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1.
The variation features of the Antarctic sea ice (Ⅱ)   总被引：1，自引：0，他引：1  
ＴｈｅｖａｒｉａｔｉｏｎｆｅａｔｕｒｅｓｏｆｔｈｅＡｎｔａｒｃｔｉｃｓｅａｉｃｅ（Ⅱ）￥ＸｉｅＳｉｍｅｉ；ＨａｏＣｈｕｎｊｉａｎｇ；ＱｉａｎＰｉｎｇａｎｄＺｈａｎｇＬｉｎ（ＲｅｃｅｉｖｅｄＦｅｂｒｕａｒｙ６，１９９３；ａｃｃｅｐｔｅｄＡｕｇｕｓｔ２９...  相似文献   

2.
The relations between the processes occurring in the equatorial latitudes of the Pacific and Atlantic oceans were studied on the basis of the Granger causality analysis and a simulation of phase dynamics using the indices of the El Niño-Southern Oscillation (ENSO) and the equatorial Atlantic mode (EAM). Data on the monthly means of the sea-surface temperature over the period 1870–2006 for the Niño 3 (5° S-5° N, 150° W-90° W) and Niño 3.4 (5° S-5° N, 170° W-120° W) regions in the Pacific and the Atlantic 3 region (20° W-0, 3° S-3° N) in the Atlantic Ocean were used as the ENSO and EAM indices. The statistically significant influence of the EAM on the ENSO is noted. The lag time of this influence is estimated at two months. No significant reverse effect is revealed. An increase in the EAM’s influence on the ENSO was observed in the second half of the 20th century.  相似文献   

3.
厄尔尼诺和台风共同影响下的7月份黄、东海海温变化   总被引：1，自引：0，他引：1  
张守文  王辉  姜华  宋春阳  杜凌 《海洋学报》2017,39(12):32-41
基于历史海温数据和台风路径数据,研究了厄尔尼诺/拉尼娜（El Niño/La Niña）背景下7月份中国近海海温变化特征。结果表明:7月黄、东海海温异常与El Niño/La Niña有显著相关关系,OISST和GODAS海温数据与Niño3指数同步相关系数分别为-0.32和-0.45。El Niño年7月,黄、东海海表温度异常低于-0.5℃的概率超过60%;La Niña年7月,黄海海温异常高于0.5℃的概率约有60%;正常年7月,海温异常的空间分布与El Niño年相反,但量值偏低。El Niño年7月,中国近海及邻近区域大气异常能够给局地带来更多降水;同时,受El Niño背景场的影响,入侵黄、东海的台风强度更强、影响时间更长。大尺度的降水和台风活动的影响是导致黄、东海海温异常降低的重要原因。因此,分析和预测7月份中国近海海温异常,在充分考虑El Niño/La Niña背景场的基础上,需要结合局地的大尺度降水和台风的影响同时分析,这为特定背景下结合不同时间尺度上的因素共同分析中国近海海温变化提供了一种思路。  相似文献   

4.
Thirty La Niña events have been selected from monthly mean sea surface temperature (SST) data of the Hadley Centre Global Sea Ice and Sea Surface Temperature (HadISST) and Centennial Observation-Based Estimates (COBE SST2) datasets from 1870 to 2013 based on a criterion of –0.5°С for a cold anomaly in the Niño 3.4 region (5° N–5° S, 170°–120° W) and its minimum duration of 5 months. The selected events are classified by hierarchical clustering analysis according to two characteristics: geographic coordinates and SST anomalies during the mature phase of La Niña. The objective classification method identifies two types of La Niña differing by the evolution of negative SST anomalies in the equatorial Pacific and by the Southern Oscillation Index.  相似文献   

5.
This study reveals the physical backgrounds of the geometric centroid and the thermal centroid of the Western Pacific Warm Pool (WPWP) and points out their differences. The geometric centroid (actually a very close approximation to the mass centroid) anomaly of the surface WPWP correlates more closely with the Niño-3 region sea surface temperature anomaly (Niño-3 SSTA, an important indicator of El Niño/La Niña events) than the surface thermal centroid. Taking the WPWP depth (or heat storage) into account, the “real” mass or thermal centroid of the WPWP might correlate better with the El Niño/Southern Oscillation (ENSO) signals.  相似文献   

