The circularly propagating pattern of the low-frequencyfluctuations of monthly MSL in the tropical PacificOcean and its correlation with El Nino

The long-term time series analysis of the SST (sea surface temperature) in the Eastern Equatorial Pacific Ocean and the monthly MSL (mean sea level) in the tropical Pacific Ocean is conducted. Their quasiperiodic and low-frequency oscillation features are revealed. The significant periods of low-frequency fluctuations for monthly MSL in the area of 20°N-20° S are between 43. 5 months and 50. 0 months, approximating closely to 47. 6 months which is the significant period of SST in the Eastern Equatorial Pacific Ocean. From the results of space-spectral analysis, the low-frequency fluctations of monthly MSL in the tropical Pacific Ocean appear to have a anticlockwise circularly-propagating pattern, which is, the Eastern Pacific Ocean (off-shore of Mexico) →the area of NEC (North Equatorial Current) →the Western Equatorial Pacific Ocean→the area of NECC (North Equatorial Counter-Current)→the Eastern Equatorial Pacific Ocean. The phases of the pattern correspond to those of El Nino cycle. On the basis     

海洋上层热结构演变与El Ni■o

对1979年1月至1987年2月热带太平洋0—400m海水垂直平均温度(TAV)时、空变化的分析表明,在热带西太平洋TAV的年际变化较SST更显著,且与E1 Ni(?)o相联系。在E1 Ni(?)o和反E1 Ni(?)o期间,海洋上层热结构的分布截然不同,E1 Ni(?)o的发生、发展与赤道Kelvin波和热带Rossby波造成的热结构再分布有关。     

赤道太平洋上层海洋垂向温度梯度距平与El Nio的关系

用赤道太平洋长达21a的温度资料以及经验正交函数(EOF)分析方法,讨论了在5°S-5°N平均纬向垂直剖面上赤道太平洋垂向温度梯度距平的时空变化,得到了一些有意义的结果。赤道太平洋垂向温度梯度距平EOF分析第1模态的正/负位相反映了El Nino/La Nina发生前赤道太平洋温跃层的分布,第2模态的正/负位相反映了El Nino/La Nina鼎盛以及开始衰减时赤道太平洋温跃层的分布。根据我们对赤道太平洋温跃层核心位置的定义,在El Nino向LaNina转换的过程中,赤道东太平洋温跃层上升了30-40m,而赤道中太平洋温跃层先是上升了40-50m,然后又下降了40-50m,赤道西太平洋温跃层下降了90m;随着赤道西太平洋暖水的堆积以及东移,温跃层首先在赤道西太平洋加深,El Nino发生前赤道中东太平洋温跃层开始加深,El Nino达到鼎盛时赤道西太平洋温跃层抬升,而赤道中东太平洋温跃层加深;赤道太平洋垂向温度梯度距平EOF分析第1特征向量的时间系数与Nino3区的SST距平有非常好的相关,并且超前于Nino3区的SST距平,超前3个月的相关系数高达0.7017,超前6个月的相关系数高达0.6467,因此可以用该量来预测Nino3区的SST距平。     

北太平洋海温与华南东部过渡季节(2—3月)降水的关系

利用1951—2010年台北、台中、福州和厦门4站2—3月降水资料和北太平洋海温资料,通过合成分析、对比分析和相关分析等方法,研究了华南东部过渡季节(2—3月)降水变化的一致性和气候变化特征及其与北太平洋海温的关系。结果表明:台北、台中、福州和厦门4站过渡季节(2—3月)降水变化具有很好的一致性和明显的年代际变化特征。华南东部过渡季节(2—3月)降水与北太平洋海温存在着很好的相关关系;不同类型的降水异常年份,有着不同的海温距平分布特征,降水偏多年,表现为厄尔尼诺分布型,降水偏少年,则表现为拉尼娜分布型,且这种距平分布型在其前期9月开始出现端倪,12月发展成熟。前期12—1月赤道东太平洋关键区和西风漂流区关键区海温变化,对华南东部过渡季节(2—3月)降水具有较好的预测指示意义。     

