热带印度洋偶极子区域海表面温度特征与海流相关性分析

为了研究热带印度洋偶极子(IOD)爆发年其耦合作用迅速消亡是否由海流异常引起,利用1958—2007年热带印度洋月均海表面温度(SST)和海流数据,分析IOD的主要特征,并探讨IOD与ENSO和海流异常之间的相关关系。通过对印度洋偶极子指数(DMI)及其经Hilber-t Huang变换后得到的固有模态函数(IMF)与南方涛动指数(SOI)的相关性分析,指出IOD与ENSO之间可能存在相关性,其中,表现出准2a周期振荡的IMF-3与ENSO相关性最好。通过对IOD爆发年DMI的进一步分析,证实IOD具有季节锁相的重要特征,并探讨该季节变化与海流异常的相关关系。结果表明,海流异常在热带印度洋SST的耦合振荡中起重要作用,但是它可能不是引起IOD迅速消亡的原因。     

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.     

热带印度洋海面温度与高度的相关性分析

基于海面温度与海面高度异常的月均数据,采用EOF、SVD和功率谱分析等方法,对热带印度洋海面温度与海面高度进行特征分析,研究两者在时空结构上的相关性。利用EOF方法分析出海面温度第二模态与海面高度第一模态的空间结构类似,呈现偶极型。相关分析与功率谱表明,两模态的时间序列存在滞后相关和类似的周期结构。SVD结果显示,第一耦合模态的相关系数达0.7左右,且左右场的空间形态呈现东西反相。这表明,海面高度偶极型与海面温度的单极型和偶极型存在着相关。同时,海面高度指数也表现与偶极子指数类似的结构特征。针对上述诊断分析事实特征,对海面温度和海面高度偶极子形成的物理机制进行了初步分析,总结了前人所做的一些工作,指出其中可能的影响因素。     

基于多卫星融合数据的海平面特征分析

利用1993—2008年法国空间局的AVISO多卫星融合高度计资料,采用随机动态、EOF等方法分析全球海平面变化的长期趋势、变化幅度以及季节变化的空间分布特征.结果表明:(a)1993—2008年间太平洋海平面呈西升东降的形态,印度洋绝大部分海区海平面呈上升趋势,大西洋除湾流流域外的其他海区海平面的长期趋势以上升为主;(b)全球海平面变化存在显著的年变化和半年变化等季节信号,无论是半球平均还是洋盆平均,北半球海平面季节变化的振幅明显大于南半球,中纬度海区季节变化的振幅最大;(c)北印度洋海平面季节变化的振幅高于同纬度带的北太平洋和北大西洋;(d)太平洋、印度洋、大西洋三大洋受西边界流、赤道流系等强流影响的海域海平面变化幅度大于周围海域;(e)赤道海域各大洋东、西边界和大洋内区海平面变化不同步,可能受赤道海洋波动的影响较大;(f)厄尔尼诺年,西太平洋暖池和赤道太平洋中部海平面明显降低,赤道东太平洋海域海平面明显升高,赤道印度洋海域东、西边界的海平面变化与其相反.     

Decadal variability of the IOD-ENSO relationship

Using three kinds of over 100-year sea surface temperature （SST） datasets as well as three-dimensional wind data from NCEP/NCAR, this paper documents the decadal variability of the Indian Ocean Dipole （IOD）-EI Nino/Southern Oscillation （ENSO） relationship. During 1948--1969, positive （negative） IOD and warm （cold） ENSO events were more independent of each other. But after 1970, they tended to occur in the same year. ENSO would influence the whole life span of IOD, and IOD also affects the developing phase of ENSO. Considering the climatological background SST, low-level winds and also equatorial vertical circulations, it is revealed that the decadal variability of the IOD-ENSO relationship may be caused by the enhanced Walker circulation with increased rising motion over the Maritime Continent after 1970. Warmer SST around the Maritime Continent gives rise to anomalous low-level convergence and intensified convection there, which apparently increases the SST linkage between the eastern Indian Ocean and the western Pacific and thereby the interaction between the IOD and ENSO event.     

The tropical Pacific-Indian Ocean temperature anomaly mode and its effect

Temperature anomaly in the Indian Ocean is closely related to that in the Pacific Ocean because of the Walker circulation and the Indonesian throughflow. So only the El Ni?o/Southern Oscillation (ENSO) in the Pacific cannot entirely explain the influence of sea surface temperature anomaly (SSTA) on climate variation. The tropical Pacific-Indian Ocean temperature anomaly mode (PIM) is presented based on the comprehensive research on the pattern and feature of SSTA in both Indian Ocean and Pacific Ocean. The features of PIM and ENSO mode and their influences on the climate in China and the rainfall in India are further compared. For proving the observation results, numerical experiments of the global atmospheric general circulation model are conducted. The results of observation and sensitivity experiments show that presenting PIM and studying its influence are very important for short-range climate prediction.     