6.
ENSO indices from sea surface salinity observed by Aquarius and Argo   总被引：1，自引：0，他引：1  
Analysis of the first 26 months of data from the Aquarius satellite confirms the existence of a sharp sea surface salinity (SSS) front along the equator in the western equatorial Pacific. Following several earlier studies, we use the longitudinal location of the 34.8-psu isohaline as an index, termed Niño-S34.8, to measure the zonal displacement of the SSS front and consequently the eastern edge of the western Pacific warm pool. The on-going collection of the Array for Real-time Geostrophic Oceanography (ARGO) program data shows high correlations between Niño-S34.8 and the existing indices of El Niño, suggesting its potential important role in ENSO evolution. Further analysis of the ARGO data reveals that SSS variability in the southeastern tropical Pacific is crucial to identify the type of El Niño. A new SSS index, termed the southeastern Pacific SSS index (SEPSI), is defined based on the SSS variability in the region (0°–10°S, 150°–90°W). The SEPSI is highly correlated with the El Niño Modoki index, as well as the Trans-Niño index, introduced by previous studies. It has large positive anomalies during central Pacific El Niño or El Niño Modoki events, as a result of enhanced zonal sea surface temperature gradients between the central and eastern tropical Pacific, and can be used to characterize the type of El Niño. The processes that possibly control these SSS indices are also discussed.  相似文献   

7.
Teleconnection between El Nino/La Nina-Southern Oscillation (ENSO) phenomenon and anomalous Antarctic sea-ice variation has been studied extensively.In this study,impacts of sea surface temperature in the Indian Ocean on Antarctic sea-ice change were investigated during Janaury 1979 and October 2009.Based on previous research results,sea areas in the western Indian Ocean (WIO;50°–70°E,10 °–20 °S) are selected for the resreach.All variables showed 1-10 year interannual timescales by Fast Founer Tranaform (FFT) transformation.Results show that i) strong WIO signals emerged in the anomalous changes of Antarctic sea-ice concentration;ii) significant positive correlations occurred around the Antarctic Peninsula,Ross Sea and its northwest peripheral sea region iii) negative correlation occurred in the Indian Ocean section of the Southern Ocean,Amundsen Seas,and the sea area over northern Ross Sea;and iv) the atmospheric anomalies associated with the WIO including wind,meridional heat flux,and surface air temperature over southern high latitudes were the possible factors for the teleconnection.  相似文献   

8.
The Pacific interior subtropical?tropical cells (STCs) and their relation to the two types of El Niño-Southern Oscillation (ENSO) are investigated by using GODAS reanalysis ocean data for the period of 1980–2017. The results show that the interior STC transport into the equatorial region across 9°S and 9°N has a close relationship with the eastern Pacific (EP) ENSO, while it is much weaker with the central Pacific (CP) ENSO. It is suggested that the effect of interior STCs on the tropical Pacific climate is reflected in its relation with the western Pacific thermocline depth or SSHA. During the EP El Niño, the anomalous interior STCs at 9°S and 9°N converge to the equatorial region from the lag months of ? 25 to ? 8, leading to an accumulation of heat content in the equatorial Pacific; from the lag months of ? 8 to 10, they diverge poleward, inducing a discharge of equatorial heat content. The peak poleward interior STC anomaly first appears at 9°N at a zero-lag time, while that at 9°S is observed 4–5 months later. But there is also no appearance of a time lag between the interior STCs at 9°N and 9°S in recharging the period during the EP La Niña mature phase. However, during CP El Niño, only the conspicuous anomalous interior STC divergence appears during the mature and decay phases for the lag months of ? 2 to 10, with being symmetric at 9°N and 9°S.  相似文献   