全球海洋环流模式中上层海洋对表面强迫的响应和调整Ⅰ.年际变率

利用一个较高分辨率的全球海洋环流模式在COADS 1945～1993年逐月平均资料的强迫下对海温和环流场进行了模拟试验,研究了全球热带海洋(主要是热带太平洋)海温和环流场的年际变化特征及模式ENSO冷暖事件演变的控制机理.结果表明,模式成功地再现了和观测一致的海温和环流的年际变化以及ENSO演变特征.其中热带印度洋年际SST变率的主要模态表现为与ENSO相联系的海盆尺度的一致性增暖或变冷现象,次级模态为热带印度洋偶极子模态;热带大西洋的SST年际变率表现为类ENSO的年际振荡现象.在热带太平洋,SST年际变化主要表现为ENSO型,环流的年际变率表现为与ENSO相对应的热带海洋质量循环圈的年际异常.对应于暖(冷)事件,前期赤道海洋垂直环流圈显示出减弱(增强)的特征.其中南赤道流异常的位相较Nino3区海温总体要超前5个月左右的时间;赤道上翻流异常的位相在表层要超前4个月,并随时间由上至下扩展;赤道潜流的异常则显示出东传特征,其中最早的较为显著的异常发生ENSO成熟前3个月180°附近.在模式ENSO冷暖事件的演变过程中,次表层海温异常沿赤道的东传起了关键作用,模式的ENSO模态主要表现为"时滞振子"模态.     

The numerical criteria and characteristics of El Nino and La Nina

-By using the sea surface temperature (SST) index of the Equatorial Pacific Ocean provided by Climate Analysis Center of U. S. A. , the numerical criteria of El Nino and La Nina events and their quantitative characteristics were calculated. Results show that the El Nino event was characterized with strong intensity, shorter life cycle and significant mature phase; however, the La Nina event has longer live cycle, weak intensity, insignificant mature phase. Through teleconnection analysis, it is found that the intensity index of SST over the Equatorial Pacific Ocean leads the intensity index of subtropical high by six months or so. During the El Nino years, the tropical cyclone over the northwestern Pacific is fewer than normal but stronger, and its genesis area shifts southeastward apparently; while in the La Nina years the number of tropical cyclones are larger.     

厄尔尼诺期间和后期南海海面温度的两次显著增暖过程

通过分析ICOADS海洋气象资料，结合ISCCP短波辐射和OISST海面温度，研究并探讨了ENSO等大尺度海气相互作用过程背景下南海海表面温度（SST）的年际变化。研究表明，南海SSTA的年际变化和ENSO关系密切，并且分为两个阶段。以增暖事件为例，在厄尔尼诺（El Nino）发生年的冬季和消亡年的夏季，南海出现了两次显著增暖。第一次增暖出现在El Nino盛期，是El Nino影响的一部分，这时南海云量减少，净太阳辐射通量增加，SST上升。第二次增暖出现在El Nino结束后的夏季，不是El Nino直接作用的结果；这时夏季风减弱，一方面使得海洋的潜热损失减少，另一方面减弱了越南东部沿岸的上升流，两者的共同作用导致SST增加。     

El Ni■o对南沙群岛海域表层水温、波浪及海况的影响

根据南沙群岛海域船舶报的表层水温和波浪资料,分析了ElMino事件对该海域上述水文要素的影响。结果表明：（1）在该海域与赤道东太平洋,表层水温变化是同位相,而与赤道西太平洋呈反位相;（2）在ElNino年,南沙群岛海域海况恶劣,大浪频率增加;更以ElNino的次年为甚。文中对产生以上现象的原因作了初步探讨。     

厄尔尼诺事件延长原因的初步分析

利用我国及美国国家气象局提供的热带太平洋月平均海温、水位、地球向外长波辐射和850hPa纬向风资料,对1980年以来的三次厄尔尼诺(El Ni(?)o)事件延长原因及其特征作一分析和探讨。文章指出,El Ni(?)o事件延长的原因主要是:在El Ni(?)o事件发生后,热带太平洋大气环流半年左右的韵律活动及在赤道南、北两侧明显的大气振荡加强,从而使大气的El Ni(?)o异常过程间隔半年相继发生。     

Spatial and temporal variability of heat content above the thermocline in the tropical Pacific Ocean

Abstract-Heat content of the upper layer above the 20℃ isotherm in the tropical Pacific Ocean isestimated by using the sea temperature data set with a resolution 2°latitude×5°longitude (1980～1993)for the water depths (every 10 m) from 0 m to 400 m, and its temporal and spatial variabilities are an-alyzed. (1) The temporal variability indicates that the total heat in the upper layer of the equatorial Pa-cific Ocean is charcterized by the interannual variability. The time series of the equatorial heat anomaly5 months lead that of the El Nino index at the best positive lag correlation between the two, and theformer 13 months lag behind the latter at their best negative lag correlation. Therefore the equatorialheat content can be used as a better predictor than the El Nino index for a warm or cold event. In addi-tion, it is also found that less heat anomaly in the equator corresponds to the stronger warm events inthe period (1980～1993) and much more heat was accumulated in the 4 years including 1992/1     

