Connection between interannual variability of the western Pacific and eastern Indian Oceans in the 1997～1998 El Niño event

In this paper,the sea surface height and the heat content of the upper ocean are analyzed to retrieve the relationship of interannual variabilities between the tropical western Pacific and eastern Indian Oceans during the 1997～1998 El Ni(n)o event.In the prophase of this El Ni(n)o,the negative sea level anomalies (SLA) occurred in the tropical western Pacific (TWP) firstly,and then appeared in the tropical eastern Indian Ocean (TEI).The negative heat content anomalies (HCA) emerged in the TWP before this El Ni?o burst while the SLA signals developed over there.During the mature stage of this El Ni(n)o,two kinds of signals in the TWP and TEI turned to be the maximum negative sequently.Due to the connected interannual adjustment between the TEI and TWP,we adopted a method to estimate the Indonesian Throughflow (ITF) transport by calculating the HCA budget in the TEI.The indirect estimation of the ITF was comparable to the observation values.Therefore,the anomalies in the TEI had been proved as advecting from the TWP through the ITF during the 1997～1998 El Ni(n)o.     

Coupling and propagating of mesoscale sea level variability between the western Pacific and the South China Sea

The coupling and propagating features of mesoscale sea level variability between the western Pacific (WP) and the South China Sea (SCS) were studied based on time series analyses of satellite altimeter measured, along-track sea surface height anomalies (SSHA) along 21°N and the slope of the northern SCS. The analyses show that mesoscale sea level fluctuations in the WP have rather limited coherent effects on the SCS, and no statistically significant propagation of mesoscale variability through the Luzon Strait was observed except in the 45-day band. Evidence suggests that the 45-day fluctuation is very much likely a character of the Kuroshio originating from its low-latitude beginning. It is also sug- gested that the westward propagating Rossby waves will deform when they encounter the dynamical barrier of the Kuroshio. The Kuroshio will then acts on the SCS in its own way. The SCS is a relatively isolated system in the sense of coupling and propagating of oceanic mesoscale waves.     

Relationship between the Antarctic oscillation in the western North Pacific typhoon frequency

Relationship between the Antarctic oscillation (AAO) and the western North Pacific typhoon number (WNPTN) in the interannual variability is examined in this research. The WNPTN is correlated with the AAO in June-July-August-September (JJAS) in 1949-1998 at -0.48 for the detrended time series, statistically significant at 99% level. The tropical atmospheric circulation as well as the sea surface temperature variability over the western Pacific associated with AAO has been analyzed. It follows that a positive phase of JJAS AAO corresponds to the larger magnitude of the vertical zonal wind shear, the anomalous low-lever anticyclonic circulation and anomalous high-level cyclonic circulation, and lower sea surface temperature in the major typhoon genesis region in the western North Pacific, thus providing unfavorable environment for the typhoon genesis, and vice versa.     

Signal propagations and linkages of subsurface temperature anomalies in the tropical Pacific and Indian Ocean

The propagation characteristics of signals along different zonal-time profiles are analyzed using surface and subsurface temperature anomalies over the tropical Pacific and Indian oceans. Analyses show that there are intrinsic relationships between El Nio events in the eastern equatorial Pacific and dipole events in the equatorial Indian Ocean. In the region of tropical North Pacific between the equator and 16°N, there is a circle of propagation of subsurface temperature anomalies. El Nio events only happen when the warm subsurface signals reach the eastern equatorial Pacific. Dipole events are characterized when a warm subsurface signal travels along off-equatorial Indian Ocean to the western boundary. From these analyses, we believe that subsurface temperature anomalies can be considered to be the oceanographic early signal to forecast El Nio events in Pacific Ocean and dipole events in Indian Ocean, respectively.     

