海洋上层温度结构特征的参数模式

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。     

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.     

Seasonal variations in temperature,salinity and density in the southern coastal waters of the Caspian Sea

Variability in water temperature, salinity and density was investigated based on field measurements near Anzali Port, in the Southern Caspian Sea in 2008. Seasonal changes of seawater properties were mainly observed through the upper 100 m layer, while below this layer seasonal variations of the parameters were minor. Vertical structure of the temperature in the southern coastal waters of the Caspian Sea is characterized by a significant seasonal thermocline between 20–50 m depths with vertical variation in temperature about 16°C in midsummer (August). Decrease of the thermocline occurs with the general cooling of the air and sea surface water, and deepening of the mixed layer during late of autumn and winter. Seasonal averages of the salinity were estimated in a range of 12.27–12.37 PSU. The structure of thermocline and pycnocline indicated agreement between changes of temperature and density of seawater. Seasonal pycnocline was observed in position of the thermocline layer.     

Oceanic response to Typhoon Nari (2007) in the East China Sea

The oceanic response to a typhoon in the East China Sea (ECS) was examined using thermal and current structures obtained from ocean surface drifters and a bottom-moored current profiler installed on the right side of the typhoon’s track. Typhoon Nari (2007) had strong winds as it passed the central region of the ECS. The thermal structure in the ECS responded to Typhoon Nari (2007) very quickly: the seasonal thermocline abruptly collapsed and the sea surface temperature dropped immediately by about 4°C after the typhoon passed. The strong vertical mixing and surface cooling caused by the typhoon resulted in a change in the thermal structure. Strong near-inertial oscillation occurred immediately after the typhoon passed and lasted for at least 4–5 days, during which a strong vertical current existed in the lower layer. Characteristics of the near-inertial internal oscillation were observed in the middle layer. The clockwise component of the inertial frequency was enhanced in the surface layer and at 63 m depth after the typhoon passed, with these layers almost perfectly out of phase. The vertical shear current was intensified by the interaction of the wind-driven current in the upper layer and the background semi-diurnal tidal current during the arrival of the typhoon, and also by the near-inertial internal oscillation after the typhoon passage. The strong near-inertial internal oscillation persisted without significant interfacial structure after the mixing of the thermocline, which could enhance the vertical mixing over several days.     

长山群岛海区春季水温垂直结构分析

利用海军大连舰艇学院2006年4月长山群岛海区的CTD调查资料,系统分析了该季节长山群岛海区的温度垂直结构,并探讨了其形成机理。分析指出:4月上、中旬是长山群岛海区季节性温跃层的生成期,群岛东侧和南侧边缘受黄海冷水团形成过程的影响,温跃层的出现概率和跃层强度都远远高于群岛内部;在生成时机上,群岛东侧和南侧边缘海域早于群岛内部水域。中间层和底层海水温度的垂直结构与海流有着很好的相关性,在海洋平流的作用下,海区会产生正跃层、逆跃层、冷中间层、暖中间层等复杂的温度垂直结构。上层海水温度结构主要受海面风场和气温的影响,较强的热辐射和充分的风力搅拌能够加速温跃层的生成。     

Anomalies of the Black Sea surface temperature and modeling of intense cold anomaly formation in September 2014

Seasonal average distribution of mesoscale anomalies of the Black Sea surface temperature (SST) and features of their localization for various seasons are considered. The area of cold SST anomalies is detected in open western and central parts of the sea. It is shown that an autumn season makes a major contribution to the formation of long-lived mesoscale cold anomalies in the central parts of the sea. The key features are reproduced and the main physical mechanism of rapid development of a cold anomaly is determined in the numerical experiment using the WRF-ARW model with the attached 3dPWP unit. It is shown that fast cooling occurs mainly due to the entrainment of cold waters from a thermocline, which results in the abrupt deepening of the upper quasi-homogeneous layer.     

