春季季风间期赤道东印度洋浮游植物光合生理特征

Phytoplankton physiologies are dynamic and have sensitive responses to the ambient environment. In this paper,we examine photosynthetic physiologies of phytoplankton communities with Phyto-PAM in the eastern equatorial Indian Ocean during the spring inter-monsoon. Environmental parameters were measured to investigate the coupling between phytoplankton photosynthetic physiologies and their habitats. During the cruise, the water column was highly stratified. The mixed layer extended to about 75 m and was characterized by high temperature(28°C) and low nutrient level. The F_v/F_m values and chlorophyll a(Chl a) concentrations were lower at the surface, as consequences of nutrient depletion and photo-inhibition. Subsurface Chl a maximum(SCM) occurred between 75 and 100 m, and had the highest F_v/F_m values. The formation of SCM was a balance between nutrient availability and light limitation. The SCM may contribute significantly to pelagic food web and primary production in the water column. Phytoplankton in different layers encountered different light, trophic and hydrographic dynamics and evolved distinct photosynthetic characteristics. Despite of co-limitation of nutrient limitation and photo-inhibition, phytoplankton in the surface layer showed their acclimation to high irradiance, had lower light utilization efficiencies(α: 0.061±0.032) and could exploit a wide range of light irradiance. Whereas, phytoplankton in the SCM layers presented the highest light utilization efficiencies(α:0.146±0.48), which guaranteed higher photosynthetic capacities under low light level. These results provide insights into phytoplankton photo-adaption strategies in this less explored region.     

不同类型厄尔尼诺事件对印度洋秋季Wyrtki急流的影响

厄尔尼诺事件是发生在赤道太平洋地区的海气相互作用现象,根据海表温度时空演化特征可以划分为不同类型,即东部型、中部型。通过对再分析资料进行分析,指出不同类型厄尔尼诺事件发生时期,印度洋秋季Wyrtki急流(Wyrtki Jet,WJ)具有显著不同的变化特征,主要表现为:厄尔尼诺东部型事件发生期间,印度洋秋季WJ显著减弱,赤道印度洋表层海流表现为弱西向流;厄尔尼诺中部型事件发生期间,印度洋秋季WJ较历史同期水平增强。进一步分析表明,不同类型厄尔尼诺事件通过影响印-太海区大气沃克环流系统,调制了秋季赤道印度洋海表风场,进而调制了印度洋秋季WJ发生和发展。     

2016下半年安达曼海潮、余流观测分析

The characteristics of currents and tidal currents in the Andaman Sea(AS) are studied during the second half of2016 using observed data from a moored acoustic Doppler current profiler(ADCP) deployed at 8.6°N, 95.6°E.During the observation period, the mean flow is 5–10 cm/s and largely southward. The root mean square and kinetic energies of the low and high frequency flows, which are divided by a cutoff period of 5 d, are at the same level, indicating their identical importance to the total current. A power spectrum analysis shows that intraseasonal oscillations, a tidal-related semilunar month signal, a semidiurnal tidal signal and periods of 3–4 d are prominent. The barocliny of an eddy kinetic energy is stronger than the mean kinetic energy, both of which are the strongest on the bottom and the weakest at 70 m depth. Residual currents are largely southward(northward) during the summer(winter) monsoon season. Two striking peaks of the southward flow cause the 80 d period of meridional currents. The first peak is part of a large-scale circulation, which enters the AS through the northern channel and exits through the southern channel, and the second peak is part of a local vortex. The 40 d oscillation of the zonal current is forced by geostrophic variations attributed to local and equatorial remote forcing. The tidal current is dominated by semidiurnal constituents, and among these, M2 and N2 are the top two largest major axes. Moreover, astronomical tidal constituents MM and MSF are also significant. Diurnal constituents are weak and shallow water tides are ignorable. The aims are to introduce the new current data observed in the AS and to provide initial insights for the tidal and residual currents in the Andaman Sea.     

季风上升流对印尼爪哇岛南部海域pH影响的初步研究

基于2013年9月底至10月初在印尼爪哇岛南部海域调查得到的碳酸盐参数和相关水文数据,首次报道了该海域pH的分布,并重点探讨了南爪哇上升流(季风上升流)对其影响。结果显示上升流影响区表层pH低于周围非上升流影响区。通过两端元混合模型,定量讨论了上升流的物理输运和生物活动对pH的影响。研究表明,上升流的物理输运至少造成了海表层盐度增加0.4个单位,溶解无机碳(DIC)增加110μmol/kg,pH降低约0.2个单位;同时,在上升流区,强烈的生物活动(叶绿素a浓度大于0.4mg/m3)使得DIC的降低量达70μmol/kg,pH的增加量达0.15个单位。总体来看,该研究区域的物理输运作用大于生物作用,综合效应表现为DIC的增加和pH的降低。另外,同上升流的物理输运作用和生物作用相比,上升流引起的表层冷却和增盐对pH的影响较小(热力学作用)。     

