南海表层水温年循环的数值模拟

本文采用一个非线性约化重力海洋模式对南海表层水温(SST)年循环过程进行了数值研究,探讨了南海表层水温年循环形成和维持的动力学和热力学机制·模拟结果表现出与观测分析相一致的年循环变化阶段性和空间结构,并发现南海SST年循环的阶段性是海面动力强迫和热力强迫共同作用的结果;南海上层海洋的热力平衡有着明显的季节特征.     

Life cycle of intraseasonal oscillation of summer SST in the western South China Sea

Intraseasonal oscillation (ISO, times-cales of 30~90 d) of summer sea surface temperature (SST) in the western South China Sea is studied using harmonic and empirical orthogonal function analyses of microwave observations by the tropical rainfall measuring mission satellite. Each summer from May to September, two or three ISO events occur off South Vietnam, with a typical period of approximately 50 d. The life cycle of these events from the initiation to decay of SST anomalies is described.     

On the heat budget of the Arabian Sea

This study analyzes the heat budget of the Arabian Sea using satellite-derived sea-surface temperature (SST) from 1985 to 1995 along with other data sets. For a better understanding of air–sea interaction, canonical average monthly fields representing the spatial and temporal structure of the various components of the heat balance of the Arabian Sea are constructed from up to 30 years of monthly atmospheric and oceanic data. The SST over the Arabian Sea is not uniform and continually evolves with time. Cooling occurs over most of the basin during November through January and May through July, with the greatest cooling in June and July. Warming occurs over most of the basin during the remainder of the year, with the greatest warming occurring in March and September. Results indicate that the sign of the net heat flux is strongly dependent on the location and month. The effects of net heat flux and penetrative solar radiation strongly influence the change in SST during February and are less important during August and September. Horizontal advection acts to cool the sea surface during the northeast monsoon months. During the southwest monsoon horizontal advection of surface waters warms the SST over approximately the southern half of the basin, while the advection of upwelled water from the Somalia and Oman coasts substantially cools the northern basin. The central Arabian Sea during the southwest monsoon is the only area where the change in SST is balanced by the entrainment and turbulent diffusion at the base of the mixed layer. Agreement between the temporal change in the satellite-derived SST and the change calculated from the conservation of heat equation is surprisingly good given the errors in the measured variables and the bulk formula parameters. Throughout the year, monthly results over half of the basin agree within 3°. Considering that the SST changes between 8° and 12° over the year, this means that our results explain from 62% to 75% of the change in SST over 56% of the Arabian Sea. Two major processes contribute to the discrepancy in the change in SST calculated according to the heat budget equation and the change in SST derived from satellite observations. The first is the effect of the horizontal advection term. The position of the major eddies and currents during the southwest monsoon greatly affects the change in SST due to the large gradient in temperature between the cold upwelled waters along the Somali coast to the warm waters in the interior of the basin. The second major process is the thermocline effect. In areas of shallow mixed-layer depth, high insolation and wind speeds of either less than 3 m/s or greater than 15 m/s, the bulk formulae parameterization of the surface heat fluxes is inappropriate.     

基于卫星遥感海温数据的南海SST预报误差订正

尝试利用卫星遥感高分辨率海表温度资料GHRSST (Group for High Resolution Sea Surface Temperature) 与海表温度(sea surface temperature, SST)数值预报产品之间的误差, 建立一种南海SST模式预报订正方法。首先, 利用南海的Argo浮标上层海温数据对GHRSST 海温数据进行验证, 结果表明两者之间均方根误差约为0.3℃, 相关系数为0.98, GHRSST 海温数据可用于南海业务化数值预报SST的订正。预报订正后的SST与Argo浮标海温数据相比, 24h、48h和72h的均方根误差均由0.8℃左右下降到0.5℃以内。与GHRSST 海温数据相比, 南海北部海域(110°E—121°E, 13°N—23°N)订正后的24h、48h和72h的SST预报空间误差均显著减小, 在冷空气影响南海期间或中尺度涡存在的过程中, SST预报订正效果也较为显著。因此, 该方法可考虑在南海业务化SST数值预报系统中应用。     

