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1.
The thermal condition anomaly of the western Pacific warm pool and its zonal displacement have very important influences on climate change in East Asia and even the whole world. However, the impact of the zonal wind anomaly over the Pacific Ocean on zonal displacement of the warm pool has not yet been analyzed based on long-term record. Therefore, it is important to study the zonal displacement of the warm pool and its response to the zonal wind anomaly over the equatorial Pacific Ocean. Based on the NCDC monthly averaged SST (sea surface temperature) data in 2°×2° grid in the Pacific Ocean from 1950 to 2000, and the NCEP/NCAR global monthly averaged 850 hPa zonal wind data from 1949 to 2000, the relationships between zonal displacements of the western Pacific warm pool and zonal wind anomalies over the tropical Pacific Ocean are analyzed in this paper. The results show that the zonal displacements are closely related to the zonal wind anomalies over the western, central and eastern equatorial Pacific Ocean. Composite analysis indicates that during ENSO events, the warm pool displacement was trigged by the zonal wind anomalies over the western equatorial Pacific Ocean in early stage and the process proceeded under the zonal wind anomalies over the central and eastern equatorial Pacific Ocean unless the wind direction changes. Therefore, in addition to the zonal wind anomaly over the western Pacific, the zonal wind anomalies over the central and eastern Pacific Ocean should be considered also in investigation the dynamical mechanisms of the zonal displacement of the warm pool. 相似文献
2.
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
3.
The eastern edge of the western Pacific warm pool (WPWP) in the upper layer (shallower than 50m) exhibits significant zonal
displacements on interannual scale. Employing an intermediate ocean model, the dynamic mechanism for the interannual zonal
displacement of the WPWP eastern edge in the upper layer is investigated by diagnosing the dynamic impacts of zonal current
anomalies induced by wind, waves (Kelvin and Rossby waves), and their boundary reflections. The interannual zonal displacements
of the WPWP eastern edge in the upper layer and the zonal current anomaly in the equatorial Pacific west of 110°W for more
than 30 years can be well simulated. The modeling results show that zonal current anomalies in the central and eastern equatorial
Pacific are the dominant dynamic mechanism for the zonal displacements of the eastern edge of the upper WPWP warm water. Composite
analyses suggest that the zonal current anomalies induced by waves dominate the zonal displacement of the WPWP eastern edge,
whereas the role played by zonal wind-driven current anomalies is very small. A sensitivity test proves that the zonal current
anomalies associated with reflected waves on the western and eastern Pacific boundaries can act as a restoring force that
results in the interannual reciprocating zonal motion of the WPWP eastern edge. 相似文献
4.
In the present paper, correlation between the South China Sea summer monsoon （SCSSM） onset and heat content in the upper layer of the warm pool in the western Pacific Ocean is examined using the Scripps Institution of Oceanography dataset for the period of 1955-1998 and an approach to prediction the SCSSM onset is proposed. Correlation showes that there exists interdecadal variability of the SCSSM onset demarcated by 1970 with the largest correlation coefficient in the area west of the center of the warm pool rather than near its centers, implying certain effect from other factors involved besides ENSO. As the correlation is poor for the period before 1970, the heat content anomaly of the warm pool after 1970 is used to indicate early or late onset of the SCSSM beforehand. An ideal representative area （1°×1°） for the warm pool heat content was determined with its center at 3°N/138°E. The nearest TAO （TAO-Tropical Atmosphere Ocean-array） mooring to the center is at 2°N/137°E, and chosen to calculate the heat content for prediction. It is suggested that the TAO mooring at 2°N/137°E could be used to predict the SCSSM onset with the heat content in the upper layer, if the correlation between the SCSSM onset and the heat content of the warm pool runs like that of after 1970. On the other hand, if the situation does like the one before 1970, the representative station is determined at 13°S/74°E with relatively poor correlation, meaning that the warm pool in the western Pacific Ocean plays more important role in the SCSSM onset than the Indian Ocean. 相似文献
5.
Previous research has defined the index of the Indian-Pacific thermodynamic anomaly joint mode (IPTAJM) and suggested that
the winter IPTAJM has an important impact on summer rainfall over China. However, the possible causes for the interannual
and decadal variability of the IPTAJM are still unclear. Therefore, this work investigates zonal displacements of both the
western Pacific warm pool (WPWP) and the eastern Indian Ocean warm pool (EIOWP). The relationships between the WPWP and the
EIOWP and the IPTAJM are each examined, and then the impacts of the zonal wind anomalies over the equatorial Pacific and Indian
Oceans on the IPTAJM are studied. The WPWP eastern edge anomaly displays significant interannual and decadal variability and
experienced a regime shift in about 1976 and 1998, whereas the EIOWP western edge exhibits only distinct interannual variability.
