共查询到20条相似文献，搜索用时 62 毫秒
1.
陈绍鑫 《中国海洋大学学报(自然科学版)》1989,(3)
通过对雷达波春季在海面上发生超折射现象的分析,发现在一定时间内由海面上吹来的空气是干而暖的,此时海洋不但没有供给陆地水汽,反而减弱了陆上的降水。 相似文献
2.
强热带风暴“莲花”(0903)非对称降水结构分析 总被引：1，自引：0，他引：1
利用雷达回波和NCEP分析资料,本文从水汽条件、环境风垂直切变和风暴移动状态等方面诊断分析了0903号强热带风暴"莲花"非对称降水结构形成的可能机制。结果表明:"莲花"南侧充足的水汽输送为强降水的发生提供了基本的水汽条件,同时水汽通量在水平空间上的非对称分布也在一定程度上导致了降水的非对称分布。环境风垂直切变是导致"莲花"降水结构改变并最终形成一波非对称降水结构的主要动力因子。随着垂直切变的增强,同时配合风暴南侧充足的水汽条件,一波非对称降水结构逐渐形成,在较强垂直切变长时间的作用下,强降水最终集中于顺切变方向左侧。在较强垂直切变的作用下,逆切变一侧的下沉运动抑制了陆地摩擦和地形抬升所形成的对流的发展。相对于较强的垂直切变而言,"莲花"相对稳定的移速和移向条件难以主导强热带风暴降水的空间分布。 相似文献
3.
本文根据Ｃ．Ａ．等（１９６３。１９６５）提出的海洋上层温度结构特征的无因次普遍函数，利用１９５７～１９６４年暖半年渤海、黄海、东海１５９个站次连续站的资料和作者（１９８３）提出的海面热量平衡的简易计算公式计算海面的热量收支，建立了海洋上均匀层厚度、温跃层强度和跃层下界深度的半经验半理论模式。该模式反映了形成海洋上层温度结构特征的主要因子及其作用，同时避开了一般理论模式中的起算点和目前难以获得的物理海洋学参数，而可以直接利用表面水温、气温和风速进行海洋上层温度特征的计算。 相似文献
4.
热带气旋-海洋的相互作用对南海一个强热带气旋过程影响的数值模拟 总被引：1，自引：0，他引：1
采用中尺度海-气耦合模式MCM v1.0对南海强热带气旋“黄蜂”(No.0214)进行了数值模拟试验,并就热带气旋-海洋的相互作用对热带气旋的影响进行了定量分析。结果表明,耦合试验中热带气旋后期路径有显著改善,36h和48h路径误差分别减小22km和110km,登陆点位置误差减小22km;气旋强度与非耦合结果基本一致,36—48h气旋强度减弱得更快;热带气旋中心大风区地面风速增大1—3m.s-1,眼区附近风速减小2—5m.s-1;近地层(取925hPa)气温降低1℃以上,且气温降温区与较大的SST下降区域大致吻合;改进了热带气旋暴雨的落区及降水强度,且主要落区误差的修正位于热带气旋移动路径的右侧并同主要的SST降温区相关;热带气旋-海洋相互作用通过SST下降减少向上的热通量,潜热通量的减少对SST的下降更敏感。 相似文献
5.
本文根据等(1963,1965)提出的海洋上层温度结构特征的无因次普遍函数,利用1957—1964年暖半年渤、黄、东海159个站次连续站的资料和作者(1983)提出的海面热量平衡的简易计算公式计算海面的热量收支,建立了海洋上均匀层厚度、温跃层强度和跃层下界深度的半经验半理论模式。该模式反映了形成海洋上层温度结构特征的主要因子及其作用,同时避开了一般理论模式中的起算点和目前难以获得的物理海洋学参数,而可以直接利用表面水温、气温和风速进行海洋上层温度特征的计算。 相似文献
6.
气旋在黑潮海域的异常发展早已为许多作者所注意。目前从统计学和动力学方法也已证实,东海气旋的异常发展与黑潮海域充沛的热量供应有关。有的作者试图从海面能量供应的角度论证上述事实,如Ninomiyo曾以半经验的方法计算黑潮海域气旋式波动的有效位能的转换。但对气旋的发生发展而言,更重要的是扰动有效位能的生成及其转换。然而迄今未见有关于黑潮对气旋扰动能量关系的详细计算和讨论。本文在计算了黑潮上空气旋区海面和高空微尺度的热涡动输送值后,着重讨论了海洋热源引起的气旋区扰动有效位能的产生及其转换。作为对照,也计算了气旋在陆地和移出黑潮区以后的扰动能量平衡。我们试图从所得结果分析气旋在陆地、海洋和黑潮 相似文献
7.