CHARACTERISTICS ON INTERANNUAL VARIATIONS OF NORTH PACIFIC SST AND ITS RELATION TO EAST ASIA CLIMATE

The interannual variations of the monthly sea surface temperature (SST) in the North Pacific (including Equatorial East Pacific) during 1951-1980 are analysed by means of EOF method. The findings are:(1) In the cold and warm ocean current areas, such as the North Pacific Current, the California Current and the Equatorial East Pacific areas, the convergence speeds are the fastest, while in the Kuroshio and the western part of the North Equatorial Current areas they are fast only in winter.(2) The physical features of the first 3 eigenvectors are obvious. The first eigenvector shows that the SST values are high in the south and low in the north in the latitudinal distribution of the SST field. The warm current area, i.e. the northwestern part of the North Pacific is positive and the cold current area, i.e. the southeastern part of the North Pacific including the Eastern Equatorial Pacific is negative. The zero line of the 2nd eigenvector field runs from northeast to southwest, in the same direction as the     

印度洋-太平洋暖池海域表层水温分析

利用1951~2003年HadISST资料集的表层海水温度（SST）资料,讨论了印度洋-西太平洋暖池（IPWP）海域,尤其是印度尼西亚贯穿流（ITF）及其周边海域SST的季节及年际变化的时空特征.研究结果表明,整个研究海域SST的年际变化均与ENSO相关,但印度洋与南海的响应特征与西太平洋的相反且不同步.前者海温变化滞后Nio3指数3~6个月,而热带太平洋西边界和ITF流经海域海温则超前1~3个月.沿ITF及其东印度洋出口,SST的年际变化规律不同于热带印度洋而与太平洋的相似,分析表明其在较大程度上受到ITF海洋桥的影响.在季节尺度上,印度洋和太平洋赤道海域SST的波动规律也有明显不同.以巽他岛弧（苏门答腊、爪哇和小巽他群岛）为界,从赤道西太平洋向西沿ITF流径,太平洋一侧SST的季节变化以0.5a周期的波动占主导,印度洋一侧则以1a周期占主导.     

Abnormality of thermal structure and current in the upper western tropical Pacific Ocean and its effect on subtropical high

-Mainly on the basis of the data obtained during PRC/US bilateral TOGA cruises, abnormal variation occurred during the 1986/1987 El Nino is shown in this paper about the thermal structure and circulation of the upper western tropical Pacific Ocean. The effects of the abmormal variation on the subtropical high over the Northwest Pacific Ocean are discussed. During the El Nino: (1) In the east part of the western tropical Pacific Ocean (the subsurface temperature data on the 165° E section are taken as an example), the water wanner than 29 C in the upper layer spread on the longitudinal section and positive temperature anormalies appeared in a large area of the sea surface. (2) In the west part of the western tropical Pacific Ocean (the subsurface temperature data on the 137°E section are representative ), the cross section occupied by the upper layer warmer water ( T >28 ℃ ) became shrunk, and the sea surface temperature showed negative amomalies. (3) The eastward flows in the upper layer of the 165°     

The PNA wavetrain and the sea surface temperature in the Northern Pacific

In this paper, the response of the atmospheric 3-5 year cycle to Northern Pacific SST is discussed, The results are as follows:1. From the simultaneous temporal correlations between the Equatorial Eastern Pacific SST, the westerly dirft area's SST and the Northern Pacific SST at all gridpoints, we find that there are three correlative regions in the Northern Pacific SST field, they are the westerly drift area, the Equatorial Eastern Pacific and the Alaska Bay , and their structures are very similar to the PNA pattern in the atmosphere The difference PTI between the Equatorial Eastern Pacific SST anomaly and the westerly drift area's SST anomaly can indicate the change of the PNA pattern of the Northern Pacific SST anomaly. It can represent SST change of 65 % areas over the Northern Pacific and can keep watch on El Nino and un-El Nino.2. Simultaneous temporal correlative field between PTI and filtered 500hPa (there is 3-5 year cycle only ) of the Northern Hemisphere presents clear PNA structure. The resp     

El Nino and the Southern Oscillation

Using the Comprehensive Ocean-Atmosphere Data Set (COADS), wind, surface pressure and SST fields in the Equatorial Eastern Pacific and the Equatorial South Indian Ocean were analysed comprehensively.lt is pointed out that the seesaw between surface pressure in the Equatorial South Indian Ocean and the Equatorial Southeast Pacific causes the seesaw between the wind fields in the two areas, and the seesaw of wind fields results in the seesaw of SST between Indonesia and the Equatorial Eastern Pacific. El Nino is the response of ocean to the forcing of monsoon system in the Indian Ocean and the trade system in the Pacific.     

