南极绕极流的经向输运

南极绕极流(ACC)是南大洋中最显著的流动，流量超过130×106m3/s (Nowlin et al.，1986)。传统认为，由于以东向运动为主的ACC的存在极大地阻碍了南大洋中上层的南北向物质和能量的交换，绕极流区的经向输运是非常小的。但是近些年的研究发现，穿过ACC的通量并不是可以忽略不计的，它对维持南极和亚南极区的动力和热力平衡起着重要作用，在全球气候系统中也有着深刻的影响(Doos et al.，1994)。     

德雷克海峡绕极流和锋面的研究

利用我国第九次南极考察队获得的德雷克海峡地区水温资料,并结合国外锚碇浮标和测流资料,分析和研究了德雷克海峡绕极流和锋面的时间变化和空间变化.研究表明,德雷克海峡绕极流的流速共有3个强流区,就德雷克海峡上层海流的空间变化而言,以亚南极锋附近的海流最强,流向和流速也最稳定少变.德雷克海峡深层海流的空间分布特点与上层海流的空间分布特点不同,深层流速明显减弱,且稳定性差.德雷克海峡绕极流有着明显的时间变化,但是这种时间变化因地而异.极锋附近在冬春季节是稳定的深层北向流,它与南半球高纬度的冬、春季节的Ventilation过程有着密切的关系,德雷克海峡上层水温的空间分布具有明显的锋面分布特征.水温在德雷克海峡的高纬度区更加稳定少变,而极锋附近深层海水温度随时间的变化最大.     

德里克海峡附近绕极流和锋面研究的进展

本文概括了近几十年来，关于德里克海峡附近绕极流研究的进展，这些研究主要以实际观测资料为基础，说明了德里克海峡附近海洋锋面分布和绕极流的体积输运，其中，主要的海洋锋面有：亚南极锋，极锋和陆缘水边界；而德里克海峡绕极流的体积输运则代表了太平洋和大西洋两大洋之间通过德里克海峡的水量交换，读者可通过本文加深关于德里克海峡锋面成因和绕极流机制的理解。     

用TOPEX/POSEIDON高度计数据研究南极绕极流流域海面高度的低频变化

采用TOPEX/POSEIDON(T/P)卫星高度计 1 993年 1月— 2 0 0 0年 1 2月海面高度数据 ,研究包含了整个南极绕极流流系 (40°— 6 0°S)的海面高度低频变化。首先采用EOF分解方法获取南大洋时空分布的主要模态 ,前 3个EOF模态分别占总方差的 2 4 .8%、1 3 .8%和 1 0 .7%。然后采用EMD方法分别分析了各个EOF模态的时间系数曲线的组成成分 ,对南极绕极流海域的各种时间尺度变化给出了清晰的描述 ,对于不同尺度变化所占的比例得到了定量的结果。研究结果表明 ,EOF的各个模态不仅在形态上存在差异 ,而且具有相互独立的物理背景。EOF的第一模态主要体现了以太阳辐射冬夏差异形成的年周期变化 ,另一个显著的特征就是南极绕极流从 1 993— 2 0 0 0年海面的整体上升趋势。EOF的第二模态体现了陆地地形对南极绕极流的约束作用 ,同时也显示了ENSO过程对南极绕极流 ,特别是对南太平洋的海面高度变化的影响。EOF的第三模态则体现了南极绕极流对南大洋表面风场东西方向不均匀变化的响应。同时 ,本文的研究也证明了EOF与EMD方法联合使用对揭示大范围时空变化有重要的实际意义     

南印度洋绕极深层水的性质和空间分布以及南极绕极流的作用

利用世界大洋环流实验的南大洋观测温度、盐度和溶解氧资料,分析并说明了南印度洋绕极深层水的性质和空间分布特征,比较了30°E,90°E和145°E断面上温度、盐度和溶解氧的垂直分布及其异同,着重指出,在南印度洋的这3个不同经度断面上,绕极深层水和锋面的不同特征与南极绕极流越洋输运和南印度洋绕极深层水的经向运动有着密切的关系。实际上,绕极流的越洋输运是南大西洋与南印度洋之间以及南印度洋与南太平洋之间水交换的主要动力因素,对形成绕极深层水的物理性质的空间分布有着重要的作用。     

普里兹湾附近绕极深层水和底层水及其运动特征

利用中国第15次南极科学考察科学考察队的CTD全深度观测资料(1998年11月至1999年2月),分析并讨论了普里兹湾以北的南大洋海域内,绕极深层水(CDW)和南极底层水(AABW)的物理特性及其空间分布.同时还与历史上其他学者的发现进行了比较.指出了在研究海域内,CDW在100～2000m之间从北向南扩展,其高温核(t>1.2℃)和高盐核(S>34.7)在75°E断面上最为深厚,向南扩展得最远;而AABW则在2500m以深由陆坡底部向北扩展,σ_θ>27.875的高密度水体在70°E断面上最为深厚,向北扩展得最远.此外还通过实测的CTD资料证实了CDW和AABW的经向环流特征,以及它们与迪肯流环(Deaconcell)、亚极地流环和深层流环的一致性.     

