“浮星”自持式剖面浮标研究现状及进展

自持式剖面浮标在水中自由沉浮,具有隐秘性好、易投弃、体积小、重量轻、移动速度慢和制造成本低的特点,可用于长期、连续海洋观测及水下安全监视。文中介绍了全球Argo海洋观测网,综述了自持式剖面浮标发展历程及国内外研究现状。针对国产自持式剖面浮标不能满足现代海洋观测的需求,设计了2000 m以下水深工作的“浮星”自持式剖面浮标,填补了国内空白。“浮星”采用可变体积式浮力调节装置、硼硅玻璃球体作为耐压壳体,可搭载CTD、溶解氧等多种传感器,具有定深悬停、卫星定位和双向通讯等功能。目前,工程样机顺利通过实验室测试、南海海试、西太平洋可靠性测试,实现了4000 m水深下潜,验证了承压密封、浮力调节、通信控制等多项功能指标及整体可靠性、稳定性,为逐步实现全水深工作奠定基础。

深海自持式剖面浮标浮力变化规律

为了分析海水温度、盐度、压力等环境参量对深海自持式剖面浮标净浮力的影响规律,以自主研发的4 000 m水深自持式智能浮标"浮星1号"为研究对象,建立理论模型,得到浮标整体变形量随压力、温度的变化规律.通过压载试验及海上试验,验证了仿真模型预测结果的准确性和可靠性,得到浮标运动过程中的体积及浮力变化规律.研究结果表明:温度对浮标体积的影响主要体现在较浅深度范围内,压力对浮标体积的影响随水深基本呈线性规律变化;浮标净浮力随着水深的增加呈非线性规律增加,在较浅深度的情况下,净浮力变化量主要受温度的影响,在较大深度的情况下,净浮力变化量主要受压力的影响;至4 000 Pa,浮标体积收缩总量为818 mL,净浮力增量等效质量为463 g.

Surface circulation patterns observed by drifters in the Yellow Sea in summer of 2001,2002 and 2003

In summer of 2001, 2002 and 2003, ten, six and seventeen satellite-tracked surface drifters with drogues centered at 15 and 4 m were deployed, respectively, in the southern Yellow Sea (YS). 23 drifters of them transmitted useful data of at least 30 days. The wind-driven component of the drift was removed from the original drift velocity of drifters. The wind data used are from NCEP (National Center for Environmental Prediction), USA.Trajectories and drift velocities of the 23 drifters depicted the upper circulation structure in the southern YS.There exists an anti-cyclonic eddy with a mean speed and radius of 0.063 m/s and 50km in the central southern YS, whose center lingered within 35.3-36.0°N / 123.5-124.0°E. Showed by 6 drifters, a basin-scale elliptic cyclonic gyre with a mean speed of 0.114 m/s, long and short radius of 250 and 200 km surrounds the anti-cyclonic eddy. In the southwestern part of the southern YS has obvious frontal eddy activities within about100 km with a mean speed about 0.076 m/s. All the drifters passing Korean coast were staggering for more than10 days west of a protruding cape of central Korea. A small-scale cyclonic eddy centered at around 120.5°E/35.1°N with a mean speed of 0.048 m/s was observed in western part of the southern YS.

Variability of surface velocity in the Kuroshio Current and adjacent waters derived from Argos drifter buoys and satellite altimeter data

By combining Argos drifter buoys and TOPEX/POSEIDON altimeter data, the time series of sea-surface velocity fields in the Kuroshio Current (KC) and adjacent regions are established. And the variability of the KC from the Luzon Strait to the Tokara Strait is studied based on the velocity fields. The results show that the dominant variability period varies in different segments of the KC: The primary period near the Luzon Strait and to the east of Taiwan Island is the intra-seasonal time scale; the KC on the continental shelf of the ECS is the steadiest segment without obvious periodicity, while the Tokara Strait shows the period of seasonal variability. The diverse periods are caused by the Rossby waves propagating from the interior ocean, with adjustments in topography of island chain and local wind stress.

Comparative analysis of significant wave height between a new Southern Ocean buoy and satellite altimeter

In-situ observation is restricted by the strong wind and waves in the Southern Ocean.A Westerlies EnvironmentalMonitoring Buoy(WEMB)was firstly deployed in the Southern Ocean during China’s 35th Antarctic Expedition,facilitating further understanding of the oceanic environmental characteristics of this region.With the develop-ment of technology and the improvement of data processing methods,the accuracy of satellite altimeter productsis constantly improved,thus making it possible to inspect and evaluate the in-situ observation data.Based on theL3 products of multiple satellite altimeters,this paper analyzes and corrects the significant wave height(SWH)data of WEMB by means of data matching,error statistics,and linear least-squares fitting.Through this study,the authors obtained the following results.The effect of gravitational acceleration changes with latitude on SWHaccuracy is fairly small.Due to the low response of WEMB to high-frequency waves,there is a systematic devia-tion.A feasible correction method is therefore proposed to improve the SWH accuracy of WEMB.The temporalvariation of the corrected SWH is highly consistent with that of the 10 m wind during the observation period,and its average value reaches 3.8 m.