热带印度洋海温与海表面高度相关关系分析

为了研究热带印度洋偶极子(IOD)与海平面异常之间的相关性,采用经验正交函数分析方法(EOF)及Hilbert-Huang变换等统计方法,分析热带印度洋的海表面温度(SST)与海平面高度异常(SLA)的相关关系。通过对热带印度洋偶极子指数(DMI)与南方涛动指数(SOI)和SLA的相关性分析,得出IOD与El Nio-Southern Oscillation(ENSO)之间可能存在一定相关关系,此外,IOD与海平面变化有很好的相关性。通过对IOD爆发年的DMI以及海平面变化的分析,证实IOD具有季节锁相的重要特征,并探讨了该季节变化与海平面变化的相关关系。结果表明,IOD事件与海平面的变化这两者之间存在很强的一致性。     

Early Pleistocene formation of the asymmetric east-west pattern of upper water structure in the equatorial Pacific Ocean

Surface-and subsurface-dwelling planktonic foraminifera from the upper 43 m of Hole A at the Ocean Drilling Program (ODP) Site 807,which was recovered from the western Pacific warm pool during ODP Leg 130,were analyzed for stable oxygen and carbon isotopes.By comparing these results with data from ODP Site 851 in the eastern equatorial Pacific,this study has reconstructed the paleoceanographic changes in upper ocean waters in the equatorial Pacific since 2.5 Ma.During the period from 1.6-1.4 Ma,the oxygen isotopes of surface and subsurface waters were found to markedly change in the western and eastern equatorial Pacific,further confirming the final formation of the well-defined asymmetric east-west (E-W) pattern at that time.This feature was similar to the zonal temperature gradient (sea surface temperature is higher in the west and lower in the east) and the asymmetric upper water structure (thermocline depth is deeper in the west and shallower in the east) in the modern equatorial Pacific.The zonal gradient change of subsurface water δ18O was greater than that of surface water δ18O,indicating that the formation of the asymmetric E-W pattern in the equatorial Pacific should be much more related to the shoaled thermocline and markedly decreased subsurface water temperature in the eastern equatorial Pacific.Moreover,since ～1.6 Ma,the carbon isotopic differences between surface and subsurface waters clearly decreased in the equatorial Pacific,and their long-term eccentricity periods changed from 400 ka to ～500 ka,reflecting the reorganization of the ocean carbon reservoir.This probably resulted from the deep water reorganization in the Southern Ocean at that time and its enhanced influence on the tropical Pacific (especially subsurface water).Our study demonstrates that the tropical ocean plays an important role in global climate change.     

Sea surface temperature east of Australia： A predictor of tropical cyclone frequency over the western North Pacific？

The relationship between sea surface temperature (SST) east of Australia and tropical cyclone frequency over the western North Pacific (WNPTCF) is analyzed by use of observation data.The WNPTCF from June to October is correlated negatively to spring SST east of Australia.When the spring SST is in the positive phase,a cyclonic circulation anomaly in the upper troposphere and an anticyclonic circulation anomaly in the lower troposphere prevail over the western North Pacific from June to October,concurrent with an anomalous atmospheric subsidence and an enlarged vertical zonal wind shear.These conditions are unfavorable for tropical cyclone genesis,and thus WNPTCF decreases.The negative phase of the spring SST east of Australia leads to more tropical cyclones over the western North Pacific.The spring SST east of Australia may give rise to simultaneous change in tropical atmospheric circulation via the teleconnection wave train,and then subsequently affect atmospheric circulation variation over the western North Pacific.     

近45年北太平洋海表风速特征统计分析

本文利用来自欧洲中期天气预报中心（ECMWF——European Centre for Medium-Range Weather Forecasts）的1957年8月—2002年7月逐6 h的ERA-40海表10 m风场资料,统计分析了近45年期间北太平洋海表风场的月变化特征,以及多年平均海表风速的分布特征,为海洋水文保障、海洋工程等提供参考。结果表明：（1）北太平洋的海表风场具有明显的月变化特征,10月至来年2月的风速整体高于其余月份。（2）从年平均风速来看,阿留申群岛附近海域为北太平洋年平均风速的明显大值中心,年平均风速基本在8 m/s以上;中纬度海域的年平均风速在6~7 m/s;15°N-20°N的东部海域存在一相对大值区,年平均风速在7 m/s以上;赤道西部海域的年平均风速较小,基本在4 m/s以内。     

A dynamic view of the tropospheric teleconnection between IOD and the Pacific Ocean

The tropospheric teleconnection pattern between the Indian Ocean Dipole （IOD） and the Pacific Ocean was studied using GISST and NECP/NCAR reanalysis data. Results show that a structure of Rossby wave train extends from the tropical Indian Ocean over southern subtropical regions of Australia and Pacific Ocean to the tropical Pacific Ocean, where a strong correlation between IOD and geopotential height （GH） anomaly of Pacific Ocean exists. Energy propagating pathways of the planetary wave with wave numbers 1-3 are qualitatively in agreement with the Rossby wave train, which implies that the energy propagation of the stationary planetary wave could be responsible for the tropospheric teleconnection between IOD and tropical Pacific Ocean.     