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。     

Interannual variability of mixed layer depth and heat storage of upper layer in the tropical Pacific Ocean

By using the upper layer data(downloaded from the web of the Scripps Institution of Oceanography ),the interannual variability of the heat storage of upper layer(from surface to 400 m depth) and the mixed layer depth in the tropical Pacific Ocean are investigated. The abnormal signal of the warm event comes from the central and west Pacific Ocean, whereas it is regarded that the abnormal signal of the warm event comes from the east Pacific Ocean in the popular viewpoint. From the viewpoint on the evolution of the interannual variability of the mixed layer depth and the heat storage of the whole upper layer, the difference between the two types of E1Nino is so small that it can be neglected. During these two E1Nino/La Nina events( 1972/1973 and 1997/1998), other than the case of the heat storage or for the mixed layer depth, the abnormal signal propagates from the central and west Pacific Ocean to the east usually by the path along the equator whereas the abnormal signal propagates from the east to the west by the path northern to the equator. For the interannual variability, the evolution of the mixed layer depth corresponds to that of the heat storage in the upper layer very well. This is quite different from the evolution of seasonality.     

The influence of ENSO on sea surface temperature variations in the China seas

Positive SST anomalies usually appear in remote ocean such as the China seas during an ENSO event.By analyzing the monthly data of HadISST from 1950 to 2007,it shows that the interannual component of SST anomalies peak approximately 10 months after SST anomalies peak in the eastern equatorial Pacific.As the ENSO event progresses,the positive SST anomalies spread throughout the China seas and eastward along the Kuroshio extension.Atmospheric reanalysis data demonstrate that changes in the net surface heat flux entering into the China seas are responsible for the SST variability.During El Ni o,the western north Pacific anticyclone is generated,with anomalous southwester lies prevailing along the East Asian coast.This anticyclone reduces the mean surface wind speed which decreases the surface heat flux and then increases the SST.The delays between the developing of this anticyclone and the south Indian Ocean anticyclone with approximately 3–6 months cause the 2–3 months lag of the surface heat flux between the China seas and the Indian Ocean.The northwestern Pacific anticyclone is the key process bridging the warming in the eastern equatorial Pacific and that in the China seas.     

西北太平洋热状况与夏季副高脊线变异

用1951～1986年亚洲太平洋地区500hpa月平均高度、西北太平洋月平均海表温度及夏季500hpa副高脊线位置资料,分析海温对夏季副高脊线年际变异的影响。得出结论:(1)1～8月海温距平EOF1～3场对夏季副高脊线变异具有明显影响的共有9个。(2)夏季各月副高脊线年际变化都具有明显的主周期。而且它们是由同期海温距平EOF2场所引起。(3)夏季各月副高脊线变异可能是由同期海温距平EOF2场的东西向“热成风效应”过程所致。     

Internnual variations of water temperature and salinity along the 137°E meridian

Analyses were performed on hydrographic data gathered along the 137°E meridian by the R/V Ryofu Maru of the Japan Meteorological Agency (JMA). Distributions were obtained of the mean and standard deviation of water temperature and salinity along the section. Relationships between interannual variations of these variables and wind forcing were examined. A correlation analysis revealed that temperature change, which occurred in the equatorial region of the western North Pacific accompanied by El Nino and La Nina events, reached about 20°N with the inclination of isotherms across the north equatorial current fluctuating around 20°N. Empirical orthogonal function (EOF) analysis of the winter water temperatures in the section was performed to extract variations following El Nino and La Nina events as the first mode and those corresponding to decadal changes of sea surface temperature (SST) in the North Pacific as the second mode. Interannual variations in the area of the North Pacific tropical saline water (NPTSW) and the North Pacific intermediate water (NPIW) along the section correspond well to interannual variations of the wind-stress curl minimum (negative value) in the area southeast of Japan. A remaining problem is to quantitatively evaluate the lag times of the variations to the wind-stress curl variation. In the equatorial region of the section, the northward extension of saline water is weak, and negative water temperature anomalies have often occurred in connection with El Nino events since the latter half of the 1970s. These changes may be part of the decadal variation of the North Pacific.