上海二次温室大棚区强尘卷风的成因分析     

戴蔚明  胡平  荣裕良  马忠芬  顾忠良 《气象科学》2019,39(1):117-128

尘卷风是近地面气层中的小旋风,使沙尘或其他细小物体随风卷起而形成的一种天气现象。2011年10月27日11时10分和2015年9月13日11时12分发生于上海地区的两次强尘卷风天气过程(北京时,下同)均造成了不同程度的灾害。两次尘卷风均发生在温室大棚区,其下垫面性质和干旱区裸露地面和水泥沥青城市地面极不相同,因此了解其发生原因很有必要。本文利用常规天气图、温度对数压力图、100 m以下5层铁塔风和温度、微波辐射仪以及温室大棚基地自动气象站等资料对这两次尘卷风过程进行了分析。发现.在常规探空都未探测到明显的超绝热现象,但在铁塔观测的地表面层温度垂直廓线结合微波辐射仪及自动气象站等资料揭示了尘卷风发生时近地面气层都具备了超绝热条件。尘卷风发生前后10∶00—12∶00的10～70 m温度垂直递减率γ平均达1.58℃/100 m,极大值达2.33℃/100 m,为干绝热递减率的两倍还多。上海地区10座铁塔测风网获得的10、30、50、70 m近地层风场的旋转和辐合特征揭示了尘卷风旋转的角动量来源。通过分析500、700、850 hPa天气形势探讨了有利于发生尘卷风的大尺度环流条件为尘卷风预报提供参考。最后对这两次尘卷风发生在温室大棚区域而不是自然农田的机理提出了初步看法供进一步讨论。  相似文献   

高密度电法在特大型滑坡应急勘查中的应用          下载免费PDF全文

郭一兵  姜鑫  郭富赟  丁保艳  吴正军  岳东霞  刘昌禄 《甘肃地质》2023,(3):82-87

为了快速、有效地评价滑坡滑动面埋深、下伏地层的起伏状况,本文以舟曲县果耶镇磨里滑坡为实例,在以地面调查和钻探等勘查手段深入了解磨里滑坡特征以及滑坡所在地形地貌和地层岩性的基础上,利用高密度电法对地下介质的敏感性特点对滑坡进行勘查,通过剖面解译推断了滑坡岩性、断裂破碎带、地下水等特征,为划定滑坡影响范围及估算滑坡体积提供数据支撑。研究结果表明：（1）在勘查区内灰岩、千枚岩是形成相对高阻的主要岩性,碎石土是形成相对低阻的主要岩性;（2）舟曲县果耶镇磨里滑坡平均深度40 m,总体积2 120 × 104 m3,属特大型深层滑坡;（3）高密度电法在特大型滑坡应急勘查中可发挥重要的作用。可为复杂性应急滑坡勘查提供一定的借鉴意义。  相似文献   

一种基于去混叠影像配准方法的POCS超分辨率序列图像重建   总被引：4，自引：0，他引：4  

范冲  龚健雅  朱建军 《测绘学报》2006,35(4):358-363

简要介绍超分辨率重建的原理和数学模型,采用一种新的超分辨率重建算法,这种算法通过去除低分辨率影像由于欠采样而产生的频率混叠部分以及频率中心的部分低频,来实现图像的精确配准;在计算旋转角度时,通过在图像中心建立极坐标系,求取设定角度精度范围内关于幅度谱的函数,将2维的相关函数转换成1维相关,大大提高计算效率;最后该算法采用POCS方法进行序列图像的高分辨率重建。实验仿真结果表明该算法具有良好的配准精度和超分辨率重建效果,具有良好的应用价值。  相似文献   

后压浆灌注桩在天津超高层建筑基础中的应用分析 张慧          下载免费PDF全文

张慧 《探矿工程》2018,45(3):84-86

阐述了后压浆技术补强灌注桩的基本原理,并以中海公园城项目为例,介绍后压浆灌注桩在天津软土地区超高层建筑基础中的实践应用,最后通过静荷载实测数据对比分析后压浆灌注桩在提高承载力和降低成本方面的优越性。  相似文献   

The Cretaceous Turn of Geological Evolution: Key Evidence from East Asia     

Victor P. NECHAEV  DAI Shifeng  F. Lin SUTHERLAND  Ian T. GRAHAM  Eugenia V. NECHAEVA 《《地质学报》英文版》2018,92(5):1991-2003

this work focuses on one of the critical points of Earth’s history when the Solar System passed through the most distant point of its galactic orbit. During this event, Earth may have suffered from maximum extension, associated with its relative proximity to the Sun at that time, followed by long-term contraction related to its later distancing. This paper is based on generalized data on the Cretaceous evolution of the Earth as a whole and of East Asia in particular. The evidence suggests that major geological processes at this time may be interpreted as transitional changes in the state of Earth. A liquid nature of its core may have reacted to the gravitational and electromagnetic transformations. When the cosmic changes took place at 135-120 Ma, more turbulent flows in the outer core would have favoured the rise of voluminous magmatic plumes and associated fluid flows. These would substantially transform the mantle, crust, hydrosphere, biosphere and atmosphere. In particular, plume-related melting of overlying subducting slabs and lower continental crust could have initiated numerous adakitic melts that formed the East Asian Adakitic Province. These and associated juvenile events produced numerous metallic ore, coal, gas and oil deposits. The Cretaceous is one of the most significant resource-producing periods.  相似文献   

Development of a New Method of Extraction of Interstitial Water from Low‐Porosity Consolidated Sediments Recovered During Super‐Deep Drilling Projects          下载免费PDF全文

Tomohiro Toki  Harue Masuda  Harunur Rashid  Sebastian Hammerschmidt  Ryuichi Shinjo 《Geostandards and Geoanalytical Research》2016,40(2):291-300

