南海中部上层海洋温度的短周期振动

南海季风试验(SCSMEX)期间,南海中部投放了3个ATLAS浮标.本文选取3个站点1998年4月13日～1999年4月8日的所有观测水层的温度数据作为研究.通过逐月功率谱分析,发现50-500m深度,温度存在全日和半日2个显著短周期的振动;利用小波分析得出了温度短周期振动的时空变化特点,并结合温度跃层时空结构的分析,发现跃层深度上,温度全日(或半日)周期振动的时空变化与跃层时空结构存在一致性,即在跃层核心深度上,跃层强度越大的时域内,温度全日(或半日)周期的振动就越显著.     

70万年来西太平洋暖池北缘有孔虫氧碳同位素特征及其古海洋学意义

选取西太平洋暖池北缘西菲律宾海本哈姆高原的MD06-3047B孔沉积物柱状样为研究材料,通过分析70万年来有孔虫氧碳同位素变化特征发现:在M1S 14～ 13期,西菲律宾海由于受夏季风影响增强,可能存在上升流活动;在冰期终止期Ⅰ、Ⅱ、Ⅳ和Ⅴ期出现Pulleniatina obliquiloculata δ13C极小值事件,表明在这几个冰期终止期来自南极的低δ13C海水到达了西太平洋暖池北部边缘地区.次表层种P.obliquiloculata与表层种Globigerinoides ruber 氧同位素差值恢复的温跃层变化具有冰期逐渐变浅,间冰期逐渐变深的特点.进一步将其与西太平洋暖池核心区ODP805站和赤道东太平洋ODP847站的次表层、表层有孔虫氧同位素差值进行对比,结果显示在过去70万年来西太平洋暖池效应逐渐加强,并且存在长时间尺度的类厄尔尼诺-南方涛动(ENSO)式变化,冰消期时表现为类厄尔尼诺状态.     

热带太平洋-印度洋温跃层海温异常联合模及其演变

利用SODA次表层海温再分析资料和卫星遥感海面高度异常数据,分析了热带太平洋和印度洋温跃层海温之间的联系,提出了太平洋-印度洋温跃层海温异常联合模(PITM)的概念、并定义了该联合模指数.结果表明,联合模指数具有准两年和3~5年的年际变化周期以及2011-2012年的年际变化周期,并具有季节锁相和振幅不对称等特征.联合模的演变过程与温跃层海温异常(TOTA)的发展和传播过程紧密相联:在太平洋,TOTA一般从西太平洋出发沿赤道(5°S-5°N)向东传播,到达东太平洋之后折向北,再沿10°N-14°N纬度带向西传播到达太平洋西岸并向赤道西太平洋扩展,形成一条回路;南太平洋也有类似回路但信号较弱;在印度洋,则主要沿8°S-12°S纬度带向西传播,到达西岸后折向北,然后迅速沿赤道(1.25°S-1.25°N)向东扩展,也形成一条回路.对NCEP/NCAR再分析风场资料的合成分析则表明,联合模的演变过程与大气环流尤其是纬向垂直环流(Walker环流)的变化密切相关,联合模的正位相对应着赤道印度洋区域顺时针的Walker环流以及赤道太平洋区域逆时针的Walker环流;而联合模的负相位则有相反的情况.此外,联合模演变过程中,TOTA的传播发展与850 hPa异常纬向风的传播发展有很好的相关.     

