干侵入对我国东部一次强飑线过程的作用分析     

崔强  王春明  张云 《沙漠与绿洲气象(新疆气象)》2016,10(2):18-24

利用NCEP/NCAR再分析资料、雷达资料、FY2E卫星资料等,对2014年7月30日至31日发生在我国东部的一次强飑线天气过程进行综合分析,并着重分析了干侵入对此次飑线过程的作用。结果表明：中层阶梯槽引导高层干冷空气向下入侵后叠加在低层暖湿气流之上,增强了大气不稳定,不稳定能量累积;低空切变线促使不稳定能量释放,是此次飑线的重要触发机制。对干侵入的分析结果表明：此次飑线过程中,干侵入来源于高空槽后下沉气流,干侵入底部风场调整使得飑线在移动过程中发生了转向。在飑线发展过程中,干侵入范围扩大、强度增强;干侵入使飑线发生区域上空空气变冷、变干,增强了大气不稳定。干侵入底部的低相当位温空气与飑线内部高相当位温空气混合是飑线长时间维持的重要原因。  相似文献   

黄土高原一次超级单体短时强降水中尺度分析   总被引：2，自引：2，他引：0  

王楠  李萍云  井宇  赵强 《气象科学》2016,36(6):742-751

2012年盛夏陕西绥德县出现短时强降水,4 h雨量超过100 mm。利用NCEP 1°×1°再分析资料进行诊断分析发现,在陕北东北部对流层中下层有一中α尺度气旋存在,且随高度向东北倾斜,垂直方向上形成次级环流,使强降水区的上升运动加剧。分析地面观测、卫星资料发现,西路冷空气引导干侵入加强层结不稳定性,东路冷空气楔形抬升作用,使得不稳定能量释放;同时,在东西两路干冷空气的夹击作用下,绥德县内形成中气旋,暖湿空气在当地得以聚集上升;2个中β尺度对流云团在东西路风场作用下合并后迅速增强。多普勒雷达资料显示,2个中γ尺度的超级单体回波在绥德先后发展形成列车效应;2个超级单体中的中气旋特征各有不同,是回波结构演变的主要原因。  相似文献   

刘店煤矿岩浆侵入与煤质特征初探   总被引：1，自引：0，他引：1  

陈富勇 《安徽地质》2007,17(1):34-36

岩浆侵入是煤矿常见的构造现象之一,岩浆侵入后对煤层与煤质的影响也十分明显,岩浆侵入不仅破坏了煤层的原生结构、厚度、构造,还改变了煤质.本文依据刘店煤矿的勘探资料,对淮北矿业集团公司筹建矿井--刘店煤矿的岩浆侵入与煤质特征进行了探讨,以期为刘店煤矿的生产提供有益的帮助.  相似文献   

莱州湾南岸潍河下游地区咸水入侵灾害成因及特征   总被引：8，自引：1，他引：7  

刘恩峰  张祖陆  沈吉  宋俊峰 《地球科学与环境学报》2004,26(3):78-82,87

通过对莱州湾南岸咸水入侵较严重地潍河下游地区晚更新世以来沉积特征及现代自然环境条件变化的分析，探讨了沉积相对咸水入侵产生及空间范围特征的环境机理。晚更新世以来的三次海平面升降变化造成了潍河下游地区海陆沉积环境交替，形成了巨厚的海陆交互相沉积层。海进时期，大面积的滨海平原被淹没，在近海平原洼地滞留的海水经过蒸发、浓缩变为卤水，成为咸水入侵的物源；海退后陆源碎屑在滨海地区沉积形成了巨厚的古河道砂层。20世纪70年代末期以来，随着对地下淡水的过度开采，淡咸水水头压力差减小．卤水通过古河道砂层快速南侵。通过对潍河下游地区100余个地质钻孔水化学连续监测资料分析，阐明了咸水入侵的特征，有针对性地提出了咸水入侵的防治措施。  相似文献   

Statistical analysis of surface hydrography and circulation variations in northern South China Sea     

吴玲娟  崔茂常 《中国海洋湖沼学报》2005,23(4):383-392

1 INTRODUCTIONThe South China Sea (SCS) is a semi-enclosedmarginal sea in western North Pacific Ocean withvery complex topography and is the important pas-sage connecting the Pacific and Indian Oceans. Ithas great impact to the global climate and a greatinterest of many oceanography researchers. Twodominant surface hydrographic and circulation fea-tures in the northern SCS are a strong fresh waterexpansion and a warm and high-salinity seawaterintrusion such as the SCS Diluted Water…  相似文献   

On salinity regimes and the vertical structure of residual flows in narrow tidal estuaries     

D. Prandle 《Estuarine, Coastal and Shelf Science》1985,20(5):615-635

An examination is made of the circulation in narrow estuaries subject to a predominant tidal forcing. Velocity structures are derived separately for residual flow components associated with (a) river flow, (b) wind stress, (c) a well-mixed longitudinal density gradient and (d) a fully stratified saline wedge. Dimensionless parameters are introduced to indicate the magnitude of each component and these parameters are evaluated for 9 major estuaries, thereby revealing their sensitivity to each component.For a channel of constant breadth and depth, formulae are deduced for the length of saline intrusion, L. Comparisons with observed data show that such formulae may be used with confidence to predict changes in L arising from variations in river flow, tidal range or channel depths.The level of stratification is shown to be related to a product of two parameters, one associated with velocity structure and a second involving the square of the ‘flow ratio’ $\text{u}\text{u}\text{?}$ (i.e. residual velocity/amplitude of the tidal velocity). This relationship provides a simple classification system for estuarine stratification which can be used to indicate the sensitivity of any particular estuary to changing conditions.  相似文献   

