共查询到20条相似文献，搜索用时 203 毫秒
1.
The oceanic circulation in the Southern California Bight (SCB) is influenced by the large-scale California Current offshore, tropical remote forcing through the coastal wave guide alongshore, and local atmospheric forcing. The region is characterized by local complexity in the topography and coastline. All these factors engender variability in the circulation on interannual, seasonal, and intraseasonal time scales. This study applies the Regional Oceanic Modeling System (ROMS) to the SCB circulation and its multiple-scale variability. The model is configured in three levels of nested grids with the parent grid covering the whole US West Coast. The first child grid covers a large southern domain, and the third grid zooms in on the SCB region. The three horizontal grid resolutions are 20 km, 6.7 km, and 1 km, respectively. The external forcings are momentum, heat, and freshwater flux at the surface and adaptive nudging to gyre-scale SODA reanalysis fields at the boundaries. The momentum flux is from a three-hourly reanalysis mesoscale MM5 wind with a 6 km resolution for the finest grid in the SCB. The oceanic model starts in an equilibrium state from a multiple-year cyclical climatology run, and then it is integrated from years 1996 through 2003. In this paper, the 8-year simulation at the 1 km resolution is analyzed and assessed against extensive observational data: High-Frequency (HF) radar data, current meters, Acoustic Doppler Current Profilers (ADCP) data, hydrographic measurements, tide gauges, drifters, altimeters, and radiometers. The simulation shows that the domain-scale surface circulation in the SCB is characterized by the Southern California Cyclonic Gyre, comprised of the offshore equatorward California Current System and the onshore poleward Southern California Countercurrent. The simulation also exhibits three subdomain-scale, persistent ( i.e., standing), cyclonic eddies related to the local topography and wind forcing: the Santa Barbara Channel Eddy, the Central-SCB Eddy, and the Catalina-Clemente Eddy. Comparisons with observational data reveal that ROMS reproduces a realistic mean state of the SCB oceanic circulation, as well as its interannual (mainly as a local manifestation of an ENSO event), seasonal, and intraseasonal (eddy-scale) variations. We find high correlations of the wind curl with both the alongshore pressure gradient (APG) and the eddy kinetic energy level in their variations on time scales of seasons and longer. The geostrophic currents are much stronger than the wind-driven Ekman flows at the surface. The model exhibits intrinsic eddy variability with strong topographically related heterogeneity, westward-propagating Rossby waves, and poleward-propagating coastally-trapped waves (albeit with smaller amplitude than observed due to missing high-frequency variations in the southern boundary conditions). 相似文献
2.
A high-resolution, multi-level, primitive equation ocean model has been used to investigate the combined role of seasonal
wind forcing, seasonal thermohaline gradients, and coastline irregularities on the formation of currents, meanders, eddies,
and filaments in the entire California Current System (CCS) region, from Baja to the Washington-Canada border. Additional
objectives are to further characterize the meandering jet south of Cape Blanco and the seasonal variability off Baja. Model
results show the following: All of the major currents of the CCS (i.e., the California Current, the California Undercurrent,
the Davidson Current, the Southern California Countercurrent, and the Southern California Eddy) as well as filaments, meanders
and eddies are generated. The results are consistent with the generation of eddies from instabilities of the southward current
and northward undercurrent via barotropic and baroclinic instability processes. The meandering southward jet, which divides
coastally-influenced water from water of offshore origin, is a continuous feature in the CCS, and covers an alongshore distance
of over 2000 km from south of Cape Blanco to Baja. Off Baja, the southward jet strengthens (weakens) during spring and summer
(fall and winter). The area off southern Baja is a highly dynamic environment for meanders, filaments, and eddies, while the
region off Point Eugenia, which represents the largest coastline perturbation along the Baja peninsula, is shown to be a persistent
cyclonic eddy generation region.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
A regional ocean model with a horizontal resolution of 1/6° encompassing the New Zealand Exclusive Economic Zone is described. The regional model successfully downscaled solutions from a high resolution, global, coupled model HadCEM. Transport estimates from the global and regional models were compared with observations, and both models supported largely consistent, climatological mean solutions. The regional model used monthly mean forcing at the surface. Nevertheless, the regional model eddy kinetic energy (EKE) spatial patterns compared favourably with long‐term mean satellite altimetric estimates, although the modelled background EKE amplitudes were much lower than observed. A series of permanent eddies associated with the western boundary current system around the top of the North Island of New Zealand were reproduced, and an eddy adjacent to Norfolk Ridge was identified in both the global and regional models. The western boundary current system around the North Island of New Zealand and the associated eddies were the most sensitive components of the model solutions, being influenced by initial conditions, wind forcing, and the model domain size. 相似文献
5.