带有侧摩擦和底摩擦的绕岛理论

绕岛理论来自于Sverdrup理论,被广泛用于估计和分析通过岛屿之间海峡的输运情况。以往的研究得到了带有侧摩擦或底摩擦的单岛理论或多岛理论。本文在线性情况下考虑了风驱动环流下的解析模型。在同时考虑侧摩擦和底摩擦的情况下,推导出了岛屿周围输运流函数的解析解,并给出了通过岛屿之间通道的流量输运。其结果与Wajsowicz相似,但摩擦常数表示不同的值。从解析解上看,摩擦常数与侧摩擦和底摩擦之间的关系比较复杂,为了推导出它们之间的相互作用原理,本文在正压β平面上随机选取了一些侧摩擦和底摩擦的值。结果表明,在构成摩擦常数方面,侧摩擦和底摩擦近似呈线性关系。我们研究了宽度对通道输运值的影响,结果表明摩擦在一定宽度内提高了流量,这种现象和只考虑侧摩擦时比较相似。本文也比较了在不同深度下的流量,发现当水平涡粘性系数和底部拖曳系数固定时,水深越大,输运减少率越小。为了进一步揭示侧摩擦和底摩擦耗散的联合作用,在两个岛屿的情况下,本文在不同宽度的通道中与Wajsowicz的只考虑底摩擦或侧摩擦的模型进行了比较。结果表明,当通道比较窄,尤其是在小于Munk边界层厚度时,侧摩擦的作用大于底摩擦。当通道宽度远大于Munk边界层厚度时,底摩擦的作用大于侧摩擦。将模型应用到印尼贯穿流,得到大约20%的输运减少量。     

对一个死亡扩张中心的调查:南极德雷克海峡菲尼克斯海岭

扩张作用停止和俘获俯冲小板块可能引起大的构造活动 ,如加利福尼亚Ｔｒａｎｓｖｅｒｓｅ海岭西部的旋转作用和来自冈瓦纳古陆的新西兰陆块上升。南美和南极之间德雷克海峡的菲尼克斯—南极扩张中心残存体———菲尼克斯海岭可能在上新世相当长的时间曾经消亡。沙克尔顿和英雄断裂带之间的前菲尼克斯板块的小部分残体与南极板块相结合。南极环流汇入德雷克海峡阻碍了沉积物堆积 ,因此 ,只有古扩张轴显示在等深图中。１９９７～１９９８年 ,西班牙“ＢＩＯＨｅｓｐｅｒｉｄｅｓ”号调查船利用多波束回声测深仪获得了完整的菲尼克斯海岭海图资…     

变性绕极深层水入侵时南极普里兹湾湍流混合特征研究

基于中国第28、29和31次南极科学考察中的CTD数据,利用Thorpe尺度方法计算了普里兹湾及其附近海域湍动能耗散率,分析了其分布特征,并对当地的水团结构进行研究.结果表明,普里兹湾及其附近海域中,前两个航次观测中次表层湍动能耗散率强度在陆架坡折区域达到最大.在水团分布方面,在第28和29航次中均观测到了变性绕极深层...     

An analytical diagnostic model of the Antarctic Circumpolar Current

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Fronts, baroclinic transport, and mesoscale variability of the Antarctic Circumpolar Current in the southeast Indian Ocean

Fronts,baroclinic transport,and mesoscale variability of the Antarctic Circumpolar Current(ACC) along 115°E are examined on the basis of CTD data from two hydrographic cruises occupied in 1995 as a part of the World Ocean Circulation Experiment(WOCE cruise I9S) and in 2004 as a part of CLIVAR/CO2 repeat hydrography program.The integrated baroclinic transport across I9S section is(97.2×106±2.2×106) m3/s relative to the deepest common level(DCL).The net transport at the north end of I9S,determined by the south Australian circulation system,is about 16.5×106m3/s westward.Relying on a consistent set of water mass criteria and transport maxima,the ACC baroclinic transport,(117×106 ±6.7×10 6)m3/s to the east,is carried along three fronts:the Subantarctic Front(SAF) at a mean latitude of 44°-49°S carries(50.6×10 6 ±13.4×106)m3/s;the Polar Front(PF),with the northern branch(PF-N) at 50.5°S and the southern branch(PFS) at 58°S,carries(51.3×106 ±8.7×106)m3/s;finally,the southern ACC front(SACCF) and the southern boundary of the ACC(SB) consist of three cores between 59°S and 65°S that combined carry(15.2×106 ±1.8×106)m3/s.Mesoscale eddy features are identifiable in the CTD sections and tracked in concurrent maps of altimetric sea level anomalies(SLA) between 44°-48°S and 53°-57°S.Because of the remarkable mesoscale eddy features within the SAF observed in both the tracks of the cruises,the eastward transport of the SAF occurs at two latitude bands separating by 1°.Both the CTD and the altimetric data suggest that the mesoscale variability is concentrated around the Antarctic Polar Frontal Zone(APFZ) and causes the ACC fronts to merge,diverge,and to fluctuate in intensity and position along their paths.     