高挂山—牛头寨地区小型环形影象构造分析及其找矿意义     

钱惠林 《湖南地质》1989,8(2):18-22

高挂山—牛头寨地区,通过大比例尺航片解译,发现6个大小不等的小型环形影象信息。这些环形影象与岩浆活动、已知矿床、矿化点、重砂异常、物化探异常等的分布有着内在的联系。为预测找矿远景区和找隐伏矿床提供了影象依据。  相似文献   

IMPACTS OF FUTURE SEA LEVEL RISE ON SALT WATER INTRUSION IN THE CHANGJIANG RIVER ESTUARY   总被引：1，自引：0，他引：1  

杨桂山 《中国地理科学(英文版)》1992,2(1):30-41

Sea level rise could increase the salinity of an estuary by altering the balance between fresh water and salt water. The implications of sea level rise for increasing salinity have been examined in the Changjiang (Yangtze) River estuary. By correlative analysis of chlorinity, discharge and tidal level and calculation of two-dimensional chlorinity, distribution of the Changjiang River estuary, the changes of the intensity and lasting hours of salt water intrusion at Wusong Station and the changes of chlorinity distribution in the South Branch of the Changjiang River estuary have been estimated when future sea level rises 50-100 cm. The intensity of salt water intrusion in the future will be far more serious than current trend.  相似文献   

Transport of oceanic nitrate from the continental shelf to the coastal basin in relation to the path of the Kuroshio   总被引：1，自引：0，他引：1  

Ryo Sugimoto  Akihide Kasai  Toshihiro Miyajima  Kouichi Fujita 《Continental Shelf Research》2009,29(14):1678-1688

Hydrographic and biogeochemical observations were conducted along the longitudinal section from Ise Bay to the continental margin (southern coast of Japan) to investigate changes according to the Kuroshio path variations during the summer. The strength of the uplift of the cold deep water was influenced by the surface intrusion of the Kuroshio water to the shelf region. When the intrusion of the Kuroshio surface water to the shelf region was weak in 2006, the cold and NO₃⁻-rich shelf water intruded into the bottom layer in the bay from the shelf. This bottom intrusion was intensified by the large river discharge. The nitrogen isotope ratio (δ¹⁵N) of NO₃⁻ (4–5‰) in the bottom bay water was same as that in the deeper NO₃⁻ over the shelf, indicating the supply of new nitrogen to the bay. The warm and NO₃⁻-poor shelf water intruded into the middle layer via the mixing region at the bay mouth when the Kuroshio water distributed in the coastal areas off Ise Bay in 2005. The regenerated NO₃⁻ with isotopically light nitrogen (δ¹⁵N=−1‰) was supplied from the shelf to the bay. This NO₃⁻ is regenerated by the nitrification in the upper layer over the shelf. The contribution rate of regenerated NO₃⁻ over the shelf to the total NO₃⁻ in the subsurface chlorophyll maximum layer in the bay was estimated at 56% by a two-source mixing model coupled with the Rayleigh equation.  相似文献   

东天山黄山西含铜镍矿镁铁-超镁铁岩体岩浆地幔源区特征研究   总被引：19，自引：10，他引：9  

邓宇峰  宋谢炎  陈列锰  程松林  张新利  李军 《岩石学报》2011,27(12):3640-3652

新疆黄山-镜儿泉铜镍成矿带位于中亚造山带东天山晚古生代造山带,铜镍总储量达百万吨,是我国仅次于金川硫化物矿床的铜镍矿基地.黄山西铜镍矿床是该成矿带内一个大型矿床,Cu平均品位是0.31％,总储量18.8×104t,Ni平均品位是0.49％,总储量32×104t.黄山西岩体岩石地球化学特征与塔里木大火成岩省镁铁-超镁铁侵入岩和玄武岩存在明显差异;较之塔里木大火成岩省镁铁-超镁铁岩体( 269～ 274Ma),黄山-镜儿泉铜镍成矿带镁铁-超镁铁岩体的形成更早(274～298Ma);此外,成矿带内并没有早二叠溢流玄武岩大量出露.黄山西岩体各岩相的MORB标准化微量元素蛛网图显示明显的Nb、Ta、Ti负异常,(87Sr/86Sr)269Ma值较低(0.7034～0.7037),而εNd(269Ma)较高(5.14～ 7.14),这些地球化学特征难以用地壳混染来解释,而显示其原始岩浆来自于交代地幔的部分熔融,表明原始岩浆可能形成于活动大陆边缘.然而,黄山西岩体的岩相学特征与阿拉斯加型岩体存在差别,因此,不能排除交代地幔的部分熔融发生于碰撞造山后的伸展阶段的可能,软流圈的上涌可能起到重要作用.  相似文献