On the general ocean circulation forced by the asymmetric wind stress curl, the role of the eddies which are detached from the western boundary current is studied using an eddy-resolving two-layered quasi-geostrophic numerical model with free-slip boundary condition. An ideal sinusoidal function is used as the wind stress curl, and amplitude is assumed to be larger over the southern basin than over the northern one. In contrast with the antisymmetric wind forcing, in the asymmetric wind stress case, the subtropical western boundary current overshoots to the north from the zero wind stress curl line. As the asymmetricity of the wind forcing becomes larger, the separation point of the time mean field is located further north. The eddies generated in the region of the subtropical recirculation are advected northward by the western boundary current and they are detached from subtropical gyre. The release of these eddies to the north basin leads to weaken the subtropical recirculation system. From the analysis of the potential vorticity budgets, in the asymmetric case, it is shown that detached eddies play an important role in transporting the negative vorticity which is excessively inputted into the southern basin, to the northern basin, in addition to the terms which transport vorticity in the antisymmetric case, i.e., the vorticity transport by the meander of the jet. Under the free-slip boundary, more than a quarter of that excess vorticity is transported by those detached eddies in some cases. 相似文献
6.
The variability of the New Guinea Coastal Current (NGCC) and New Guinea Coastal Undercurrent (NGCUC) were examined from one year time series of current data from ADCP moorings at 2°S, 142°E and 2.5°S, 142°E. Change in the hydrographic structure induced by monsoonal wind forcing was also examined from hydrographic data along the 142°E covering consecutively two winter seasons and two summer seasons. The westward NGCUC was observed to persist year around. The annual mean depth of the current core was 220 m, the mean speed of the zonal component was 54 cm/s with a standard deviation of 15 cm/s at the 2.5°S site. Velocity fluctuations at 20–30 day period were observed year around. Seasonal reversal of the surface intensified NGCC was clearly observed. In the boreal summer characterized by the southeasterly monsoon, westward currents of over 60 cm/s were dominant in the surface layer. The warm, low-salinity layer thickened at this time and sloped down toward the New Guinea coast from the equator. This surface water accumulation may be caused by onshore Ekman drift at the New Guinea coast, combined with weak Ekman upwelling at the equator. In the boreal winter, an eastward surface current developed to 100 cm/s extending down to 100 m depth in response to the northwesterly monsoonal winds. Coastal upwelling was indicated in this season and the surface water accumulated at the equator due to Ekman convergence. Shipboard ADCP data indicated that the NGCUC intensified in boreal summer as the width and depth of the NGCUC increased. 相似文献
7.
Sea Surface Height (SSH) variability in the Indian Ocean during 1993-1995 is studied using TOPEX/POSEIDON (T/P) altimetry data. Strong interannual variability is seen in the surface circulation of the western Arabian Sea, especially in the Somali eddy structure. During the Southwest (SW) monsoon, a weak monsoon year is characterized by a single eddy system off Somalia, a strong or normal monsoon year by several energetic eddies. The Laccadive High (LH) and Laccadive Low (LL) systems off southwest India are observed in the altimetric SSH record. The variability of the East India Coastal Current (EICC), the western boundary current in the Bay of Bengal, is also detected. Evidence is found for the propagation of Kelvin and Rossby waves across the northern Indian Ocean; these are examined in the context of energy transfer to the western boundary currents, and associated eddies. A simple wind-driven isopycnal model having three active layers is implemented to simulate the seasonal changes of surface and subsurface circulation in the North Indian Ocean and to examine the response to different wind forcing. The wind forcing is derived from the ERS-1 scatterometer wind stress for the same period as the T/P altimeter data, enabling the model response in different (active/weak) monsoon conditions to be tested. The model output is derived in 10-day snapshots to match the time period of the T/P altimeter cycles. Complex Principal Component Analysis (CPCA) is applied to both altimetric and model SSH data. This confirms that long Rossby waves are excited by the remotely forced Kelvin waves off the southwest coast of India and contribute substantially to the variability of the seasonal circulation in the Arabian Sea. 相似文献
8.
