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1.
《中国海洋湖沼学报》2016,(6)
A set of absolute geostrophic current(AGC) data for the period January 2004 to December 2012 are calculated using the P-vector method based on monthly gridded Argo profi les in the world tropical oceans. The AGCs agree well with altimeter geostrophic currents, Ocean Surface Current Analysis-Real time currents, and moored current-meter measurements at 10-m depth, based on which the classical Sverdrup circulation theory is evaluated. Calculations have shown that errors of wind stress calculation, AGC transport, and depth ranges of vertical integration cannot explain non-Sverdrup transport, which is mainly in the subtropical western ocean basins and equatorial currents near the Equator in each ocean basin(except the North Indian Ocean, where the circulation is dominated by monsoons). The identifi ed nonSverdrup transport is thereby robust and attributed to the joint effect of baroclinicity and relief of the bottom(JEBAR) and mesoscale eddy nonlinearity. 相似文献
2.
Absolute geostrophic currents in the North Pacific Ocean are calculated using the P-vector method and gridded Argo profiling data from January 2004 to December 2012. Three-dimensional structures and seasonal variability of meridional heat transport (MHT) and meridional salt transport (MST) are analyzed. The results show that geostrophic and Ekman components are generally opposite in sign, with the southward geostrophic component dominating in the subtropics and the northward Ekman component dominating in the tropics. In combination with the net surface heat flux and the MST through the Bering Strait, the MHT and MST of the western boundary currents (WBCs) are estimated for the first time. The results suggest that the WBCs are of great importance in maintaining the heat and salt balance of the North Pacific. The total interior MHT and MST in the tropics show nearly the same seasonal variability as that of the Ekman components, consistent with the variability of zonal wind stress. The geostrophic MHT in the tropics is mainly concentrated in the upper layers, while MST with large amplitude and annual variation can extend much deeper. This suggests that shallow processes dominate MHT in the North Pacific, while MST can be affected by deep ocean circulation. In the extratropical ocean, both MHT and MST are weak. However, there is relatively large and irregular seasonal variability of geostrophic MST, suggesting the importance of the geostrophic circulation in the MST of that area. 相似文献
3.
Interannual variability of transport and bifurcation of the North Equatorial Current in the tropical North Pacific Ocean 总被引：1，自引：0，他引：1
The relationship of the interannual variability of the transport and bifurcation latitude of the North Equatorial Current (NEC) to the El Ni o-Southern Oscillation (ENSO) is investigated. This is done through composite analysis of sea surface height (SSH) observed by satellite altimeter during October 1992-July 2009, and correspondingly derived sea surface geostrophic currents. During El Nio/La Ni a years, the SSH in the tropical North Pacific Ocean falls/rises, with maximum changes in the region 0-15°N, 130°E-160°E. The decrease/increase in SSH induces a cyclonic/anticyclonic anomaly in the western tropical gyre. The cyclonic/anticyclonic anomaly in the gyre results in an increase/decrease of NEC transport, and a northward/southward shift of the NEC bifurcation latitude near the Philippine coast. The variations are mainly in response to anomalous wind forcing in the west-central tropical North Pacific Ocean, related to ENSO events. 相似文献
4.
The North Equatorial Countercurrent(NECC) is an important zonal fl ow in the upper circulation of the tropical Pacifi c Ocean, which plays a vital role in the heat budget of the western Pacifi c warm pool. Using satellite-derived data of ocean surface currents and sea surface heights(SSHs) from 1992 to 2011, the seasonal variation of the surface NECC in the western tropical Pacifi c Ocean was investigated. It was found that the intensity(INT) and axis position(Y_(CM)) of the surface NECC exhibit strikingly different seasonal fl uctuations in the upstream(128°–136°E) and downstream(145°–160°E) regions. Of the two regions, the seasonal cycle of the upstream NECC shows the greater interannual variability. Its INT and Y CM are greatly infl uenced by variations of the Mindanao Eddy, Mindanao Dome(MD), and equatorial Rossby waves to its south. Both INT and YC M also show semiannual signals induced by the combined effects of equatorial Rossby waves from the Central Pacifi c and local wind forcing in the western Pacifi c Ocean. In the downstream region, the variability of the NECC is affected by SSH anomalies in the MD and the central equatorial Pacifi c Ocean. Those in the MD region are especially important in modulating the Y CM of the downstream NECC. In addition to the SSH-related geostrophic fl ow, zonal Ekman fl ow driven by meridional wind stress also plays a role, having considerable impact on INT variability of the surface NECC. The contrasting features of the variability of the NECC in the upstream and downstream regions refl ect the high complexity of regional ocean dynamics. 相似文献
5.