During the Integrated Ocean Drilling Program (IODP) Expedition 338, several methods were tested for the extraction of interstitial water in consolidated, low‐porosity deep‐sea sediments from Site C0002 in the Kumano Basin. On the basis of those tests, we propose a modified ground rock interstitial normative determination (GRIND) method of extraction of interstitial water. In separate runs of the new method, sediment samples were ground in a ball mill with either ultrapure water or a solution of HNO₃. The interstitial water was then extracted with a conventional squeezer. Sufficient solution was extracted by this method to analyse most major and a few minor components of interstitial water that were comparable to those previously reported for samples extracted by the conventional squeezing method. The new method requires much smaller amounts of sediment than that of the conventional method and will be useful for analysis of samples recovered during super‐deep drilling programmes.  相似文献   

白垩纪以来太平洋上地幔组成和温度变化   总被引：1，自引：0，他引：1  

张国良 《海洋学报(英文版)》2016,35(4):19-25

The geological evolution of the Earth during the mid-Cretaceous were shown to be anomalous, e.g., the pause of the geomagnetic field, the global sea level rise, and increased intra-plate volcanic activities, which could be attributed to deep mantle processes. As the anomalous volcanic activities occurred mainly in the Cretaceous Pacific, here we use basalt chemical compositions from the oceanic drilling(DSDP/ODP/IODP) sites to investigate their mantle sources and melting conditions. Based on locations relative to the Pacific plateaus, we classified these sites as oceanic plateau basalts, normal mid-ocean ridge basalts, and near-plateau seafloor basalts. This study shows that those normal mid-ocean ridge basalts formed during mid-Cretaceous are broadly similar in average Na8, La/Sm and Sm/Yb ratios and Sr-Nd isotopic compositions to modern Pacific spreading ridge(the East Pacific Rise). The Ontong Java plateau(125–90 Ma) basalts have distinctly lower Na8 and143Nd/144 Nd, and higher La/Sm and 87Sr/86 Sr than normal seafloor basalts, whereas those for the near-plateau seafloor basalts are similar to the plateau basalts, indicating influences from the Ontong Java mantle source. The super mantle plume activity that might have formed the Ontong Java plateau influenced the mantle source of the simultaneously formed large areas of seafloor basalts. Based on the chemical data from normal seafloor basalts, I propose that the mantle compositions and melting conditions of the normal mid-ocean ridges during the Cretaceous are similar to the fast spreading East Pacific Rise. Slight variations of mid-Cretaceous normal seafloor basalts in melting conditions could be related to the local mantle source and spreading rate.  相似文献   

Trimble S6超站仪在大比例尺地形图检验中的应用研究     

葛中华  申仲舒  李凉  张盼兴 《测绘与空间地理信息》2016,(1)

超站仪是将全站仪与GNSS整合在一起的新型测量设备,使用超站仪测量,无须控制点,利用CORS系统和似大地水准面精化模型,采用GNSS RTK技术获取测站点坐标和高程,并按全站仪功能进行地形要素采集。本文以Trimble S6超站仪为研究对象,在大比例尺地形图测绘成果质量检验应用中提高了检验效率,实现了检验智能化。  相似文献   

2015年西北太平洋台风季提早展开:2015/2016超级厄尔尼诺的影响   总被引：1，自引：0，他引：1       下载免费PDF全文

钱伊恬  徐邦琪 《大气科学学报》2016,39(6):788-800

2015年1-5月西北太平洋上异常出现了7个热带风暴（Tropical Storms,TS）,其中有5个发展成台风（Typhoons,TY）,分别为气候平均态（1979-2015年）的2.5和3.6倍,亦即2015年的台风季提前展开。利用ERA-Interim再分析资料、JTWC热带气旋最佳化路径数据等资料,通过计算台风生成指数（Genesis Potential Index,GPI）和比较天气尺度和季节内振荡分量,探讨2015年台风季提前的原因。结果表明：1）2015年初异常活跃的台风活动与2015/2016年超级El Niño事件于西北太平洋上引发的海气状态异常有关。2）通过对大尺度环境场和台风潜在生成指数（GPI）的诊断分析发现,动力因子（低层涡度、垂直速度）和热力因子（与海表面温度、大气温度有关的潜在强度、中低层大气相对湿度）均对2015年1-5月台风的发生有正贡献。其中,涡度项的贡献最大,相对湿度的贡献次之。3）3~10 d天气尺度扰动和10~90 d季节内振荡在2015年1-5月也异常活跃,有利于TS和TY的生成与发展。  相似文献   

2016年6月23日江苏阜宁EF4级龙卷天气分析   总被引：7，自引：0，他引：7  

张小玲  杨波  朱文剑  方翀  刘鑫华  周康辉  蓝渝  田付友 《气象》2016,42(11):1304-1314

2016年6月23日,江苏省盐城市阜宁县发生了历史罕见的EF4级龙卷,导致99人死亡,846人受伤,并有大量建筑物被损毁。文章利用观测资料对产生强龙卷的天气背景和中尺度特征进行了分析,发现：阜宁龙卷发生在我国东部龙卷最高发的地区和季节,产生龙卷的天气尺度背景为典型的梅雨期暴雨环流,产生龙卷的中尺度对流系统发生在地面暖锋南侧,这里也是高低空急流耦合的区域,与高空急流相伴的动力强迫特征明显,大气热力不稳定条件为中等偏强;产生阜宁龙卷的中尺度对流系统与美国大部分强龙卷相似,为块状的离散单体对流模态,且具有经典超级单体的钩状回波和强中气旋特征,并伴有龙卷涡旋特征（tornado vortex signature,TVS）;龙卷位于钩状回波顶端,主要发生在中气旋底高高度低于1 km期间。  相似文献