太平洋内区经向热输送的季节变化分析

为刻画整个太平洋内区经向热输送的基本特征及其季节变化,并初步探讨变化的原因,基于Argo温盐资料,利用P矢量法反演了太平洋的绝对地转流(AGC),并结合Ekman流,分析了年平均和季节平均的经向热输送。结果显示,在13°S~13°N,经向热输送主要由Ekman经向热输送控制,季节变化显著,且南北半球变化相反,北半球1-3月有北向输送最大值,8-10月当经向热输送转为南向时,Ekman经向热输送达到最小;南北太平洋经向热输送的季节变化存在显著的不对称特征,北太平洋的明显强于南太平洋,低纬度海域的明显大于高纬度海域。分析表明,经向热输送的季节变化与纬向风应力的变化直接相关,由于未能有效包含西边界流及赤道区域,对比前人的研究结果后推测,西边界流和赤道流在维持南北太平洋经向热输送的平衡中扮演了重要角色。     

热带太平洋和热带印度洋次表层海温异常信号的传播与联系

利用太平洋和印度洋表层与次表层月海温距平信号沿不同纬向-时间剖面的传播分析,发现赤道东太平洋海温异常的El Ni(n)o事件和赤道印度洋海温异常的Dipole事件分别与沿赤道太平洋东传的次表层海温异常信号和沿赤道外印度洋西传的次表层海温异常信号同期到达东太平洋和西印度洋有着内在的联系.在赤道和赤道外16°N之间的热带北太平洋,次表层海洋中存在着海温异常信号传播的一条回路,El Ni(n)o事件就发生在暖信号到达赤道东太平洋的时候.次表层海温异常沿赤道太平洋的东传和沿赤道外印度洋的西传分别是El Ni(n)o事件和Dipole事件发生的海洋学早期信号.     

西北太平洋环流和海温数值模拟

基于Ecom-si建立了一个西北太平洋海洋数值模式,综合考虑了侧边界通量、海表面风应力、热通量、蒸发和降水等因素,模拟并分析了西北太平洋环流和海温的基本特征.模式验证结果表明,模式计算的海温与日本2008年西北太平洋实测温度走航断面资料吻合良好.模式再现了低纬度海区表层自东向西流动的北赤道流、强西边界流黑潮、东海的台湾...     

印度洋一太平洋海表温度异常的持续性特征

用Reynolds&Smith重构的1950-1998年月平均SST资料分析了印度洋-太平洋海表温度距平SSTA的持续性特征.结果表明SSTA的持续性在空间上分布不均匀,可将有明显差异的SSTA持续性特征的海区分为3类全年各月持续性好的区域,主要包括热带中东太平洋马蹄形海域、赤道中东印度洋、热带西太平洋,持续时间一般在10个月以上;全年各月持续性差的区域,主要包括西北太平洋、东亚沿海和东南太平洋,持续时间一般为3个月左右;各月持续性有季节性变化的区域,主要包括赤道东太平洋,南海.SSTA持续性的整体空间分布存在冬夏两种主要分布型,夏季型SSTA的持续性要比冬季好.冬夏间SSTA持续性最明显的差异出现在赤道东太平洋和东亚沿海、南海区域,由冬季转入夏季时,赤道东太平洋SSTA的持续性由差变好,东亚沿海、南海地区的情况则与之相反.     

太平洋海表面温度季节内振荡特征

为了研究太平洋海表面温度季节内振荡的特征,利用NOAA(national oceanic and atmospheric ad-ministration)周平均SST资料,采用谐波方法重构了太平洋海表面温度季节内振荡信号,针对不同海域,用小波分析等方法,揭示了SST季节内振荡的空间、频谱、季节性和传播特征.结果表明:海表面温度季节内振荡在黑潮区、黑潮续流区和赤道东太平洋较活跃,在赤道东西太平洋有相对重要的地位;在北太平洋谱特征均为单峰结构,在赤道东西太平洋呈双峰结构.不同海域海表面温度季节内振荡的活跃期分别为:北太平洋夏秋季,赤道东太平洋春和秋季,热带西太平洋活跃期较分散;在北太平洋以缓慢东传为主,在赤道东太平洋以西传为主,在热带西太平洋无明显传播.     