Improving the estimate of wind energy input into the Ekman layer within the Antarctic Circumpolar Current

Based on the data and method offered by Liu et al. (2009), the direct wind and Stokes drift-induced energy inputs into the Ekman layer within the Antarctic Circumpolar Current (ACC) area are reestimated since the results of the former have been proved to be underestimated. And the result shows that the total rate of energy input into the Ekman-Stokes layer within the ACC area is 852.41 GW, including 649.75 GW of direct wind energy input (76%) and 202.66 GW of Stoke drift-induced energy input (24%). Total increased energy input, due to wave-induced Coriolis-Stokes forcing added to the classical Ekman model, is 52.05 GW, accounting for 6.5% of the wind energy input into the classical Ekman layer. The long-term variability of direct wind and Stokes drift-induced energy inputs into the Ekman layer within the ACC is also investigated, and the result shows that the Stokes drift hinders the decadal increasing trend of direct wind energy input. Meanwhile, there is a period of 4-5 a in the energy spectrums, as same as the Antarctic circumpolar wave.     

Seasonal variability of the Antarctic Coastal Current and its driving mechanisms in the Weddell Sea

Insight into the dynamics of the Antarctic Coastal Current (ACoC) is achieved by quantifying the contributions of its driving mechanisms to the seasonal variability of its barotropic and baroclinic components. These mechanisms are sought out in the local wind, the sea-ice concentration, wind curl of the Weddell Gyre (Sverdrup transport) and the thermohaline forcing related to warming/cooling and ice melting and freezing. These driving mechanisms induce most of the seasonal variability of both the barotropic and baroclinic components of the ACoC by deepening the pycnocline towards the coast and sharpening the baroclinic profile following thermal wind balance. The resulting coastal current has mainly a barotropic transport (82%) and a major annual cycle, which explains 37% of this component's variability (tides and other high-frequency events generate 40%). The wind contributes with 58% of the seasonal variability of the barotropic component and 23% of the baroclinic; the sea-ice concentration contributes with 8% and 18%, respectively; Sverdrup transport with 4% and 30% and the thermohaline forcing with 30% and 29%. The results of this study are obtained with analysis of fifteen CTD sections (potential density and geostrophic velocities) of RV-Polarstern obtained between 1992 and 2005, as well as composite, spectral and harmonic analyses of 9 years of time series from moored instruments (current speed and temperature), wind speed, atmospheric pressure and sea-ice concentration of satellite imagery.     

德雷克海峡上层海洋温度的年代际变化

采用经验模分解方法分析了德雷克海峡上层海洋温度的年代际变化特征.结果表明德雷克海峡上层海洋平均温度在1976-1986年以平均每年0.124 ℃的速度下降,而在1987-1998年以每年0.144 ℃的速度上升.与南方涛动指数的年代际时间尺度分量的相关性分析结果表明,热带太平洋海面气压场的变化对德雷克海峡上层海洋温度的年代际变化有一定影响.     

南太平洋南极中层水的中尺度特征

The Argo float observations are used to investigate the mesoscale characteristics of the Antarctic Intermediate Water(AAIW) in the South Pacific in this paper. It is shown that a subsurface mesoscale phenomenon is probably touched by an Argo float during the float's ascent-descent cycles and is identified by the horizontal salinity gradient between the vertical temperature-salinity profiles. This shows that the transportation of the AAIW may be accompanied with the rich mesoscale characteristics. To derive the spatial length, time, and propagation characteristics of the mesoscale variability of the AAIW, the gridded temperature-salinity dataset ENACT/ENSEMBLE Version 3 constructed on the in-situ observations in the South Pacific since 2005 is used. The Empirical Mode Decomposition method is applied to decompose the isopycnal-averaged salinity anomaly from26.8 σθ–27.4 σθ, where the AAIW mainly resides, into the basin scale and two mesoscale modes. It is found that the first mesoscale mode with the length scale on the order of 1 000 km explains nearly 50% variability of the mesoscale characteristics of the AAIW. Its westward-propagation speeds are slower in the mid-latitude(around 1cm/s) and faster in the low latitude(around 6 cm/s), but with an increasing in the latitude band on 25°–30°S. The second mesoscale mode is of the length scale on the order of 500 km, explaining about 30% variability of the mesoscale characteristics of the AAIW. Its westward-propagation speed keeps nearly unchanged(around 0.5cm/s). These results presented the stronger turbulent motion of the subsurface ocean on the spatial scale, and also described the significant role of Argo program for the better understanding of the deep ocean.     

