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1.
Interdecadal Pacific variability (IPV) is commonly observed in both the tropical and mid-latitude Pacific Ocean, and has a widespread influence on surface climate in the Pan-Pacific Basin. This variability is recorded by climate proxies such as geochemical parameters preserved in corals. However, the origins of IPV remain uncertain. To shed light on this, interdecadal variations in two long coral δ18O records from Nauru Island and the South China Sea (SCS), respectively located in the tropical Pacific and the mid-latitude North Pacific Ocean, were investigated. The interdecadal fluctuations in the δ18O series from Nauru Island (tropical Pacific) match those of the NINO3.4 index reasonably well (r=–0.30, n=96, p=0.0015), but are not correlated with those of the Pacific decadal oscillation (PDO) index (r=–0.17, n=96, p=0.05). The δ18O time series from the SCS (northwestern Pacific), by contrast, co-vary with the PDO index (r=–0.30, n=156, p=0.0007), but are out of phase with the NINO3.4 index at the interdecadal timescale (r=0.04, n=156, p=0.31). The impact on the interdecadal variability of processes occurring outside the growth region of corals is generally weak. The results thus do not support a tropical origin of IPV, but demonstrate that the interdecadal variability in the tropical Pacific and the North Pacific originates predominantly from local coupled ocean–atmosphere processes within these regions. The results also suggest that tropical–extratropical interactions played a role in IPV between 1920 and 1940, which indicates that IPV is a complex climatic phenomenon that involves multiple forcing mechanisms. 相似文献
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西北太平洋波候与大气涛动的联系 总被引：1，自引：0，他引：1
利用ECMWF 1958-2001年44 a的ERA-40海浪再分析资料计算了西北太平洋海域(0°~45°N,99°~160°E)月平均有效波高(SWH)、平均周期(T)与北太平洋模态指数(NPI)、太平洋年代际振荡(PDO)和多变量ENSO指数(MEI)等大气涛动之间的时间和空间的相关性,重点探讨了NPI对北半球西太平洋波候(SWH和T)的影响。结果表明:NPI、PDO和MEI均与SWH和T有显著的相关性;NPI与SWH和T呈现正相关性,NPI超前SWH和T半年左右正相关最强,最强的相关海域位于日本和菲律宾以东洋面;NPI还存在3~5 a、8~9 a和13~15 a的年际和年代际周期变化; NPI高指数且PDO负位相或MEI负位相均使得SWH和T 增大; MEI冷位相且叠加PDO负位相时也利于SWH和T增大。NPI影响西北太平洋波候的可能机制是:NPI处于低(高)指数时,阿留申低压加深(减弱)且位置偏东(西),北太平洋西风带海面风速急流出现(消失),太平洋副热带东北信风大值区东移(西移),西北太平洋海域信风减弱(加强),西北太平洋海域有效波高和平均周期随之减小(增大)。中、东太平洋西向传播的涌浪对西北太平洋海域波侯有重要影响。 相似文献
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太平洋海温场两种不同时间尺度气候模态的分析 总被引：8，自引：1，他引：7
利用经验正交函数分解、多元线性回归分析、小波分析和离散功率谱等方法,对太平洋年代际振荡(PDO)和ENSO的关系进行研究,发现太平洋海温场中主要存在着PDO和ENSO两种气候模态.用线性回归分析方法对这两种模态进行分离,结果表明,去除ENSO信息后,太平洋海温变化的关键区出现于北太平洋中纬度地区,PDO的信号很明显;而去除PDO信息后,海温变化的关键区位于赤道中、东太平洋地区,ENSO的信号较明显,此时ENSO循环不具有年代际振荡的特征,表明PDO对ENSO的调制作用是ENSO事件具有年代际变化特征的重要原因. 相似文献
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《Deep Sea Research Part I: Oceanographic Research Papers》2003,50(6):691-699
The analysis of interdecadal physical and biological variability is made challenging by the relative shortness of available time series. It has been suggested that rapid temporal changes of the most energetic empirical orthogonal function of North Pacific sea surface temperature (sometimes called the Pacific Decadal Oscillation or PDO) represents a “regime shift” between states with otherwise stable statistics. Using random independent time series generated to have the same frequency content as the PDO, we show that a composite analysis of climatic records recently used to identify regime shifts is likely to find them in Gaussian, red noise with stationary statistics. Detection of a shift by this procedure is not evidence of nonlinear processes leading to bi-stable behavior or any other meaningful regime shift. 相似文献
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Pacific Basin climate variability and patterns of Northeast Pacific marine fish production 总被引：1，自引：0，他引：1
