Integration of Tibetan Plateau ice-core temperature records and the influence of atmospheric circulation on isotopic signals in the past century

Temperature signals in ice-core δ¹⁸O on the Tibetan Plateau (TP), particularly in the central and southern parts, continue to be debated because of the large scale of atmospheric circulation. This study presents ten ice-core δ¹⁸O records at an annual resolution, with four (Malan, Muztagata, Guliya, and Dunde) in the northern, three (Puruogangri, Geladaindong, Tanggula) in the central and three (Noijin Kangsang, Dasuopu, East Rongbuk) in the southern TP. Integration shows commonly increasing trends in δ¹⁸O in the past century, featuring the largest one in the northern, a moderate one in the central and the smallest one in the southern TP, which are all consistent with ground-based measurements of temperature. The influence of atmospheric circulation on isotopic signals in the past century was discussed through the analysis of El Niño/Southern Oscillation (ENSO), and of possible connections between sea surface temperature (SST) and the different increasing trends in both ice-core δ¹⁸O and temperature. Particularly, El Niño and the corresponding warm Bay of Bengal (BOB) SST enhance the TP ice-core isotopic enrichment, while La Niña, or corresponding cold BOB SST, causes depletion. This thus suggests a potential for reconstructing the ENSO history from the TP ice-core δ¹⁸O.     

Study of the global and regional climatic impacts of ENSO magnitude using SPEEDY AGCM

ENSO is considered as a strong atmospheric teleconnection that has pronounced global and regional circulation effects. It modifies global monsoon system, especially, Asian and African monsoons. Previous studies suggest that both the frequency and magnitude of ENSO events have increased over the last few decades resulting in a need to study climatic impacts of ENSO magnitude both at global and regional scales. Hence, to better understand the impact of ENSO amplitude over the tropical and extratropical regions focussing on the Asian and African domains, ENSO sensitivity experiments are conducted using ICTPAGCM (‘SPEEDY’). It is anticipated that the tropical Pacific SST forcing will be enough to produce ENSO-induced teleconnection patterns; therefore, the model is forced using NINO3.4 regressed SST anomalies over the tropical Pacific only. SPEEDY reproduces the impact of ENSO over the Pacific, North and South America and African regions very well. However, it underestimates ENSO teleconnection patterns and associated changes over South Asia, particularly in the Indian region, which suggests that the tropical Pacific SST forcing is not sufficient to represent ENSO-induced teleconnection patterns over South Asia. Therefore, SST forcing over the tropical Indian Ocean together with air–sea coupling is also required for better representation of ENSO-induced changes in these regions. Moreover, results obtained by this pacemaker experiment show that ENSO impacts are relatively stronger over the Inter-Tropical Convergence Zone (ITCZ) compared to extratropics and high latitude regions. The positive phase of ENSO causes weakening in rainfall activity over African tropical rain belt, parts of South and Southeast Asia, whereas, the La Niña phase produces more rain over these regions during the summer season. Model results further reveal that ENSO magnitude has a stronger impact over African Sahel and South Asia, especially over the Indian region because of its significant impact over the tropical Atlantic and the Indian Ocean through Walker circulation. ENSO-induced negative (positive) NAO-like response and associated changes over Southern Europe and North Africa get significantly strong following increased intensity of El Niño (La Niña) in the northern (southern) hemisphere in the boreal winter (summer) season. We further find that ENSO magnitude significantly impacts Hadley and Walker circulations. The positive phase of ENSO (El Niño) overall strengthens Hadley cell and a reverse is true for the La Niña phase. ENSO-induced strengthening and weakening of Hadley cell induces significant impact over South Asian and African ITCZ convective regions through modification of ITCZ/monsoon circulation system.     

古里雅冰芯气候记录对ENSO事件的响应

ENSO现象是一个产生于大尺度海-气相互作用的全球事件, 它是影响全球中低纬度大部分地区气候年际变化的一个重要的因子. 通过高通滤波法、累积异常法以及非参数检验等方法, 对古里雅冰芯中所记录的气候信息与ENSO事件进行相关分析表明, 在厄尔尼诺年, 古里雅冰芯中记录的降水量显著减少, 但对于δ¹⁸O而言, 虽然也在厄尔尼诺年偏低, 但未达到显著性水平.     