北太平洋副热带海洋环流强度异常对长江中下游夏季降水的影响 总被引：3，自引：0，他引：3
利用SODA资料和ECCO资料计算得到的北太平洋副热带海洋环流强度,和国家气候中心整编的中国160站逐月降水资料,结合NCEP/NCAR再分析资料和Hadley中心海表面温度资料,分析了1970－2007年海洋环流强度异常同期的大尺度大气环流异常特征及对中国东部夏季降水的影响。结果表明:海洋环流强度变化与长江中下游地区降水存在密切的反相关。环流强度异常可以通过影响西太平洋副热带高压的南北位置异常进而影响长江中下游降水。海洋环流偏弱时,副高位置偏南,长江中下游地区受气旋性环流异常影响,来自副高西北侧的强西南水汽输送至此,在该地区形成强水汽辐合中心,同时伴随上升运动加强和对流的加强,进一步导致该地区降水偏多;当海洋环流偏强时,西太平洋副高位置偏北,长江中下游地区受反气旋性环流异常影响,伴随辐散下沉及水汽辐散,导致该地区降水偏少;海洋环流强度异常导致的中纬度海区海表面温度异常,可能是导致副高南北位置异常的主要原因。 相似文献
8.
利用中尺度自动站加密资料、雷达和卫星资料以及NCEP全球分析资料,诊断分析1818号台风"温比亚"登陆前后大暴雨特征及其成因。结果表明:(1)台风登陆前后,降水具有时间集中、局地性强、雨强大等中尺度降水特征,强降水集中在距台风中心100 km以内的台风前进方向的左前部和后部,主要由两个移动性雨团和1个相对少动雨团产生,距台风中心25～50 km的降水量中心小时降水量普遍较大;(2)杭州湾区域地面辐合一方面加强了低空水汽辐合,另一方面促进了上升运动的发展和维持,使得中尺度对流雨团在宁波东北部至舟山一带发展加强,同时引导气流偏弱和地形作用导致台风在舟山附近移速减慢,延长了影响时间,造成了杭州湾附近区域的大暴雨;(3)地面辐合的增强和减弱对应于其后1 h降水的增大和减小;水汽通量散度的减小、增大与降水的增大、减小有较好的对应关系,水汽通量散度在-16×10~(-5)g/(cm~2·hPa·s)以下的时段降水较强;垂直螺旋度大值中心所对应区域未来6 h有强降水,垂直螺旋度的减小对应于该区域其后6 h降水的减弱。 相似文献
9.
10.
《中国海洋大学学报(自然科学版)》2016,(5)
利用星载激光雷达资料等多种卫星遥感数据,结合大气再分析资料等,对2008年12月4—6日发生在山东半岛北部的一次海效应暴雪云团降雪过程进行了分析。结果表明:(1)暴雪云团发生在东北冷涡西南部对流层中低层强西北冷平流、地面气压场气旋式弯曲的天气背景下。(2)受冷平流作用,对流层中下层降温明显,导致渤海低层大气不稳定度增加,海面风场辐合产生上升运动,并将大量的水汽和热量输送至低层大气,这有利于浅对流的加强,并进一步促进降雪云团的形成。(3)降雪云团虽然为浅对流云,但云系冷中心较强;云团发展旺盛时期的云内平均降雪率为0.41mm/h,且降雪率的大值区表现为强弱相间的条状分布。(4)云团的射出长波辐射通量不仅与云团温度有关,还与云内冰水含量有关,冰水含量越高,射出长波辐射通量越低;在研究云对辐射的影响时,没有降水(雪)的云系和有降水(雪)的云系应该分别考虑,降水(雪)弱的云系和降水(雪)强的云系也应该分别考虑。 相似文献
11.
Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths. 相似文献
12.
Shigehisa Nakamura 《Marine Geodesy》2000,23(1):55-61
Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone. 相似文献
13.
The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics. 相似文献
14.
Coastal inundation associated with extreme sea levels is the main factor which leads to the loss of life and property whenever a severe tropical cyclonic storm hits the Indian coasts. The Andhra and Orissa coasts are most vulnerable for coastal inundation due to extreme rise in sea levels associated with tropical cyclones. Loss of life may be minimized if extreme sea levels and associated coastal flooding is predicted well in advance. Keeping this in view, location specific coastal inundation models are developed and applied for the Andhra and Orissa coasts of India. Several numerical experiments are carried out using the data of past severe cyclones that struck these regions. The simulated inland inundation distances are found to be in general agreement with the reported flooding. 相似文献
15.
