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1.
Shilimkar Vivek Abe Hiroto Roxy Mathew Koll Tanimoto Youichi 《Journal of Oceanography》2022,78(5):337-352
The Indonesian throughflow (ITF) transports a significant amount of warm freshwater from the Pacific to the Indian Ocean, making it critical to the global climate system. This study examines decadal ITF variations using ocean reanalysis data as well as climate model simulations from the Coupled Model Inter-comparison Project Phase 5 (CMIP5). While the observed annual cycle of ITF transport is known to be correlated with the annual cycle of sea surface height (SSH) difference between the Pacific and Indian Oceans, ocean reanalysis data (1959–2015) show that the Pacific Ocean SSH variability controls more than 85% of ITF variation on decadal timescales. In contrast, the Indian Ocean SSH variability contributes less than 15%. While those observed contributions are mostly reproduced in the CMIP5 historical simulations, an analysis of future climate projections shows a 25–30% increase in the Indian Ocean SSH variability to decadal ITF variations and a corresponding decrease in the Pacific contribution. These projected changes in the Indian Ocean SSH variability are associated with a 23% increase in the amplitudes of negative zonal wind stress anomalies over the equatorial Indian Ocean, along with a 12º eastward shift in the center of action in these anomalies. This combined effect of the increased amplitude and eastward shift in the zonal wind stress increases the SSHA variance over the Indian Ocean, increasing its contribution to the ITF variation. The decadal ITF changes discussed in this study will be crucial in understanding the future global climate variability, strongly coupled to Indo-Pacific interactions.
相似文献2.
Eko Siswanto Makio C. Honda Yoshikazu Sasai Kosei Sasaoka Toshiro Saino 《Journal of Oceanography》2016,72(3):465-477
We used 16 years of multiplatform-derived biophysical data to reveal the footprint of the Pacific Decadal Oscillation (PDO) on the phytoplankton biomass of the northwestern Pacific Ocean in terms of chlorophyll a concentration (Chl), and to discern the probable factors causing the observed footprint. There were meridional differences in the response of phytoplankton to changes of environmental conditions associated with deepening of the mixed layer during the positive phase of the PDO. In general, deepening of the mixed layer increased phytoplankton biomass at low latitudes (increase of Chl due to increase of nutrient supply), but lowered phytoplankton at high latitudes (decrease of Chl due to reduction of average irradiance and temperature in the mixed layer). The areas where Chl increased or decreased changed meridionally and seasonally in accord with regulation of nutrient and light/temperature limitation by changes of mixed layer depth. The observed PDO footprint on Chl in the northwestern Pacific is likely superimposed on the high-frequency component of the PDO excited by El Niño/Southern Oscillation interannual variability. On a decadal time scale, however, Chl in the northwestern Pacific were more strongly associated with the recently discovered North Pacific Gyre Oscillation. 相似文献
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西北太平洋海平面异常模态在纯拉尼娜事件与拉尼娜和负印度洋偶极子（IOD）事件同时发生时表现出完全不同的形态。在纯拉尼娜事件期间，西北太平洋海平面呈现显著的正异常；而2010/2011拉尼娜事件期间西北太平洋海平面明显降低，呈显著的负异常，其与印度洋负IOD事件密切相关。研究结果表明，负IOD事件能在热带西太平洋驱动显著的西风异常，由此减弱了拉尼娜峰值期间西北太平洋海平面正异常。同时，在负IOD峰值期的9月，在日经线附近存在显著的风应力旋度正异常，激发负的海平面异常以Rossby波的形式向西传播，并在第二年6月抵达菲律宾以东海域，维持并加强该海域海平面负异常，进而对北赤道流分叉点位置及输运产生重要的影响。 相似文献