A three-layer model for the thermal structure in the Huanghai Sea

A one-dimentional three-layer model for the thermal structure in the Huanghai Sea is presented in this study, me model consists of the upper mixed layer caused by heating and wind mixing, the lower mixed layer driven by tidal mixing, and the thermocline with certain thickness. The entrainment velocities of the upper and lower layers are obtained respectively. The results show that the model is capable of describing the development and decline processes of the seasonal thermocline in the Huanghai Sea, simulating successfully the Huanghai Sea Cold Water Mass, the nearshore front and surface cold water off North Jiangsu and explaining reasonably their formation mechanisms as well as the strong thermocline off Qingdao. It is suggested that the tidal mixing plays key role in the formation of the nearshore front off North Jiangsu and the strong thermocline off Qingdao. The wind mixing and the tidal mixing make the lower layer water with high nutrients go up to the upper layer. This physical process may be sig     

A quasi-three-dimensional numerical prediction model of salinity structure in Bohai Sea and Huanghai Sea

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Upper Ocean Four-Dimensional Variational Data Assimilation in the Arabian Sea and Bay of Bengal

A regional ocean circulation model with four-dimensional variational data assimilation scheme is configured to study the ocean state of the Indian Ocean region (65°E–95°E; 5°N–20°N) covering the Arabian Sea (AS) and Bay of Bengal (BoB). The state estimation setup uses 10 km horizontal resolution and 5 m vertical resolution in the upper ocean. The in-situ temperature and salinity, satellite-derived observations of sea surface height, and blended (in-situ and satellite-derived) observations of sea surface temperature alongwith their associated uncertainties are used for data assimilation with the regionally configured ocean model. The ocean state estimation is carried out for 61 days (1 June to 31 July 2013). The assimilated fields are closer to observations compared to other global state estimates. The mixed layer depth (MLD) of the region shows deepening during the period of assimilation with AS showing higher MLD compared to the BoB. An empirical forecast equation is derived for the prediction of MLD using the air–sea forcing variables as predictors. The surface and sub-surface (50 m) heat and salt budget tendencies of the region are also investigated. It is found that at the sub-surface, only the advection and diffusion temperature and salt tendencies are important.     

秋季和春季黄渤海黄色物质空间分布特征

利用2013年秋季和2014年春季两个季节黄渤海现场数据对黄色物质的水平分布及垂向分布的变化进行研究,并初步分析了其主要控制因素。垂向黄色物质表现为底部高上层低的特征。其中,秋季混合作用加强导致上层40m黄色物质混合较为均匀;春季北黄海温盐跃层已经形成,黄色物质分布开始出现明显的分层现象,上下层浓度差约为2?g/L。春季南黄海盐度跃层尚未形成,水深小于50m的水层黄色物质垂向分布均匀,近岸和远岸海域浓度分界线明显。水平方向上,黄色物质在秋季和春季分布趋势一致,由渤海、北黄海至南黄海浓度依次降低,且呈现出由近岸向中央海区递减的趋势,但整体上春季浓度较秋季明显偏低。海表盐度与黄色物质浓度两者整体上呈现负相关关系,可以将黄色物质浓度分布作为研究黄海暖流走向、划分水团性质的重要指标。     

南海南部上层的湍流混合特征

A turbulent microstructure experiment was undertaken at a low latitude of 10°N in the South China Sea in late August 2012. The characteristics of the eddy diffusivity above 650 m were analyzed, which is one order of magnitude larger than that in the open ocean at that low latitude. Enhanced eddy diffusivities by strong shears and sharp changes in topography were observed. The strongest eddy diffusivity occurred in the mixed layer, and it reached O(10–2 m2/s). Strong stratification in the thermocline inhibited the penetration of surface eddy diffusivities through the thermocline, where the mixing was weakest. Below the thermocline, where the background eddy diffusivity was approximately O(10–6 m2/s), the eddy diffusivity increased with depth, and its largest value was O(10–3 m2/s).     