基于石笋记录的晚全新世太平洋东西两岸季风区气候事件对比研究

研究晚全新世季风气候演变有助于进一步认识与预测未来季风区气候变化。太平洋东西两岸是全球季风集中分布的地区,已经有大量的古气候记录发表,但是缺乏对各个季风区气候突变事件以及整体变化趋势的对比研究。针对这一问题,选取亚洲季风区、印澳季风区、北美季风区、南美季风区11个洞穴石笋δ18O和1个湖泊Ti含量,对比研究各个记录在3.5~0.5 ka B.P.期间指示的夏季风变化特征。通过对比发现四大季风区的石笋δ18O在晚全新世整体上呈现偏正趋势,指示夏季风减弱;2次重要的气候突变事件1.5 ka B.P.和2.7 ka B.P.弱夏季风事件在各个季风区内均有表现;同时也记录了一系列十年际-百年际尺度的弱夏季风事件,表明太平洋东西两岸和南北半球的夏季风都有减弱的趋势,这与先前研究认为的南北半球呈现"see-saw"模式表现出不一样的特征。晚全新世以来ENSO(El Nino-Southern Oscillation)活动的增强对太平洋东西两岸南北半球夏季风减弱具有重要影响。在El Nino事件发生时,Walker环流减弱,而且它的上升支向东移动远离西太平洋暖池,西太平洋副热带高压增强并向西移动,导致亚洲夏季风减弱。Walker环流的东移也会使得印度尼西亚-太平洋暖池(Indo-Pacific Warm Pool,简称IPWP)海温下降,热带季节内震荡减弱致使印澳夏季风减弱;此外,El Nino事件发生时,赤道东太平洋海水温度上升导致东西太平洋海水温度梯度减弱,在此状态下南美季风区低空急流(Low Level Jet,简称LLJ)减弱,导致南美夏季风减弱;同时,北美洲加勒比海低空急流增强,使得该季风区下沉气流增强,导致北美夏季风减弱。我们的研究表明,在晚全新世ENSO活动增强的状态下,太平洋东西两岸南北半球夏季风变化可能都呈现减弱趋势。     

Correlation between the oxygen isotope record from Dasuopu ice core and the Asian Southwest Monsoon during the last millennium

Long high-resolution proxy records are valuable for understanding Asian Southwest Monsoon (ASM) dynamics on decadal to centennial timescales. A millennium long δ¹⁸O ice core record from the central Himalayas provides an opportunity to study the ASM variability on decadal to centennial timescales. The Dasuopu ice core δ¹⁸O record indicates that a relatively warm period corresponding with the Medieval Warm Period lasted from AD 1140s to 1390s, a notable warming trend is apparent from 1800s to 1990s, and several cool periods occurred between AD 1010–1130s, 1290–1330s, 1400–1460s, 1520s, 1590–1630s, 1740s, and 1770–1790s. Comparisons with other high-resolution monsoon proxy records from the Arabian Sea, south Oman, and southern China reveal a high correspondence between temperature changes in the central Himalayas and the ASM variability during the last 1000 years. A pronounced warming trend since AD 1670 coincides with an abrupt transition from a weak to a strong intensity of the ASM. The thermal conditions in the Himalayas and on the Tibetan Plateau and associated glacial boundary conditions may have been predominantly responsible for variations of the ASM intensity and for a latitudinal movement in the mean position of the ITCZ on decadal to centennial timescales.     

工业革命以来青藏高原与南极冰芯高分辨率甲烷记录对比研究

自工业革命以来全球大气CH4含量呈快速的增长趋势, 但达索普冰芯记录所显示的北半球中低纬度地区大气CH4增长的启动时间要晚于极地冰芯记录近100 a. 由于受北半球人类活动CH4排放、CH4在大气中的寿命及大气中CH4的传输等过程的影响, 最近150 a以来, 中低纬度大气CH4与南极大气CH4含量在不同的时段表现出不同的净积累量和增长速率, 且20世纪两次世界大战期间达索普冰芯记录明确显示出人类活动排放的减缓使大气CH4呈负增长. 对比研究认为, 到20世纪中叶人类活动的甲烷排放已达到极高值, 中低纬度大气中CH4增长率及年积累逐步趋于平稳且略有降低. 可以认定, 工业革命以来中低纬度地区大气CH4与南极大气CH4含量的变化在不同的时段在受控于人类活动影响的同时, CH4在大气中的行为和传输过程以及东亚中低纬度季风气候的影响决定了两地之间大气CH4含量变化存在显著的差异.     

