南海北部海面高度的季节内变异及其传播特征

利用25年(1993-2017)的卫星高度计资料,采用复经验正交函数(complex empirical orthogonal function, CEOF)方法,分析南海北部海区海面高度季节内变异的时空分布及传播特征。标准差分析表明,南海北部海面高度的季节内变异(intra-seasonal variability of sea level anomalies, SLA-ISV)在沿陆坡外侧区较强,且 SLA-ISV 表现出明显的季节性变化,冬半年强于夏半年。 CEOF 前两个主要模态能较好地揭示研究海区 SLA-ISV 的时空分布及其传播特征,并表明 SLA-ISV的强度受到季节性变化和年际变化的调制。全年 CEOF 的第一模态揭示 SLA-ISV 从台湾岛西南至西沙群岛以东区域的冬半年西南向传播特征;而全年 CEOF 的第二模态则表现了 SLA-ISV 分别在台湾岛西南和东沙群岛西南的西南向传播特征。南海北部中尺度涡季节变化统计分析表明, CEOF 的分解结果与南海北部的涡旋活动一致。

A review on the South China Sea western boundary current

The advances in understanding the South China Sea （SCS） western boundary current （SCSwbc） have been reviewed since the works of Dale （1956） and Wyrtki （1961） in the middle of the 20th century. The features of the pattern of SCSwbc and the oceanic phenomena associated with it are focused on. The current is driven mainly by monsoon over the SCS and partially by winds over the tropical Pacific governed by the island rule. The SCSwbc exhibits strong seasonal variation in its direction and patterns. In winter, the current is strong and flows southwestward along the South China shelf and slope from the east of Dongsha Islands to the northern central Vietnamese coast, then turns to the south along the central and southern Vietnamese coast, and finally partially exits the SCS through the Karimata Strait. In summer and early fall, the SCSwbc can be divided into three segments based on their characteristics. The southern segment is stable, flowing northward from the Karimata Strait up to about 11 N, where it separates from the coast forming an eastward offshore current. The separation of the current from Vietnamese coast induces some striking features, such as upwelling and cold sea-surface temperature. The middle segment off the central Vietnamese coast may have a bimodal behavior： northward coastal current and meandering current in early summer （June–July）, and cyclonic gyre in later summer and early fall （August–September）. The northern segment is featured by the summer SCS Warm Current on the South China shelf and a southwestward subsurface current along the continental slope.

基于浮标观测的南海西沙群岛潟湖区潮流特征研究

本文利用南海西沙群岛潟湖区29 d的全水深浮标观测资料研究了潟湖区内正压潮和内潮的基本特征,采用深度平均方法分析海流的适用性,并讨论潟湖区内潮的主要来源。深度平均流的动能谱显示全日潮流占主导,其动能占整体海流动能的41%。对比分析深度平均流和Tpxo7.2模式预测的全日、半日潮流的调和常数,两者均表明全日正压潮流受地形调制,主轴方向为西北-东南向,而半日正压潮流主轴方向为东-西向。两种方法得到的全日正压潮流大-小潮存在半个相位(6~7 d)的差异,进一步分析发现全日正压潮和全日内潮潮龄不同,存在部分相互抵消,且全日内潮大潮发生时间在深度上存在差异,推测由于缺少海表和海底的测量数据,导致深度平均方法得到的全日正压潮仍然包含全日内潮信号。调和分析结果表明,全日内潮的动能中相干部分占比高达91%,说明潟湖区的全日内潮是正压潮与局地岛礁地形相互作用产生,而从远场传播而来的可能性很小。

芜湖市某高校桶装水及饮水机微生物检测分析

目的:通过对芜湖市某高校桶装水及饮水机水样进行检测,评估某高校桶装水及饮水机水样的微生物污染情况,为提高高校饮用水卫生质量提供基础资料。方法:采集某高校由当地不同桶装水厂供应的教师办公室、教师公寓和学生宿舍未拆封桶装水和饮水机冷水出水口水样,依据GB 4789.2.3.15-2010分别进行细菌总数、大肠菌群、霉菌和酵母菌检测。结果:桶装水水样细菌总数的合格率(78.00%)高于饮水机水样细菌总数的合格率(50.00%),差异有统计学意义(P<0.05),而在大肠菌群、霉菌和酵母菌的合格率上差异无统计学意义(P>0.05)。桶装饮用水综合指标合格率(72.00%)高于饮水机水合格率(45.45%),差异有统计学意义(P=0.031)。结论:芜湖市某高校桶装水和饮水机存在微生物污染问题。