Interannual variation of North China rainfall in rainy season and SSTs in the equatorial eastern Pacific

The rainfall in North China during rainy season （July and August （JA）） exhibits a strong interannual variability. In this study, the atmospheric circulation and SST anomalies associated with the interannual variation of JA North China rainfall are examined. It is found that on the interannual timescale, the JA North China rainfall is associated with significant SST anomalies in the equatorial eastern Pacific, and the North China rainfall and SST anomaly in the equatorial eastern Pacific correspond to the similar variation of the upper-level westerly jet stream over East Asia. A possible mechanism is proposed for the influence of the SST anomalies in the equatorial eastern Pacific on the North China rainfall.     

The cause of the fragile relationship between the Pacific El Niño and the Atlantic Niño

El Ni?o, the most prominent climate fluctuation at seasonal-to-interannual timescales, has long been known to have a remote impact on climate variability in the tropical Atlantic Ocean, but a robust influence is found only in the northern tropical Atlantic region. Fluctuations in the equatorial Atlantic are dominated by the Atlantic Ni?o, a phenomenon analogous to El Ni?o, characterized by irregular episodes of anomalous warming during the boreal summer. The Atlantic Ni?o strongly affects seasonal climate prediction in African countries bordering the Gulf of Guinea. The relationship between El Ni?o and the Atlantic Ni?o is ambiguous and inconsistent. Here we combine observational and modelling analysis to show that the fragile relationship is a result of destructive interference between atmospheric and oceanic processes in response to El Ni?o. The net effect of El Ni?o on the Atlantic Ni?o depends not only on the atmospheric response that propagates the El Ni?o signal to the tropical Atlantic, but also on a dynamic ocean-atmosphere interaction in the equatorial Atlantic that works against the atmospheric response. These results emphasize the importance of having an improved ocean-observing system in the tropical Atlantic, because our ability to predict the Atlantic Ni?o will depend not only on our knowledge of conditions in the tropical Pacific, but also on an accurate estimate of the state of the upper ocean in the equatorial Atlantic.     

Nd isotope as the tracer of seawater evolution of early Miocene in the eastern Pacific Ocean

Fifty-six samples of nannofossil ooze were collected from Core PC5794 in the northern equatorial Pacific at 5 cm intervals. With the methods of mass spectrometer (VG354) and ICP, the Nd isotopic compositions (εNd(t)), Mn contents and Mg/Sr ratios of carbonate phase have been analyzed. CaCO3 contents of bulk sediments were obtained by dissolution of 0.5 mol/L HCl. Based on these data, the high-resolution εNd(t) profile of seawater in early Miocene with core depth(or time) have been established. The values of εNd(t) range from -6.2 to -2.97 and 4 fluctuation cycles existed during 24.06-22.02 Ma. 4 low εNd(t) values (about -6.4) correspond to high CaCO3 contents, which implicates that there were 4 cold epochs or 4 times of Antarctic Bottom Water activity. They occurred at the time of 24.06 Ma, 23.85 Ma,22.88 Ma and 22.26 Ma, respectively. High εNd(t) values correspond to the high Mn contents and high values of Mg/Sr ratio, which indicates the existence of 4 intense hydrothermal activity periods during 24.06-22 Ma, the durations of them are 4.05-23.98 Ma, 23.69-23.15 Ma, 22.74-22.37 Ma and 22.06-22.02 Ma, respectively.     

Occurrence of two types of El Nin?o events and the subsurface ocean temperature anomalies in the equatorial Pacific