Recent 200 Years Climatic and Environmental Records From the Far East Rongbuk Ice Core, Mt. Qomolangma(Everest)

RECENT 200 YEARS CLIMATIC AND ENVIRONMENTAL RECORDS FROM THE FAR EAST RONGBUK ICE CORE, MT. QOMOLANGMA (EVEREST)     

Dynamics of upper tropospheric stationary wave anomalies induced by ENSO during the northern summer: A GCM study

Ensemble seasonal integrations are carried out with the COLA GCM, with a view to understand the dynamical connection between warm SST anomalies in the equatorial central-eastern Pacific Ocean and the upper level stationary wave anomalies seen during drought years over the Indian summer monsoon region. In addition, experiments with and without orography are performed in order to examine the role of the Himalayas in modulating the El Niño induced stationary wave anomalies over the summer monsoon region. The GCM simulations show a statistically significant weakening of the summer monsoon activity over India in response to the SST forcing in the equatorial Pacific Ocean. This weakening of the summer monsoon appears to be largely related to modifications of the local Hadley and Walker cells over the summer monsoon region. In addition, it is seen that the anomalous ENSO divergent forcing over the tropical Pacific Ocean can act as a potential source for Rossby wave dispersion. Here one finds the possibility of meridionally propagating Rossby waves, which emanate from the ENSO forcing region, to interact with the subtropical westerlies and generate anomalous highs and lows in the subtropics and extratropics. The quasi-stationary perturbations seen over west Asia, Pakistan and northwest India during drought years, seem to be generated by the above mechanism. An alternate mechanism that could be important for the persistence of the quasi-stationary perturbations seems to be based on the dynamic excitation of middle latitude normal modes which can extract energy from the zonally varying unstable basic flow. It is seen from the GCM simulations, that the Himalayan orography plays a crucial role in anchoring the El Niño induced extratropical westerly troughs far to the west in the high latitude belt. In the absence of orography it is seen that the ENSO induced extra-tropical cyclonic anomalies tend to intrude southward into the monsoon region thereby destroying the regional scale circulations completely. Another effect due to the Himalayas is to generate lee waves on the eastern side of the topographic barrier which encircle the globe in the subtropics and midlatitudes.     

贵州石笋记录的中晚全新世东亚夏季风变化

研究全新世典型气候突变事件的内部结构及区域特征,有助于明晰季风气候突变事件的成因机制。通过对贵州七星洞石笋14个高精度²³⁰Th定年和779个氧同位素数据的分析,重建了过去6 380～2 700 yr B.P.时段平均分辨率达4.7年的东亚夏季风演化序列。该石笋δ¹⁸O值整体上呈逐渐偏正的特征,指示中晚全新世以来东亚夏季风持续变弱的趋势。叠加在此长期季风减弱变化趋势上,最为显著的百年尺度振荡主要发生在4 548～3 715 yr B.P.时段,对应于4.2 kyr B.P.事件。该记录与同区域董哥洞石笋δ¹⁸O记录一致,均显示在此事件内部并非持续干旱,而是具有两次显著的季风强降雨期。相似的季风强降雨期在我国北方气候记录中也有体现。在更大的空间尺度上,这种4.2 kyr B.P.事件的内部结构特征与澳洲—印度尼西亚(澳—印)季风区的石笋记录结构相对应,但呈显著的反相位耦合关系,证实了亚洲与澳—印季风间的动力学联系。此外,该事件结构与ENSO记录的耦合暗示了4.2 kyr B.P.事件的发生可能与热带太平洋密切相关。     

中国南方降水δ18O年际变化响应ENSO机理的再分析

中国南方石笋δ18O记录已成为重建过去季风变化历史的重要载体,然而对石笋δ18O记录的气候解译目前仍存在争议。本文基于模拟数据和气象观测数据建立了1979-2016年中国南方16个主要城市的降水δ18O年际变化序列,并利用主成分分析方法提取了这些δ18O序列的第一主成分。该主成分序列与海洋尼诺指数总体上呈现出显著正相关,表明厄尔尼诺-南方涛动（ENSO）对中国南方降水δ18O年际变化具有显著影响。进一步分析表明,ENSO主要通过控制孟加拉湾和南海等水汽上游地区对流强度和西太平洋副热带高压强度来对中国南方降水δ18O施加影响,但水汽上游地区对流强度的作用可能更强。此外,降水δ18O与ENSO在不同时段的相关性并非稳定,这可能影响石笋δ18O对ENSO历史重建的准确性。      