A review of oceanographic and climate data from the North Pacific and Bering Sea has revealed climate events that occur on two principal time scales: a) 2–7 years (i.e. El Niño Southern Oscillation, ENSO), and b) inter-decadal (i.e. Pacific Decadal Oscillation, PDO). The timing of ENSO events and of related oceanic changes at higher latitudes were examined. The frequency of ENSO was high in the 1980s. Evidence of ENSO forcing on ocean conditions in the North Pacific (Niño North conditions) showed ENSO events were more frequently observed along the West Coast than in the western Gulf of Alaska (GOA) and Eastern Bering Sea (EBS). Time series of catches for 30 region/species groups of salmon, and recruitment data for 29 groundfish and 5 non-salmonid pelagic species, were examined for evidence of a statistical relationship with any of the time scales associated with Niño North conditions or the PDO. Some flatfish stocks exhibited high autocorrelation in recruitment coupled with a significant step in recruitment in 1977 suggesting a relationship between PDO forcing and recruitment success. Five of the dominant gadid stocks (EBS and GOA Pacific cod, Pacific hake and EBS and GOA walleye pollock) exhibited low autocorrelation in recruitment. Of these, Pacific hake, GOA walleye pollock and GOA Pacific cod exhibited significantly higher incidence of strong year classes in years associated with Niño North conditions. These findings suggest that the PDO and ENSO may play an important role in governing year-class strength of several Northeast Pacific marine fish stocks. 相似文献
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Quantitative identification of long-term changes in the abundance of Japanese anchovy (Engraulis japonicus) in the Yellow Sea is particularly important for understanding evolutionary processes of the Yellow Sea ecosystem. Unfortunately, the driving mechanisms of climate variability on the anchovy are still unclear due to the lack of long-term observational data. In this study, we used the fish scale deposition rate in the central Yellow Sea to reconstruct the time series of the anchovy stock over the past 400 a. On this basis, we further explored the impacts of the Pacific Decadal Oscillation (PDO) on the anchovy. Our results show that the anchovy stock is positively correlated with the PDO on a decadal time scale. In addition, anchovy abundance was relatively high during 1620–1860 AD (the Little Ice Age, LIA), though in a state of constant fluctuation; anchovy abundance maintained at a relatively low level after ~1860 AD. In particular, followed by overfishing since the 1980s, the anchovy stock has declined sharply. Based on these findings, we infer that fluctuations of the anchovy stock may be regulated by basin-scale “atmosphere–ocean” interactions. Nevertheless, the role of overfishing should not be ignored. 相似文献
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南海是西北太平洋最大的边缘海, 是联系北太平洋和北印度洋的关键通道。黑潮北上经过吕宋海峡时会将来自西太平洋的信号传入南海, 进而影响南海的水动力环境。研究了南海次表层盐度的空间分布特征、低频变化规律及其与太平洋年代际振荡(Pacific Decadal Oscillation, PDO)的关系, 并进一步探究了次表层盐度近年来的变化。结果显示: 1)南海次表层高盐水的位势密度主要介于24~26σθ, 受次表层气旋式环流所驱动, 盐度气候态空间分布北高南低, 以吕宋海峡处为起点, 呈逆时针自北向南逐渐降低。2)次表层盐度低频变化显著, 与PDO呈显著的正相关关系。当PDO处于正位相时, 吕宋海峡处西向平流输送加强, 次表层盐度升高; 当PDO处于负位相时, 吕宋海峡处西向平流输送减弱, 次表层盐度降低, 盐度的变化受到水平环流场的直接影响。3)近年来, 南海次表层盐度呈现先降低后升高再降低的趋势, 滞后PDO约10个月, 2006— 2014年初, 盐度呈下降趋势; 2014—2017年初, 盐度呈上升趋势, 且上升速率远大于先前下降的速率; 2017年后盐度再次逐渐降低。 相似文献
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The adjustment of the North Pacific Subtropical and Subpolar Gyres towards changes in wind stress leads to different time-scale variabilities, which plays a significant role in climate changes. Based on the Simple Ocean Data Assimilation (SODA) and Global Ocean Data Assimilation System (GODAS) datasets, the variations of the Subtropical and Subpolar Gyres are diagnosed using "three-dimension Ocean Circulation Diagnostic Method", and established three types of index series describe the strength, meridional and depth center of the Subtropical and Subpolar Gyres. The above indices present the seasonal, interannual and interdecadal variabilities of the Subtropical and Subpolar Gyres, which proves well. Both the Gyres are the strongest in winter, but the Subtropical Gyre is the weakest in summer and the Subpolar Gyre is the weakest in autumn. The Subtropical Gyre moves northward from February to March, southward in October, and to the southernmost in around January, while the Subpolar Gyre moves northward in spring, southward in summer, northward again in autumn and reaching the extreme point in winter to the south. The common feature of the interannual and