16.
《海洋学报(英文版)》2014,(9):F0003-F0003
<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology, 相似文献
17.
Hoi-Soo Jung Kap-Sik Jeong Yong-Shik Chu Sung-Hyun Park Ki-Hyune Kim 《Marine Georesources & Geotechnology》2001,19(3):181-195
Grain size and water content in box-core sediments from the Clarion-Clipperton fracture zone (C-C zone) in the northeast equatorial Pacific were analyzed in detail to understand the downcore variations across a hiatus between Quaternary and Tertiary layers. Grain-size distributions in the topmost core sediments show two modes: a coarse mode (peaked at 50 μm) and a fine mode (at 2-25 μm). The coarse mode disappears gradually with depth accompanied by the dissolution of siliceous fossil tests, whereas the fine mode coarsens due to the formation of authigenic minerals. Water content increases abruptly across a color boundary between an upper pale brown layer and a lower dark brown layer that is the hiatus between Quaternary and Tertiary layers. Abundant smectites and microvoid molds, which are created by the prolonged fossil dissolution in the underlying sediment, are attributed for the abrupt downcore variation of water content. Overall variations in grain size and water content in the topmost core sediments in the western C-C zone are possibly constrained by the dissolution of biogenic siliceous fossils. Variations in geotechnical properties related to these changes must be considered in the design of nodule collectors. 相似文献
18.
Shigehisa Nakamura 《Marine Geodesy》2001,24(1):27-33
This article concerns an interrelation between the sea levels and the western boundary flow near a tectonic boundary in a local zone in the Northwestern Pacific. In this zone, sea level variations at stations located on the coast facing the Pacific are studied to find the interrelation between variations of the Kurosio flow as an index of the distance of the flow axis off a specific coast. The result is discussed after data processing of the monthly means of the sea levels, and a notice is taken of variations caused by active crustal upheavals during a seismic event, a local earthquake. 相似文献
19.
This study tests the hypothesis that the in situ void ratio of surficial marine sediments may be predicted from shear wave velocity-depth data with a reliability equal to that of other methods currently available. Shear wave velocity is fundamentally controlled by the number of grain-to-grain contacts per unit volume of material and by the effective stress across those contacts. In this study, three previously established empirical formulae are used to predict void ratio from velocity-depth data. Field data were acquired along a transect off the northern Californian coast across which water depth increased from 35 to 70 m and seafloor sediment type varied from sand to silty-sand, respectively. A towed seafloor sled device was used to collect shear wave refraction data, and a marked, systematic decrease in velocity was observed along the line, ranging from 35-70 m/s for the coarse, near-shore material to 25-40 m/s for the finer, offshore deposits. Void ratios predicted from these velocities were compared with data measured directly from box-core samples. Of the formulae used for prediction, two agree remarkably well with the control data. Both predicted and control values increase from 0.6-0.8 for the sandy material to 1.1-1.5 for the silty-sand. Thus, this study does not disprove the hypothesis set and demonstrates the potential of field shear wave velocity-depth data as a means of delineating spatial variation in void ratio for surficial marine sediments in a remote, nondestructive manner. 相似文献
20.
Particulate samples were collected from the Changjiang river system during a flood period, in May 1997, and POC, stable isotope and lipids associated with particles were examined. Results showed the decrease (0.84% ～ 1.88%) of organic carbon content from the upper reaches to the estuary.δ13C values of particulate organic carbon was in the range of -24.9×10-3 to -26.6×10-3, which were close to the isotopic signature of continental C3 vegetation. Total particulate n-alkanes concentrations varied from 1.4 to 10.1μg/dm3,or from 23.7 to 107μg/g of total suspended matter. Fatty acids were present in all the samples, from 1.4 to 5.4μg/dm3, with saturated and unsaturated straight-chain and branched compounds in the carbon number range from C12 to C30. Both δ13C and the ratio of carbon content to nitrogen content indicate the predominance of terrestrial inputs (soil organic matter) among the particles. The biomarker approach has been used to identify the relative portion of terrigenous and autochthonous fraction in the particulate samples. The distribution of fatty acids suggests a striking phytoplanktonic and microbial signal in most particle samples. The terrestrial alkanes are used to estimate the contribution of terrestrial inputs along the mainstream. 相似文献