The formulation and justification of a three-layer baroclinic ocean model developed to simulate thegeneral circulation of the ocean are described in this paper.Test of the model in simulating the annualmean circulation patterns in the North Pacific under the prescribed atmospheric forcing,which consists ofthe climatological surface wind stress and sea surface heat flux,and comparison of the results withobservations showed that the model basically simulated the large scale features of the annual meancirculation patterns in the North Pacific Ocean such as those of the intensified western boundary currentsand the North Equatorial Currents and Undercurrents.But due to the coarse resolution of the model,some details of these currents were poorly reproduced.The seasonal variations of the North Pacific Oceancirculation driven by the seasonal mean sea surface wind stress was calculated,the different aspects of theseresults were analyzed and the main current(the intensified western boundary currents)transports we 相似文献
6.
ImODUcrIONTheIndo-PadricregionbeweenMindanao,NewGuinea,andtheIndonesianArchipelagoistheonlydeeppassagefromthePadricOceantotheIndiandrincyig.l),Fig.lMapoftheIndoThdficopon(Internalframeisthemodeldomain)andobendupper1aperimtSthereinsmrandhasareivedconsiderableattentionhauseofitSlocationbetweretheIn.TheIndonesianThappearstobepotentiallyboortantintheevoluhonsofthewesternboundaryatandthewarmpoolinthewesternPadric,andplaysacrudelroleinthehcatandsaltbalanceoftheworkl'soasnoprdon,l986).Nume… 相似文献
7.
《中国海洋大学学报(英文版)》2015,(4)
The seasonal and interannual variability of zonal mean Hadley circulation are analyzed, and the important effects of sea surface temperature(SST), especially the tropical Pacific SST, on the meridional circulation are discussed. Following results are obtained: 1) the Hadley circulation presents a single clockwise(anticlockwise) cross-equator circulation in the Northern(Southern) Hemisphere winter,while it is a double-ring-shaped circulation quasi-symmetric about the equator in spring and autumn. The annual mean state just indicates the residual of the Hadley cell in winter and summer. 2) The first mode of interannual anomalies shows a single cell crossing the equator like the climatology in winter and summer but with narrower width. The second mode shows a double ring-shaped cell quasi-symmetric about the equator which is similar to the Hadley cell in spring or autumn. 3) Vertical motion of the Hadley circulation is driven by sea surface temperature(SST) through latent and sensible heat in the tropics, and the interannual anomalies are mainly driven by the SST anomaly(SSTa) in the tropical Pacific. 4) The meridional gradient of SSTa is well consistent with the lower meridional wind of Hadley circulation in the interannual part. For the spatial distribution, the meridional gradient of SSTa in the Pacific plays a major role for the first two modes while the effects of the Indian Ocean and the Atlantic Ocean can be ignored. 相似文献
8.