interdecadal variabilities is that the two gyres were weaker and to the north before 1976-1977, while they were stronger and to the south after 1976-1977. The Subpolar Gyre has made a paramount contribution to the variability on interdecadal scales. As is indicated with the Subpolar Gyre strength indices, there was an important shift from weak to strong around 1976-1977, and the correlation coefficient with the North Pacific Decadal Oscillation (PDO) indices was 0.45, which was far better than that between the Subtropical Gyre strength indices and the PDO. Tests show that influenced by small and mesoscale eddies, the magnitude of large-scale gyres strength is strongly dependent on data resolution. But seasonal interannual and interdecadal large-scale variabilities of the two gyres presented with indices is less affected by model resolution. 相似文献
10.
David W. Pierce 《Progress in Oceanography》2001,49(1-4)
When considering physical mechanisms for decadal-timescale climate variability in the North Pacific, it is useful to describe in detail the expected response of the ocean to the chaotic atmospheric forcing. The expected response to this white-noise forcing includes strongly enhanced power in the decadal frequency band relative to higher frequencies, pronounced changes in basin-wide climate that resemble regime shifts, preferred patterns of spatial variability, and a depth-dependent profile that includes variability with a standard deviation of 0.2–0.4°C over the top 50–100 m. Weak spectral peaks are also possible, given ocean dynamics. Detecting coupled ocean–atmosphere modes of variability in the real climate system is difficult against the spectral and spatial structure of this ‘null-hypothesis’ of how the ocean and atmosphere interact, especially given the impossibility of experimentally decoupling the ocean from the atmosphere. Turning to coupled ocean–atmosphere models to address this question, a method for identifying coupled modes by using models of increasing physical complexity is illustrated. It is found that a coupled ocean–atmosphere mode accounts for enhanced variability with a time scale of 20 years/cycle in the Kuroshio extension region of the model's North Pacific. The observed Pacific Decadal Oscillation (PDO) has many similarities to the expected noise-forced response and few similarities to the model's coupled ocean–atmosphere variability. However, model deficiencies and some analyses of observations by other workers indicate that the possibility that part of the PDO arises from a coupled ocean–atmosphere mode cannot be ruled out. 相似文献
11.
Chum salmon, Oncorhynchus keta, are distributed widely in the North Pacific Ocean, and about 76% of chum salmon were caught from Russian, Japanese, and Korean waters of the northwestern Pacific Ocean during the last 20 years. Although it has been speculated that the recent increase in salmon production was aided by not only the enhancement program that targeted chum salmon but also by favorable ocean conditions since the early 1990s, the ecological processes for determining the yield of salmon have not been clearly delineated. To investigate the relationship between yield and the controlling factors for ocean survival of chum salmon, a time-series of climate indices, seawater temperature, and prey availability in the northwestern Pacific including Korean waters were analyzed using some statistical tools. The results of cross-correlation function (CCF) analysis and cumulative sum (CuSum) of anomalies indicated that there were significant environmental changes in the North Pacific during the last century, and each regional stock of chum salmon responded to the Pacific Decadal Oscillation (PDO) differently: for Russian stock, the correlations between PDO index and catch were significantly negative with a time-lag of 0 and 1 years; for Japanese stock, significantly positive with a timelag of 0–2 years; and for Korean stock, positive but no significant correlation. The results of statistical analyses with Korean chum salmon also revealed that a coastal seawater temperature over 14°C and the return rate of spawning adults to the natal river produced a significant negative correlation. 相似文献
12.
