引起“碧利斯”强降水的MCS数值模拟研究

利用多种观测资料和数值模拟,对0604号强热带风暴碧利斯登陆后在湖南、广东等地引发强降水的中尺度对流系统活动特征进行了分析.结果表明,在"碧利斯"登陆后西行减弱过程中,由于西南季风的持续维持,"碧利斯"减弱后的低压环流中仍保持有强降水所需的充足水汽供应,造成局地强降水的MCS十分活跃.ARPS模式较好地模拟了7月15日发生在湖南南部的中尺度降雨过程,并揭示出"碧利斯"变性过程中,环境风场垂直切变结构强迫的次级环流决定了MCS活动特点,同时利用湿Q矢量诊断了低压次级环流的垂直运动特征.造成这次强降水过程的MCS在台风低压切变线以北的偏北潮湿气流中生成发展,低层偏北急流造成的动力辐合效应、对流不稳定性层结的建立是MCS在湖南南部迅速发展的重要原因.     

海南岛白沙陨击坑及其成坑陨石

海南岛白沙陨击坑是一个直径约３．５ｋｍ的环形镶边坳陷，组成陨击坑边缘的环形山连续性好，并具二元结构；下部是层理清晰的下白垩统紫红色砂岩，其中长石、石英等粒状矿物普遍受冲击破碎，发育有冲击微页理和击变玻璃，云母呈膝折状变形；上部是冲击角砾岩块杂乱堆垒成的溅射覆盖层，冲击角砾岩因冲击熔融结晶而貌似凝灰岩，但其中矿物成分十分复杂，含有镁橄榄石、镍纹石以及高密度石英等，岩石化学计算结果说明它是由砂岩变质而成的，与火成岩无关。坑内保留有回落角砾岩，常见到沿裂缝贯入的脉状角砾岩。在陨击坑内找到了重３．７５ｋｇ的石陨石碎块，其中含碱硅镁石、陨铁大隅石、四方镍纹石、陨硫钙石和陨硫铁等陨石标型矿物，但不具球粒结构，ＣａＯ含量为９．１９％，属富钙的无球粒陨石，认为是白沙陨石坑的成坑陨石。在陨击坑中找到富钙无球粒陨石，为陨击坑提供了最直接可靠的证据，也为石陨石撞击成坑提供了实例。     

地学巨著 益学益用——评《冯增昭文集》

《冯增昭文集》是庆祝冯增昭教授80华诞暨从事地质教育工作55年而出版的综合性地学类著作。全书包括4个部分:第一部分为20篇岩相古地理学文章,第二部分为13篇沉积学文章及其他文章,第三部分为17部沉积学及岩相古地理学专著的序,第四部分为6部沉积学翻译著作的序及两篇译文。她是冯增昭教授近50年来已刊和未刊著作的代表和精炼,是一部地学鸿篇,有诸多特点。     

四川盆地东北部春夏两次冰雹天气过程对比分析

利用常规气象资料、NECP 1°×1°6小时再分析资料和达州CINRAD/SC多普勒天气雷达资料对出现在四川东北部的两次冰雹天气过程进行了综合分析。分析结果表明,这两次过程都发生在高空西北气流和低层暖空气形成的不稳定层结中,均具有中等到强垂直风切变,为冰雹的出现提供了有利的环境条件;0℃和-20℃层高度是影响冰雹直径的关键因素。从雷达分析得知,"7.19"冰雹为多单体线性风暴,回波结构呈块状分布,具有弱的中气旋,回波悬垂不明显,"4.20"冰雹过程回波结构呈钩状分布,具有回波悬垂和中气旋结构特征。      

基于动态统计预报方法的京津冀雾霾中期预报试验

利用欧洲中期天气预报中心（ECMWF）数值预报产品和动态统计预报方法,对北京、天津、石家庄等14个京津冀重点城市雾霾与空气污染进行定量化的中期预报试验,包括对首要污染物PM_2.5浓度和能见度的逐时定量化预报及雾霾现象的客观化判断,并对2015年10月1日-2016年11月10日试验预报效果进行了检验评估。检验结果显示:该方法对北京及周边城市未来10 d逐时和逐日能见度、PM_2.5浓度及雾霾现象的预报值与观测值之间具有显著正相关系数、较高的误差减少量和TS评分等,表明基于ECMWF数值预报产品和动态统计预报方法的京津冀雾霾污染中期定量化预报技术整体上具有较高的可靠性、稳定性与预报技巧性。此外,检验指标还显示出该动态统计预报方法对能见度的预报效果要略优于PM_2.5浓度预报,同时对霾的预报准确率高于对雾的预报。个例分析显示,该动态统计预报方法能提前5~6 d预报出北京地区典型持续性雾霾污染的发展过程,对持续性雾霾的提前预报预警具有较好的参考意义。     