安达曼海的热收支分析及其水交换研究

The characteristics of the T/S structures, water mass exchange and deep circulation in the Andaman Sea are investigated based on the simulation from a high-resolution general circulation model(MITgcm). The results show that, below 1 000 m, the water mass is saltier, warmer and more homogeneous in the Andaman Sea than that in the Bay of Bengal, attributing to the strong vertical mixing at the depth of ～1 800 m. The water mass exchange between the Andaman Sea and the Bay of Bengal goes through three major channels, which manifests itself as follows: the northern channel(Preparis Channel) is the main passage of water mass transport from the Bay of Bengal to the Andaman Sea, whereas the Middle Channel(the south of Andaman Islands and the north of Nicobar Islands) has an opposite transport; the southern channel(Great Channel) features with a four-layer water exchange which results in the least net transport among the three channels; all the transports through the three channels have an intra-annual variation with a period of half a year. At 1 000-m depth, the entire Andaman Sea is occupied by a cyclonic circulation in January and July while by an anticyclonic one in April and October. The semiannual cycle found in both the deep circulation and water mass exchange is likely associated with the downwelling eastward-propagating Kelvin waves induced by the semiannual westerly component in the equatorial Indian Ocean during intermonsoon seasons.     

南海表层水温年循环的谐波特征

通过对ＮＣＥＰ１°×１°周平均ＳＳＴ资料（１９８２～１９９４）进行谐波分析,发现南海ＳＳＴ年循环中基波Ｗ１和第二谐波Ｗ２是决定性的谐波;诸谐波具有准驻波特征：气候平均意义下的季节内振荡不显著。此外,还讨论了南海全区ＳＳＴ在夏季风爆发之前迅速增温的原因     

2008/2009年冬季南海冷涌天气过程的海-气热通量交换及热量收支

冬季风期(11月—翌年3月)南海显著的气候特点是盛行东北季风并频繁地发生冷涌天气过程。使用2008年10月到2009年4月在西沙群岛永兴岛近海进行的海-气通量观测试验资料,分析了西沙海域冬季风期,尤其是冷涌时段的海-气通量交换和热量收支特征。结果表明:冬季风前期由于海-气温差增大,感热通量比西南季风期稍增加;潜热通量平均值与西南季风期接近;太阳总辐射明显降低,大气长波辐射减小,海洋热量净收入成为负值,使得秋季之后海面温度不断降低。冷涌期间海-气之间的感热通量高于冬季风期平均值,潜热通量大部分(1月份之前)也高于冬季风期平均值;由于潜热通量增大和太阳短波辐射减小,1月份之前的冷涌过程海洋热量净收支普遍出现较大负值,海洋失热量强于冬季风期,甚至强于2008年台风过程平均值。到了冬季后期太阳总辐射增强,海洋热量净收入转为正值,海水温度又逐渐升高。季节之间比较,观测区感热通量以冬季风期间最大,秋季次之,春季最小;而潜热通量夏季风期出现最大值,冬季次之,秋季最小。     

南海北部集合卡曼滤波同化SST试验

基于POM(Princeton Ocean Model)建立一个南海北部集合卡曼滤波的同化模式,主要用于卫星海表面温度的同化.模式的平均水平分辨率为5km,垂向分层为20层;侧边界条件嵌套到一个大范围的南海海洋模式,在同化方案上采用一个均方根集合卡曼滤波算法,避免观测的扰动;适当引入局地化算子,消除样本在空间上的虚假相关,同时增加集合样本的自由度.该同化试验同化了2008年夏季6月到7月的GHRSST(Global High-Resolution Sea Surface Temperature),然后采用2008年夏季SCOPE(Northern South China Sea Coastal Oceanographic Process Experiment)航次的温、盐数据对同化结果进行评估.结果表明,相对于未同化模式模拟结果,同化模式温度的改善比较明显,表现在加强了南海北部的上升流,校正了海表温度的偏差,改善了温度的垂向分布.由于集合卡曼滤波是一种多变量调整的同化方法,同化SST不仅能改善表层与次表层的温度分布,而且对流场和盐度的调整也比较明显.     