Sea Surface Height (SSH) variability in the Indian Ocean during 1993-1995 is studied using TOPEX/POSEIDON (T/P) altimetry data. Strong interannual variability is seen in the surface circulation of the western Arabian Sea, especially in the Somali eddy structure. During the Southwest (SW) monsoon, a weak monsoon year is characterized by a single eddy system off Somalia, a strong or normal monsoon year by several energetic eddies. The Laccadive High (LH) and Laccadive Low (LL) systems off southwest India are observed in the altimetric SSH record. The variability of the East India Coastal Current (EICC), the western boundary current in the Bay of Bengal, is also detected. Evidence is found for the propagation of Kelvin and Rossby waves across the northern Indian Ocean; these are examined in the context of energy transfer to the western boundary currents, and associated eddies. A simple wind-driven isopycnal model having three active layers is implemented to simulate the seasonal changes of surface and subsurface circulation in the North Indian Ocean and to examine the response to different wind forcing. The wind forcing is derived from the ERS-1 scatterometer wind stress for the same period as the T/P altimeter data, enabling the model response in different (active/weak) monsoon conditions to be tested. The model output is derived in 10-day snapshots to match the time period of the T/P altimeter cycles. Complex Principal Component Analysis (CPCA) is applied to both altimetric and model SSH data. This confirms that long Rossby waves are excited by the remotely forced Kelvin waves off the southwest coast of India and contribute substantially to the variability of the seasonal circulation in the Arabian Sea. 相似文献
9.
The seasonal variability of sea surface height (SSH) and currents are defined by analysis of altimeter data in the NE Pacific Ocean over the region from Central America to the Alaska Gyre. The results help to clarify questions about the timing of seasonal maxima in the boundary currents. As explained below, the long-term temporal mean of the SSH values must be removed at each spatial point to remove the temporally invariant (and large) signal caused by the marine geoid. We refer to the resulting SSH values, which contain all of the temporal variations, as the ‘residual’ SSH. Our main findings are: - 1. The maximum surface velocities around the boundaries of the cyclonic Alaska Gyre (the Alaska Current and the Alaska Stream) occur in winter, at the same time that the equatorward California Current is weakest or reversed (forming the poleward Davidson Current); the maximum surface velocities in the California Current occur in summer. These seasonal maxima are coincident with the large-scale atmospheric wind forcing over each region.
- 2. Most of the seasonal variability occurs as strong residuals in alongshore surface currents around the boundaries of the NE Pacific basin, directly connecting the boundaries of the subpolar gyre, the subtropical gyre and the Equatorial Current System.
- 3. Seasonal variability in the surface velocities of the eastward North Pacific Current (West Wind Drift) is weak in comparison to seasonal changes in the surface currents along the boundaries.
- 4. There is an initial appearance next to the coast and offshore migration of seasonal highs and lows in SSH, alongshore velocity and eddy kinetic energy (EKE) in the Alaska Gyre, similar to the previously-described seasonal offshore migration in the California Current.
- 5. The seasonal development of high SSH and poleward current residuals next to the coast appear first off Central America and mainland Mexico in May–June, prior to their appearance in the southern part of the California Current in July–August and their eventual spread around the entire basin in November–December. Similarly, low SSH and equatorward transport residuals appear first off Central America and Mexico in January–February before spreading farther north in spring and summer.
- 6. The maximum values of EKE occur when each of the boundary currents are maximum.