The relationships between the evolution of two types of El Ni?o events and the subsurface ocean temperature anomaly(SOTA) in the equatorial Pacific are compared in this study. The results show that both types of El Ni?o are negatively correlated to the SOTA in the equatorial western Pacific, but relationships are different in different phases of El Ni?o. Furthermore, the occurrence of different types of El Ni?o is related to different features of the equatorial thermocline, e.g. its zonal gradient, significant variation area, amplitude and duration of thermocline oscillation. The propagation of SOTA in the equator plays an important role during the evolution of both types of El Ni?o, but shows dramatic differences in intensity, duration and phase reverse of warm SOTA. Moreover, the pathways of SOTA signal are different between these two types of El Ni?o. The dominant pathway in the life cycle of Eastern Pacific(EP)-El Ni?o lies on the equator and to its north, but there is no loop to the south of the equator. In contrast, the dominant pathway in Central Pacific(CP)-El Ni?o is located on the equator and to its south, and the propagation signal of SOTA to the north of the equator is very weak.The relationships between the zonal wind anomalies and the two types of El Ni?o are also preliminarily discussed. It is shown that EP-El Ni?o is more likely to respond to the westerly anomalies over the equatorial central and western Pacific, while CP-El Ni?o is more likely to respond to the westerly anomalies over the equatorial western Pacific and need the cooperation of easterly anomalies over the equatorial eastern Pacific to certain extent.     

Occurrence of two types of El Niño events and the subsurface ocean temperature anomalies in the equatorial Pacific

The relationships between the evolution of two types of E1 Nifio events and the subsurface ocean temperature anomaly （SOTA） in the equatorial Pacific are compared in this study. The results show that both types of E1 Nifio are negatively correlated to the SOTA in the equatorial western Pacific, but relationships are different in different phases of E1 Nifio. Furthermore, the occurrence of different types of E1 Nifio is related to different features of the equatorial thermocline, e.g. its zonal gradient, significant variation area, amplitude and duration of thermocline oscillation. The propagation of SOTA in the equator plays an important role during the evolution of both types of E1 Nifio, but shows dramatic differences in intensity, duration and phase reverse of warm SOTA. Moreover, the pathways of SOTA signal are different between these two types of E1 Nifio. The dominant pathway in the life cycle of Eastern Pacific （EP）-E1 Nifio lies on the equator and to its north, but there is no loop to the south of the equator. In contrast, the dominant pathway in Central Pacific （CP）-E1 Nifio is located on the equator and to its south, and the propagation signal of SOTA to the north of the equator is very weak. The relationships between the zonal wind anomalies and the two types of E1 Nifio are also preliminarily discussed. It is shown that EP-E1 Nifio is more likely to respond to the westerly anomalies over the equatorial central and western Pacific, while CP-E1 Nifio is more likely to respond to the westerly anomalies over the equatorial western Pacific and need the cooperation of easterly anomalies over the equa- torial eastern Pacific to certain extent.     

Growth ages of ferromanganese crusts from the western and central Pacific： Comparison between nannofossil analysis and ^10Be dating

Based on results of nannofossil analysis and 10Be dating in ferromanganese crusts M1-1 and A1-1 (no nannofossils were found in it),from the western and central Pacific respectively,it is found that the crust growth ages from nannofossil biostrati-graphy agree well with those based on 10Be isotope analysis. Both crusts have three growth layers,and the oldest layer was deposited in Miocene at about 12.80 Ma. The maximum,minimum,and average growth rates of crust A1-1 (from the central Pacific) are 8.11,1.92 and 3.47 mm/Ma,and those of crust M1-1 (from the western Pacific) are 2.93,0.47,and 0.94 mm/Ma.     

Premonitory phenomenon of El Ni(n)o event reflected in the observations of LOD and sea level

Data sets of the changes of the length of day, the sea surface temperature in the eastern Pacific and of the sea level in Hong Long from tide gauge observations are used to analyze and reveal the reflections in the observations of the length of day and the sea level changes concerned with the premonitory phenomenon of next El Ni(n)o event. The results from this study indicate that a new El Ni(n)o event has been brewing with the ending of the strong La Nina event that started in early summer of 1998. The estimated formation period of the new El Ni(n)o event will begin before the end of 2000, and the peak period may be reached at around the end of 2001.     