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Low-frequency variability of the North Equatorial Current bifurcation in the past 40 years from SODA 总被引：1，自引：1，他引：0
The low-frequency variability of the North Equatorial Current (NEC) bifurcation during 1958 to 2001 was investigated with the Simple Ocean Data Assimilation (SODA) 2.0.2 dataset.In agreement with recent observations,the NEC bifurcation latitude (NBL) shifted northward as depth increases, from about 12.7°N near the surface to about 17.1°N at depths around 500 m for the annual average. This study reveals that the interannual variations of NBL,with five years period,mainly focused on the upper 500 m with amplitude increasing as depth increased.The NBL shifted southward in the past 40 years,which was more significant in the subsurface at more than -0.02°/a.The NBL manifests itself in the transports of NMK (NEC-Mindanao Current (MC)-Kuroshio) system in strong relationship with MC (0.7) and Kuroshio (-0.7).The EOF analysis of meridional velocity off the Philippine coast shows that the first mode,explaining 62% of variance and 5 years period,was highly correlated with the southward shift of NBL with coefficient at about 0.75.The southward shift of NBL consists with the weakening of MC and strengthening of Kuroshio,which exhibited linear trends at -0.24Sv/a and 0.11Sv/a.Both interannual variation and trend of NBL were closely related to the variation of NMK system. 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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ENSO循环相联系的北太平洋低纬度异常西边界流 总被引：1，自引：1，他引：0
用SODA海洋同化和NCEP大气再分析资料,分析了热带太平洋次表层海温异常主要模态与北太平洋低纬度西边界流海域上层海洋环流和亚洲-北太平洋地区大气垂直和水平流场变化之间的关系,得到以下结果:（1） 在热带太平洋海洋次表层ENSO事件具有两种模态,二者组合构成ENSO循环。第一模态为ENSO成熟期,主要出现在冬季,第二模态为ENSO过渡期,主要出现夏季。（2） ENSO循环对北太平洋低纬度西边界流区上层海洋环流有重要影响。在El Niño发展期或La Niña 衰退期,该区出现气旋性异常环流,北赤道流（NEC）加强,NEC分叉位置北移,棉兰老海流（MC）加大,菲律宾以东黑潮（KC）减小,北赤道逆流（NECC）最强。在El Niño（La Niña）成熟期,该区气旋性（反气旋性）异常环流达最强,NEC最强（最弱）,NEC分叉位置最北（最南）,MC最大（最小）,KC最小（最大）,NECC减弱（加强）。在El Niño衰退期或La Niña发展期与El Niño发展期相反,该区出现反气旋性异常环流,由此导致相应流系异常发生反位相变化。（3） ENSO循环对北太平洋低纬度西边界流海域上层海洋环流的影响是通过ENSO事件期间热带太平洋热力状况异常改变上空大气环流来实现的。ENSO事件首先造成热带太平洋海洋热力状况异常,导致其上空对流活动异常,后者直接或间接通过“大气桥”能量传输引起相关地区大气环流场的变化,致使海面风应力场异常,进而强迫上层海洋环流场的相应变化。文章最后还分析了ENSO事件期间菲律宾附近异常反气旋或异常气旋性风场的产生和持续原因,讨论了北太平洋低纬度西边界流海域海气相互作用在ENSO循环中的贡献。 相似文献
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秘鲁外海茎柔鱼栖息地适宜性年代际变动 总被引：1，自引：0，他引：1
茎柔鱼广泛分布于东南太平洋海域，是我国重要的远洋捕捞对象之一，其种群易受气候和栖息地环境的影响。利用海表面温度(SST)和海表面高度距平(SSHA)两个关键环境因子，计算1950?2015年1?12月秘鲁外海茎柔鱼栖息地适宜性指数(HSI)，对比分析太平洋年代际涛动(PDO)位于冷暖位相下茎柔鱼渔场环境以及栖息地质量的变动。结果显示，1950?2015年PDO呈现冷、暖、冷3个位相变化，其中PDO冷位相内的SST距平(SSTA)和SSHA明显低于PDO暖位相。交相关分析结果表明，PDO指数与SSTA和SSHA均呈显著正相关，而HSI与PDO指数、SSTA和SSHA均呈显著负相关。PDO位于冷位相时，茎柔鱼渔场内水温变冷，海面高度下降，适宜的SST和SSHA范围增加，因此茎柔鱼有利的栖息地面积增大；而PDO位于暖位相时，水温增暖，海面高度上升，适宜的SST和SSHA范围缩减，导致茎柔鱼适宜的栖息地面积缩小。研究认为，太平洋年代际涛动调控了茎柔鱼渔场内的环境变化，进而对茎柔鱼栖息地质量及适宜栖息地范围产生显著影响。 相似文献
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本文利用HYCOM （Hybrid Coordinate Ocean Model）再分析数据对北赤道流（NEC）、棉兰老流（MC）以及黑潮（KC）所构成的NMK环流系统在2015/2016年超强厄尔尼诺事件期间的变化特征及其影响机制进行了研究，并与其他厄尔尼诺期间的变化特征进行了对比。结果表明，在2015/2016年超强厄尔尼诺事件期间，NEC和MC输运均显著增强，最大值分别达到66 Sv （1 Sv=106 m3/s）和49.4 Sv，北赤道流分叉纬度最北可达16°N，KC输运没有明显增强。NMK环流系统的年际变化主要与此次厄尔尼诺事件期间热带西北太平洋15°N以南、160°E以西海域出现的气旋式环流异常有关。该环流异常出现自厄尔尼诺事件的前期阶段，并于爆发阶段达到顶峰，主要是由15°N以南区域出现的强西风异常所引起的。进一步分析表明，此次厄尔尼诺事件期间NEC、MC输运和NBL的平均值均大于1992— 2014年间所有厄尔尼诺事件的平均状况，但与1997/1998年超强厄尔尼诺事件期间的平均值相近。 相似文献
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The Pacific Decadal Oscillation 总被引：60，自引：1，他引：60
