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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
2.
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
3.
太平洋海温场两种不同时间尺度气候模态的分析 总被引：7，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
4.
《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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6.
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
7.
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
8.
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
9.
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
10.
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