The decadal variability of the IPTAJM may be mainly caused by both the zonal migration of the WPWP and the 850 hPa zonal wind
anomaly over the central equatorial Pacific. On the other hand, the zonal migrations of both the WPWP and the EIOWP and the
zonal wind anomalies over the central equatorial Pacific and the eastern equatorial Indian Ocean may be all responsible for
the interannual variability of the IPTAJM. 相似文献
6.
Southern ocean SST variability and its relationship with ENSO on inter-decadal time scales 总被引：1，自引：0，他引：1
Empirical orthogonal function (EOF) analysis reveals a co-variability of Sea surface temperatures (SSTs) in the Southern Hemisphere (0°-60°S). In the South Indian and Atlantic Oceans, there is a subtropical dipole pattern slanted in the southwest- north-east direction. In the South Pacific Ocean, a meridional tripole structure emerges, whose middle pole co-varies with the dipoles in the South Indian and Atlantic Oceans and is used in this study to track subtropical Pacific variability. The South Indian and Atlantic Ocean dipoles and the subtropical Pacific variability are phase-locked in austral summer. On the inter-decadal time scales, the dipoles in the South Indian and Atlantic Oceans weaken in amplitude after 1979/1980. No such weakening is found in the subtropical South Pacific Ocean. Interestingly, despite the reduced amplitude, the correlation of the Indian Ocean and Atlantic dipoles with El Nio and Southern Oscillation (ENSO) are enhanced after 1979/1980. The same increase in correlation is found for subtropical South Pacific variability after 1979/1980. These inter-decadal modulations imply that the Southern Hemisphere participates in part of the climate shift in the late 1970s. The correlation between Southern Hemisphere SST and ENSO reduces after 2000. 相似文献
7.
NUMERICAL SIMULATION OF INTERANNUAL AND INTERDECADAL VARIABILITY OF SURFACE WIND OVER THE TROPICAL PACIFIC 总被引：2，自引：0，他引：2
A global atmospheric general circulation model (L9R15 AGCMs) forced by COADS SST was integrated from 1945 to 1993. Interannual and interdecadal variability of the simulated surface wind over the tropical Pacific was analyzed and shown to agree vey well with observation. Simulation of surface wind over the central-western equatorial Pacific was more successful than that over the eastern Pacific. Zonal propagating feature of interannual variability of the tropical Pacific wind anomalies and its decadal difference were also simulated successfully. The close agreement between simulation and observation on the existence of obvious interdecadal variability of tropical Pacific surface wind attested to the high simulation capability of AGCM. 相似文献
8.
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
9.
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
10.
1 IntroductionManymeteorologistsandoceanographerspaidmuchattentiontothestudyofthemechanismofENSOformanyyears,suchasBjerknes(1 966) ,Wyrtki(1 975) ,McCreary(1 983 ) ,Philander(1 984) ,ZhangandChao(1 993 )andMcCPhaden(1 998)havemadegreatdevelopmentinthestudyofENSO .Especiallyinthe 1 990’s,withtheincreasingofthedatainthedeepocean ,thesomeonearguedthattheENSOepisodehadcloserelation shipwiththeeasterntransportationoftheanomalousseasurfacetemperatureinthewestPacific(LiandMu 1 999;Huang 2… 相似文献
11.
Heat center of the western Pacific warm pool 总被引：1，自引：0，他引：1
A heat center (HC) of the western Pacific warm pool (WPWP) is defined, its variability is examined, and a possible mechanism is discussed. Analysis and calculation of a temperature dataset from 1945-2006 show that the mean position of the HC during this period was near 0.4°S/169.0°E, at 38.0 m depth. From a time series of the HC, remarkable seasonal variability was found, mainly in the meridional and vertical directions. Interannual variabilities were dominant in the zonal and vertical directions. In addition, semiannual variation in the HC depth was discovered. The longitude of the HC varies with ENSO events, and its latitude is weakly related to ENSO on time scales shorter than a decade. The variation of the HC longitude leads the Nio-3 index by about 3-4 months, and its depth lags the index for approximately 3 months. It is concluded that the HC depth results from a combination of its longitudinal and latitudinal variations. Low-pass-filtered time series reveal that the HC has moved eastward since the mid 1980s. 相似文献
12.
