On the Development of Meso-Scale Heavy Rain Parcels in China     

Zhang Yan 《大气科学进展》1995,12(1):79-86

Heavy rains occur in China frequently, which often bring us floods and serious disasters in the summer half-year. The meso-scale heavy rain parcels (MHRP) in the mid-latitude are usually developed in following cases:I.By the approaching, meeting and / or overlapping of different weather systems, when two or more different rainfall systems are getting to conjugate, some MHRPs could be developed, such as: 1) a new cold/warm front or squall line approaches an old front or squall, even when the old one is somewhat decrepit; 2) at the places where two or more synoptic systems with different characteristics are meeting together, such as the meeting of tropical cyclone with the cold airs coming from the mid- and / or high-latitudes, or the low latitude vortex meeting with the westerly trough; 3) at the intersections of some different weather systems, such as the intersection of drylines, squall lines or fronts moving from different directions; and 4) by the overlapping of rainfall parcels produced continuously  相似文献   

不同晶形石盐沉积生长特征及对包裹体温度的影响     

冯阵东  吴伟  周永  刘惟庆  魏国营  贾天让 《地质学报》2022,96(4):1469-1477

石盐晶体生长过程中捕获流体包裹体，利用冷冻测温法得到的均一温度信息与古水温存在良好的相关性。在部分地区，利用包裹体最大均一温度评价古气候时，温度数据与孢粉学反映的气候特征存在冲突，不同晶形的石盐沉积特征，及其晶体条纹内包裹体温度代表的地质含义需进一步探讨。笔者在分析经典测温数据的基础上，观察常温蒸发实验中漏斗晶和人字晶的形成及生长过程，分析了不同温度段均一温度与气温、水温之间的关系。结合现代气象记录数据，分析了最大均一温度评价气候时存在的局限性。研究认为：漏斗晶晶核形成与卤水表面，包裹体温度受温度和气压共同影响，漏斗晶在卤水底部绕核生长，漏斗晶外围包裹体温度对应水底温度，沉入水下后漏斗晶生长缓慢，包裹体最大温度可能代表年度最高温度，以此为指标评价气候得出的结论过于炎热；人字晶是多个漏斗晶之间的桥接部分，大部分形成于卤水蒸发将近结束之时，人字形条纹内包裹体温度受气温和地表温度共同影响，地表温度远大于气温是造成包裹体最高温度过高的主要原因。  相似文献   

膜下滴灌模式下种植密度对棉田蒸散发规律影响研究     

王小军 《沙漠与绿洲气象(新疆气象)》2020,14(1):138-143

为探求绿洲棉区膜下滴灌条件下不同种植密度棉田蒸散发规律，运用大型称重式蒸渗仪对膜下滴灌棉田蒸散过程连续监测，结果表明：在不同种植密度条件下，棉花的日蒸散量曲线都表现为单峰曲线，不同生育时期一膜六行（30株/m2）种植的棉田蒸散量比一膜四行（20株/m2）大，花铃期棉田的蒸散发强度最大，一膜四行、一膜六行分别为4.76mm/d、5.94mm/d。同时，一膜六行种植的叶面积指数大于一膜四行种植,株高小于一膜四行种植。花铃期棉田的蒸散发量与日平均气温（p<0.01）和空气相对湿度(p<0.01)具有很好的相关性，与日平均风速和日平均水汽压的关系不大。  相似文献   

A methodology to estimate renewal time scales in estuaries: the Tagus Estuary case   总被引：2，自引：0，他引：2  

Frank?BraunschweigEmail author  Flávio?Martins  Paulo?Chambel  Ramiro?Neves 《Ocean Dynamics》2003,53(3):137-145

High-resolution hydrodynamic models are a common tool to simulate water dynamics in estuaries. Results from these models are, however, difficult to interpret without the aid of additional parameters to integrate the information. In this paper a methodology to understand the transport patterns in the Tagus Estuary is proposed. It is based on the computation of two renewal time scales: residence time and integrated water fraction. This last parameter is used to build a dependency matrix that gives the integrated influence of each region of the estuary at a selected point. The parameters are computed using a Lagrangian transport model coupled to the hydrodynamic model. Results show that Tagus Estuary has two different types of regions: the central part of the estuary, with low renewal efficiency, and three regions with higher renewal efficiency. Renewal mechanisms are, however, different for each region as shown by the dependency matrix. Comparison of renewal time scales with results from a water-quality model revealed that residence time is not a limiting parameter for primary production in the Tagus Estuary.Responsible Editor: Hans Burchard  相似文献   

赣西北修水、武宁地区中新生代“红盆”地质时代和沉积相研究   总被引：1，自引：0，他引：1       下载免费PDF全文

张雄华  章泽军 《沉积与特提斯地质》2003,23(4):50-55

通过新发现的古生物资料分析,确定了赣西北修水、武宁地区的武宁、三都及马坳盆地的地层时代。对3个盆地的沉积相进行了详细的划分和描述,查明其为冲积扇沉积类型;划分出22个岩相,归属于泥石流、泥流、颗粒流、水道(包括主水道和分枝水道2个次级类型)、片流、筛积和洪泛7个沉积类型。重力流沉积分布在扇根或主要沉积旋回的底部,其类型的差别与邻近物源区的岩性有关;分枝水道、片流及筛积主要分布在扇中,交错层理及砾石叠瓦状构造发育,主要呈现牵引流特征;扇缘主要为洪泛沉积夹少量决口扇成因的砂砾岩透镜体,钙结壳发育,反映了一种干旱强蒸发的古气候环境。  相似文献   