ENSO cycle and climate anomaly in China 总被引：2，自引：0，他引：2
The inter-annual variability of the tropical Pacific Subsurface Ocean Temperature Anomaly (SOTA) and the associated anomalous atmospheric circulation over the Asian North Pacific during the El Ni o-Southern Oscillation (ENSO) were investigated using National Centers for Environmental Prediction/ National Center for Atmospheric Research (NCEP/NCAR) atmospheric reanalysis data and simple ocean data simulation (SODA). The relationship between the ENSO and the climate of China was revealed. The main results indicated the following: 1) there are two ENSO modes acting on the subsurface tropical Pacific. The first mode is related to the mature phase of ENSO, which mainly appears during winter. The second mode is associated with a transition stage of the ENSO developing or decaying, which mainly occurs during summer; 2) during the mature phase of El Ni o, the meridionality of the atmosphere in the mid-high latitude increases, the Aleutian low and high pressure ridge over Lake Baikal strengthens, northerly winds prevail in northern China, and precipitation in northern China decreases significantly. The ridge of the Ural High strengthens during the decaying phase of El Ni o, as atmospheric circulation is sustained during winter, and the northerly wind anomaly appears in northern China during summer. Due to the ascending branch of the Walker circulation over the western Pacific, the western Pacific Subtropical High becomes weaker, and south-southeasterly winds prevail over southern China. As a result, less rainfall occurs over northern China and more rainfall over the Changjiang River basin and the southwestern and eastern region of Inner Mongolia. The flood disaster that occurred south of Changjiang River can be attributed to this. The La Ni a event causes an opposite, but weaker effect; 3) the ENSO cycle can influence climate anomalies within China via zonal and meridional heat transport. This is known as the "atmospheric-bridge", where the energy anomaly within the tropical Pacific transfers to the mid-high latitude in the northern Pacific through Hadley cells and Rossby waves, and to the western Pacific-eastern Indian Ocean through Walker circulation. This research also discusses the special air-sea boundary processes during the ENSO events in the tropical Pacific, and indicates that the influence of the subsurface water of the tropical Pacific on the atmospheric circulation may be realized through the sea surface temperature anomalies of the mixed water, which contact the atmosphere and transfer the anomalous heat and moisture to the atmosphere directly. Moreover, the reason for the heavy flood within the Changjiang River during the summer of 1998 is reviewed in this paper. 相似文献
9.
Seasonal variability of the North Equatorial Current transport in the western Pacific Ocean 总被引：2，自引：0，他引：2
Seasonal variability of the North Equatorial Current （NEC） transport in the western Pacific Ocean is investigated with ECMWF Ocean Analysis/Reanalysis System 3 （eRA-S3）. The result shows that NEC transport （NT） across different longitudes in the research area shows a similar double-peak structure, with two maxima （in summer and winter）, and two minima （in spring and autumn）. This kind of structure can also be found in NEC geostrophic transport （NGT）, but in a different magnitude and phase. These differences are attributable to Ekman transport induced by the local meridional wind and transport caused by nonzero velocity at the reference level, which is assumed to be zero in the NGT calculation. In the present work, a linear vorticity equation governing a 1.5-layer reduced gravity model is adopted to examine the dynamics of the seasonal variability of NGT. It is found that the annual cycle of NGT is mainly controlled by Ekman pumping induced by local wind, and westward-propagating Rossby waves induced by remote wind. Further research demonstrates that the maximum in winter and minimum in spring are mostly attributed to wind east of the dateline, whilst the maximum in summer and minimum in autumn are largely attributed to that west of the dateline. 相似文献
10.
热带气旋作为一种海上灾害性天气,对“海上丝绸之路”海上航运影响重大。本文基于西北太平洋和北印度洋1990—2017年的热带气旋路径数据,结合热带气旋风场参数模型,利用缓冲区分析、叠加分析等GIS空间分析技术,系统研究了“海上丝绸之路”主要海域、主要海区、关键通道受热带气旋影响频次以及热带气旋危险性的时空分布特征。主要结论：① “海上丝绸之路”主要海域受热带气旋影响严重,表现在热带气旋影响范围广、影响频次高,其中西北太平洋较北印度洋受热带气旋影响更为严重,危险性更大;② 西北太平洋的15°N—30°N,120°E-—145°E海域热带气旋危险性最高;③ 热带气旋危险性季节变化较为明显,秋夏两季危险性较高,冬春两季危险性较低,在夏秋两季各月份中,7、8、9、10月危险最高;④ 在各海区中,中国东部海区热带气旋危险最高,其次是南海、日本海、孟加拉湾、阿拉伯海,而红海和波斯湾不受热带气旋影响;在各关键通道中,吕宋海峡热带气旋危险性最高,其次是台湾海峡、对马海峡、宗谷海峡、鞑靼海峡、保克海峡、霍尔木兹海峡,而马六甲海峡和曼德海峡无热带气旋危险。 相似文献
11.