导致西太平洋海温异常的主要因素研究

通过对不同区域海表面温度(SST)资料做超前/滞后相关性分析, 研究导致西太平洋SST异常的主要因素。基于东、西太平洋相互作用理论和印度洋电容器效应理论, 将热带西太平洋SST异常的变化分别与热带东太平洋和印度洋SST异常做超前/滞后相关性分析, 得到每个格点与强迫场之间相关性最显著的月份, 从时间的角度研究西太平洋SST异常变化与东太平洋和印度洋之间的关系。按照上述两种理论, 由于海洋的比热大, 热响应时间较长, 西太平洋SST变化应滞后于东太平洋或印度洋2~3个月。分析结果显示, 在El Nino和La Nina事件下, 西太平洋SST异常变化均超前于东太平洋1~2个月时相关性最显著; 同时, 西太平洋SST异常变化超前于印度洋3~4个月时相关性最显著。 这表明热带东太平洋和印度洋都不是导致西太平洋SST异常变化的主要因素, 西太平洋SST异常可能由多种因素共同作用所导致。     

副热带太平洋海温异常对赤道海洋的影响

利用完全耦合的气候模式进行敏感性试验, 定量研究副热带太平洋不同经度带的海表面温度异常(SSTA)对赤道太平洋的影响。研究发现, 赤道表层和温跃层海温对副热带太平洋(20°?30°N)西部、中部和东部SSTA的热力响应是相当的。 研究中强调大气?海洋耦合在副热带SSTA影响赤道温跃层过程中的决定性作用, 并提出一种间接的、较“海洋通道”机制更为快速的机制: 副热带SSTA引发局地大气的气旋性响应, 继而引起局地海洋内区的上升流和其面向赤道一侧海洋内区的下沉流, 该下沉流造成的局部温跃层暖异常向着赤道传播, 导致赤道温跃层增暖。     

江淮流域夏季降水异常及与全球中低纬海温异常关系的诊断研究

对1951－1999年中国夏季江淮流域降水异常与海温异常关系的分析表明,前期及同期各季节三大洋海表温度异常（SSTA）与长江流域降水异常的关系是非常显著的,而对淮河流域降水异常总体上的影响较小,前期冬季SSTA的影响显著区主要有：热带印度洋、黑潮、热带中东太平洋和大西洋,各关键区海温异常对亚洲夏季风的影响特征为：当前期冬季赤道印度洋、黑潮、赤道大西洋和热带东太平洋海表温度异常升高（降低）,当年夏季印度西南季风和东亚热带辐合带减弱（加强）,副热带高压位置偏南（北）,副热带辐合带加强（减弱）,长江流域易发生洪涝（干旱）,相关显著性分析表明,前冬赤道印度洋和黑潮区的海温异常对中国夏季降水的影响更为显著。     

江淮流域梅雨期雨量的变化特征及其与太平洋海温的相关关系及年代际差异

运用相关分析和滑动相关方法,分析了江淮流域5个代表站1903-2000年梅雨期雨量的变化特征及其与太平洋海温的相关关系及年代际差异.结果表明,江淮地区梅雨期雨量在近百年来存在明显的年际和年代际变化特征.通过分析梅雨期雨量与太平洋海温的年代际相关特征发现,江淮流域梅雨期雨量与前期及同期太平洋海温关系密切,前一年冬季及梅雨期东北太平洋海温与江淮流域梅雨期雨量负相关,在热带东太平洋的Nino1 2区两者正相关显著,同年春季西太平洋部分海域海温与江淮流域梅雨期雨量正相关.从年际相关分析发现,前一年冬季太平洋海温与梅雨期雨量正相关,同年春季以及梅雨期两者相关不明显.通过分析年代际差异发现,江淮流域梅雨期雨量与前期及同期热带太平洋关键区海温的21a滑动相关存在显著的年代际差异,这种差异与海温的21a滑动平均的年代际冷暖背景关系密切,热带太平洋海温关键区前一年冬季冷海温背景下,梅雨期雨量同海温正相关显著,同年春季暖海温背景下,两者之间负相关显著,而江淮流域梅雨期雨量同中国近海海温之间(从冬季到梅雨期)维持显著的正相关,与该区海温冷暖背景的关系则并不明显.     