9.
Spatial patterns of interannual sea level variations in the South China Sea (SCS) are investigated by analyzing an EOF-based 2-dimensional past sea level reconstruction from 1950 to 2009 and satellite altimetry data from 1993 to 2009. Long-term tide gauge records from 14 selected stations in this region are also used to assess the quality of reconstructed sea levels and determine the rate of sea level along the coastal area. We found that the rising rate of sea levels derived from merged satellite altimetry data during 1993–2009 and past sea level reconstruction over 1950–2009 is about 3.9 ± 0.6 mm/yr and 1.7 ± 0.1 mm/yr, respectively. For the longer period, this rate is not significantly different from the global mean rate (of 1.8 ± 0.3 mm/yr). The interannual mean sea level of the SCS region appears highly correlated with Niño 4 indices (a proxy of El Niño-Southern Oscillation/ENSO), suggesting that the interannual sea level variations over the SCS region is driven by ENSO events. Interpolation of the reconstructed sea level data for 1950–2009 at sites where tide gauge records are of poor quality (either short or gapped) show that sea level along the Chinese coastal area is rising faster than the global mean rate of 1.8 mm/yr. At some sites, the rate is up to 2.5 mm/yr.  相似文献   

10.
热带太平洋第二类El Nio事件及其对中国气候的影响   总被引：1，自引：0，他引：1  
基于热带太平洋次表层海温资料,分析了热带太平洋第二类El Nio事件海温异常的分布特征及其形成机制,讨论了与经典El Nio事件、El Nio Modoki、WP(西太平洋暖池)及CT(冷舌)El Nio事件之间的关系,揭示了第二类El Nio事件对中国降水的影响,得到以下结论。(1)第二类El Nio事件表征为热带太平洋次表层海温异常第三模态,占总方差贡献的4.7%。在海洋表面层,第二类El Nio事件暖期赤道东太平洋为沿赤道西伸的冷舌,热带中西太平洋为环绕冷舌的马蹄型大范围暖区。该型具11a和30~40a年代际振荡及3~4a年际变率,峰值多出现在春季。第二类El Nio事件是热带太平洋异常海面风应力场和赤道两侧的风应力旋度共同作用的结果,在赤道东印度洋-中西太平洋与赤道东太平洋-南美洲上空出现以反号垂直运动为特征的异常Walker环流。(2)El Nio Modoki与第二类El Nio事件有密切关系,它实质上是第二类El Nio事件次表层海温与近海面大气相互作用的结果,捕捉了第二类El Nio事件的主要信息。(3)第二类El Nio事件对中国春季及夏初降水有一定影响。在事件暖期,东海地区存在一个显著的异常反气旋性环流,其南侧的中国南方地区盛行异常东北气流,水汽来源减少,导致该地区少雨,其西侧的异常偏南气流北上直达华北地区,异常多水汽向北输送,并与北方的偏北流场相遇,导致该地区降水偏多。在第二类El Nio事件冷期相反。本文结果还指出,WP与CT El Nio事件是由经典El Nio事件第一模态与El Nio Modoki事件组合而成,它们不是独立的El Nio类型。此外,还讨论了夏半年El Nio事件对大气环流影响的物理过程。  相似文献   

11.
应用海洋表层水温资料（ＣＯＡＤＳ资料）,分析研究了对全球气候有重要影响的热带西太平洋、印度洋海洋表层水温的年变化和年际变化的特性,探讨了与ＥＮＳＯ和南极冰面积变化之间的联系。结果表明,热带西太平洋及印度洋表层水温具有明显的年变化和年际变化而且它们之间存在不同的变化趋势。这种结果是两大洋的水温振荡周期不同有较大关系。热带印度洋表层水温的年际变化与Ｅ１ Ｎｉ￣／ｎｏ和Ｌａ Ｎｉ￣／ｎａ的发生年份存在较  相似文献   