This paper attempts to analyze in detail the remote influence of the Indian Ocean Basin warming on the Northwest Pacific (NWP) during the year of decaying El Niño. Observation data and the Fast Ocean-Atmosphere coupled Model 1.5 were used to investigate the triggering conditions under which the remote influence is formed between the positive sea surface temperature (SST) anomaly in the North Indian Ocean and the Anomalous Northwest Pacific anticyclone (ANWPA). Our research show that it is only when there is a contributory background wind field over the Indian Ocean, i.e., when the Indian Summer Monsoon (ISM) reaches its peak, that the warmer SST anomaly in the North Indian Ocean incites significant easterly wind anomalies in the lower atmosphere of the Indo-West tropical Pacific. This then produces the remote influence on the ANWPA. Therefore, the SST anomaly in the North Indian Ocean might interfere with the prediction of the East Asia Summer Monsoon in the year of decaying El Niño. Both the sustaining effect of local negative SST anomalies in the NWP, and the remote effect of positive SST anomalies in the North Indian Ocean on the ANWPA, should be considered in further research. 相似文献
12.
The Sea Level Anomaly-Torque （SLAT, relative to a reference location in the Pacific Ocean）, which means the total torque of the gravity forces of sea waters with depths equal to the Sea Level Anomaly （S/A） in the tropical Pacific Ocean, is defined in this study. The time series of the SLAT from merged altimeter data （1993-2003） had a great meridional variation during the 1997-1998 E1 Nifio event. By using historical upper layer temperature data （1955-2003） for the tropical Pacific Ocean, the temperature-based SLAT is also calculated and the meridional variation can be found in the historical E1 Nifio events （1955-2003）, which suggests that the meridional shifts of the sea level anomaly are also intrinsic oscillating modes of the E1 Nifio cycles like the zonal shifts. 相似文献
13.
Based on the Had ISST1 and NCEP datasets,we investigated the influences of the central Pacific El Ni?o event(CP-EL)and eastern Pacific El Ni?o event(EP-EL)on the Sea Surface Temperature(SST)anomalies of the Tropical Indian Ocean.Considering the remote ef fect of Indian Ocean warming,we also discussed the anticyclone anomalies over the Northwest Pacific,which is very important for the South China precipitation and East Asian climate.Results show that during the El Ni?o developing year of EP-EL,cold SST anomalies appear and intensify in the east of tropical Indian Ocean.At the end of that autumn,all the cold SST anomaly events lead to the Indian Ocean Dipole(IOD)events.Basin uniform warm SST anomalies exist in the Indian Ocean in the whole summer of EL decaying year for both CP-and EP-ELs.However,considering the statistical significance,more significant warm SST anomalies only appear in the North Indian Ocean among the June and August of EP-EL decaying year.For further research,EP-EL accompany with Indian Ocean Basin Warming(EPI-EL)and CP El Ni?o accompany with Indian Ocean Basin Warming(CPI-EL)events are classified.With the remote ef fects of Indian Ocean SST anomalies,the EPI-and CPI-ELs contribute quite differently to the Northwest Pacific.For the EPI-EL developing year,large-scale warm SST anomalies arise in the North Indian Ocean in May,and persist to the autumn of the El Ni?o decaying year.However,for the CPI-EL,weak warm SST anomalies in the North Indian Ocean maintain to the El Ni?o decaying spring.Because of these different SST anomalies in the North Indian Ocean,distinct zonal SST gradient,atmospheric anticyclone and precipitation anomalies emerge over the Northwest Pacific in the El Ni?o decaying years.Specifically,the large-scale North Indian Ocean warm SST anomalies during the EPI-EL decaying years,can persist to summer and force anomalous updrafts and rainfall over the North Indian Ocean.The atmospheric heating caused by this precipitation anomaly emulates atmospheric Kelvin waves accompanied by low level easterly anomalies over the Northwest Pacific.As a result,a zonal SST gradient with a warm anomaly in the west and a cold anomaly in the east of Northwest Pacific is generated locally.Furthermore,the atmospheric anticyclone and precipitation anomalies over the Northwest Pacific are strengthened again in the decaying summer of EPI-EL.Af fected by the local WindEvaporation-SST(WES)positive feedback,the suppressed East Asian summer rainfall then persists to the late autumn during EPI-EL decaying year,which is much longer than that of CPI-EL. 相似文献
14.