ENSO事件对青藏高原古里雅冰芯中现代δ18O的影响

对１９５１～１９９２年青藏高原古里雅冰芯中δ＾１８Ｏ与Ｉ（南方涛动指数）,δ＾１８Ｏ与赤道东太平洋ＳＳＴ（海表面温度）的关系进行了分析。在Ｅ１Ｎｉｎｏ年,无论是隆冬还是盛夏,古里雅冰芯中δ＾１８Ｏ均减小。表现为明显的降温,平均降温幅度分别为１．２℃和０．４５。在特强Ｅ１Ｎｉｎｏ年,平均降温幅度分别为２．０３℃和１．４６℃。在ＬａＮｉｎａ年,盛夏古里雅;冰芯中δ＾１８Ｏ增大,表现为明显的增温,平均     

Tropospheric biennial oscillation and south Asian summer monsoon rainfall in a coupled model

In this study Tropospheric Biennial Oscillation (TBO) and south Asian summer monsoon rainfall are examined in the National Centers for Environmental Prediction (NCEP) Climate Forecast System (CFSv2) hindcast. High correlation between the observations and model TBO index suggests that the model is able to capture most of the TBO years. Spatial patterns of rainfall anomalies associated with positive TBO over the south Asian region are better represented in the model as in the observations. However, the model predicted rainfall anomaly patterns associated with negative TBO years are improper and magnitudes are underestimated compared to the observations. It is noted that positive (negative) TBO is associated with La Niña (El Niño) like Sea surface temperature (SST) anomalies in the model. This leads to the fact that model TBO is El Niño-Southern Oscillation (ENSO) driven, while in the observations Indian Ocean Dipole (IOD) also plays a role in the negative TBO phase. Detailed analysis suggests that the negative TBO rainfall anomaly pattern in the model is highly influenced by improper teleconnections allied to IOD. Unlike in the observations, rainfall anomalies over the south Asian region are anti-correlated with IOD index in CFSv2. Further, summer monsoon rainfall over south Asian region is highly correlated with IOD western pole than eastern pole in CFSv2 in contrast to the observations. Altogether, the present study highlights the importance of improving Indian Ocean SST teleconnections to south Asian summer rainfall in the model by enhancing the predictability of TBO. This in turn would improve monsoon rainfall prediction skill of the model.     

THE PROCESSES OF ATMOSPHERIC IMPURITIES TRANSPORTATION OVER THE QINGHAI—TIBET PLATEAU AS REVEALED BY SEASONAL RECORDS OF SNOW CHEMISTRY

THE PROCESSES OF ATMOSPHERIC IMPURITIES TRANSPORTATION OVER THE QINGHAI—TIBET PLATEAU AS REVEALED BY SEASONAL RECORDS OF SNOW CHEMISTRY     

Causes of interannual variability in the sea ice cover of the Eastern Bering Sea

It has been shown that large-scale weather patterns in both the tropical South Pacific (El Niño-Southern Oscillation, or ENSO, events) and the North Pacific (Pacific-North American, or PNA, patterns) have strong teleconnection effects on the air, ice, and ocean environments of the Bering Sea. This signal apparently comes via the atmosphere and not the ocean. The connection between variability of the Bering Sea and the ENSO and PNA appears to be the winter position of the Aleutian Low. Interannual variability in air temperatures, ice cover, and surface winds in the Bering Sea generally are in phase with each other, whereas sea-surface temperatures (SST) tend to lag these variables by 1–3 months. These Bering Sea time-series are significantly correlated with the Southern Oscillation Index (SOI) time-series (an indicator of ENSO events) when the Bering sea data are lagged behind the SOI for up to 18 months. The correlations suggest that warming in the Bering Sea follows negative anomalies in the SOI (i.e., El Niño events). Cooling in the Bering Sea tends to follow positive anomalies (i.e., precursors of El Niños) in the SOI. Maximal correlations for the PNA also lag the SOI by a mouth or two.Analyses of variance indicate that the SOI can explain 30–40% of the variability in the Bering Sea. Stepwise multiple regressions can explain up to 54% of the variation in air temperatures, up to 39% of the variation in sea ice cover, and up to 46% of the variation in SST in the Bering Sea. PNA and SOI were significant variables only in the equation for air temperatures, indicating a close relationship between them and the atmosphere in the Bering Sea and suggesting that energy is transmitted to the water and ice via the atmosphere. The three variables airtemps, ice, and SST were significant each time they were used as independent variables, indicating a rapid and strong feedback relationship among them.Three ENSO events have occurred since the mid-1970s, but none have been typical. There have been either two positive SOI anomalies preceding an El Niño or there have been none preceding an El Niño. When there has been a positive anomaly, ice cover has been above normal, but neither a positive anomaly nor above-normal ice has occurred in the past two ENSO events. An ice retreat has occurred any time there has been an ENSO event, except in the case of the great El Niño of 1982–1983; the anomalous position of the Aleutian Low at that time explains the lack of response of the ice. Finally, one ice retreat occurred that was unrelated to an ENSO event, but was related to a PNA event.     