夏季黄东海硝酸盐垂向扩散通量的分析

湍流扩散过程导致的硝酸盐垂向输运对海水表层的浮游植物生长和初级生产力的大小有着重要影响。本文基于2018年夏季黄、东海水文环境、硝酸盐浓度和湍动能耗散率的同步、原位数据,分析了海域温度、盐度和硝酸盐的空间分布特征,结果表明营养盐含量丰富的黄海冷水团、长江冲淡水、东海北部底层混合水与黑潮次表层水是影响研究海域硝酸盐分布的主要水团。利用垂向湍扩散硝酸盐通量公式,计算了三个选定断面上的硝酸盐垂向扩散通量,其高值区与湍流扩散系数的高值区的位置基本一致。针对存在明显硝酸盐跃层的站位,计算得到跨硝酸盐跃层的垂向通量F_ND的范围在-9.78—36.60mmol/（m²·d）之间,在黄海冷水团区,夏季温跃层限制了该区营养盐向近表层的湍流垂向扩散;东海北部底层混合水区,湍流垂向扩散向上层补充了大量硝酸盐,促进了跃层之上浮游植物的生长;黑潮次表层水影响海区,夏季中层水体混合较弱,跨跃层的垂向通量也普遍偏低。开展硝酸盐垂向扩散通量的计算与分析,对进一步明确营养盐的输运机制有着重要研究意义。     

黄海在有无潮作用下对“布拉万”不同响应的数值模拟研究

黄海是典型的强潮驱动的陆架浅海。为了研究黄海对台风的响应特点,本文利用区域海洋模式(Regional Ocean Modeling Systems,ROMS)分别模拟了在有潮和无潮作用下黄海对台风"布拉万"的响应过程。结果表明,不管潮存在与否,"布拉万"经过黄海后都引起了海表面降温和流速的近惯性振荡响应,这种响应主要分布于黄海中部较深区域,带通滤波提取的近惯性流速具有垂向第一模态特征。同时,研究发现强背景潮流能显著地影响黄海对"布拉万"的响应过程。主要结论如下:一方面,由于潮的存在,近岸垂向混合均匀的较暖水体与远岸较冷水体之间会形成潮混合温度锋面,"布拉万"过后,暖水发生了明显的离岸扩张,尽管路径右侧的混合层降温更显著,但是左侧即黄海西岸的暖水扩张更明显;另一方面,潮的存在减弱了布拉万产生的近惯性振荡响应,半日潮流在黄海仍然占据主导地位。在混合层中潮流的作用减弱了"布拉万"产生的近惯性能量,但也使其更易穿过跃层传入黄海内部。     

Phytoplankton communities in the Bering Sea and adjacent seas

Vertical distribution of phytoplankton in early warming season in the eastern Bering Sea and adjacent sea areas was investigated. In the surface layer which was under the influence of newly melted sea ice in the shelf water region of the Bering Sea in May, remarkably dense populations ofThalassiosira hyalina andT. nordenskiöldii and relatively large populations ofFragilaria andNavicula occupied large part of phytoplankton community. In June, although theThalassiosira populations sunk into the bottom layer and withered, a certain part of theFragilaria-Navicula populations was still suspended in subsurface layer. Thus,Fragilaria-Navicula were the leading components of the June community in the shelf region.In the Bering Basin region, no dense phytoplankton populations were developed until a shallow thermocline was established. In June when the shallow thermocline developed near shelf edge,Thalassiosira decipiens burst out. As the shallow thermocline extended from near shelf to central part of the Basin region with surface warming, the areas of blooming also shifted from near shelf to the central part.Contribution No. 73 from the Research Institute of North Pacific Fisheries, Hokkaido University.     

潮汐作用下渤海温跃层波动与起伏的数值研究

研究了潮汐(四大分潮 M₂,S₂,K₁,O₁同时输入)作用下渤海温跃层起伏与波动的三维数值模型(将海洋分为3层,即上混和层、跃层和下混和层),揭示了整个海区温跃层上界面处跃层起伏(在文中指每个时刻跃层波高的周期平均值)的地理分布及叠加在起伏之上的潮周期波动的时空变化,模拟出跃层波动与实测基本一致.结果发现大振幅的跃层波动均发生在海峡及近海地形突变之处.一般界面波动的波高大于甚至远远大于同一位置的表层潮波.从位相以及周期来看,潮波和跃层上下界面波动相互之间,有些海域一致,有些地方则相差甚远.跃层上界深度及厚度的梯度,对跃层起伏分布有一定的影响.跃层起伏还可能与海岸海底摩擦有关.     