Article Outline- 1. Introduction and background
- 2. Data and methods
- 2.1. Altimeter and tide gauge data
- 2.2. Atmospheric forcing—sea level pressure
- 2.3. Statistical gridding
- 3. Results
- 4. Summary and discussion
- 4.1. Alaska Gyre
- 4.2. Connections around the boundaries of the subarctic and subtropical gyres
- 4.3. Connections to the North Pacific Current
- 4.4. Offshore ‘propagation’ of the seasonal height and transport signals
- 4.5. Connections to the equatorial current systems along the boundaries
- Acknowledgements
- References
1. Introduction and backgroundThis is the first of a two-part analysis of temporal variability of the NE Pacific Ocean’s surface circulation, as measured by satellite altimeters. Here we examine the seasonal variability. In Part 2 (Strub & James, 2002) we analyze the non-seasonal anomalies of the surface circulation over the 1993–1998 period, during which the 1997–1998 El Niño creates the largest signal. Formation of the seasonal cycles discussed here is the first step in creating the non-seasonal anomalies. The seasonal cycles themselves, however, provide new information on the response of the NE Pacific to strong seasonal forcing, on scales not previously addressed. This analysis quantifies the degree of connection, on seasonal time scales, between the boundary currents in the eastern subarctic and subtropical gyres, as well as the connection between the boundaries and the interior NE Pacific. It further shows a connection to the equatorial current system.Numerous papers describe aspects of the seasonal cycles for certain parameters in subregions of our larger domain. Chapters in Robinson and Brink (1998) review some of the past results from the coastal ocean in the regions between the Equator and the Alaska Gyre ( Badan; Hickey and Royer). Fig. 1 presents the climatological surface dynamic height field (relative to 500 m) in the NE Pacific, calculated from the long-term mean climatological temperature and salinity data of Levitus and Gelfeld (1992). The 500 m reference level is used to concentrate on the surface flow seen by altimeters. Although this climatology is overly smooth, it shows the major currents in the area. The broad, eastward North Pacific Current (also called the West Wind Drift) splits into the counterclockwise Alaska Gyre and the equatorward California Current. South of 20°N in summer, the California Current turns westward and flows into the North Equatorial Current, while in winter–spring, part of it continues along the Mexican mainland before turning westward ( Badan; Fiedler and Fiedler). The long-term climatology shows both paths. The North Equatorial Countercurrent (NECC) flows eastward between 5° –10°N to approximately 120°W, but is only weakly seen in the annual climatology from there to the cyclonic flow around the Costa Rica Dome near 8°N, 92°W. The NECC is a shallow current (found in the upper 200 m) and might appear more strongly if a shallower reference were used, but it is also seasonally intermittent. When the Intertropical Convergence Zone (ITCZ) is in its northern location near 10°N (summer), surface divergences and upwelling create a zonal trough in surface height, driving the NECC along the southern side of the trough. When the ITCZ moves south in winter, the NECC weakens or reverses. 相似文献
10.
The statistical characteristics and mechanisms of mesoscale eddies in the North Indian Ocean are investigated by adopting multi-sensor satellite data from 1993 to 2019. In the Arabian Sea(AS), seasonal variation of eddy characteristics is remarkable, while the intraseasonal variability caused by planetary waves is crucial in the Bay of Bengal(BOB). Seasonal variation of the eddy kinetic energy(EKE) is distinct along the west boundary of AS,especially in the Somali Current region. In the BOB, lar... 相似文献
11.
A zonal-average model of the upper branch of the meridional overturning circulation of the southern ocean is constructed and used to discuss the processes – wind, buoyancy, eddy forcing and boundary conditions – that control its strength and sense of circulation. The geometry of the thermocline ‘wedge’, set by the mapping between the vertical spacing of buoyancy surfaces (the stratification) on the equatorial flank of the Antarctic Circumpolar Current and their outcrop at the sea surface, is seen to play a central role by setting the interior large-scale potential vorticity distribution. It is shown that the action of eddies mixing this potential vorticity field induces a residual flow in the meridional plane much as is observed, with upwelling of fluid around Antarctica, northward surface flow and subduction to form intermediate water. Along with this overturning circulation there is a concomitant air-sea buoyancy flux directed in to the ocean. 相似文献
12.
南海的环流复杂,但通过近20 a来的研究工作,国内外学者对此已取得了不少的成果.本文就南海环流框架性的问题,综述了有关的文献,认为对南海上层海洋三方面的环流分量的驱动机制已有了初步的认识.这三方面分别是:(1)准季节性风场;(2)黑潮向南海的净输运;(3)黑潮向南海的涡度平流输送.但是对这些驱动的时空变化仍相当不清楚.三者皆增强了南海北部的海盆尺度气旋式环流,其强化的西南向西边界流靠近东沙群岛,建议称为“东沙海流”.没有水文证据显示黑潮水是以分支形式进入南海,其向南海的输运也不可能主要通过中尺度涡过程,具体机制有待研究.每年在南海生成的中尺度涡平均约有10个,风场与沿岸地形所生成的强风应力旋度可能是其主要的驱动机制.作为框架性的认识,也有三方面的工作进行得较少,即:(1)吕宋海峡的上层水交换;(2)南海的中尺度涡生成机制,虽然强风应力旋度及前述的第三种环流驱动机制也有中尺度涡伴生;(3)自吕宋海峡进入的深层水对南海上层海洋环流的影响. 相似文献
13.