印度洋-太平洋海表温度异常的持续性特征

用Reynolds＆Smith重构的1950-1998年月平均SST资料分析了印度洋-太平洋海表温度距平SSTA的持续性特征。结果表明:SSTA的持续性在空间上分布不均匀,可将有明显差异的SSTA持续性特征的海区分为3类:全年各月持续性好的区域,主要包括热带中东太平洋马蹄形海域、赤道中东印度洋、热带西太平洋,持续时间一般在10个月以上;全年各月持续性差的区域,主要包括西北太平洋、东亚沿海和东南太平洋,持续时间一般为3个月左右;各月持续性有季节性变化的区域,主要包括赤道东太平洋,南海。SSTA持续性的整体空间分布存在冬夏两种主要分布型,夏季型SSTA的持续性要比冬季好。冬夏间SSTA持续性最明显的差异出现在赤道东太平洋和东亚沿海、南海区域,由冬季转入夏季时,赤道东太平洋SSTA的持续性由差变好,东亚沿海、南海地区的情况则与之相反。     

江淮流域夏季降水异常及与全球中低纬海温异常关系的诊断研究

对1951－1999年中国夏季江淮流域降水异常与海温异常关系的分析表明,前期及同期各季节三大洋海表温度异常（SSTA）与长江流域降水异常的关系是非常显著的,而对淮河流域降水异常总体上的影响较小,前期冬季SSTA的影响显著区主要有：热带印度洋、黑潮、热带中东太平洋和大西洋,各关键区海温异常对亚洲夏季风的影响特征为：当前期冬季赤道印度洋、黑潮、赤道大西洋和热带东太平洋海表温度异常升高（降低）,当年夏季印度西南季风和东亚热带辐合带减弱（加强）,副热带高压位置偏南（北）,副热带辐合带加强（减弱）,长江流域易发生洪涝（干旱）,相关显著性分析表明,前冬赤道印度洋和黑潮区的海温异常对中国夏季降水的影响更为显著。     

六层斜压有地形的全球海洋环流数值模拟（二）

用年平均风应力，海表热，盐通量作强迫积分４４年，结果得到和海流，温，盐分布。再现了全球海洋上气候平均的温盐分及主要海流的大尺度特征，如西边界强化流，赤道地区狭长冷水带和强上翻区，赤道流和赤道潜流。又做了二个试验，第一用各季平均风应力强迫得到洋流对信风季节变化的响应。第二是给定 赤道西太平洋一个风应力异常区，积分一年，结果，结果在赤道太平洋产生了正温度距平，因Ｋｅｌｖｉｎ波作用东传，到东海岸后，以Ｒ     

热带太平洋海平面年际和年代际变化研究进展

回顾热带太平洋对海平面长期趋势有重要影响的海平面年际和年代际变化的相关研究,总结包括近期提出的中部型厄尔尼诺在内的2种类型厄尔尼诺对热带太平洋海平面年际变化的影响,揭示了热带太平洋海平面年代际变化与信风年代际变化之间的紧密联系。指出赤道信风的增强对近期热带太平洋海平面变化格局的形成有决定性作用,厄尔尼诺强度的减弱对这种格局有贡献,而拉尼娜的影响有待深入研究。研究资料的局限性导致年代际变化的定量研究成果较少,在研究海平面年际和年代际变化时应用的热通量评估模型有待改进。     

热带印度洋和太平洋海气相互作用事件间的联系

在次表层海温距平极值面上海温距平的分布和变化表明,热带西、东印度洋的海温距平呈偶极子模态,即当西印度洋海温距平为正(负)时,东印度洋海温距平为负(正),偶极子模态的海温距平分布在热带太平洋同样存在,两大洋海温距平的偶极子模态间有密切的联系,在分析它们和850 hPa纬向风距平后指出,不仅这种海温距平偶极子模态的形成、发展是和这两大洋热带上空Walker环流相互作用的结果,同时正是Walker环流异常把两大洋的海温距平变化联系起来.     

Indian Ocean temperature dipole and SSTA in the equatorial Pacific Ocean

The observed sea surface temperature (SST) data of recent 100 years are analyzed and the existence of the Indian Ocean temperature dipole in the equatorial region is exposed further. It is very clear that the amplitude of the positive phase (higher SST in the west and lower SST in the east than normal) is larger than that of the negative phase (higher SST in the east and lower SST in the west). The dipole is stronger in September-November and weaker in January-April than in other months and it also appears obviously inter-annual and inter-decadal variations. Although the Indian Ocean dipole in the individual year seems to be independent of ENSO in the equatorial Pacific Ocean, in general, the Indian Ocean dipole has obviously negative correlation with the Pacific Ocean dipole (similar to the inverse phase of ENSO mode). The atmospheric zonal (Walker) circulation over the equator is fundamental to relate the two dipoles to each other.     