20世纪太平洋海温变化中人为因子与自然因子贡献的模拟研究 总被引：1，自引：0，他引：1
基于中国科学院大气物理研究所大气科学和地球流体力学国家重点实验室(LASG/IAP)发展的气候系统模式FGOALS_gl对20世纪太平洋海温变化的模拟,讨论了自然因子和人为因子对20世纪太平洋海温变化的相对贡献。观测资料表明,20世纪太平洋平均的SST变化主要分为3个时段:20世纪上半叶的增暖,40—70年代的微弱变冷,70年代之后的迅速增暖。20世纪太平洋SST变化的主导模态是全海盆尺度的振荡上升模态,其次为PDO振荡型,在70年代末PDO存在明显的年代际转型。通过全强迫试验、自然强迫试验、控制试验对上述现象进行归因分析,结果表明,人为因子和内部变率都对第一次增暖有贡献,而人类活动(主要是温室气体的增加)是70年代之后太平洋SST迅速增暖的主要原因。分区域来看,在两个增暖时段中,影响黑潮延伸体区SST变化的主要是自然因子和内部变率,影响其它海域SST变化的则主要是人为因子。全强迫试验可以较好的模拟出前两个模态的空间分布及时间序列。在没有人为因子的影响下,PDO成为太平洋海温变化的主导模态,其年代际转变发生在60年代中期,意味着人为因子是全海盆振荡增暖的主导原因,并且它使得年代际转型滞后了10a。因此,自然因子是导致SST年代际转型中的主导因子,人为因子有"调谐"作用。 相似文献
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Decadal variations of the transport and bifurcation latitude of the North Equatorial Current (NEC) in the northwestern tropical Pacific Ocean over 1959–2011 are investigated using outputs of the Ocean Analysis/Reanalysis System 3 prepared by the European Centre for Medium-Range Weather Forecasts. The results indicate that the NEC transports at different longitudes have different decadal fluctuations, which are strongest around 139°E. The NEC bifurcation latitude (NBL) has its largest decadal variations around 150 m. Extremes of the decadal NEC transport and NBL before 1975 correspond to different circulation anomalies from those after 1975. The regression map against decadal NBL exhibits negative sea surface height (SSH) anomalies and a cyclonic gyre anomaly over the northwestern tropical Pacific Ocean, while that against the decadal NEC transport exhibits a dipole structure, with positive/negative SSH anomalies to the north/south of about 13°N. Furthermore, decadal variations of the NEC transport and NBL over the whole period have different correlations with Pacific Decadal Oscillation (PDO) and Tropical Pacific Decadal Variability (TPDV). Generally, the decadal NEC transport shows higher correlations with PDO than with TPDV, while the NBL has higher correlations with TPDV than with PDO. The high correlation of decadal NEC transport with PDO mainly comes from that of its northern branch with PDO, while its southern branch shows higher correlation with TPDV. 相似文献
16.