回忆父亲点滴          下载免费PDF全文

陈家莹 《第四纪研究》2000,(1):18-23

父亲是世纪同龄人 ,从 50岁到 80岁是他生命的春天。他以常人在这个年龄难以迸发的热情、智慧、不懈努力和顽强开拓的精神 ,在地质战线上为新中国建设辛勤耕耘 ,是一位在地学领域涉足宽广、具有科学预见能力、富有领导组织才能的科学家和领导者。他总是关注未来 ,特别热心于培养年轻人 ,对建立一支高水平、有解决问题能力的地质队伍下了很大功夫。父亲沉静善思、富有哲学头脑 ,他的许多预见性学术观点和开创性思维都源于他宁静淡泊的心态。没有浮华和功利 ,这便是他智慧的源泉。  相似文献   

砂岩储层中不同赋存状态油砂抽提物的地球化学特征:长链酮①——以鄂尔多斯盆地三叠系延长组为例     

赵欣  史基安  谢正温  王琪  王有孝 《沉积学报》2006,24(1):129-134

对采自西峰油田三叠系延长组六个油砂样品中游离烃、束缚烃的饱和烃、芳烃和氯仿馏分进行了系统的分析。在氯仿馏分中检测出一系列异常丰富的正构烷基酮化合物，其碳数分布范围C13～ C33,具有强烈的奇碳优势。研究表明:正构烷基酮的演化受热演化（成熟度）的影响，在成熟度较低的束缚烃中，主要分布正构烷基 2 酮；而在成熟度较高的游离烃中，主要为正构烷基 3,4,5,6（或更高） 酮异构体。表现为随着成熟度的增加，正构烷基酮的羰基(∶CO)由2位向更高位迁移的趋势。正构烷基酮的形成是由于菌藻类和高等植物类脂中的脂肪酸，在粘土矿物等催化作用下，经β 氧化后脱羧基而形成。在束缚烃和游离烃中正构烷基酮的分布特征，可用于油气成藏差异的研究。  相似文献   

内蒙古额济纳旗呼伦西白隐爆角砾岩型金矿地质特征   总被引：3，自引：0，他引：3  

杨亮  杨富林  汤超 《华北地质》2006,29(2):100-106

内蒙古额济纳旗境内发现的呼伦西白金矿,矿脉产状陡、延深较大。多数矿脉产于华力西期斜长花岗斑岩体内部或岩体与上泥盆统西屏山组地层的内接触带中,个别矿脉产于斑岩上覆的西屏山组安山质板岩中的构造破碎带内(下部隐伏华力西期斜长花岗斑岩)。研究认为,矿体赋存在与华力西期花岗斑岩体隐爆作用有关的不同隐爆构造部位,属于与华力西期岩浆隐爆角砾岩型金矿床,具中低品位和厚度较大等特点,其找矿前景良好。  相似文献   

Fine upper crustal structure of Jiashi strong earthquake swarm region in Xinjiang inferred from high resolution seismic refraction profile data     

徐朝繁张先康  段永红杨卓欣酆少英  胡修奇 《地震学报(英文版)》2006,19(1):62-71

Introduction Jiashi-Artux area in southwest Xinjiang is one of the most active earthquake provinces at pre-sent in Chinese mainland. In the last century, about 3/4 strong earthquakes in Chinese mainland hit this area, and especially from January 21 to April 16 in 1997, 7 earthquakes with the magnituderanging from 6.0 to 6.9 occurred in a very small area of 9 km×18 km near Jiashi (ZHU et al, 1998). It has never taken place before in Chinese mainland that a series of strong earthquakes shoo…  相似文献   

THE RELATIONSHIP BETWEEN SCS SUMMER MONSOON INTENSITY AND OCEANIC THERMODYNAMIC VARIABLES AT DIFFERENT TIME SCALE     

谷德军  纪忠萍  王东晓  梁建茵  方一川 《热带气象学报(英文版)》2007,13(1):85-88

The oscillation characteristics of 1948 - 2003 South China Sea (SCS) summer monsoon intensity (SCSSMI) is analyzed by wavelet transform and the relationship between SCSSMI filtered by Lanczos filter at different time scale and oceanic thermal conditions is studied. The results show that SCSSMI exhibits dominant interannual (about 4 a), decadal (about 9 a) and interdecadal (about 38 a) oscillation periods. The interannual variation is the strongest and the interdecadal variation the weakest. The region of significant correlation between SCS summer monsoon intensity and oceanic thermodynamic variables at different time scale is greatly different. Significant correlation area of interannual variation of SCSSMI is concentrated in near equatorial region. Corresponding correlation displays quasi-biannual variability. If positive anomalies of SST and the depth of thermocline happen in eastern equatorial Indian Ocean and western equatorial Pacific, and negative anomalies of SST and the depth of thermocline happen in western equatorial Indian Ocean and eastern equatorial Pacific in previous autumn and winter, the interannual variation of SCSSMI will enhance. If the condition is contrary, interannual variation of SCSSMI will weaken. The interannual variation of SCSSMI will influence SST. The region surrounding SCS and east of Australia shows significantly negative correlation in autumn, and significantly positive correlation exhibits in west equatorial Indian Ocean, eastern equatorial Pacific and equatorial Atlantic in winter. The decadal variation of SCSSMI is modulated by PDO. Interdecadal variation of SCSSMI is relevant to the global warming and PDO.  相似文献