基于表层及温跃层环境变量的南太平洋长鳍金枪鱼栖息地适应性指数模型比较

为了量化比较海表层环境及温跃层环境对南太平洋长鳍金枪鱼渔场分布的影响程度;本研究采用2010-2012年南太平洋长鳍金枪鱼延绳钓渔船实际生产统计数据;结合卫星遥感所获取的海表面温度（sea surface temperature;SST）和海表面高度（sea surface height;SSH）数据以及Argo浮标所获取的温跃层上、下界水温和深度数据;运用外包络法分别构建了基于海表层环境变量、温跃层上界环境变量以及温跃层下界环境变量的3种栖息地适应性指数（habitat suitability index;HSI）模型。模型验证结果显示;基于海表层环境变量的HSI模型;HSI>0.6时所占产量比重为70.04%;投钩数量比重为70.86%;HSI>0.8时所占产量比重为24.92%;投钩数量比重为25.79%;基于温跃层上界环境变量的HSI模型;HSI>0.6时所占产量比重为82.17%;投钩数量比重为80.95%;HSI>0.8时所占产量比重为33.24%;投钩数量比重为32.69%;基于温跃层下界环境变量的HSI模型;HSI>0.6时所占产量比重为81.01%;投钩数量比重为81.54%;HSI>0.8时所占产量比重为43.51%;投钩数量比重为43.73%。研究发现;基于温跃层上界和下界环境变量的两个HSI模型预报精度明显高于基于表层环境变量的HSI模型;且基于温跃层下界环境变量的HSI模型预报精度高于基于温跃层上界环境变量的HSI模型。研究结果表明;相较于海表层环境;温跃层环境;尤其是温跃层下界环境特征对南太平洋长鳍金枪鱼资源分布的影响更为显著。     

Further evidence for the existence of sub‐littoral populations of toheroa,Amphidesma ventricosum Gray (eulamelli‐branchiata), off the west coast of New Zealand

The finding of shells of toheroa (Amphidesma ventricosum Gray) which had been drilled by gastropods absent from the littoral zone, is presented as evidence for the existence of sub‐littoral populations of toheroa.     

Effects of the surface wave-induced mixing on circulation in an isopycnal-coordinate oceanic circulation model

The influence of the nonbreaking surface wave-induced mixing under the mixed layer on the oceanic circulation was investigated using an isopycnal-coordinate oceanic circulation model. The effect of the wave-induced mixing within the mixed layer was eliminated via a bulk mixed layer model. The results show that the wave-induced mixing can penetrate through the mixed layer and into the oceanic interior. The wave-induced mixing under the mixed layer has an important effect on the distribution of temperature of the upper ocean at middle and high latitudes in summer, especially the structure of the seasonal thermocline. Moreover, the wave-induced mixing can affect the oceanic circulation, such as western boundary currents and the North Equatorial Currents through changes of sea surface height associated with the variation of the thermal structure of the upper ocean.     

The Mechanism of the 20°C Isotherm Depth Oscillations for the Bay of Bengal

The monthly variation of thermocline depth in terms of 20°C isotherm depth (Z20) in the Bay of Bengal has been studied using SODA and ARGO datasets. During a southwest monsoon, the Bay of Bengal is deepest in the western basin and shallowest in the eastern basin while it is the opposite during northeast monsoon. The Z20 oscillation is not only affected by semiannual reversing wind forcing but also influenced by coastal Kelvin waves from the eastern coast and remote effect from the Northern Indian Ocean and Malacca Strait. A linear relationship between SSHA and Z20 has been found from both SODA and observational studies.     

High-resolution records of thermocline in the Okinawa Trough since about 10000 aBP

The present paper uses planktonic foraminifera and their stable isotopes to study the changes in the depth of thermocline (DOT) in the Okinawa Trough since the last 10000 a based on the analysis of Core B-3GC in the northern Okinawa Trough, together with that of the core in the southern Okinawa Trough. As results show, the thermocline was shallow before 6400 aBP, and deepened afterward, then became shallow again from 4000 to 2000 aBP. The DOT fluctuations display a positive correlation with those of sea surface temperature (SST). In addition, the changes in the northern Okinawa Trough are similar to those in the southern trough, implying a possible connection with the variation of the Kuroshio Current. The changes of SST and DOT suggest that the Kuroshio Current changed its intensity or main axis from 4000 to 2000 aBP and around about 6400 aBP respectively. Moreover, the changes of DOT from 8200 to 6400 aBP may indicate a gradual intensification of the Kuroshio Current.     

浅海环流研究的一种新方法

提出在较强夏季跃层存在条件下的一种研究浅海环流的新方法。该方法是根据海洋温度和盐度的时间和空间变化资料．以及该水层通过其边界（海－气或跃层）所进行的热量和质量交换，计算环流的流速和流向。作为实例，对南黄海冷水团区进行了试验，结果表明，该方法合理、可行。