Ommastrephes bartramii is an ecologically dependent species and has great commercial values among the AsiaPacific countries. This squid widely inhabits the North Pacific, one of the most dynamic marine environments in the world, subjecting to multi-scale climatic events such as the Pacific Decadal Oscillation(PDO). Commercial fishery data from the Chinese squid-jigging fleets during 1995–2011 are used to evaluate the influences of climatic and oceanic environmental variations on the spatial distribution of O. bartramii. Significant interannual and seasonal variability are observed in the longitudinal and latitudinal gravity centers(LONG and LATG) of fishing ground of O. bartramii. The LATG mainly occurred in the waters with the suitable ranges of environmental variables estimated by the generalized additive model. The apparent north-south spatial shift in the annual LATG appeares to be associated with the PDO phenomenon and is closely related to the sea surface temperature(SST)and sea surface height(SSH) on the fishing ground, whereas the mixed layer depth(MLD) might contribute limited impacts to the distribution pattern of O. bartramii. The warm PDO regimes tend to yield cold SST and low SSH, resulting in a southward shift of LATG, while the cold PDO phases provid warm SST and elevated SSH,resulting in a northward shift of LATG. A regression model is developed to help understand and predict the fishing ground distributions of O. bartramii and improve the fishery management. 相似文献
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A simulation is conducted with a realistic ocean general circulation model to investigate the three dimensional spreading of a passive tracer prescribed at the sea surface with the same distribution as the interdecadal sea surface temperature (SST) anomalies observed in the North Pacific. The tracers reaching the equator have the same sign as the major oval-shaped SST anomaly pattern in the central North Pacific but with a magnitude reduced less than 10% of the mid-latitude SST anomaly. The mixing both with the water containing SST anomalies of an opposite sign off the west coast of North America, and with the Southern Hemisphere thermocline water both contribute to the reduced equatorial amplitude. On the way to the equator in the southwestern part of the subtropical gyre, the subducted water is replenished by tracers leaking from the recirculation region to the north. The simulated passive tracer field in the subsurface layers agrees with the observed interdecadal temperature anomalies, suggesting the relevance of the processes studied here to the thermocline variability in the real North Pacific. 相似文献
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黑潮入侵南海的强弱与太平洋年代际变化及厄尔尼诺-南方涛动现象的关系 总被引：2，自引：1，他引：1
在黑潮入侵南海强弱的问题上,到底是太平洋年代际变化(Pacific Decadal Oscillation,PDO)还是厄尔尼诺-南方涛动(El Nio-Southern Oscillation,ENSO)现象在起关键作用,目前还存在着较大争议。本文先以高盐水作为黑潮入侵强弱的示踪物,用120°E断面的高盐水数据和北赤道流分叉点(North Equator Current Bifurcation,NEC-Y)的南北变动进行相关分析,接着,进一步用学者所用的黑潮入侵指数(KI指数,Kuroshio intrusion index和NEC指数,North Equatorial Current index)与北赤道流分叉点南北变动进行相关分析。最后,用EMD(Empirical Mode Decomposition)方法和相关关系分析法分别分析了PDO指数、Nio3.4指数与北赤道流分叉点南北变动的关系并用NECP风场数据探讨其影响机制。结果表明:(1)通过对120°E断面的高盐水的KI指数、NEC指数与NEC-Y的相关分析,表明了北赤道流分叉点的南北变动能够很好地指代黑潮入侵南海的强弱;(2)通过PDO指数和Nio3.4指数与北赤道流分叉点的南北变动的相关性分析,发现PDO指数、Nio3.4指数与北赤道流分叉点的南北变动都具有较好的相关性,都在0.5水平。这些良好的相关性表明了PDO和ENSO对黑潮入侵南海的强弱都具有重要的影响;(3)当处于厄尔尼诺年(拉尼娜)时,赤道太平洋发生西(东)风异常,使得北赤道流分叉点偏北(南),使吕宋岛东侧的黑潮流速减弱(加强),黑潮入侵南海增强(减弱);当PDO处于暖(冷)阶段时,会加强热带太平洋的西(东)风异常,使得黑潮入侵南海增强(减弱)。 相似文献
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利用奇异谱分析和小波分析的方法,分析了南海海表面温度异常(SSTA)在年代际尺度上的变化特征及其与太平洋年代际涛动(PDO)之间的关系.发现南海 SSTA 年代际振荡与年循环之间存在一定程度上的锁相:在冬、春季较强,而夏、秋季则较弱.此外,在过去的140多年,南海 SSTA 年代际振荡显著衰弱.通过与 PDO 指数进行相关分析发现,在年代际尺度上 PDO 与南海 SSTA 具有一定的相关性.一方面这种相关性只在20世纪前50年比较显著,这在一定程度上解释了为何南海 SSTA 的年代际振荡表现出衰减的趋势;另一方面,当 PDO 位相超前南海 SSTA 位相3到6个月时,两者表现出较强的相关性.进一步分析表明,PDO 可能通过调控赤道东太平洋 SST,从而影响南海 SSTA 的年代际变化. 相似文献