The Pacific Decadal Oscillation (PDO) has been described by some as a long-lived El Niño-like pattern of Pacific climate variability, and by others as a blend of two sometimes independent modes having distinct spatial and temporal characteristics of North Pacific sea surface temperature (SST) variability. A growing body of evidence highlights a strong tendency for PDO impacts in the Southern Hemisphere, with important surface climate anomalies over the mid-latitude South Pacific Ocean, Australia and South America. Several independent studies find evidence for just two full PDO cycles in the past century: “cool” PDO regimes prevailed from 1890–1924 and again from 1947–1976, while “warm” PDO regimes dominated from 1925–1946 and from 1977 through (at least) the mid-1990's. Interdecadal changes in Pacific climate have widespread impacts on natural systems, including water resources in the Americas and many marine fisheries in the North Pacific. Tree-ring and Pacific coral based climate reconstructions suggest that PDO variations—at a range of varying time scales—can be traced back to at least 1600, although there are important differences between different proxy reconstructions. While 20th Century PDO fluctuations were most energetic in two general periodicities—one from 15-to-25 years, and the other from 50-to-70 years—the mechanisms causing PDO variability remain unclear. To date, there is little in the way of observational evidence to support a mid-latitude coupled air-sea interaction for PDO, though there are several well-understood mechanisms that promote multi-year persistence in North Pacific upper ocean temperature anomalies. 相似文献
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Limitations in sea surface salinity (SSS) observations and timescale separation methods have led to an incomplete picture of the mechanisms of SSS decadal variability in the tropical Pacific Ocean, where the El Niño Southern Oscillation (ENSO) dominates. Little is known regarding the roles of the North Pacific Gyre Oscillation (NPGO) and the Pacific Decadal Oscillation (PDO) in the large-scale SSS variability over the tropical basin. A self-organizing map (SOM) clustering analysis is performed on the intrinsic mode function (IMF) maps, which are decomposed from SSS and other hydrological fields by ensemble empirical mode decomposition (EEMD), to extract their asymmetric features on decadal timescales over the tropical Pacific. For SSS, an anomalous pattern appeared during 1997 to 2004, a period referred to as the anomalous late 1990s, when strong freshening prevailed in large areas over the southwestern basin and moderate salinization occurred in the western equatorial Pacific. During this period, the precipitation and surface currents were simultaneously subjected to anomalous fluctuations: the precipitation dipole and zonal current divergence along the equator coincided with the SSS increase in the far western equatorial Pacific, while the weak zonal current convergence in the southwestern basin and large-scale southward meridional currents tended to induce SSS decreases there. The dominant decadal modes of SSS and sea surface temperature (SST) in the tropical Pacific both resemble the NPGO but occur predominantly during the negative and positive NPGO phases, respectively. The similarities between the NPGO and Central Pacific ENSO (CP-ENSO) in their power spectra and associated spatial patterns in the tropics imply their dynamical links; the correspondence between the NPGO-like patterns during negative (positive) phases and the CP La Niña (CP El Niño) patterns for SSS is also discussed. 相似文献