12.
热带太平洋海温异常对北极海冰的可能影响   总被引：1，自引：1，他引：0  
本文利用1950-2015年间Hadley环流中心海冰和海温资料及NCEP/NCAR再分析资料,研究了热带太平洋海温异常对北极海冰的可能影响,并从大气环流和净表面热通量两个角度探讨了可能的物理机制。结果表明,在ENSO事件发展年的夏、秋季节,EP型与CP型El Niño事件与北极海冰异常的联系无明显信号。而La Niña事件期间北极海冰出现显著异常,并且EP型与CP型La Niña之间存在明显差异。EP型La Niña发生时,北极地区巴伦支海、喀拉海关键区海冰异常减少,CP型La Niña事件则对应着东西伯利亚海、楚科奇海地区海冰异常增加。在EP型La Niña发展年的夏、秋季节,热带太平洋海温异常通过遥相关波列,使得巴伦支海、喀拉海海平面气压为负异常并与中纬度气压正异常共同构成类似AO正位相的结构,形成的风场异常有利于北大西洋暖水的输入,同时造成暖平流,偏高的水汽含量进一步加强了净表面热通量收入,使得巴伦支海、喀拉海海冰异常减少。而在CP型La Niña发展年的夏季,东西伯利亚海、楚科奇海关键区受其东侧气旋式环流的影响,以异常北风分量占主导,将海冰从极点附近由北向南输送到关键区,海冰异常增加,而净表面热通量的作用较小。  相似文献   

13.
ENSO-induced interannual variability in the southeastern South China Sea   总被引：5，自引：0，他引：5  
In this study, El Niño Southern Oscillation (ENSO)-induced interannual variability in the South China Sea (SCS) is documented using outputs from an eddy-resolving data-assimilating model. It is suggested that during an El Niño (La Niña) event, off-equatorial upwelling (downwelling) Rossby waves induced by Pacific equatorial wind anomalies impinge on the Philippine Islands and excite upwelling (downwelling) coastal Kelvin waves that propagate northward along the west coast of the Philippines after entering the SCS through the Mindoro Strait. The coastal Kelvin waves may then induce negative (positive) sea level anomalies in the southeastern SCS and larger (smaller) volume transport through the Mindoro and Luzon Straits during an El Niño (La Niña) event.  相似文献   

14.
《Oceanologica Acta》1999,22(3):249-263
Mean conditions, seasonal, and ENSO-related (El Niño Southern Oscillation) variability in the vicinity of Wallis, Futuna, and Samoa islands (13°–15° S, 180°–170° W) over the 1973–1995 period are analysed for wind pseudo-stress, satellite-derived and in situ precipitation, sea surface temperature (SST) and salinity (SSS), sea level, and 0–450 m temperature and geostrophic current. The mean local conditions reflect the presence of the large scale features such as the western Pacific warm pool, the South Pacific Convergence Zone (SPCZ), and the South Pacific anticyclonic gyre. The seasonal changes are closely related to the meridional migrations of the SPCZ, which passes twice a year over the region of study. During the warm phase of ENSO (El Niño), we generally observe saltier-than-average SSS (of the order of 0.4), consistent with a rainfall deficit (0.4 m yr−1), a hint of colder-than-average surface temperature is also identified in subsurface (0.3°C), a weak tendency for westward geostrophic current anomalies (2 cm s−1 at the surface), a sea level decrease (5–10 cm), together with easterly (5 m2s−2) and well marked southerly (10 m2s−2) wind pseudo-stress anomalies. Anomalies of similar magnitude, but of opposite sign, are detected during the cold phase of ENSO (La Niña). While these ENSO-related changes apply prior to the 1990s, they were not observed during the 1991–1994 period, which appears atypical.  相似文献   

15.
Based on the analysis of wind,ocean currents,sea surface temperature(SST) and remote sensing satellite altimeter data,the characteristics and possible causes of sea level anomalies in the Xisha sea area are investigated.The main results are shown as follows:(1) Since 1993,the sea level in the Xisha sea area was obviously higher than normal in 1998,2001,2008,2010 and 2013.Especially,the sea level in 1998 and 2010 was abnormally high,and the sea level in 2010 was 13.2 cm higher than the muti-year mean,which was the highest in the history.In 2010,the sea level in the Xisha sea area had risen 43 cm from June to August,with the strength twice the annual variation range.(2) The sea level in the Xisha sea area was not only affected by the tidal force of the celestial bodies,but also closely related to the quasi 2 a periodic oscillation of tropical western Pacific monsoon and ENSO events.(3)There was a significant negative correlation between sea level in the Xisha sea area and ENSO events.The high sea level anomaly all happened during the developing phase of La Ni?a.They also show significant negative correlations with Ni?o 4 and Ni?o 3.4 indices,and the lag correlation coefficients for 2 months and 3 months are–0.46 and –0.45,respectively.(4) During the early La Ni?a event form June to November in 2010,the anomalous wind field was cyclonic.A strong clockwise vortex was formed for the current in 25 m layer in the Xisha sea area,and the velocity of the current is close to the speed of the Kuroshio near the Luzon Strait.In normal years,there is a "cool eddy".While in 2010,from July to August,the SST in the area was 2–3°C higher than that of the same period in the history.  相似文献   