太平洋海表面温度季节内振荡特征

为了研究太平洋海表面温度季节内振荡的特征,利用NOAA(national oceanic and atmospheric ad-ministration)周平均SST资料,采用谐波方法重构了太平洋海表面温度季节内振荡信号,针对不同海域,用小波分析等方法,揭示了SST季节内振荡的空间、频谱、季节性和传播特征.结果表明:海表面温度季节内振荡在黑潮区、黑潮续流区和赤道东太平洋较活跃,在赤道东西太平洋有相对重要的地位;在北太平洋谱特征均为单峰结构,在赤道东西太平洋呈双峰结构.不同海域海表面温度季节内振荡的活跃期分别为:北太平洋夏秋季,赤道东太平洋春和秋季,热带西太平洋活跃期较分散;在北太平洋以缓慢东传为主,在赤道东太平洋以西传为主,在热带西太平洋无明显传播.     

Anomalous activity of East Asian winter monsoon and the tropical Pacific SSTA

The relationship between the anomalous East Asian winter monsoon (EAWM) activity and the tropical Pacific SST anomalies has been identified using the results of 40-year integration of the IAP CGCM1 model and 10-year observational data. In the strong EAWM year, the western and central Pacific are dominated by positive SST anomalies while the eastern Pacific is negative ones. In the weak EAWM year, the SSTA pattern is quite different and shows El Nino-like SST anomalies. The strong EAWM activity tends to create extra easterly flow to the east and extra westerly flow to the west of the warm SSTA region over the equatorial western and central Pacific, thus leading to the enhancement of convergence and convection of the flow in this region and favorable to the maintenance and development of such an SSTA pattern. On the other hand, the warm SST anomaly over the western and central Pacific, as a forcing, may lead to a specific pattern of the northern extratropical atmosphere, which is favorable to the strong EAWM activity. The tropical Pacific SSTA pattern related closely to the strong EAWM activity differs significantly from that of the La Nina year.     

The wavelet analysis of satellite sea surface temperature in the South China Sea and the Pacific Ocean

Using wavelet transform, the sea surface temperature (SST) during the period of 1982–1999 of the South China Sea and the equatorial Pacific, from datasets of NOAA/AVHRR, was analyzed. It is shown that there are 4- and 8-year interannual oscillations in the eastern equatorial Pacific and 8-year interannual oscillation in the western equatorial Pacific. In terms of attractive time-frequency localization and multi-scale properties of wavelet transform, as shown by the Morlet wavelet, it is found that an in-phase coupling oscillation occurs between the SCS and the equatorial Pacific. The SST changes of SCS will have echoed every event of EI Niño (abnormally warm) and La Niño (abnormally cold) in the equatorial Pacific. There is a positive correlation between the SCS and the western equatorial Pacific in the 8-year time-scale. Evidence is presented that the SST anomalies of the equatorial Pacific influence the SST of the SCS.     

亚澳季风区内水汽汇的准两年振荡及其与大气环流的关系

利用1950-2000年大气视水汽汇资料,分析了亚澳季风区内水汽汇准两年振荡的变化特征及其与大气环流的关系.亚澳季风区内水汽汇有显著的准两年振荡,其关键区位于西太平洋暖池、孟加拉湾、东南印度洋和西南印度洋,它们对应3种遥相关型.当暖池水汽汇偏强时,我国华南为偏北风距平,东亚季风区水汽汇偏弱;印度洋水汽汇距平呈现为偶极子分布,东南印度洋附近水汽汇偏强时,东南印度洋至赤道西印度洋为偏西风距平,赤道西印度洋水汽汇偏弱;孟加拉湾水汽汇偏强时,孟加拉湾至西南印度洋为偏南风距平,西南印度洋的水汽汇偏弱.反之亦然.     

北太平洋海浪特征分析

利用最新的欧洲中尺度天气预报中心(ECMWF)提供的1979—2014年逐6 h的ERA-Interim有效波高和风速数据,分析近36a北太平洋海浪场的变化特征。结果表明:有效波高经验正交函数分解(EOF)的第1模态呈同相位分布,该模态与太平洋10 a涛动指数(PDO)和厄尔尼诺事件(ENSO)呈显著的遥相关,可以通过这些气候因子的变化来预测有效波高的年代际变化;第2模态表明北太平洋西部海域的有效波高有显著的递增趋势,而东部海域则逐渐减小;第3模态以45°N为界,西风带呈现高低纬反相的双涡型分布,并有显著的2.5 a左右年际变化周期。北太平洋海域有效波高和风速重现期极值的大值区位于西风带,重现期越长,日本群岛南部海域风速加强越显著,加强的极值区延伸到中国的东海甚至是菲律宾群岛的东部海岸。