On the Conversion of Antarctic Ice-Mass Change to Sea Level Equivalent

This technical note aims to provide a quick reference and some computational examples for the conversion between Antarctic ice-mass changes and global sea level equivalent (SLE) changes using a few assumptions that computationally simplify this complex problem and that acknowledge gaps in our knowledge of the Antarctic environment. A number of factors involved in the conversion process are discussed, and the sensitivity of the conversion result to certain aspects is analyzed. It was found that the global ocean area calculated from a recently improved global shoreline dataset has little impact on the uncertainty of the SLE estimation. SLE estimation using satellite gravity observations, such as those by GRACE, are sensitive to glacial isostatic adjustment (GIA) models. One more important result from the computation is that the effective density of the volume that is gained or lost during mass change may greatly affect the outcome of the conversion if it differs greatly from the actual density of the firn/ice layers. Finally, a table of computational examples is provided for reference under some assumptions for simplifying the computation.     

产胞外多糖极地微生物的筛选及其胞外多糖对大菱鲆免疫活力的初步研究

采用苯酚硫酸法和醇沉淀法,从600余株南极微生物中筛选得到10株胞外多糖产量较高的菌株.分子鉴定与系统发育分析表明,9株菌株属于假交替单胞菌属(Pseudoalteromonas),1株属于嗜冷杆菌属(Psych robacter).对10株菌株进行发酵培养,发酵液经醇沉、除蛋白、冷冻干燥后得到粗胞外多糖.其中菌株3-3-1-2的胞外多糖产量达0.6 g/L.对粗多糖产量较高的4株菌所产的胞外多糖进行免疫活性试验,粗胞外多糖20#3在注射3d时,实验组AKP活性比对照组增加了39％,CAT活性比对照组增加了24％,二者均差异显著(P＜0.05),注射5d时,ACP活性比对照组增加了20％,差异显著(P＜0.05),总超氧化物歧化酶(T-SOD)活性比对照组增加了14％,差异极显著(P＜0.01);粗胞外多糖33-1-2在注射3d时,实验组AKP活性比对照组增加了12％,差异不显著(P＞0.05),注射5d时,酸性磷酸酶(ACP)活性比对照组增加了24％,过氧化氢酶(CAT)活性比阳性对照组增加了5％,二者均差异显著(P＜0.05).研究结果表明,菌株20#3与3-3-12产生的胞外多糖对大菱鲆(Scophthalmus maxoimus)具有显著的免疫促进作用.由此可知,筛选出的极地细菌胞外多糖20#3和3-31-2可显著提高大菱鲆非特异性免疫力,可作为水产饲料添加剂应用于大菱鲆的生产养殖.     

南极冰藻 Chlamydomonas sp.ICE-L的 cDNA文库构建及品质检测

为构建南极冰藻Chlamydomonassp.ICE-L的cDNA文库,提取对数生长期南极冰藻ICE-L的总RNA,以此为模板,通过PowerScript逆转录酶逆转录合成第一链cDNA;再以第一链cDNA产物为模板,用LD-PCR合成第二链cDNA。该cDNA产物经分级分离转入大肠杆菌中,即获得南极冰藻ICE-L的cDNA原始文库,其滴度为1.6×106cfu/mL。扩增后的cDNA文库的滴度为1.0×1010cfu/mL。用PCR方法测得文库的重组率大于97%,插入cDNA的长度为0.5~1.8 kb,0.9 kb以上插入片段占50%以上。取适量扩增文库稀释并铺平板,挑取72个独立菌落,对其中22个独立菌落所插入的cDNA进行测序,克隆到了一个具有5′和3′非编码区的40S ribosomalprotein S5全长基因序列,GenBank收录号为AM167929。     

南极适冷菌Pseudoaltermonas sp.S-15-13胞外多糖低温保护作用的研究

研究了南极适冷菌Pseudoaltermonas sp.S-15-13胞外多糖(Exopolysaccharides,EPSs)对重复冻融的菌体的保护作用。结果表明,重复冻融循环后,有胞外多糖包被的菌体仍能保持较好的生长能力,无胞外多糖包被的菌体生长缓慢,甚至死亡;不同浓度的胞外多糖均可降低水溶液的冰点,其效果较浓度相同的葡聚糖明显。说明南极适冷菌S-15-13对反复冻融的耐受能力与菌体分泌的胞外多糖直接相关,除了形成机械隔离屏障,胞外多糖还可能通过降低冰点等途径使菌体免受伤害。