利用高度计海面高度异常数据和非线性1½层约化重力模式研究了南海东部中尺度涡的生成机制。模式结果表明,南海内区风场是南海东部中尺度涡生成的主要驱动力,且南海内区高频风场能解释约54%的南海东部中尺度涡。从西太平洋传来的信号同样有十分重要的作用,由西太区域高频风场大致能解释南海东部40%的中尺度涡。风驱动的赤道附近的海面异常信号能经过锡布图通道和民都洛海峡传播到吕宋岛西海岸,其中有部分能量会以罗斯贝波的形式往西传播。这种信号在西传的过程中会发生不稳定,可能形成孤立的涡旋。 相似文献
14.
The formation of the South China Sea (SCS) deep basin warm-core and cool-core eddies was studied numerically using the Princeton
Ocean Model (POM) with 20 km horizontal resolution and 23 sigma levels conforming to a realistic bottom topography. Numerical
integration was divided into pre-experimental and experimental stages. During the pre-experimental stage, we integrated the
POM model for three years from zero velocity and April temperature and salinity climatological fields with climatological
monthly mean wind stresses, restoring type surface salt and heat fluxes, and observational oceanic inflow/outflow at the open
boundaries. During the experimental stage, we integrated the POM model for another 16 months under three different conditions:
one control and two sensitivity runs (no-wind and no lateral transport). We take the fields of the last 12 months for analysis.
The simulation under control run agrees well with earlier observational studies on the South China Sea surface thermal variabilities.
In addition, the sensitivity study further confirms that the wind effect is the key factor for generation of the SCS deep
basin warm/cool eddy and that the lateral boundary forcing is the major factor for the formation of the strong western boundary
currents, especially along the southeast Chinese coast during both summer and winter monsoon seasons. 相似文献
15.
The theoretical problem of formation of boundary currents in an idealized basin subject to seasonally varying buoyancy forcing
is considered in an attempt to apply it to the seasonally varying Tsushima Current. Until now, all the theories intended to
explain the branching of the Tsushima Current have been for the annual mean Tsushima Current—the seasonally varying Tsushima
Current has never been properly explained. A simple numerical experiment shows that eastern and western boundary currents
change in time, concurrently, when local buoyancy forcing is sufficient, as it is in the Tsushima Current. However, this is
not true for ineffective local buoyancy forcing. The importance of the role played by local buoyancy forcing is further supported
by simple theoretical considerations. Overall, this study suggests that effective local buoyancy forcing is probably essential
to the formation of seasonally varying eastern and western boundary currents of the Tsushima Current. 相似文献
16.
Historical hydrographic data, spanning the period 1896–2006, are used to examine the annual mean and seasonal variations in the distribution of freshwater along and across the shelf/slope boundary along the Labrador and Newfoundland Shelves and the Grand Banks of Newfoundland. Particular attention is paid to the export of freshwater along the eastern Grand Banks, between Flemish Cap and the Tail of the Grand Banks, as this has long been identified as a preferential region for the loss of mass and freshwater from the boundary. The data are combined into isopycnally averaged long-term annual and monthly mean gridded property fields and the evolving distribution of fresh arctic-origin water is analyzed in fields of salinity anomaly, expressed as departures from the “central water” temperature–salinity relation of the Gulf Stream. The climatology confirms that cold/fresh northern-source waters are advected offshore within the retroflecting Labrador Current along the full length of the boundary between Flemish Cap and the Tail of the Grand Banks. In fact, it is estimated that most of the equatorward baroclinic transport at the boundary must retroflect back toward the north in order to explain the annual mean distribution of salinity in the climatology. While the retroflection of the Labrador Current appears seasonally robust, the freshwater distribution within the retroflection region varies in response to (1) the freshness of the water available for export which is set by the arrival and rapid flushing of the seasonal freshwater pulse at the boundary, (2) seasonal buoyancy forcing at the surface which alters the vertical stratification across the retroflection region, restricting certain isopycnal export pathways, and (3) the density structure along the eastern Grand Banks, which defines the progressive retroflection of the Labrador Current. 相似文献
17.