El Nio events with an eastern Pacific pattern(EP) and central Pacific pattern(CP) were first separated using rotated empirical orthogonal functions(REOF).Lead/lag regression and rotated singular value decomposition(RSVD) analyses were then carried out to study the relation between the surface zonal wind(SZW) anomalies and sea surface temperature(SST) anomalies in the tropical Pacific.A possible physical process for the CP El Ni o was proposed.For the EP El Ni o,strong westerly anomalies that spread eastward continuously produce an anomalous ocean zonal convergence zone(ZCZ) centered on about 165°W.This SZW anomaly pattern favors poleward and eastward Sverdrup transport at the equator.For the CP El Nio,westerly anomalies and the ZCZ are mainly confined to the western Pacific,and easterly anomalies blow in the eastern Pacific.This SZW anomaly pattern restrains poleward and eastward Sverdrup transport at the equator;however,there is an eastward Sverdrup transport at about 5°N,which favors the warming of the north-eastern tropical Pacific.It is found that the slowness of eastward propagation of subsurface warm water(partly from the downwelling caused by Ekman convergence and the ZCZ) is due to the slowdown of the undercurrent in the central basin,and vertical advection in the central Pacific may be important in the formation and disappearance of the CP El Nio. 相似文献
15.
We analyzed the temporal and spatial variation, and interannual variability of the North Pacific meridional overturning circulation using an empirical orthogonal function method, and calculated mass transport using Simple Ocean Data Assimilation Data from 1958–2008. The meridional streamfunction field in the North Pacific tilts N-S; the Tropical Cell (TC), Subtropical Cell (STC), and Deep Tropical Cell (DTC) may be in phase on an annual time scale; the TC and the STC are out of phase on an interannual time scale, but the interannual variability of the DTC is complex. The TC and STC interannual variability is associated with ENSO (El Niño-Southern Oscillation). The TC northward, southward, upward, and downward transports all weaken in El Niños and strengthen in La Niñas. The STC northward and southward transports are out of phase, while the STC northward and downward transports are in phase. Sea-surface water that reaches the middle latitude and is subducted may not completely return to the tropics. The zonal wind anomalies over the central North Pacific, which control Ekman transport, and the east-west slope of the sea level may be major factors causing the TC northward and southward transport interannual variability and the STC northward and southward transports on the interannual time scale. The DTC northward and southward transports decrease during strong El Niños and increase during strong La Niñas. DTC upward and downward transports are not strongly correlated with the Niño-3 index and may not be completely controlled by ENSO. 相似文献
16.
吴德星 《中国海洋湖沼学报》1997,15(4):314-321
ImODUcnONThedeepequatorialoceanhasobvioussignilicantflowapparentlycarryinghacelsa1ongandacrosstheequator(WissCtal.,l985).RmtfloatmsurementSshoWedthattheflowishigh1yvariable(Richardsonetal.,l993).ThomPsonandKawase(l993)pro-posedthatthelargeinstantaneousandfloatvelocitiesasWellasthevariabilitysuggestthatthetracersignaIsreflCCtreCtificationoftimedependentmotionsandniinginsteadofrneanEulerianflow.TheresultSoftheirstudyonthegenerationofmeancurrentSbyperi-odicfordngintheequatorialoceaninasir… 相似文献
17.