手做七星浮

七星标看起来很简单，但想做出灵敏且像样的七星标，也需要下一番功夫。

Impacts of internal waves on chlorophyll a distribution in the northern portion of the South China Sea

Internal waves can bring nutrients to the upper level of water bodies and facilitate phytoplankton photosynthesis.Internal waves occur frequently in the northern portion of the South China Sea and inflict an important effect on chlorophyll a distribution.In this study,in-situ observation and satellite remote sensing data were used to study the effects of internal waves on chlorophyll a distribution.Based on the in-situ observations,lower chlorophyll a concentrations were present in the middle and bottom level in areas in which internal waves occur frequently,while the surface chlorophyll a distribution increased irregularly,and a small area with relatively higher chlorophyll a concentrations was observed in the area around the Dongsha Island.Satellite remote sensing showed that the chlorophyll a concentration increased in the area near Dongsha Island,where internal waves frequently occurred.The results of the increased chlorophyll a concentration in the surface water near Dongsha Island in the northern portion of the South China Sea indicated that internal waves could uplift phytoplankton and facilitate phytoplankton growth.

Evaluation of the retrieval of total suspended matter concentration in Taihu Lake,China from CBERS-02B CCD

Remote sensing techniques is used to quantify the total suspended matter concentration （CTSM）. In this study, we used remotely sensed data to retrieve the CTSM for the Taihu Lake, China, and developed an atmospheric correction algorithm especially for CBERS-02B CCD data. We simulated the remote sensing reflectance （Rr~） of CCD bands using in-situ observations made in a cruise over the Taihu Lake in autumn 2004, from which a retrieval model is established with simulated Rrs（830） and measured CTSM. In addition, we applied the atmospheric correction algorithm and retrieval model to process the CCD data over the lake in 2008 and to retrieve the CTSM. The RMS relative error between the CTSM retrieved from MODIS and from the CCD images is about 42.9%, indicating that algorithms described in this paper can be used for the application of CCD data in monitoring the CTSM distribution in the Taihu Lake.

Vertical structure and evolution of the Luzon Warm Eddy

Eddies are frequently observed in the northeastern South China Sea （SCS）. However, there have been few studies on vertical structure and temporal-spatial evolution of these eddies. We analyzed the seasonal Luzon Warm Eddy （LWE） based on Argo float data and the merged data products of satellite altimeters of Topex/Poseidon, Jason-1 and European Research Satellites. The analysis shows that the LWE extends vertically to more than 500 m water depth, with a higher temperature anomaly of 5℃ and lower salinity anomaly of 0.5 near the thermocline. The current speeds of the LWE are stronger in its uppermost 200 m, with a maximum speed of 0.6 m/s. Sometimes the LWE incorporates mixed waters from the Kuroshio Current and the SCS, and thus has higher thermohaline characteristics than local marine waters. Time series of eddy kinematic parameters show that the radii and shape of the LWE vary during propagation, and its eddy kinetic energy follows a normal distribution. In addition, we used the empirical orthogonal function （EOF） here to analyze seasonal characteristics of the LWE. The results suggest that the LWE generally forms in July, intensifies in August and September, separates from the coast of Luzon in October and propagates westward, and weakens in December and disappears in February. The LWE＇s westward migration is approximately along 19°N latitude from northwest of Luzon to southeast of Hainan, with a mean speed of 6.6 cm/s.

Estimating thermohaline variability of the equatorial Pacific Ocean from satellite altimetry

The vertical thermohaline structure in the western equatorial Pacific is examined with a Gravest Empirical Mode(GEM)diagnosis of in-situ mooring measurements. The poor GEM performance in estimating deep thermohaline variability from satellite altimetry confirms a lack of vertical coherence in the equatorial ocean. Mooring observation reveals layered equatorial water with phase difference up to 6 months between thermocline and sub-thermocline variations. The disjointed layers reflect weak geostrophy and resemble pancake structures in non-rotating stratified turbulence. A coherency theorem is then proved, stating that traditional stationary GEM represents in-phase coherent structure and can not describe vertically out-of-phase variability. The fact that stationary GEM holds both spatial and temporal coherence makes it a unique tool to diagnose vertical coherent structure in geophysical flows. The study also develops a non-stationary GEM projection that captures more than 40% of the thermohaline variance in the equatorial deep water.