16.
利用中国气象局743站日降水、NCEP-/NCAR大气环流、英国气象局Hadley中心全球月平均海表温度（SST）等资料,探讨了两类El Niño不同衰减型的演变特征及其对衰减阶段夏季（6-8月）我国降水异常分布的可能影响。根据海表温度异常（SSTA）沿赤道（5°S~5°N）的演变特征,EP-El Niño存在两种衰减型:自东向西（E-W）衰减（大于0.5℃的海温正距平首先在南美沿岸消失,并向西扩展）和自西向东（W-E）衰减（大于0.5℃的海温正距平首先在赤道中太平洋消失,并向东扩展）;CP-El Niño存在3种衰减方式:对称（S）衰减（赤道中太平洋暖海温的发展和衰减关于某一峰值对称）、延迟（P）衰减（衰减阶段紧接着呈现EP-El Niño分布）、突然（A）衰减（衰减阶段紧接着发生EP-La Niña事件）。对于EP-El Niño,在华北、华南、长江和黄河（简称两河）之间及两河的上游地区,E-W与W-E衰减阶段夏季降水呈现完全相反的异常分布特征。E-W衰减阶段夏季两河之间及上游地区偏旱的可能性显著增大,华北地区降水异常偏多,长江以南略偏多;而W-E衰减阶段夏季,两河之间及上游地区降水偏多,降水异常大值中心主要位于沿江地区,华南大部和华北地区降水明显偏少。对于CP-El Niño的3种衰减方式:夏季降水异常大值带在S衰减方式下主要位于黄河和淮河之间;在P方式衰减时,出现在长江流域;而在A型衰减时,主要位于黄河下游地区。S和A衰减方式下,东北大部尤其东北北部降水偏少,而处于P衰减时,东北大部降水明显偏多;在西南地区,S衰减时夏季降水总体偏多,A衰减时情况相反;在西北北部地区,A衰减时偏旱,而S和P衰减时降水总体偏多。不同的衰减方式均对应不同的降水异常空间分布,区分衰减型使得两类El Niño次年我国夏季降水异常显著区的分布范围和信号强度均较未区分衰减型时有较好的改善,为我国汛期降水短期气候预测工作提供了重要依据。  相似文献   

17.
The 4.2 ka event that occurred during the period from 4 500–3 900 a BP was characterized by cold and dry climates and resulted in the collapse of civilizations around the world. The cause of this climatic event, however, has been under debate. We collected four corals(Porites lutea) from Yongxing Island, Xisha Islands, South China Sea, dated them with the U-series method, and measured the annual coral growth rates using X-ray technology. The dating results showed that the coral growth ages were from 4 500–3 900 a BP, which coincide well with the period of the4.2 ka event. We then reconstructed annual sea surface temperature anomaly(SSTA) variations based on the coral growth rates. The growth rate-based SSTA results showed that the interdecadal SSTA from 4 500–3 900 a BP was lower than that during modern times(1961–2008 AD). A spectral analysis showed that the SSTA variations from4 500–3 900 a BP were under the influence of El Ni?o-Southern Oscillation(ENSO) activities. From 4 500–4 100 a BP, the climate exhibited La Ni?a-like conditions with weak ENSO intensity and relatively stable and lower SSTA amplitudes. From 4 100–3 900 a BP, the climate underwent a complicated period of ENSO variability and showed alternating El Ni?o-or La Ni?a-like conditions at interdecadal time scales and large SSTA amplitudes. We speculate that during the early and middle stages of the 4.2 ka event, the cold climate caused by weak ENSO activities largely weakened social productivity. Then, during the end stages of the 4.2 ka event, the repeated fluctuations in the ENSO intensity caused frequent extreme weather events, resulting in the collapse of civilizations worldwide. Thus, the new evidence obtained from our coral records suggests that the 4.2 ka event as well as the related collapse of civilizations were very likely driven by ENSO variability.  相似文献   