Impact of Southern Oscillation on the Frequency of Monsoon Depressions in the Bay of Bengal

The impact of Southern Oscillation on thecyclogenesis over the Bay of Bengal duringthe summer monsoon has been investigated.The analysis of correlation coefficients(CCs) between the frequency of monsoondepressions and the Southern OscillationIndex (SOI) reveals that more depressionsform during July and August of El Niñoyears. Due to this, the seasonal frequencyof monsoon depressions remains little higherduring El Niño epochs even though thecorrelations for June and September are notsignificant. The CCs for July and August aresignificant at the 99% level.The El Niño-Southern Oscillation (ENSO)is known to affect Indian MonsoonRainfall (IMR) adversely. The enhancedcyclogenesis over the Bay of Bengal duringJuly and August is an impact of ENSO whichneeds to be examined closely. Increasedcyclogenesis over the Bay of Bengal may bereducing the deficiency in IMR duringEl Niño years by producing more rainfallover the eastern parts of India duringJuly and August. Thus there is a considerablespatial variation in the impact of ENSOon the monsoon rainfall over India and El Niñoneed not necessarily imply a monsoonfailure everywhere in India.The area of formation of monsoon depressionsshifts eastward during El Niño years.Warmer sea surface temperature (SST) anomaliesprevail over northwest and adjoiningwestcentral Bay of Bengal during premonsoon andmonsoon seasons of El Niño years.May minus March SOI can provide useful predictionsof monsoon depression frequencyduring July and August.     

东太平洋暖池

利用1950-2002年间的海面温度(SST)资料,研究了东太平洋暖池的形态和热状态特征,并探讨了暖池变异与恩索(ENSO)的关系。结果表明,暖池形态和热状态均有明显的季节特征和年际变化,其年际变化与ENSO循环相联系;暖池热含量、面积和南界与ENSO有着十分密切的相关关系。合成分析结果显示,在厄尔尼诺(El Nino)事件爆发的前一年,暖池热含量偏少,面积偏小,南界偏北,而在事件爆发后,暖池热含量增多,面积增大,南界南移;在拉尼娜(La Ni?a)事件期间,暖池热含量、面积和南界的演变趋势基本与El Nino事件期间的情况相反。东太平洋暖池的经向变异可能对ENSO暖(El Nino)、冷(La Nina)事件的发展有重要作用。     

Interdecadal Change of Relation between East Asian Summer Monsoon and ENSO in Previous Winter in An Ocean Assimilation System Based on FGOALS-s2

Ocean Assimilation System (OAS) is an important component for decadal prediction experiment, providing initial conditions. Evaluating the atmosphere response in OAS can provide reference for analyzing results from decadal prediction. We analyzed the interdecadal change in relation between the East Asian Summer Monsoon (EASM) and El Niño/Southern Oscillation (ENSO) in the previous winter based on an OAS on the coupled climate model FGOALS-s2. It shows that two factors impact the performance: ① interdecadal change of Ssea Surface Temperature (SST) pattern in the summer Indo-Pacific Basin related with ENSO in previous winter and ② bias in model response of the western North Pacific anticyclone to tropical SST anomalies. The anticyclone shows steady relation with the warm eastern Indian Ocean. When ENSO’s impact on the summer Indian Ocean is strengthened around the end of 1970s, the OAS can reproduce the strengthened EASM-ENSO relation. However, the trend of intensified EASM-ENSO relation in the OAS is still significant after the mid-1990s due to the stronger link between the anticyclone and the northeastern Indian Ocean, differing with the observation which shows a weakened effect of the Indian Ocean on the anticyclone. In addition, the bias in response to the SST anomalies in the central Pacific also partly contributes to the failure in reproducing the weakening EASM-ENSO relation after the mid-1990s. It implies that prediction skill of interdecadal ENSO impact on the tropical Indo-Pacific SST and response bias of model to SST anomalies may to some extent limit the capability to predict the interdecadal change in the EASM-ENSO relation.     