利用Argo剖面浮标分析上层海洋对台风“布拉万”的响应

In situ observations from Argo profiling floats combined with satellite retrieved SST and rain rate are used to investigate an upper ocean response to Typhoon Bolaven from 20 through 29 August 2012. After the passage of Typhoon Bolaven, the deepening of mixed layer depth(MLD), and the cooling of mixed layer temperature(MLT) were observed. The changes in mixed layer salinity(MLS) showed an equivalent number of increasing and decreasing because the typhoon-induced salinity changes in the mixed layer were influenced by precipitation, evaporation, turbulent mixing and upwelling of thermocline water. The deepening of the MLD and the cooling of the MLT indicated a significant rightward bias, whereas the MLS was freshened to the left side of the typhoon track and increased on the other side. Intensive temperature and salinity profiles observed by Iridium floats make it possible to view response processes in the upper ocean after the passage of a typhoon. The cooling in the near-surface and the warming in the subsurface were observed by two Iridium floats located to the left side of the cyclonic track during the development stage of the storm, beyond the radius of maximum winds relative to the typhoon center. Water salinity increases at the base of the mixed layer and the top of the thermocline were the most obvious change observed by those two floats. On the right side of the track and near the typhoon center when the typhoon was intensified, the significant cooling from sea surface to a depth of 200×104 Pa, with the exception of the water at the top of the thermocline, was observed by the other Iridium float. Owing to the enhanced upwelling near the typhoon center, the water salinity in the near-surface increased noticeably. The heat pumping from the mixed layer into the thermocline induced by downwelling and the upwelling induced by the positive wind stress curl are the main causes for the different temperature and salinity variations on the different sides of the track. It seems that more time is required for the anomalies in the subsurface to be restored to pretyphoon conditions than for the anomalies in the mixed layer.     

Monitoring regional sea ice of the Bohai Sea by SSM/I scattering index

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Monitoring regional sea ice of the Bohai Sea by SSM/I scattering index

SSM/I data on the Bohai Sea of China from 1994 to 1996 have been studied.The sea ice algorithms of calibration/validation such as the brightness temperature index [AES/YORK TBI (Hollinger et al.,1992)] and ocean scattering index [OSI (Ferraro et al.,1996, The Bulletin of the American Meteorological Society, 77(5), 891-905)] are not applicable to the detection of regional sea ice of mid-latitude Bohai area.This paper presents a method of the scatfeting index SI and polarization index PI to identify regional Bohai Sea ice.Numerical results of vector radiative transfer for a model of a layer of sea ice over ocean simulate the relationship between SI/PI and sea ice depth, and others.It is employed to categorize the SI/PI indexes for the detection of sea ice.     

"苏拉"和"达维"双台风过程中台风浪和海温的数值模拟

本文基于FVCOM-SWAVE耦合模型,以双台风"苏拉"和"达维"的台风过程为例,研究了台风过程中海浪和海温的变化,通过与高度计和Argo资料的对比,发现耦合模型能较准确的模拟出有效波高和海表面温度。由于双台风风场相互作用,风场结构和最大风速位置发生改变,影响着有效波高的分布,台风"苏拉"产生的最大有效波高位于台风后侧。海表面温度的降低与风场、浪场分布密切相关,强风强浪处的降温现象更明显,"苏拉"产生的降温区域位于路径附近,"达维"产生的降温区域位于路径右侧。台风对海表面温度的降低与初始的混合层厚度、温跃层强度存在相关性,具体表现为初始的混合层越薄、温跃层强度越大,降温越明显。     

Upper ocean near-inertial response to 1998 Typhoon Faith in the South China Sea

During the South China Sea monsoon experiment (SCSMEX),three autonomous temperature line acquisition system (ATLAS) buoys with acoustic Doppler current profiler (ADCP) were moored in the South China Sea to measure temperature,salinity and current velocity.Typhoon Faith passed through about 250 km south to one of the mooring buoys located at 12 58.5 N,114 24.5 E from December 11 to 14,1998.The data analysis indicates that the typhoon winds induce a great increase in the kinetic energy at near-inertial frequencies with two maxima in the mixed layer and thermocline.The near-inertial oscillations were observed at the upper 270 m in the wake of Typhoon Faith.The oscillations were originally excited in the sea surface layer and propagated downward.The amplitudes of the oscillations decrease with depth except in the thermocline.The near-inertial oscillation signals are also remarkable in temperature and salinity fields.