18.
南极海冰和陆架冰的变化特征   总被引：8，自引：1，他引：8       下载免费PDF全文
利用美国冰中心和雪冰中心提供的海冰资料和我国南极考察现场的海冰观测资料,对南极海冰的长期变化进行了研究.研究表明20世纪70年代后期是多冰期;80年代是少冰期;90年代南极海冰属于上升趋势,后期偏多,区域性变化差别大,东南极海冰偏多,西南极海冰即南极半岛两侧尤其是威德尔海区和别林斯高晋海的冰明显偏少.东南极和西南极海冰的变化趋势总是反相的.90年代后期普里兹湾的海冰明显偏多,南极大陆陆架冰外缘线总体没有明显的收缩,有崩解也有再生的自然变化现象.西南极威德尔海的龙尼冰架和罗斯海冰架东部崩解和收缩趋势明显,东南极的冰架也有崩解和收缩,但没有西南极明显.陆架冰崩解向海洋输送的冰山对全球海平面升高有一定的影响.目前南极冰盖断裂崩解形成的冰山,向海洋输入的水量可使全球海平面上升约14mm.南极海冰没有随着全球气候温暖化而明显减少,而是按照东南极和西南极反相的变化规律进行周期性的变化、调整和制约.  相似文献   

19.
The El Niño–Southern Oscillation (ENSO) phase state is reported to drive interannual variability in sea temperatures along South Africa’s south coast through its influence on wind-induced upwelling processes. Whether ENSO drives the intensity of localised, abrupt, intermittent upwelling is less well known. To explore this relationship, we used an index of localised, extreme (>2 °C anomaly), intermittent upwelling intensity, derived from in situ sea temperature data within the Tsitsikamma National Park Marine Protected Area, and quantified the relationship between annual cumulative upwelling intensities (1991–2013) with an annual ENSO index, namely the Southern Oscillation Index. We found that ENSO phase state modulates the cumulative intensity of extreme intermittent upwelling events during an annual period, with more and greater events during La Niña phases compared with El Niño phases. Furthermore, these extreme upwelling events have increased with time along South Africa’s south coast as ENSO phase state becomes more intense and variable. Our findings support the emerging notion that the biological effects of climate change may be manifested through increased environmental variability rather than long-term mean environmental changes as ENSO is predicted to remain the dominant driver of local climate patterns in the future.  相似文献   

20.
Changes and fluctuations in sea surface temperature (SST) around the South African coast are analysed at a monthly scale from 1982 to 2009. There is a statistically significant negative trend of up to 0.5 °C per decade in the southern Benguela from January to August, and a cooling trend of lesser magnitude along the South Coast and in the Port Elizabeth/Port Alfred region from May to August. The cooling is due to an increase in upwelling-favourable south-easterly and easterly winds. There is a positive trend in SST of up to 0.55 °C per decade in most parts of the Agulhas Current system during all months of the year, except for KwaZulu-Natal where warming is in summer. The warming was attributed to an intensification of the Agulhas Current in response to a poleward shift of westerly winds and an increase in trade winds in the South Indian Ocean at relevant latitudes. This intensification of the Agulhas Current could also have contributed to the coastal cooling in the Port Alfred dynamic upwelling region. The El Niño Southern Oscillation (ENSO) is significantly positively correlated at a 95% level with the southern Benguela and South Coast from February to May, and negatively correlated with the Agulhas Current system south of 36° S. The correlation with the Antarctic Annular Oscillation is weaker and less coherent. El Niño suppresses upwelling along the coast, whereas La Niña increases it. Although there does not seem to be a linear relationship between the strength of the ENSO and the magnitude of coastal SST perturbation, El Niño and La Niña appear to be linked to major warm and cool events, respectively, at a seasonal scale in summer in the southern Benguela and along the South Coast. However, care must be taken in interpreting low-resolution reanalysed climate data (ERA40 and NCEP) and optimally interpolated Reynolds SST, such as used here.  相似文献   

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