This study investigated the impact of sea surface temperature(SST)in several important areas of the Indian-Pacific basin on tropical cyclone(TC)activity over the western North Pacific(WNP)during the developing years of three super El Ni?o events(1982,1997,and 2015)based on observations and numerical simulations.During the super El Ni?o years,TC intensity was enhanced considerably,TC days increased,TC tracks mostly recurved along the coasts,and fewer TCs made landfall in China.These characteristics are similar to the strong ENSO-TC relationship but further above the climatological means than in strong El Ni?o years.It indicates that super El Ni?o events play a dominant role in the intensities and tracks of WNP TCs.However,there were clear differences in both numbers and positions of TC genesis among the different super El Ni?o years.These features could be attributed to the collective impact of SST anomalies(SSTAs)in the tropical central-eastern Pacific and East Indian Ocean(EIO)and the SST gradient(SSTG)between the southwestern Pacific and the western Pacific warm pool.During 2015,the EIO SSTA was extremely warm and the anomalous anticyclone in the western WNP was enhanced,resulting in fewer TCs than normal.In 1982,the EIO SSTA and spring SSTG showed negative anomalies,followed by an increased anomalous cyclone in the western WNP and equatorial vertical wind shear.This intensified the conversion of eddy kinetic energy from large-scale flows,favorable for the westward shift of TC genesis.Consequently,anomalous TC activities during the super El Ni?o years resulted mainly from combined SSTA impacts of different key areas over the Indian-Pacific basin. 相似文献
13.
Sea level observed by altimeter during the 1993–2007 period and the thermosteric sea level from 1945 through 2005 obtained by using the global ocean temperature data sets recently published are used to investigate the interannual and decadal variability of the sea level in the Japan/East Sea (JES) and its response to El Niño and Southern Oscillation (ENSO). Both the interannual variations of the sea level observed by altimeter and those of the thermosteric sea level obtained from reanalyzed data in the JES are closely related to ENSO. As a result, one important consequence is that the sea level trends are mainly caused by the thermal expansion in the JES. An ‘enigma’ is revealed that the correlation between the thermosteric sea level and ENSO during the PDO (Pacific Decadal Oscillation) warm phase (post mid-1970s) is inconsistent with that during the cold phase (pre mid-1970s) in the JES. The thermosteric sea level trends and the Southern Oscillation Index (SOI) suggest a strong negative correlation during the period 1977–1998, whereas there appears a relatively weak positive correlation during the period 1945–1976 in the JES. Based on the SODA (Simple Oceanographic Data Assimilation) datasets, possible mechanisms of the interannual and decadal variability of the sea level in the JES are discussed. Comprehensive analysis reveals that the negative anomalies of SOI correspond to the positive anomalies of the southeast wind stress, the net advective heat flux and the sea level in the JES during the PDO warm phase. During the PDO cold phase, the negative anomalies of SOI correspond to the positive anomalies of the southwest wind stress, the negative anomalies of the net advective heat flux and the sea level in the JES. 相似文献
14.
《中国海洋湖沼学报》2020,(4)
The equatorial wave dynamics of interannual sea level variations between 2014/2015 and2015/2016 El Nino events are compared using the Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics Climate Ocean Model(LICOM) forced by the National Centers for Environmental Prediction(NCEP) reanalysis I wind stre s s and heat flux during 2000-2015.In addition,the LICOM can reproduce the interannual variability of sea surface temperature anomalies(SSTA) and sea level anomalies(SLA) along the equator over the Pacific Ocean in comparison with the Hadley center and altimetric data well.We extracted the equatorial wave coefficients of LICOM simulation to get the contribution to SLA by multiplying the meridional wave structure.During 2014/2015 El Nino event,upwelling equatorial Kelvin waves from the western boundary in April2014 reach the eastern Pacific Ocean,which weakened SLA in the eastern Pacific Ocean.However,no upwelling equatorial Kelvin waves from the western boundary of the Pacific Ocean could reach the eastern boundary during the 2015/2016 El Nino event.Linear wave model results also demonstrate that upwelling equatorial Kelvin waves in both 2014/2015 and 2015/2016 from the western boundary can reach the eastern boundary.However,the contribution from stronger westerly anomalies forced downwelling equatorial Kelvin waves overwhelmed that from the upwelling equatorial Kelvin waves from the western boundary in 2015.Therefore,the western boundary reflection and weak westerly wind burst inhibited the growth of the 2014/2015 El Nino event.The disclosed equatorial wave dynamics are important to the simulation and prediction of ENSO events in future studies. 相似文献
15.