近45年北太平洋海表风速特征统计分析

本文利用来自欧洲中期天气预报中心（ECMWF——European Centre for Medium-Range Weather Forecasts）的1957年8月—2002年7月逐6 h的ERA-40海表10 m风场资料,统计分析了近45年期间北太平洋海表风场的月变化特征,以及多年平均海表风速的分布特征,为海洋水文保障、海洋工程等提供参考。结果表明：（1）北太平洋的海表风场具有明显的月变化特征,10月至来年2月的风速整体高于其余月份。（2）从年平均风速来看,阿留申群岛附近海域为北太平洋年平均风速的明显大值中心,年平均风速基本在8 m/s以上;中纬度海域的年平均风速在6~7 m/s;15°N-20°N的东部海域存在一相对大值区,年平均风速在7 m/s以上;赤道西部海域的年平均风速较小,基本在4 m/s以内。     

北大西洋海表风速季节特征及长期变化趋势分析

利用来自欧洲中期天气预报中心（ECMWF——European Centre for Medium-Range Weather Forecasts）的长时间序列、高精度的ERA-40海表10 m风场资料,对北大西洋海域海表风场的季节特征、长期变化趋势进行深入研究,研究发现：（1）北大西洋海域的海表风速等值线在各季均大致呈东西带状分布,且由高纬度向赤道表现出高—低—高—低的分布特征。MAM和SON期间海表风速的分布特征较为相似,大值中心分布于北半球西风带海域;DJF期间的海表风速为全年最大;JJA期间的海表风速为全年最小。加勒比海海域常年存在一风速的相对大值中心。从多年平均来看,风速存在一明显的、范围较广的大值区：西风带海域,加勒比海也存在一范围较小的大风区。（2）1958年至2001年期间,北大西洋海域的海表风速以0.0049 m.s-1.a-1的速度显著性逐年线性递增。（3）北大西洋海表风速的变化趋势表现出较大的区域性差异：呈显著性逐年线性递增的区域主要分布于30°N以下的低纬度海域,变化趋势在0.01～0.025 m.s-1.a-1左右,西班牙东北部近海的递增趋势最为强劲,达到0.035 m.s-1.a-1以上,墨西哥湾和加勒比海则呈显著性逐年线性递减,趋势为-0.015 m.s-1.a-1左右,其余海域的海表风速无显著变化趋势。（4）近44年期间,北大西洋海域的海表风速存在明显的突变现象,突变期为1972年前后。     

Interconnections between the Asian monsoon, ENSO, and high northern latitude climate during the Holocene

The International Geosphere Biosphere Program (IGBP), which promotes better understanding of the living environment, was initiated in the early 1990s. IGBP and other programs have uncovered much evi-dence that the Earth system is complex and nonlinear, ex…     

Eastern Pacific cooling and Atlantic overturning circulation during the last deglaciation

Surface ocean conditions in the equatorial Pacific Ocean could hold the clue to whether millennial-scale global climate change during glacial times was initiated through tropical ocean-atmosphere feedbacks or by changes in the Atlantic thermohaline circulation. North Atlantic cold periods during Heinrich events and millennial-scale cold events (stadials) have been linked with climatic changes in the tropical Atlantic Ocean and South America, as well as the Indian and East Asian monsoon systems, but not with tropical Pacific sea surface temperatures. Here we present a high-resolution record of sea surface temperatures in the eastern tropical Pacific derived from alkenone unsaturation measurements. Our data show a temperature drop of approximately 1 degrees C, synchronous (within dating uncertainties) with the shutdown of the Atlantic meridional overturning circulation during Heinrich event 1, and a smaller temperature drop of approximately 0.5 degrees C synchronous with the smaller reduction in the overturning circulation during the Younger Dryas event. Both cold events coincide with maxima in surface ocean productivity as inferred from 230Th-normalized carbon burial fluxes, suggesting increased upwelling at the time. From the concurrence of equatorial Pacific cooling with the two North Atlantic cold periods during deglaciation, we conclude that these millennial-scale climate changes were probably driven by a reorganization of the oceans' thermohaline circulation, although possibly amplified by tropical ocean-atmosphere interaction as suggested before.     

