南沙海区晚上新世海水上层结构变化

对南沙海区水深2772m的ODP1143站100～150m井段共101块沉积样品进行了浮游有孔虫分析,结果表明,从3．27Ma到2．55Ma该区表层海水温度逐步降低,温跃层逐步加深,推测是晚上新世北半球冰盖形成过程中,东亚季风相应加强的结果。与此同时,南沙与南海北部的温跃层深度差值不断加大,可能是西太平洋暖池最终形成或加强的表现。3．2Ma前后,表层海水温度和海水温跃层深度都发生了急剧变化,反映出北半球冰盖和西太平洋暖池的发育可能存在一定的相关性。     

台风过境对黄海冷水团及其环流结构的影响

台风能够对黄海的水文结构及人民群众的生产生活产生重要的影响,严重威胁了人们的生命财产安全。利用ROMS(regional ocean modeling system)模式,分析了台风"灿鸿"在过境黄海期间对黄海温度及环流结构的影响过程。结果表明,台风期间强烈的风致混合能够使温跃层的深度增大,强度减弱,同时,使得近岸的底层温度迅速升高,推动底层的温度锋面向黄海内区移动。台风过境也会对黄海冷水团环流产生重要的影响,台风过境前,混合层中的北向流会迅速加深增强,同时伴随着混合层及温跃层的下移,从而使得黄海冷水团环流的流核下移至跃层以下。当台风过境时,黄海上空的气旋式风场会加剧黄海上层的气旋式环流,导致黄海冷水团环流的流幅及流量迅速增加。当台风登陆后,黄海上层的温度及黄海冷水团环流的结构开始逐渐恢复。     

浅海双跃层脉冲声传播

利用在东海测量的双跃层声速剖面和修改的单跃层声速剖面,数值模拟了2种跃层条件下不同收发深度声脉冲传播的波形。模拟结果表明,当声源或接收器位于上混合层时,信号波形在2种条件下都出现梳状多途结构。当声源和接收器都位于下混合层时,信号波形在2种条件下均相似。当声源位于中间均匀层时,信号波形在除上混合层以外的4层都有显著差异。用简正波的深度-简正波号域的幅度和相应的群速度解释了双跃层和单跃层声速剖面条件下信号波形特点以及异同的原因。     

北黄海冷水团对獐子岛微微型浮游生物分布的影响

Picoplankton distribution around the Zhangzi Island(northern Yellow Sea)was investigated by monthly observation from July 2009 to June 2010.Three picoplankton populations were discriminated by flow cytometry,namely Synechococcus,picoeukaryotes and heterotrophic prokaryotes.In summer(from July to September),the edge of the northern Yellow Sea Cold Water Mass(NYSCWM)resulting from water column stratification was observed.In the NYSCWM,picoplankton(including Synechococcus,picoeukaryotes and heterotrophic prokaryotes)distributed synchronically with extremely high abundance in the thermocline(20 m)in July and August(especially in August),whereas in the bottom zone of the NYSCWM(below 30 m),picoplankton abundance was quite low.Synechococcus,picoeukaryotes and heterotrophic prokaryotes showed similar response to the NYSCWM,indicating they had similar regulating mechanism under the influence of NYSCWM.Whereas in the non-NYSCWM,Synechococcus,picoeukaryotes and heterotrophic prokaryotes exhibited different distribution patterns,suggesting they had different controlling mechanisms.Statistical analysis indicated that temperature,nutrients(NO3–and PO43–)and ciliate were important factors in regulating picoplankton distribution.The results in this study suggested that the physical event NYSCWM,had strong influence on picoplankton distribution around the Zhangzi Island in the northern Yellow Sea.     

三沙永乐龙洞悬浮体垂直分布特征及其影响因素

为研究中国唯一已知、全球最深海洋蓝洞的形成、发育和演化机制，应用LISST-100X现场激光粒度仪、CTD温盐仪等搭载工作级水下机器人，于2017年5月在三沙永乐龙洞进行了悬浮体、温盐剖面测量，获得了全洞深的悬浮体体积浓度、温盐和溶解氧等数据，并进行了悬浮体垂向分布特征研究。研究结果表明，洞内90 m以下水体为无氧环境，悬浮体浓度呈现5个变化旋回，温度、盐度均存在3个跃层，并且它们之间有着较好的对应关系。龙洞内水体表层悬浮体总浓度约为20 μL/L，悬浮体平均浓度值为5.93 μL/L。悬浮体旋回层Ⅰ位于5 m以浅水层；旋回层Ⅱ位于10～43 m之间，与第一个温盐跃层(深度10～20 m)部分对应；旋回层Ⅲ位于70～110 m之间，与第二个温盐跃层(深度70～110 m)完全对应；旋回层Ⅳ位于130～150 m之间，与第三个温盐跃层(深度130～150 m)完全对应；旋回层Ⅴ位于260 m以深至洞底300 m。龙洞表层悬浮体浓度较高，主要是受到洞外周边珊瑚礁松散沉积物输入的影响。洞内悬浮体垂直分布特征主要受到水动力、洞体形态、温盐跃层、溶解氧含量以及浮游生物等的控制和影响。     

An Observational and Numerical Modeling of Thermocline Development in the Persian Gulf

An observational and numerical (Princeton Ocean Model) study of the summer thermocline development in the Persian Gulf (PG) shows that as the northwesterly cold winter wind weakens and become warmer, the fresher inflow from Oman Sea penetrates much further into the PG. This is also associated with stronger solar radiation leading to the near surface thermocline development over the whole of the PG. For more realistic monthly averaged wind, the thermocline develops as is indicated by observations. This is particularly marked in the deeper central part in which it grows in depth about 0.2(m) per day. The formation of thermocline decreases the dissolved oxygen in water column due to induced stratification. Over the PG the temperature difference between surface and subsurface increases exponentially from March until May when it levels off, with similar smaller variations for salinity differences than observed.     