南海海表温时空演变与南海夏季风爆发早晚相关性初探

利用我国近海1986-2008年间的海温再分析资料,分析了南海海温异常的时空变化,重点揭示了南海夏季风爆发前后(4-6月)南海表层海温异常的时空演变特征,并探讨了其与南海夏季风爆发早晚的相关关系。结果显示,南海夏季风爆发前后南海表层海温异常存在一个显著时空演变模态,4月南海全域海表温度异常几呈负位相态势,其中正值信号首先出现于巴拉望岛以西海域,随后逐步向西向北扩展,5月南海大部已被海表温异常正位相控制,6月南海表层海温异常完成负-正位相转换。分析表明,南海表层海温异常时空演变的年际差异与南海夏季风爆发的早晚存在显著相关。综合已有研究认为,南海海表温异常时空演变所形成的季节内尺度的热力差异(主要包含演进趋势、速度和幅度等)可能是影响南海夏季风爆发早晚的一个重要因子,据此建立了海表温温差异常指标,其对南海夏季风爆发早晚具有较好的反映能力。此外,南海海表温异常时空演变与南海暖池的变化紧密关联。相关分析还发现,南海夏季风爆发前期南海暖池与印度洋暖池的海表温差异常存在显著正相关关系,而与西太平洋暖池为负相关关系。南海海表温异常季节内演变在印-太暖池区海表热力格局及差异形成背景下或可通过影响大尺度经向和纬向环流而引发南海夏季风爆发早晚之年际异常。     

CMIP5模式对南海SST的模拟和预估

分析了32个CMIP5模式对南海历史海表温度(SST)的模拟能力和不同排放情景下未来SST变化的预估。通过检验各气候模式对南海历史SST增温趋势和均方差的模拟,发现大部分模式都能较好地模拟出南海20世纪历史SST的基本特征和变化规律,但也有部分模式的模拟存在较大偏差。尽管这些模拟偏差较大的模式对SST多模式集合平均的影响不大,但会增加未来情景预估的不确定性。剔除15个模式后,分析了南海SST在RCP26、RCP45和RCP85三种排放情景下的变化趋势,发现在未来百年呈明显的增温趋势,多模式集合平均的增温趋势分别为0.42、1.50和3.30℃/(100a)。这些增温趋势在空间上变化不大,但随时间并不是均匀变化的。在前两种排放情景下,21世纪前期的增温趋势明显强于后期,而在RCP85情景下,21世纪后期的增温趋势强于前期。     

吕宋海峡Ekman输运和南海SST的相关性分析

在利用1950—2009年NCEP(National Center for Environmental Prediction)资料分析风场数据的基础上,计算吕宋海峡的Ekman输运,研究表明其存在显著的季节变化,除了夏季外,其它季节均为由太平洋向南海输运。分析吕宋海峡Ekman输运和南海海盆表征上层热力状况的海表面温度SST(Sea Surface Temperature)之间的关系发现:在年内时间尺度上,两者不存在显著的同期相关,Ekman输运对SST的影响开始于一个月之后,从北部向南扩展,第二个月最为明显,并扩展至整个海盆,第三个月开始衰减,第四个月影响消失,且相关性为正;在年际尺度上,吕宋海峡Ek-man输运的异常同南海SSTA(Sea Surface Temperature Abnormal)的第二模态存在显著的相关联系,并且吕宋海峡Ekman输运和南海SSTA的相关关系在北部为正,南部为负。吕宋海峡Ekman输运调制南海大尺度环流,通过暖、冷平流的作用影响南海SST的变化。     