Evolution of heat transport pathways in the Indonesian Archipelago during last deglaciation

The Indonesian Archipelago provides important heat transport pathways of the Western Pacific Warm Pool between the northern Indian Ocean and western equatorial Pacific Ocean, that exert important impacts on global climate change. This study investigated AMS ¹⁴C, δ¹⁸O, planktonic foraminifer assemblages and sedimentation rates in three piston cores collected in the Indonesian Archipelago. The results indicate that changes in the Indonesian Archipelago heat transport pathways were phase characteristic and in steps during the last deglaciation. In the deglaciation Termination IA, at about 12.5 kaBP, sea level rose rapidly in a short time period, and Makassar and Lombok straits widened suddenly for warm and fresh water from the Pacific to pour into the Java Sea and eastern Indian Ocean. During the Termination IB, about 9.5 kaBP, sea level rose rapidly again, and the South China Sea (SCS) started to connect with the Java Sea. With monsoon actions, a large amount of fresh water from the SCS shelf area flew through the Indonesian Archipelago.     

Moisture transport across Central America as a positive feedback on abrupt climatic changes

Moisture transport from the Atlantic to the Pacific ocean across Central America leads to relatively high salinities in the North Atlantic Ocean and contributes to the formation of North Atlantic Deep Water. This deep water formation varied strongly between Dansgaard/Oeschger interstadials and Heinrich events-millennial-scale abrupt warm and cold events, respectively, during the last glacial period. Increases in the moisture transport across Central America have been proposed to coincide with northerly shifts of the Intertropical Convergence Zone and with Dansgaard/Oeschger interstadials, with opposite changes for Heinrich events. Here we reconstruct sea surface salinities in the eastern equatorial Pacific Ocean over the past 90,000 years by comparing palaeotemperature estimates from alkenones and Mg/Ca ratios with foraminiferal oxygen isotope ratios that vary with both temperature and salinity. We detect millennial-scale fluctuations of sea surface salinities in the eastern equatorial Pacific Ocean of up to two to four practical salinity units. High salinities are associated with the southward migration of the tropical Atlantic Intertropical Convergence Zone, coinciding with Heinrich events and with Greenland stadials. The amplitudes of these salinity variations are significantly larger on the Pacific side of the Panama isthmus, as inferred from a comparison of our data with a palaeoclimate record from the Caribbean basin. We conclude that millennial-scale fluctuations of moisture transport constitute an important feedback mechanism for abrupt climate changes, modulating the North Atlantic freshwater budget and hence North Atlantic Deep Water formation.     

Closing of the Indonesian seaway as a precursor to east African aridification around 3-4 million years ago

Global climate change around 3-4 Myr ago is thought to have influenced the evolution of hominids, via the aridification of Africa, and may have been the precursor to Pleistocene glaciation about 2.75 Myr ago. Most explanations of these climatic events involve changes in circulation of the North Atlantic Ocean due to the closing of the Isthmus of Panama. Here we suggest, instead, that closure of the Indonesian seaway 3-4 Myr ago could be responsible for these climate changes, in particular the aridification of Africa. We use simple theory and results from an ocean circulation model to show that the northward displacement of New Guinea, about 5 Myr ago, may have switched the source of flow through Indonesia-from warm South Pacific to relatively cold North Pacific waters. This would have decreased sea surface temperatures in the Indian Ocean, leading to reduced rainfall over eastern Africa. We further suggest that the changes in the equatorial Pacific may have reduced atmospheric heat transport from the tropics to higher latitudes, stimulating global cooling and the eventual growth of ice sheets.     

全球地表温度大气遥相关路径研究

基于复杂网络方法,分析不同区域地表温度之间存在的相关关系及其时滞,建立了体现大气遥相关的全球地表温度网络,进而给出地表温度网络遥相关路径．研究表明:网络连接的空间距离在3 500和7 000 km处有1个峰值,这与大气Rossby波的1/2和1倍波长一致．地表温度网络中,影响传播的主导节点在北半球分布在东亚、向西延伸的北太平洋、美国东海岸及邻接的北大西洋地区;在南半球分布在50° S纬度带．遥相关现象在南半球比北半球更显著,典型遥相关路径与不同的环流作用有明确对应:1）北太平洋中部到墨西哥的连接反映了西风带的作用;2）北大西洋传播到非洲北部、格陵兰岛到里海的连接,均属于连接北大西洋到欧亚大陆的跨欧亚波列的一部分;3）俄罗斯喀拉海到北太平洋的连接与北大西洋涛动（NAO）密切关联;4）南半球的连接反映了大气西风带和Rossby波的影响．大气遥相关路径分析有利于深化对地表温度变化的认识,可为减缓气候全球变化提供理论基础．