Georg Heygster 《中国海洋大学学报(英文版)》2009,8(1):9-14
An algorithm to detect tropical deep convective clouds and deep convective overshootings based on the measurements from the three water vapor channels (183.3GHz±1 GHz, 183.3GHz±3GHz and 183.3GHz±7GHz) of the Advanced Microwave Sounding Unit-B (AMSU-B) is presented. This algorithm is an improved version of the method of Hong et al. (2005). The proposed procedure is based on the statistical analysis of seven years'(2001-2007) measurements from AMSU-B on NOAA-16 From the 1-d histograms of the brightness temperature of the three water vapor channels and the 2-d tustograms of the brightness temperature dif-ference between these channels, new thresholds for brightness temperature differences and the brightness temperature of channel 18 (183.3 GHz±1 GHz) are suggested. The new algorithm is employed to investigate the mean distribution of tropical deep convective clouds and convective overshootings from 30°S to 30°N for the years 2001 to 2007. The major concentration of deep convective clouds and convective overshootings is found over the Intertropical Convergence Zone (ITCZ), the South Pacific Convergence Zone (SPCZ), tropical Africa, South America, the Indian Ocean and Indonesia with an average fraction of 0.4%. In terms of these clouds we identify the secondary Intertropical Convergence Zone located in the eastern South Pacific and parallel to the main ITCZ in the North Pacific. The convective overshooting is more frequently observed over land than over the ocean. 相似文献
16.
热带海洋热状况是影响中国气候变化的主要因子之一,为了研究热带次表层海温如何影响中国气候,通过相关计算和合成分析等方法讨论了热带太平洋至印度洋次表层海温异常对中国东部夏季降水和温度的影响。结果表明:当冬季赤道东印度洋至西太平洋次表层海温偏暖(偏冷),中印度洋和东太平洋次表层海温偏冷(偏暖),夏季,长江中下游地区降水偏少(偏多),华南、华北和东北大部地区降水偏多(偏少);中国东部大范围高温(低温)。其可能的影响途径为,东亚夏季风环流对热带次表层海温异常的响应导致了其年际变化,进而引起中国东部夏季气候的异常分布。 相似文献
17.
????1992??11???2007??5?μ???????????????????????????仯???????????????1???????24~42???μ???????Я???????????ENSO?????2??SLA_2442?????????????????????????????????????????????????????????????????3?????????У????????????SLA_2442?????????·??????O???Σ??????????????,??γ????????λ??????9.86??N??8??S?????? 相似文献
18.
The rate of regional sea level rise(SLR) provides important information about the impact of human activities on climate change.However,accurate estimation of regional SLR can be severely affected by sea surface height(SSH) change caused by the Pacific Decadal Oscillation(PDO-SSH).Here,the PDOSSH signal is extracted from satellite altimeter data by multi-variable linear regression,and regional SLR in the altimeter era is calculated,before and after removing that signal.The results show that PDO-SSH trends are rising in the western Pacific and falling in the eastern Pacific,with the strongest signal confined to the tropical and North Pacific.Over the past 20 years,the PDO-SSH accounts for about 30%-40%of altimeter-observed SLR in the regions 8°-15°N,130°-160°E and 30°-40°N,170°-220°E.Along the coast of North America,the PDO-SSH signal dramatically offsets the coastal SLR,as the sea level trends change sign from falling to rising. 相似文献
19.
This paper focuses on the effects of two types of El Niño events on tropical cyclone activity. We classified El Niño events from 1961 to 2015 according to their sea surface temperature (SST) anomalies into an eastern type and a central type. Then we selected strong tropical cyclones to statistically analyze the tropical cyclone characteristics during different events and their effects, as well as to study the possible mechanisms related to thermodynamic and dynamic factors. The tropical cyclone generation areas were found to be very similar during the two kinds of events. The average number of tropical cyclone in the eastern event is more than that in central event, and the hurricane in northeastern Pacific (HNP) has more energy than the typhoon in northwestern Pacific (TNP) in all cases. The seasonal distribution of the TNP high-incidence centers during central El Niño events is opposite to that of the HNP. The TNP accumulated cyclone energy (ACE) intensity is similar in the fall and summer, and the HNP ACE intensity in the summer is greater than that in the fall. The SSTs are consistent with the TNP and HNP movement trends. The Walker circulation intensity was strongly affected by the eastern events, but it quickly returned to its normal state, while the intensity was slightly reduced in the central events, and it slowly returned to its normal state. The vertical velocity distributions in the Pacific are different at different stages of both events, and the distributions of vertical velocity anomalies for typhoons and hurricanes are consistent. 相似文献
20.
Based on the temperature data along 34°N, 35°N and 36°N sections in August from 1977 to 2003, the structure and formation of the Southern Yellow Sea Cold Water Mass (SYSCWM) and its responses to El Nino events are analyzed. Results show that: (1) There exist double cold cores under the main thermocline along the 35°N and 36°N sections. Also, double warm cores exist above the main thermocline along the 36°N section. (2) Thermocline dome by upwelling separates the upper warm water into two parts, the eastern and western warm waters. Additionally, the circulation structure caused by upwelling along the cold front and northeastward current along the coast in summer is the main reasons of double warm cores along the 36°N section. The intermediate cold water is formed in early spring and moves eastward slowly, which results in the formation of the western one of double cold cores. (3) Position of the thermocline dome and its intensity vary interannually, which is related to El Nino events. However, the 相似文献