Changes in the hydrography of Central California waters associated with the 1997–98 El Niño     

C. A. Collins  C. G. Castro  H. Asanuma  T. A. Rago  S. -K. Han  R. Durazo  F. P. Chavez 《Progress in Oceanography》2002,54(1-4)

Oceanographic conditions off Central California were monitored by means of a series of 13 hydrographic cruises between February 1997 and January 1999, which measured water properties along an oceanographic section perpendicular to the California Coast. The 1997–98 El Niño event was defined by higher than normal sea levels at Monterey, which began in June 1997, peaked in November 1997, and returned to normal in March 1998. The warming took place in two distinct periods. During June and July 1997, the sea level increased as a result of stronger than normal coastal warming below 200 dbars and within 100 km of the coast, which was associated with poleward flow of saltier waters. During this period, deeper (400–1000 dbar) waters between 150–200 km from shore were also warmed and became more saline. Subsequently, sea level continued to rise through January 1998, mostly as a result of the warming above 200 dbars although, after a brief period of cooling in September 1997, waters below 200 dbar were also warmer than normal during this period. This winter warm anomaly was also coastally trapped, extending 200 km from shore and was accompanied by cooler and fresher water in the offshore California current. In March and April 1998, sea level dropped quickly to normal levels and inshore waters were fresher and warmer than the previous spring and flowed southward.The warming was consistent with equatorial forcing of Central California waters via propagation of Kelvin or coastally-trapped waves. The observed change in heat content associated with the 1997–98 El Niño was the same as that observed during the previous seasonal cycle. The warming and freshening events were similar to events observed during the 1957–58 and 1982–83 El Niños.  相似文献   

3D gravity modelling for Anyongbok Seamount in the East Sea     

Moo Hee Kang  Hyun-Chul Han  Hyesu Yun  Gee Soo Kong  Kyong O. Kim  Youn Soo Lee 《Marine Geophysical Researches》2007,28(3):257-269

A seamount chain with an approximately WNW trend is observed in the northeastern Ulleung Basin. It has been argued that these seamounts, including two islands called Ulleung and Dok islands, were formed by a hotspot process or by ridge related volcanism. Many geological and geophysical studies have been done for all the seamounts and islands in the chain except Anyongbok Seamount, which is close to the proposed spreading ridge. We first report morphological characteristics, sediment distribution patterns, and the crustal thickness of Anyongbok Seamount using multibeam bathymetry data, seismic reflection profiles, and 3D gravity modeling. The morphology of Anyongbok Seamount shows a cone shaped feature and is characterized by the development of many flank cones and flank rift zones. The estimated surface volume is about 60 km³, and implies that the seamount is smaller than the other seamounts in the chain. No sediments have been observed on the seamount except the lower slope, which is covered by more than 1,000 m of strata. The crustal structure obtained from a 3D gravity modeling (GFR = 3.11, SD 3.82 = mGal) suggests that the seamount was formed around the boundary of the Ulleung Plateau and the Ulleung Basin, and the estimated crustal thickness is about 20 km, which is a little thicker than other nearby seamounts distributed along the northeastern boundary of the Ulleung Basin. This significant crustal thickness also implies that Anyongbok Seamount might not be related to ridge volcanism.  相似文献   

太平洋波高分布及变化规律研究   总被引：4，自引：0，他引：4  

韩树宗  朱大勇  郭佩芳 《中国海洋大学学报(自然科学版)》2003,33(6):825-832

使用 Topex/ Poseidon卫星高度计 1 992年 1 0月～ 1 998年 1 2月连续 75个月 ,2 30个重复周期的有效波高资料对南北太平洋的有效波高进行了统计 ,分析了太平洋有效波高的多年平均、多年各月平均和多年各季平均的空间分布特征和时间变化规律。结果表明 ,太平洋波高分布具有明显季节变化的规律 ,与太平洋的风速分布特征具有良好的对应关系  相似文献   

High Frequency Current Fluctuations and Cross-shelf Flows around the Pycnocline near the Shelf Break in the East China Sea     

In-Seong Han  Koichiro Kamio  Takeshi Matsuno  Atsuyoshi Manda  Atsuhiko Isobe 《Journal of Oceanography》2001,57(2):235-249