Horizontal water velocities were measured using three current meters moored at the levels of 5, 18, and 30 m depth in the oriental side of Concepción Bay (36°40′S; 73°02′W), an almost rectangular, shallow bay off central Chile, connected with the open sea through two mouths.The large momentum transfer from the wind to the water causes variations of the internal volume of the bay generating circulation layers having almost anti-parallel directions. Northerly winds carry superficial water into the bay, causing a compensating flow leaving the bay near its bottom. Winds from the SW, on the other hand, cause an outgoing circulation layer in the surface and a circulation layer entering into the bay near the bottom. During wind calm periods, longer than 12 h, the two layers disappear, leaving a current system comprising only one circulation layer. The response time necessary for the generation or dissipation of these layers, which fluctuates between 1 and 7 h, depends on the initial conditions of the bay and on the intensity, direction and persistence of the wind. 相似文献
18.
Seasonal variation in the tropical Pacific is studied by use of climatological monthly mean data of upper layer thickness of a linear reduced-gravity model with realistic basin geometry. Complex empirical orthogonal function (CEOF) analysis is applied to the data on a closed circuit which consists of the equator, eastern boundary, 7° latitude, and western boundary. The first and second CEOF represent the annual and semiannual variations, respectively. At the equator, absolute maximum anomalies associated with the first CEOF can be found near 160°W in spring and fall. Westward propagation of the annual variation is remarkable west of 130°W. However, similar westward propagation cannot be detected in either the eastern or western part of the equator. Maximum anomalies at 7° and the equator can be found in similar longitude and time. These maxima at both latitudes originate from the annual variation of Ekman pumping associated with the meridional movement of wind fields. We also decomposed the model results into Kelvin and Rossby modes. The Kelvin mode is characterized by seminnual variation, while first and third-mode Rossby waves have annual variations. In the present results, first and third-mode Rossby waves do not appear to be a trigger for Kelvin waves. 相似文献
19.
渤海的风和温度层结有明显的季节变化 ,因而其环流与输运亦有明显的季节信号。以季节平均的海面气象条件和开边界的潮波系统驱动三维斜压水动力模型———HAMSOM ,模拟了渤海冬、夏季的总环流。渤海环流冬强夏弱 ,表层风漂流常被下层逆风流所补偿。深度平均环流 ,即水柱内的输运 ,流型有显著的季节变化 :冬季在渤海中部沿逆时针方向旋转 ,辽东湾顶有一个顺时针流涡 ,阻碍了湾顶水与外海水的交换 ;夏季则为一个大的贴岸的顺时针流环 ,内嵌许多局地涡旋。这些与渤黄东海海洋水文图集中给出的多年观测的环流基本相同 ,同时也被水文要素分布及耐盐浮游动物的出现所佐证。风的季节变化决定了渤海大部分海区、特别是海峡附近环流的季节变化 ,但辽东湾东岸众多的岬角涡旋却不随季节变化 ,因为它们是由潮波系统与岬角岸型变化的非线性相互作用产生的。 相似文献
20.
为了研究黑潮跨过200m等深线对东海入侵的年际变化特征,本文基于ROMS(Regional Ocean Modeling System)海洋模式,对西北太平洋海域进行了高分辨率的数值模拟,模式水平分辨率高达4km,该分辨率可以很好地分辨黑潮以东区域的中尺度涡旋等过程。模式首先进行了6年的气候态模拟,然后进行了1993到2015年的后报模拟。模式很好地再现了东海陆架已知的环流结构,模拟出的对马海峡和台湾海峡的年平均流量和观测结果也比较一致。基于模式结果,利用旋转经验正交函数(REOF)的方法,对黑潮跨过200m等深线流量的年际变化进行分析。REOF的主要模态表明,黑潮跨过200m等深线对东海陆架的入侵主要发生台湾东北,并且入侵主要集中在黑潮次表层水中。主要模态的时间系数表明,黑潮入侵东海陆架的年平均流量存在一个8年的变化周期。相关性分析表明,黑潮入侵东海陆架的年际变化和太平洋年代际振荡PDO(Pacific Decadal Oscillation)指标具有显著的负相关,其相关系数达–0.63。该相关可以通过如下过程解释:PDO会导致东太平洋风应力涡度异常,由Sverdrup关系可知向赤道的体积输运也会相应地产生异常,根据质量守恒,向赤道体积输运的异常必然通过西边界流-黑潮的异常来平衡,从而导致黑潮入侵东海陆架强烈的年际变化。 相似文献
|