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In this study, we use existing observational datasets to evaluate 20th century climate simulations of the tropical Pacific. The emphasis of our work is decadal variability of the shallow meridional overturning circulation, which links the tropical and subtropical Pacific Ocean. In observations, this circulation is characterized by equatorward geostrophic volume transport convergence in the interior ocean pycnocline across 9°N and 9°S. Historical hydrographic data indicate that there has been a decreasing trend in this convergence over the period 1953–2001 of about 11 Sverdrup (1 Sv = 106 m3 s−1), with maximum decade-to-decade variations of 7–11 Sv. The transport time series is highly anti-correlated with sea surface temperature (SST) anomalies in the central and eastern tropical Pacific, implying that variations in meridional overturning circulation are directly linked to decadal variability and trends in tropical SST. These relationships are explored in 18 model simulations of 20th century climate from 14 state-of-the-art coupled climate models. Significant correlation exists between meridional volume transport convergence and tropical SST in the majority of the models over the last half century. However, the magnitude of transport variability on decadal time scales in the models is underestimated while at the same time modeled SST variations are more sensitive to that transport variability than in the observations. The effects of the meridional overturning circulation on SST trends in most the models is less clear. Most models show no trend in meridional transport convergence and underestimate the trend in eastern tropical Pacific SST. The eddy permitting MIROCH model is the only model that reasonably reproduces the observed trends in transport convergence, tropical Pacific SST, and SST gradient along the equator over the last half century. If the observed trends and those simulated in the MIROCH model are ultimately related to greenhouse gas forcing, these results suggest that the Bjerknes feedback, by affecting pycnocline transport convergences, may enhance warming that arises from anthropogenic forcing in the eastern tropical Pacific. 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
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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
16.
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
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近年来厄尔尼诺期间北赤道流输运的年际变化 总被引：1，自引：0，他引：1
为了研究近年来厄尔尼诺期间北赤道流输运的年际变化,本文利用海洋客观分析数据MOAA GPV(Grid Point Value of the Monthly Objective Analysis)以及P-vector方法计算了北太平洋绝对地转流,探讨了2001~2013年期间厄尔尼诺与北赤道流输运之间的关系。在此期间发生的4次厄尔尼诺事件中,北赤道流输运在2002~2003、2006~2007、2009~2010年的厄尔尼诺成熟期都出现了明显的增强,但是在2004~2005年的厄尔尼诺成熟期并没有明显的增强。进一步分析发现,在2002~2003年、2006~2007年、2009~2010年的厄尔尼诺成熟期,10°N以南的热带西北太平洋区域出现了负的海面高度异常和气旋式环流异常,这主要是由热带环流区域出现的西风异常和正的Ekman抽吸通过Rossby波西传到热带西太平洋区域所致;但是在2004~2005年厄尔尼诺成熟期,海面温度异常的分布明显不同,西风异常和正的Ekman抽吸异常明显北移,导致负的海面高度异常和气旋式环流异常出现在了10°N以北的西北太平洋区域,使得北赤道流输运在2004~2005年的厄尔尼诺成熟期没有明显的增强。 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
19.
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
20.
用59年Ishii再分析温度资料,讨论了热带西南印度洋(SWTIO)上升流区的季节和年际变化以及与上升流区有关的温度距平的变化,同时分析了其与热带印太海气系统的关系,结果显示SWTIO 上升流在南半球冬、夏季比较强,春季最弱。它的范围在5°~1°S,在东西向从50°E可以伸展到90°E。该上升流区的变化与温跃层的温度距平有密切的关系,并存在明显的5 a振荡周期。SWTIO上升流区温度距平的5 a周期振荡是由热带东印度洋温度距平在最大垂直温度距平曲面(MTAL)上向西沿着11.5°~6.5°S传播过来的,它与热带太平洋的温度距平传播方式不同。SWTIO上升流是热带印太海气系统的一个重要组成部分,印度洋偶极子 超前SWTIO上升流区温度变化5个月,最大相关系数达到0.57,NINO3区指数超前SWTIO上升流区指数2个月达到0.49。当热带印太区域的大气风场改变,影响热带太平洋和印度洋表层SSTA,出现ENSO和DIPOLE,进一步向西传播到SWTIO次表层,导致SWTIO上升流区出现改变。 相似文献