Siliceous microplankton fluxes and seasonal variations in the central South China Sea during 1993-1995:monsoon climate and El Ni(n)o responses

Seasonal variations of radiolarian and diatom fluxes in the central South China Sea during 1993-1995 were overwhelmingly controlled by monsoon climate. Radiolarian and diatom increased obviously during the Northeast (from November to February) and Southwest (from June to September) monsoons and decreased during the periods between the monsoons. The change of circulation driven by the monsoons improved water exchange in the different areas that brought rich nutrient materials for the surface microplankton, thereby enhancing radiolarian and diatom fluxes. Variation of radiolarian flux coincided with organic carbon flux, surface primary and export productivities. High radiolarian flux corresponded to high surface primary productivity. Radiolarian and diatom fluxes raised abnormally during 1994-1995 could be attributed to the El Ni(n)o event during the period.     

Ni^＋Nen（n=1-7）和Ni^＋Arn（n=1-6）团簇的结构与稳定性

用密度泛函理论(DFT)的杂化密度泛函B3LYP方法在6-311+G(d)基组水平上对Ni+Nen(n=1-7),Ni+Arn(n=1-6)团簇的各种可能构型进行了几何优化,得到了团簇的最稳定结构,并对最稳定构型的电子结构、电荷分布进行了理论分析.结果表明:当团簇离子n≤4时为平面构型,n>4时为立体构型.同时,能量分析和自然键轨道(NBO)分析表明Ni+Nen团簇的稳定性不如Ni+Arn.     

热带太平洋海平面年际和年代际变化研究进展

回顾热带太平洋对海平面长期趋势有重要影响的海平面年际和年代际变化的相关研究,总结包括近期提出的中部型厄尔尼诺在内的2种类型厄尔尼诺对热带太平洋海平面年际变化的影响,揭示了热带太平洋海平面年代际变化与信风年代际变化之间的紧密联系。指出赤道信风的增强对近期热带太平洋海平面变化格局的形成有决定性作用,厄尔尼诺强度的减弱对这种格局有贡献,而拉尼娜的影响有待深入研究。研究资料的局限性导致年代际变化的定量研究成果较少,在研究海平面年际和年代际变化时应用的热通量评估模型有待改进。     

2010-2011年冬季La Ni(n)a事件对北半球极涡的影响分析

为了探讨强极涡与La Ni(n)a事件之间的关系,利用NCEP/NCAR(日平均、月平均位势高度及温度场)再分析资料对2010-2011年冬季进行个例研究.与气候态相比,2010-2011年冬季北半球平流层极涡偏强,同时,显著的强海温负异常(La Ni(n)a事件)也持续整个冬季.结果表明,受La Ni(n)a事件影响,对流层环流场和温度场得到较大的调整,出现PNA (Pacific North American)型异常环流形势和相对应的温度异常分布.2010年12月,阿留申地区出现负值的热量经向输送,使得该地区从对流层上升至平流层的行星波动与气候态相比明显减弱,从而导致平流层极涡较气候平均态偏强.这一La Ni(n)a事件对平流层极涡影响的动力过程也从1948-2010年期间选出的13个冬季强La Ni(n)a事件的合成分析结果中得到证实.     

Relationship between El Ni(n)o and sea surface temperature variation in coastal region of Yellow Sea and East China Sea

利用黄、东海沿岸8个长期水文观测站多年海表温度资料,分析黄、东海沿岸海表温度的季节和年际变化特征,重点分析在1982-1983年和1997-1998年两次厄尔尼诺年期间的异常变化,以及ENSO影响黄、东海沿岸海表温度的可能机制.结果表明,在厄尔尼诺发生年,夏季风较弱,鄂霍次克海高压加强,西太平洋副高位置偏南,强度偏强,江淮流域及长江中下游降水偏多,黄、东海沿岸海表温度偏低.黄、东海沿岸海表温度受到ENSO和PDO(太平洋年代际振荡)的影响和调制,在厄尔尼诺发生的前冬半年及当年,黄、东海沿岸海表温度偏低;在厄尔尼诺发生次年,黄、东海沿岸海表温度偏高.厄尔尼诺对黄、东海沿岸海表温度变化的影响通过海洋和大气2个通道,1982-1983年海表温度异常以负异常为主,1997-1998年海表温度异常以正异常为主;ENSO期间,北赤道流减弱,黑潮流量减少,海表温度降低.海表温度受局地气温影响显著,如果ENSO期间东亚气温升高,则黄、东海沿岸海表温度偏高.     