The role of atmospheric teleconnection in the subtropical thermal forcing on the equatorial pacific

The equatorial response to subtropical Pacific forcing was studied in a coupled climate model.The forcings in the western,central and eastern subtropical Pacific all caused a significant response in the equatorial thermocline,with comparable magnitudes.This work highlights the key role of air-sea coupling in the subtropical impact on the equatorial thermocline,instead of only the role of the ＂oceanic tunnel＂.The suggested mechanism is that the cyclonic （anticyclonic） circulation in the atmosphere caused by the subtropical surface warming （cooling） can generate an anomalous upwelling （downwelling） in the interior region.At the same time,an anomalous downwelling （upwelling） occurs at the equatorward flank of the forcing,which produces anomalous thermocline warming （cooling）,propagating equatorward and resulting in warming （cooling） in the equatorial thermocline.This is an indirect process that is much faster than the ＂oceanic tunnel＂ mechanism in the subtropical impact on the equator.     

声跃层结构变化对深海汇聚区声传播的影响

根据射线理论建立了线性声速结构条件下的声跃层强度与深海汇聚区关系模型,用最小位移角讨论了海洋环境变化（如声跃层强度变化、声跃层位置变化及季节性跃层生消等）与汇聚区距离和宽度变化的相关性.结果表明,声跃层的结构变化对汇聚区特征影响很大.声跃层强度增大使汇聚区向远离声源的方向变化,跃层强度每增加0.01 s-1对应的汇聚区位移增大约为3.5～5.0 km.声跃层位置变化对汇聚区的影响小于声跃层强度,与两层结构的声速剖面相比,上行结构使汇聚区向靠近声源的方向变化,声跃层上升200 m对应的汇聚区位移减小约为1.0～1.5 km,声跃层越浅,汇聚区距离越近;下行结构使汇聚区向远离声源的方向变化,混合层加深200 m对应的汇聚区位移增大约为1.0～1.5 km,混合层越深,汇聚区距离越远.季节性跃层的生消使近表层有负梯度、零梯度和正梯度的变化.负梯度结构的变化规律与两层结构条件下的声跃层强度变化类似,但对汇聚区的影响程度相对较小;正梯度结构使汇聚区在近表层出现表面声道,梯度值的增强将使汇聚区向靠近声源的方向变化.     

Characteristics of the transition Layer in the South China Sea in 1998

CTD data on standard levels coolected during July and December in 1998 and the cubic spline interpolating method were used to study the characteristics of the transition layer temperature and salinity.The thermocline undergoes remarkable seasonal variation in the South China Sea (SCS),and especially in the region of the north shelf where the thermocline disappears in december.The thermocline is stronger and thicker in July than in December,There is no obvious seasonal variation in the halocline.Due to the upper Ekman transport caused by monsoon over the SCS,the thermocline slopes upward in July and downward in december from east to west in the northern SCS.The characteristics of the thermocline and halocline are influenced by local eddies in the SCS.The Zhujiang diluted flow influences significantly the SCS shelf‘s halocline.     

中国科学院气候系统模式模拟的ENSO循环

On the basis of more than 200-year control run, the performance of the climate system model of Chinese Academy of Sciences(CAS-ESM-C) in simulating the El Ni?o-Southern Oscillation(ENSO) cycle is evaluated, including the onset, development and decay of the ENSO. It is shown that, the model can reasonably simulate the annual cycle and interannual variability of sea surface temperature(SST) in the tropical Pacific, as well as the seasonal phase-locking of the ENSO. The model also captures two prerequisites for the El Ni?o onset, i.e., a westerly anomaly and a warm SST anomaly in the equatorial western Pacific. Owing to too strong forcing from an extratropical meridional wind, however, the westerly anomaly in this region is largely overestimated. Moreover, the simulated thermocline is much shallower with a weaker slope. As a result, the warm SST anomaly from the western Pacific propagates eastward more quickly, leading to a faster development of an El Ni?o. During the decay stage, owing to a stronger El Ni?o in the model, the secondary Gill-type response of the tropical atmosphere to the eastern Pacific warming is much stronger, thereby resulting in a persistent easterly anomaly in the western Pacific. Meanwhile, a cold anomaly in the warm pool appears as a result of a lifted thermocline via Ekman pumping. Finally, an El Ni?o decays into a La Ni?a through their interactions. In addition, the shorter period and larger amplitude of the ENSO in the model can be attributed to a shallower thermocline in the equatorial Pacific, which speeds up the zonal redistribution of a heat content in the upper ocean.