Relation between internal waves with short time scale and density distribution near the shelf break in the East China Sea is studied utilizing moored current meters, thermometers and conductivity-temperature-depth (CTD) casts. A well developed pycnocline was frequently observed around 150–200 m depth near the shelf break accompanied with the development of internal waves with short time scale. During the cruise in May 1998, the intensified internal wave motion with short time scale and the distinct offshore flow were observed just below the lower pycnocline, which shoaled and extended above the shelf area. It is suggested that vertical mixing generated by amplified internal waves would produce cross-shelf ageostophic density current around the pycnocline. During the cruise in May 1999, on the other hand, the lower pycnocline was located offshore below the shelf break, and the internal wave motion was amplified just above the lower pycnocline. In this case, the offshore flow should be generated above the lower pycnocline, but vertical profiles of current velocity were not obtained because acoustic Doppler current profiler (ADCP) data were not available around the lower pycnocline.  相似文献   

莱州湾东部滨海水域砂金分布特征   总被引：1，自引：0，他引：1  

谭启新  姜玉池 《海洋地质与第四纪地质》1996,16(4):79-86

通过对莱州湾东部滨海水域地球物理和地质钻综合调查，业已查明该海区地质的构造和古地理环境特征，并发现区内砂金分布较普遍，本文从砂金分布的地貌单元，沉积物类型，砂金成因类型，物质来源，古气候，构造作用，砂金成因等诸方面，研究了该海域内砂金特征。  相似文献   

莱州湾东部滨海水域第四纪沉积及古地理特征   总被引：5，自引：0，他引：5  

韩春瑞  谭启新 《海洋地质与第四纪地质》1996,16(2):75-84

本文通过对６个钻孔和４６１ｋｍ浅层地震剖机测量获得的测年、微古、孢粉、藻类、古地磁以及岩持征和地震反射界面等资料的综合分析，将本区第四系划分为中更新统、上更新统和全新统，对各时期的沉积进行了较详细的阐述，并对不同时期的沉积相特征和古地理环境的变化进行了初步地揭示。  相似文献   

利用卫星遥感监测南极海冰的研究和进展     

郝春江  解思梅 《海洋预报》1996,13(4):9-14

本文是根据南极“八五”国家攻关课题中的“南极海冰监测和预报”的考核目标，实现为南极考察船在 冰区中航行提供精确和清晰的冰图和预报。  相似文献   

强壮箭虫对温度、盐度的耐受性研究   总被引：7，自引：0，他引：7  

刘青  曲晗  张硕 《海洋湖沼通报》2007,(1):111-116

研究强壮箭虫对突变温度、突变盐度和渐变温度、渐变盐度的耐受性.结果表明:水温由15℃突变到1℃时,存活率为75%;水温由15℃突变为30℃时,存活率仅为5%.求得24h急性半致死温度上限为27.2℃.水温从20℃逐渐上升至25、30、35℃,存活率分别为85 %、10 %、0 %;水温从20℃逐渐下降至15、10、5℃,其存活率分别为 100 %、95 %和80 %.盐度从31突变为20、40,箭虫的存活率均为100%,随着盐度突变幅度的增大,强壮箭虫的存活率呈降低趋势.求得24h急性半致死盐度上限为45,24h急性半致死盐度下限为13.3.盐度逐渐从31上升到46、 52,其存活率由90%下降到0%;盐度逐渐从31降到13、6,其存活率由95%下降到0%.求得间隔12h半致死渐变盐度上限为48.7,半致死渐变盐度下限为9.3.根据实验结果,强壮箭虫应属喜冷广温种和近岸广盐种.  相似文献   

莱州湾海湾扇贝养殖区海水中悬浮颗粒的动态变化   总被引：3，自引：0，他引：3  

梁兴明  方建光  崔毅  唐启升 《海洋与湖沼》2001,32(6):635-640

1997年10月和1998年6月，在莱州湾两个主要海湾扇贝养殖区－芙蓉岛海区和金城海区，各定点进行了24h连续观测和取样，并在实验室内分析了总颗粒物（TPM）、颗粒有机物（POM）和叶绿素α的含量。结果表明，6月份金城海区的颗粒有机物和叶绿素α的含量均高于荚蓉岛海区；在10月份，芙蓉岛海区颗粒有机物的含量高于金城海区，但其叶绿素α的含量却低于金城海区，表明金城海区颗粒有机物的质量高于芙蓉岛海区。  相似文献   

层结流体中的非线性惯性重力内波     

侯一筠  李炜  王新生 《海洋与湖沼》1994,25(5):539-545

根据地球流体力学基本方程组,在密度垂直层结的情况下,引进行波坐标,研究非线性定形波在相平面上的几何拓扑结构。严格论证了不存在定形孤立波,并通过Ｈａｍｉｌｔｏｎ函数及其角作用变把行波系统化成最简形式,由此而得到非线性惯性重力内波的解析解。  相似文献