A possible role of the South China Sea in ENSO cycle

A data-based hypothesis on the role of the South China Sea (SCS) in ENSO cycle is proposed: during El Nino, there are westerly wind anomaly over the western equatorial Pacific and positive SST anomaly in the eastern equatorial Pacific. Meanwhile anomalous convection moves to the central Pacific with anomalous sinking over Indonesian Archipelago. The latter can cause southerly wind anomaly over the north of South China Sea (NSCS) and makes the NSCS warmer. The warm NSCS can attract the anomalous convection to it in some degree. This attraction is in favor for producing easterly wind anomaly over the western equatorial Pacific, so it helps to form a cycle.     

Sea surface height variations in the South China Sea from satellite altimetry

Sea surface elevation in the South China Sea is examined in the Topex/Poseidon altimeter data from 1992 to 1995. Sea level anomalies are smoothed along satellite tracks and in time with tidal errors reduced by harmonic analysis. The smoothed data are sampled every ten days with an along-track separation of about 40 km. The data reveal significant annual variations in sea level. In winter, low sea level is over the entire deep basin with two local lows centred off Luzon and the Sunda Shelf. In summer, sea level is high off Luzon and off the Sunda Shelf, and a low off Vietnam separates the two highs. The boundary between the Vietnam low and Sunda high coincides with the location of a jet leaving the coast of Vietnam described in earlier studies. Principal component analysis shows that the sea level variation consists mainly of two modes, corresponding well to the first two modes of the wind stress curl. Mode 1 represents the oscillation in the southern basin and shows little inter-annual variation. The mode 2 oscillation is weak in the southern basin and is strongest off central Vietnam. During the winters of 1992–1993 and 1994–1995 and the following summers, the wind stress curl is weak, and the mode 2 sea level variation in the northern basin is reduced, resulting in weaker winter and summer gyres. Weakening of the Vietnam low in summer implies diminishing of the eastward jet leaving the coast of Vietnam. The results are consistent with model simulations.     

MODIS月平均海面温度在太平洋的检验与在南海的应用

使用由我国投放的位于太平洋海域的ARGO浮标表屡温度数据,对相应时相和海区的MODIS月平均海洋表面温度(SST)产品进行检验,验证结果表明,MODIS月平均SST产品的均方根误差为0.78℃,平均偏差为-0.37 ℃,二者的相关系数为0.994 5,因此,使用MODIS月平均SST数据对我国南海表层水温年变化规律进行...     

基于ROMS模式的南海SST与SSH四维变分同化研究

卫星遥感观测获得了大量高分辨率的海面实时信息,包括海面温度（SST）和海面高度（SSH）等,同化进入数值模式可有效提升模拟精度。本文基于ROMS模式与四维变分同化方法（4DVAR）,使用AVHRR SST和AVISO SSH数据,开展了南海区域同化实验。为检验同化的效果,分别利用HYCOM再分析资料和Argo温盐实测数据分析了同化结果的海面高度、流场及温盐剖面的精度。对比结果表明,SST和SSH的同化能够改善ROMS的模拟结果:同化后海面高度场能够更为准确地捕捉海洋的中尺度特征,与HYCOM海面高度再分析资料相比,平均绝对偏差和均方根误差分别为0.054 m和0.066 m;与HYCOM 10 m层流场相比,东向与北向流速平均绝对偏差分别为0.12 m/s和0.11 m/s,相比未同化均提升约0.01 m/s;温盐同化结果与Argo温盐实测具有较高的一致性,温度和盐度平均绝对偏差为0.45℃、0.077,均方根误差为0.91℃、0.11,单个的温盐廓线对比说明,同化结果与HYCOM再分析资料精度相当。     