亚洲树轮稳定氧同位素研究进展

树轮稳定氧同位素作为一种高精度的古气候代用指标,在亚洲地区的发展起步晚进步快。树轮稳定氧同位素比率（δ¹⁸O）对区域气候信息有较强的记录能力,且与水汽循环关系密切,对于理解复杂的亚洲气候起着重要作用。亚洲地区树轮δ¹⁸O对温度的响应主要出现在高纬度地区,中低纬度树轮δ¹⁸O主要记录与水分（降水、相对湿度、PDSI等）有关的信号。对亚洲地区已发表的树轮δ¹⁸O与气候要素（温度、降水、相对湿度）的相关分析显著性统计显示,生长季气候对树轮δ¹⁸O至关重要,树轮δ¹⁸O 与温度的显著相关关系呈正相关,与降水和相对湿度的呈负相关,温度和降水通过降水δ¹⁸O影响树轮δ¹⁸O,但各自的信号强度存在区域差异,而相对湿度信号则广泛记录在不同区域不同树种之中。亚洲树轮稳定氧同位素研究集中于中低纬度地区,因而对大气水文循环的响应主要侧重于对亚洲夏季风和ENSO的研究,对季风降水的记录反映了季风活动的变化特征以及与之有关的环流信息;季节分辨率的树轮稳定氧同位素研究限于低纬热带亚热带区域,但对于理解区域气候和季风活动的年内变化、挖掘年轮不清晰树种的树轮学研究潜力具有重要的意义。     

神农架天鹅洞石笋76～58 kaB.P.时段DO事件

据神农架高海拔天鹅洞一支石笋9个230Th年龄和332组氧、碳同位素数据,建立了76～58 kaB.P. Dansgaard Oeschger (DO)事件时间序列,揭示了深海氧同位素4阶段(MIS4)东亚季风降水百年尺度变化过程。天鹅洞和葫芦洞石笋、格陵兰NGRIP冰芯δ18O对比显示,天鹅洞记录DO18事件暖湿程度相当于深海氧同位素3阶段(MIS3)水平,其振幅类似于格陵兰冰芯δ18O记录。起始时间上,天鹅洞记录DO18事件在710年230Th测年误差范围内和葫芦洞记录保持一致,并支持了NGRIP冰芯记录对应时标。在全球降温背景下,如此典型DO事件指示了强季风降水过程。70 kaB.P.左右,冰芯DO19事件至少老于石笋记录约950年,远大于700年左右的230Th测年误差,对老于该时段的冰芯时标需高分辨率地质记录进一步验证。69.09～64.64 kaB.P.（ DO19ˊ~18）期间,冰芯记录的百年尺度峰谷变化和天鹅洞石笋记录一一对应,反映了低纬热带海洋和北大西洋温盐环流之间耦合作用。     

Change of the ENSO-related δ18O–SST correlation from coral skeletons in northern South China Sea: A possible influence from the Kuroshio Current

Chemical proxies are useful analogs for reconstructing physical properties of sea water, such as sea surface temperature (SST) and sea surface salinity (SSS). Time series of these inferred properties would allow for reconstructions of past El Niño–Southern Oscillation (ENSO) events, where no instrumental records exist. In this study, a monthly oxygen isotope record from a Porites coral is used to explain how past ENSO events are recorded in the coral skeletons. The sample covers a 12 year period and was collected from Nanwan Bay, Taiwan. During El Niño events the coral skeleton is shown to produce a δ¹⁸O–SST correlation with a slope of −0.12 ± 0.04‰ °C⁻¹. During other times, this value is significantly different, with a slope of −0.21 ± 0.04‰ °C⁻¹. Coral that grew during El Niño summers have δ¹⁸O values which are enriched by ∼0.2‰, relative to other times. A possible mechanism to explain this difference may be enhanced penetration of Kuroshio Current waters into the South China Sea during summer. The observed contrast in the correlation of δ¹⁸O–SST variability in this sample supports the influence of El Niño in eastern Asia.