气溶胶光学厚度及(A)ngstr(o)m指数遥感反演的不确定性对紫外线指数计算的影响

以地面站观测为参照,分析香港地区2005-2013年间MISR气溶胶光学厚度产品和(A)ngstr(o)m指数的不确定性,通过辐射传输方程模拟该不确定性对香港地区夏季和冬季地方时06:00-18:00之间紫外线指数造成的影响.结果表明,气溶胶光学厚度的不确定性在夏季和冬季对紫外线指数造成的偏差最大分别为0.55和0.36,(A)ngstr(o)m指数不确定性在夏季和冬季对紫外线指数造成的偏差最大分别为0.13和0.11.对比世界卫生组织划分的紫外线危害等级,不论是气溶胶光学厚度还是(A)ngstr(o)m指数的不确定性,所引起的紫外线风险等级的最大偏差为一级,夏、冬季基本上都不会影响对民众发布的紫外线风险分级.因此,可认为使用MISR气溶胶光学厚度产品以及(A)ngstr(o)m指数计算紫外线指数是可靠的.     

Relationship between El Nino /South Oscillation (ENSO) and population outbreaks of some lemmings and voles in Europe

Ecologists have been puzzled by population cycles of lemmings and voles for the over 70 years. At present, our understanding and explanation to this phenomenon remain controversial. Recently, El Ni?o/South Oscillation has attracted attention of ecologists on its links with population outbreaks of terrestrial animals. This paper aims to investigate the statistical relationship between outbreaks of microtine rodents and ENSO events by scanning available literature. During 1862—1894, outbreaks of Norway lemmings in Norway tended to occur in the Southern Oscillation Index (SOI) peak years or 1 year after the SOI peak years with an approximate significance level ( p = 0.057). During 1885—1931, outbreaks of voles in France tended to occur 1 year before the SOI peak years (p = 0.01). During 1946—1993, outbreaks of lemmings and voles in North Finland tended to occur 1 year before the SOI peak years with a significant level (p = 0.022); the peaks of population abundance corresponded well to the SOI trough years (equal to 1 year before the SOI peak years). Outbreaks of common voles in Poland during 1946—1975 tended to occur in the SOI peak years or 1 year before the SOI peak years (p = 0.011), and also tended to occur 1 year before the SOI peak years (p = 0.030). It was also found that the rodent outbreaks in Norway and France, rodent outbreaks in Finland and Poland synchronized well. It was suggested that the ENSO-related climate or food were key factors in causing outbreaks of microtine rodents in Europe.     

(Me2InN3)n(n=1～3)簇合物的结构,IR和热力学性质的理论研究

采用密度泛函理论B3LYP/Lanl2dz方法,计算研究了(Me2InN3)n(n=1～3)簇合物的结构和性质.研究表明,环状多聚体(Me2InN3)n(n=2～3)的优化构型均为由不同子体系的叠氮基α-N和In原子相连形成的环状结构.三聚体的船扭式构象比椅式构象的能量低3.76 kJ/mol.比较分析几何参数后发现Na-In、Na-Nβ、Nβ-Nr和In-C键键长随聚合度的变化趋势,环状构型中In-Na-In键角总是较Na-In-Na键角大.同时对所有优化构型进行振动频率计算,并对其IR谱进行归属.通过热力学计算,发现三聚体的船扭式构象较椅式构象稳定.由298.2 K焓变和Gibbs自由能变可知,单体形成二聚体和三聚体在热力学上是有利的,而由二聚体形成三聚体的Gibbs自由能则变为正.