Dimethylsulfide enrichment in the surface microlayer of the South China Sea

A total of 22 sea surface microlayer samples collected from the Nansha Islands waters of the South China Sea were analyzed for dimethylsulfide (DMS), chlorophyll a and nutrients including nitrate, phosphate and silicate. The DMS concentrations in surface microlayer samples ranged from 82 to 280 ng S/l with a mean of 145 ng S/l. A significant correlation was found between DMS and chlorophyll a data both in the surface microlayer as well as in the subsurface water. However, no correlation was observed between DMS and nutrient concentrations in the surface microlayer. The DMS concentrations were higher in all surface microlayer samples, compared with subsurface samples. The enrichment factor (EF) of DMS in the surface microlayer varied from 1.21 to 3.08 with an average of 1.95. The EF of DMS was significantly correlated with that of chlorophyll a in the microlayer. The enrichment of DMS in the microlayer may be due to two factors, including the in situ production from phytoplankton and the transportation from the underlying seawater. The diel variations in DMS and chlorophyll a concentrations were studied at a fixed station. The highest concentrations of DMS in the surface microlayer and subsurface water were simultaneously observed in the late afternoon (1800 h), while the highest levels of chlorophyll a were simultaneously found at night (0200 h).     

On a new Siphonophora from the East China Sea and South China Sea

In the course of identifying the samples of Siphonophora from the East China Sea and South China Sea, a new Siphonophora, Vogtia microsticella sp. nov. , was noted. The new species is distinguished from other five species in the genus in nectophore as follows: Parahorse-shoe shaped with five bluntly rounded projections, the two projections below the ostium, i. e. the basal projections, approach each other. The dorsal facet is smooth without any gelatinous prominence. Smaller are the nectosac and the ostium.     

南海海神信仰文化研究——以南海神和妈祖为例

海神信仰是海洋文化中的一种特殊的历史文化现象.文章从起源、封号、发展现状3个方面对比分析了南海神和妈祖两种海神信仰的差异,不同的发展轨迹使得两者的影响广度和深度都有很大不同,而如何更好地继承和发展海神文化是亟待进一步研究的课题.     

南海东北部亚中尺度过程时空分布特征

基于高分辨率模型2009-2012年的模拟结果,本文对南海东北部亚中尺度过程的时空分布特征进行了研究。模拟结果表明,南海东北部上层广泛存在着相对涡度接近于局地行星涡度的亚中尺度过程。统计结果发现,亚中尺度过程的相对涡度的分布具有着明显的非对称性,即正涡度明显强于负涡度。这意味着相比于负涡度,具有正涡度的亚中尺度过程要更为活跃,而这主要是由离心不稳定导致。同时,亚中尺度过程在时间分布上表现出明显的冬强夏弱的季节变化特征。通过对该海区亚中尺度过程可能生成机制的分析发现,该季节变化与流场拉伸和混合层的厚度有着密切关系,冬季更强的流场拉伸和更深的混合层有利于通过锋生过程和混合层不稳定为亚中尺度过程生成提供更多的能量。     

LICOM模拟的南海贯穿流及其对南海上层热含量的影响

利用SODA(Simple Ocean Data Assimilation)数据、XBT(Expendable Bathythermograph)观测数据和绕岛环流理论(island rule)诊断计算结果评估了一个涡相容(eddy-permitting)全球海洋环流模式——LICOM对南海贯穿流及南海上层热含量的模拟能力,同时利用模式输出探讨了南海贯穿流对南海上层热含量的影响。NEC(North Equatorial Current)分叉的垂向结构、南海内区环流的季节和吕宋海峡体积输送的年际变化等分析结果都表明,LICOM能获取西北太平洋-印尼海域环流和南海贯穿流的合理模拟结果。模式模拟的南海上层热含量季节变化与观测及同化数据都表现出良好的一致性,尤其在南海内区。相关分析表明,吕宋海峡热输送主要控制着南海内区上层的热含量变化,两者呈显著负相关,这进一步证实了南海贯穿流作为一支冷平流调制着南海上层热含量变化的重要事实。