Low-amplitude BSRs and gas hydrate concentration on the northern margin of the South China Sea

The passive northern continental margin of the South China Sea is rich in gas hydrates, as inferred from the occurrence of bottom-simulating reflectors (BSR) and from well logging data at Ocean Drilling Program (ODP) drill sites. Nonetheless, BSRs on new 2D multichannel seismic reflection data from the area around the Dongsha Islands (the Dongsha Rise) are not ubiquitous. They are confined to complex diapiric structures and active fault zones located between the Dongsha Rise and the surrounding depressions, implying that gas hydrate occurrence is likewise limited to these areas. Most of the BSRs have low amplitude and are therefore not clearly recognizable. Acoustic impedance provides information on rock properties and has been used to estimate gas hydrate concentration. Gas hydrate-bearing sediments have acoustic impedance that is higher than that of the surrounding sediments devoid of hydrates. Based on well logging data, the relationship between acoustic impedance and porosity can be obtained by a linear regression, and the degree of gas hydrate saturation can be determined using Archie’s equation. By applying these methods to multichannel seismic data and well logging data from the northern South China Sea, the gas hydrate concentration is found to be 3–25% of the pore space at ODP Site 1148 depending on sub-surface depth, and is estimated to be less than values of 5% estimated along seismic profile 0101. Our results suggest that saturation of gas hydrate in the northern South China Sea is higher than that estimated from well resistivity log data in the gas hydrate stability zone, but that free gas is scarce beneath this zone. It is probably the scarcity of free gas that is responsible for the low amplitudes of the BSRs.     

Deposition of duststorm particles during 2000–2012 in the South Yellow Sea,China based on satellite data

In this study,about 220 satellite images between 2000 and 2012 were obtained from FY-series,MODIS,CBERS,HJ-1A and HJ-1B to estimate the impact of duststorms on the South Yellow Sea(SYS),which serve as an important source of particles there.The analyzing results from the images support a total occurrence of 88 duststorms(including the locally-generated dusty weather) that affected the SYS during 2000–2012.The annual occurrence was about 4–10 times(10 times in 2000 and 2004;four times in 2009 and 2012),predominantly in March(29%),April(33%) and May(22%).By mapping the distribution of their frequency,the duststorms influencing the SYS were found primarily moving from the northwest(39 times,44.3%) and west(37 times,42%) to the study region with only 11 duststorms(12.5%) coming from the north and 1 duststorm(1%) from the southwest.We estimated that an annual amount of 0.5–3.5 million tons of sediment particles was brought to the SYS by the duststorms during 2000–2012.     

Research in migration route of hatchery released Chinese shrimp (Fenneropenaeus chinensis) in the Bohai Bay using method of SSR marker

This study provides new insights for the hatchery released Chinese shrimp(Fenneropenaeus chinensis), including proportion, dynamic migration route, after they were released into nature for stock enhancement using a new strategy quite different than ever. Chinese shrimp were sampled at 22 survey stations during two investigation voyages acrossing 74 survey stations in the Bohai Sea from July 16 to August 9 in 2015. Among 289 sampled individuals during the second voyage, totally 155 shrimps were i...     

广东省突发性地质灾害气象预警实践

本文基于十年来的地质灾害气象预警工作实践,统计分析了广东省历年来降雨及突发性地质灾害的特点,揭示了广东省突发性地质灾害在不同降雨量、降雨强度及降雨类型下的成灾规律;并在总结地质灾害气象预警工作实践成果的基础上,分析存在问题,提出进一步完善地质灾害预警的技术与方法,为地质灾害气象预警精细化和实时临灾预警提供科学依据。     

鄂尔多斯盆地西北部上三叠统延长组长8油层组浅水三角洲沉积特征及湖岸线控砂

鄂尔多斯盆地西北部上三叠统延长组长8油层组主要受西北沉积体系控制,沉积期构造背景稳定,发育浅水三角洲沉积。大量的岩心观察表明,煤线、植物叶片、根系、虫孔、沉积构造等浅水环境标志广泛分布,反映了沉积时水体较浅（数米至十余米）。研究区长8油层组主要发育浅水三角洲前缘亚相沉积,水下分流河道是主要的沉积微相。与典型的河控三角洲不同,其沉积相带分布范围宽广,三角洲平原与三角洲前缘、前三角洲在平面上平缓相接,无明显的转折。其中,三角洲前缘可进一步细分为三角洲内前缘和三角洲外前缘。长8油层组水下分流河道砂体延伸较远,规模较大,具有顺河道方向局部厚层砂体呈坨状分布、垂直河道方向坨状砂体围绕湖盆呈环带状展布的特征,这种砂体展布特征主要受湖岸线位置控制,即湖岸线控砂,与拗陷湖盆坡折带控砂特征明显不同。