The sensitivity of the global atmospheric and oceanic response to sea surface temperature anomaly (SSTA) throughout the South China Sea (SCS) is investigated using the Fast Ocean-Atmosphere Model (FOAM). Forced by a warming SST, the experiment explicitly demonstrates that the responses of surface air temperature (SAT) and SST exhibit positive anomalous center over SCS and negative anomalous center over the Northern Pacific Ocean (NPO). The atmospheric response to the warm SST anomalies is characterized by a barotropical anomaly in middle-latitude, leading to a weak subtropical high in summer and a weak Aleutian low in winter. Accordingly, Indian monsoon and eastern Asian monsoon strengthen in summer but weaken in winter as a result of wind convergence owing to the warm SST. It is worth noting that the abnormal signals propagate poleward and eastward away in the form of Rossby Waves from the forcing region, which induces high pressure anomaly. Owing to action of the wind-driven circulation, an anomalous anti-cyclonic circulation is induced with a primary southward current in the upper ocean. An obvious cooling appears over the North Pacific, which can be explained by anomalous meridional cold advection and mixing as shown in the analysises of heat budget and other factors that affect SST. 相似文献
18.
The Sea Level Anomaly-Torque (SLAT, relative to a reference location in the Pacific Ocean), which means the total torque of the gravity forces of sea waters with depths equal to the Sea Level Anomaly (SLA) in the tropical Pacific Ocean, is defined in this study. The time series of the SLAT from merged altimeter data (1993-2003) had a great meridional variation during the 1997-1998 El Ni(n)o event. By using historical upper layer temperature data (1955-2003) for the tropical Pacific Ocean, the temperature-based SLAT is also calculated and the meridional variation can be found in the historical El Ni(n)o events (1955-2003), which suggests that the meridional shifts of the sea level anomaly are also intrinsic oscillating modes of the El Ni(n)o cycles like the zonal shifts. 相似文献
19.
Interannual variations of Pacific North Equatorial Current (NEC) transport during eastern-Pacific El Niños (EP-El Niños) and central-Pacific El Niños (CP-El Niños) are investigated by composite analysis with European Centre for Medium-Range Weather Forecast Ocean Analysis/Reanalysis System 3. During EP-El Niño, NEC transport shows significant positive anomalies from the developing to decay phases, with the largest anomalies around the mature phase. During CP-El Niño, however, the NEC transport only shows positive anomalies before the mature phase, with much weaker anomalies than those during EP-El Niño. The NEC transport variations are strongly associated with variations of the tropical gyre and wind forcing in the tropical North Pacific. During EP-El Niño, strong westerly wind anomalies and positive wind stress curl anomalies in the tropical North Pacific induce local upward Ekman pumping and westward-propagating upwelling Rossby waves in the ocean, lowering the sea surface height and generating a cyclonic gyre anomaly in the western tropical Pacific. During CP-El Niño, however, strength of the wind and associated Ekman pumping velocity are very weak. Negative sea surface height and cyclonic flow anomalies are slightly north of those during EP El Niño. 相似文献
20.
基于中国热带气旋年鉴资料,从气候学角度出发,对西北太平洋TC(热带气旋)发生温带变性的频数与大尺度环流系统间的关系进行了诊断和分析.研究发现变性TC多发生于夏、秋两季,通过对NCEP月平均再分析资料的500hPa高度场进行EOF分解,发现西北太平洋TC变性的频数与65°N附近强冷高压系统在夏、秋两季都存在着正相关关系,且相关性在秋季高于夏季;与30°N附近强副热带高压系统存在负相关关系,夏季副热带高压系统的作用更大;与30°N以南西北太平洋多台风活动区域的弱低压存在显著的负相关,低压越弱,对流越弱,则TC的生成数越少,其中发生变性的TC数也会减少.500hPa高度场EOF分解的第一特征向量所对应的时间函数分布在20世纪70年代中期前后出现了反号,较好地对应了变性TC年频数的年际变化趋势,70年代中期之前变性TC呈总体偏多,之后变性TC的频数总体偏少,呈明显下降趋势. 相似文献