依据。     

青藏高原新生代地堑构造研究中几个问题的讨论

青藏高原新生代近南北走向地堑构造是高原现今最为显著的构造现象,对探讨青藏高原构造演化具有重要意义,也是现今高原研究的热点构造问题之一。针对目前地堑构造研究中存在的分布范围、形成时代和形成机制等关键问题,根据笔者新的研究和对以往研究资料综合分析认为,地堑构造广泛发育于喜马拉雅地体、冈底斯地体和羌塘地体,地堑构造形成于14～7Ma。地堑构造是高原地壳南北向强烈挤压短缩隆升之后,构造体制发生转变并在深部热动力学机制作用下快速隆升的结果,地堑构造标志着高原隆升作用由早期挤压短缩机制向晚期深部热动力机制的转变,并非高原隆升达到最大高度重力塌陷的标志。     

沉积物再悬浮对食浮游动物鱼类捕食浮游动物的影响

在亚热带浅水湖泊中,由风浪引起沉积物再悬浮是其重要特征之一.沉积物再悬浮一方面直接影响浮游动物群落结构,另一方面通过影响食浮游动物鱼类对浮游动物的捕食而产生间接影响.以食浮游动物鱼类——餐条(Hemiculter leucisculus)为实验对象,通过模拟实验,比较不同再悬浮条件下餐条对浮游动物群落结构的影响.结果显示,在有餐条的处理组中,大型枝角类短钝溞(Daphnia obtusa)只在弱再悬浮条件下出现,并成为枝角类群落的优势种;在无餐条的处理组中,短钝溞生物量随再悬浮强度减弱而增加.强再悬浮(无餐条)和无再悬浮(有餐条)条件下,小型枝角类角突网纹溞(Ceriodaphnia cornuta)和盘肠溞(Chydorus sp.)为优势种.无论有、无餐条条件下,桡足类优势种均为中剑水蚤(Mesocyclops sp.),其生物量随再悬浮强度减弱而增加.所有处理组中,轮虫丰度均低于枝角类和桡足类丰度.研究表明,在亚热带浅水湖泊中,适当的悬浮质浓度既能干扰食浮游动物鱼类对大型浮游动物的捕食,又不影响大型浮游动物的生存,使得它们保持一定的丰度,通过对浮游植物的摄食,降低叶绿素a浓度.     

烟台市及其邻近地区活断层地震危险性评价

本文是"十二五"国家科技支撑计划项目专题(2012BAK19B04-01)"郯庐地震断裂带中段地震活动规律及地震危险区判定研究"部分成果的总结。在分析了烟台市及其邻近地区的地震地质、地球物理、断层综合地球物理探测、探槽开挖、断层活动性鉴定等技术手段获得的反映区域地震构造环境、深部构造背景、活动断裂长期滑动习性的定性和定量资料、历史与现代地震活动性和地球动力学资料的基础上,甄别出了具有发生破坏性地震的活断层段。同时采用定性、定量和综合判定的方法,评价了烟台市及其邻近地区主要活动断裂的地震危险性。本文的研究成果可为胶东半岛地区的地震监测预报、地震区划、震害预测和断层危害性评价提供基础依据。     

A comparison of summer precipitation structures over the South China Sea and the East China Sea based on tropical rainfall measurementmission

The three-dimensional structures of summer precipitation over the South China Sea （SCS） and the East China Sea （ECS） are investigated based on tropical rainfall measurement mission （TRMM）. The primary results are as follows. First, both the convective and stratiform precipitation rates in the SCS are much higher than those of the ECS. The contribution of the convective cloud precipitation to the surface precipitation is primarily over the SCS and the ECS with a proportion of about 70%, but the contribution of convective cloud precipitation is slightly larger in the SCS than the ECS. The contribution of stratus precipitation is slightly larger in the ECS than that in the SCS. Second, the content of cloud particles and precipitation particles in the ECS in June was greater than that in the SCS, while in July and August, the content of cloud and precipitation particles in the ECS was less than that in the SCS. Third, the latent heat profile of the ECS is quite different from that of the SCS. In June, the peak values of evaporation and condensation latent heating rates in the ECS are greater than those in the SCS. In July and August, however, the peak values of evaporation and condensation latent heating rates in the ECS are about 0.05°/h less than those in the SCS.     

The impact of coastal defence structures (tetrapods) on decapod crustaceans in the southern North Sea

Although the use of coastal defence structures is expected to increase, little is known about the ecological impact of such structures on the natural environment. In particular, the temporal and spatial patterns of communities in association with artificial substrate are still poorly understood. This study examined possible effects of experimental tetrapod fields on the decapod crustacean community in a subtidal hard-bottom area in the southern North Sea. We performed in situ studies in the fields and along transects oriented away from the tetrapod fields. Species composition and abundances were assessed before and after the introduction of the artificial material. The study revealed a significant decrease of smaller, less vagile species (Pisidia longicornis, Pilumnus hirtellus, Galathea squamifera) over the entire study area in the years following the tetrapod introduction. For 2 species, Hyas araneus and Homarus gammarus, the tetrapods appeared to be highly attractive as habitat and shelter because their abundance increased over time. No distinct spatial or temporal effects were observed for mobile predatory crabs, such as Cancer pagurus and Liocarcinus spp. The results of the study demonstrate that possible effects of artificial structures on macro-invertebrates in temperate hard-bottom areas are highly species-specific and depend on the size, lifestyle and ecological requirements of the species. This work highlights the importance of long-term studies. Our findings clearly indicate that more time is needed to distinguish between natural and anthropogenic influences on species distributions.