收稿日期:2011-10-28

为研究南黄海浮游动物垂直迁移的季节变化,分析了2006年至2007年4个季节布放潜标中声学测流仪的观测数据.结果是:声学测流仪测量的后向散射强度呈现显著的日变化特征,这是由浮游动物垂直迁移造成的;在4个季节中都出现这一凌晨向下、黄昏向上的垂直迁移,但是垂直迁移发生的时间有季节变化.利用南黄海辐射通量的直接观测数据,讨论了垂直迁移发生时间与光照的关系,结果表明垂直迁移的季节变化主要受光照的影响.这对于研究浮游动物垂直迁移机制有一定意义.     

山东半岛东端毗邻海域冬季海雾的季节内分布特征与变化规律

山东半岛东部耳状锋面区的冬季海雾是一个重要但被忽视了的海气相互作用现象。利用AVHRR Pathfinder Version 5.2数据中SST资料的质量数值,通过转换和归一化处理,简单有效地提取了耳状锋面区海雾的覆盖区域和海雾强度的信息。结果显示海雾的空间分布与耳状锋面非常一致,亦呈现"耳状",其覆盖面积和强度存在显著的季节内变化。海雾一般开始出现于12月的上旬,位于耳状锋面南段的海域。之后,海雾的覆盖区域迅速北扩,覆盖面积不断增大且强度不断增强,并于2月达到峰值后进入衰减期,至3月下旬基本消失。海雾的季节内变化与冬季风风速、黄海西侧沿岸流、黄海暖流的季节内变化及它们之间的超前/滞后关系密切相关。海雾强度的主轴位置相对比较固定,位于40~50m等深线附近,没有显著的季节内变化,其原因是耳状锋面的主轴位置受控于水深分布,不随时间变化。本研究所建立的提取海雾关键信息的方法以及海雾与季风、环流、耳状锋面这三者的相互关系还需要观测和数值模拟的进一步验证。     

基于CMIP6模式的热带太平洋海表温度增暖初步评估

热带太平洋是影响全球气候系统的重要区域,热带太平洋海表温度(SST)的长期变化趋势模拟是国际研究领域关注的热点。基于12个参加第六期国际耦合模式比较计划(CMIP6)的模式结果,本研究对1950年至1999年间多模式模拟得到的热带太平洋SST增暖现象进行了初步评估。结果表明,不同模式对热带太平洋SST增暖的模拟能力差别较大,特别在赤道东太平洋区域,部分模式模拟得到了偏强的SST降温趋势,与实际观测中的SST增温趋势相反,多模式集合平均结果给出了中部型厄尔尼诺事件的增温趋势。通过引入SST增暖变率分析方法,本研究对多模式模拟的热带太平洋SST在过去50 a中的增暖内在变化进行了进一步评估,结果表明目前各模式对热带太平洋SST增暖变率模拟偏弱,空间分布差异较大。     

Dramatic weakening of the ear-shaped thermal front in the Yellow Sea during 1950s–1990s

The ear-shaped thermal front(ESTF), formed by the convergence of the Yellow Sea Warm Current(YSWC) and the Shandong Coastal Current(SCC), is a very important oceanic phenomenon in the Yellow Sea(YS) in winter. In situ measurements and reanalysis datasets all demonstrate that the ESTF has been weakening during1950s–1990s, and a similar weakening trend is also found in winter monsoon over the YS. Numerical experiments show that the weakening of winter monsoon can induce an anomalous circulation in the YS on multi-decadal timescale with northward anomalous currents along China's coast and southward anomalous currents in the central YS—generally opposite to seasonal mean circulation. The anomalous circulation causes slowdown of the YSWC and the SCC, and thus weakens the ESTF. Since the ESTF plays important roles in regional ocean dynamics and air-sea interactions, its weakening has important implications for regional climate in the YS in winter.     

楚科奇海夏季潮流和余流观测研究

根据2008年8月5日至9月7日在楚科奇海布放的一套锚碇潜标观测系统(71°40.024′N,167°58.910′W)获得的海流剖面资料研究了该海区的海流分布特征,重点探讨了潮流的垂向结构、余流剖面特征及海流的斜压性.结果表明:(1)该海域主要分潮为半日潮M1,S2和N2,近日分潮O1,天文分潮MM和MSF,其中以M...