G试验影响因素分析

近年来,免疫抑制和危重患者IFD发生率持续上升。早期诊断IFD对降低患者死亡率、改善预后具有十分重要的意义。G试验是早期诊断侵袭性真菌病(IFD)重要的血清学方法之一,目前已广泛应用于临床。然而,医源性污染、细菌感染、肠道黏膜受损会导致G试验结果假阳性;抗真菌药物治疗、突破性念珠菌感染等会导致G试验结果假阴性。文章对G试验的影响因素进行综述,以帮助临床和实验室正确根据G试验结果及时制定相应的治疗策略。

Interannual to decadal variation of spring sea level anomaly in the western South China Sea

Satellite observations of sea level anomalies(SLA) from January 1993 to December 2012 are used to investigate the interannual to decadal changes of the boreal spring high SLA in the western South China Sea(SCS) using the Empirical Orthogonal Function(EOF) method. We find that the SLA variability has two dominant modes. The Sea Level Changing Mode(SLCM) occurs mainly during La Ni?a years, with high SLA extension from west of Luzon to the eastern coast of Vietnam along the central basin of the SCS, and is likely induced by the increment of the ocean heat content. The Anticyclonic Eddy Mode(AEM) occurs mainly during El Ni?o years and appears to be triggered by the negative wind curl anomalies within the central SCS. In addition, the spring high SLA in the western SCS experienced a quasi-decadal change during 1993–2012; in other words, the AEM predominated during 1993–1998 and 2002–2005, while the La Ni?a-related SLCM prevailed during 1999–2001 and 2006–2012. Moreover, we suggest that the accelerated sea level rise in the SCS during 2005–2012 makes the SLCM the leading mode over the past two decades.

Internal solitons in the northern South China Sea from insitu observations

In this paper, we demonstrate the characteris- tics of strong internal solitons at the southern edge of Dong- sha Islands in the northern South China Sea (SCS) during May―June 1998, using in situ time series data from the con- ductivity temperature depth (CTD), acoustic Doppler current profiler (ADCP) and thermistor chain. Our measurements indicated that the strongest internal solitons were larger than 90 m in wave amplitude, and propagated approximately westward in traveling direction, with the maximum current speed of about 2 m/s and the period of 10―20 min. The strongest internal solitons occurred noticeably during May 14―16, 1998, which is consistent with the occurrence period of the diurnal-dominated spring internal tides.

Variability of surface circulation in the South China Sea from satellite altimeter data

11-year satellite altimeter sea surface height (SSH) anomaly data from January 1993 to December 2003 are used to present the dominant spatial patterns and temporal variations of the South China Sea (SCS) surface circulation through Empirical Orthogonal Function (EOF) analysis. The first three EOF modes show the obvious seasonal variations of SSH in the SCS. EOF mode one is generally characterized by a basin-wide circulation. Mode two describes the double-cell basin scale circulation structure. The two cells were located off west of the Luzon Island and southeast of Vietnam, respectively. EOF mode three presents the mesoscale eddy structure in the western SCS, which develops into a strong cyclonic eddy rapidly from July to September. EOF mode one and mode three are also embedded with interannual signals, indicating that the SCS surface circulation variation is influenced by El Ni o events prominently. The strong El Ni o of 1997/98 obviously changed the SCS circulation structure. This study also shows that there existed a series of mesoscale eddies in the western SCS, and their temporal variation indicates intra-seasonal and in-terannual signals.

Observational study of the circulation in the southern South China Sea

CTD data from two oceanographic survey cruises, conducted by "Shiyan No.3" R/V during two reversing monsoons, were employed to calculate and analyze the distributions of temperature, salinity and geopotential anomaly in the southern South China Sea (SSCS). Based on these distributions, the horizontal structures of the SSCS circulation are described systematically. Study results show that the SSCS circulation structure could be classified as a two-layer (the upper and the lower) pattern, and that the main circulation in the upper layer (0-400 m) is driven by the South China Sea monsoons and is opposite in direction to the reversal of the monsoons. The distributions of principal current systems and their features are presented. Two important local phenomena, local eddy and oceanic front, were observed.