Geochemical characteristics and geological implication of ferromanganese crust from CM6 Seamount of the Caroline Ridge in the Western Pacific

Ferromanganese crusts(Fe-Mn crusts) grow very slow and can be treated as condensed stratigraphic sections recording paleo-oceanographic environmental information and local key geological events during the mineralization process.Geochronology,textures,mineralogy,and geochemistry of a Fe-Mn crust sample from the CM6 Seamount of the Caroline Ridge in the Western Pacific Ocean were analyzed by means of electron probe microanalysis and X-ray diffraction.The Fe-Mn crust shows three layers in textural characteristics from bottom to top.The lower,middle,and upper layers presence mottled,botryoidal,and columnar textures,respectively.Ferruginous vernadite,Fe hydroxide,amorphous silicate minerals,calcite,quartz,and feldspar are the main minerals of the Fe-Mn crust.Using cobalt chronometry method,the cumulative growth time of the Fe-Mn crust was determined to be 11 Ma or 25 Ma,of which25 Ma is inconsistent with other lines of age constraint brought by dating of the substrate.The co-existence of abundant silicate minerals and bioclasts in the middle and lower layers of the Fe-Mn crust diluted the ferromanganese oxide deposits,thus affected the texture,minerals,and geochemical characteristics of the Fe-Mn crust.Variations in Mn Co,Ni,and other elements content and the burial of opal-A recorded the expansion of oxygen minimum zone(OMZ) in the upper layer of the Fe-Mn crust.In addition,the highreflectivity Fe-rich laminae might indicate the surrounding volcanic activity.The Fe-Mn crust sample was determined to be hydrogenic by electron probe micro-analyzer(EPM A).The findings help us understand the geochemical characteristics of the Fe-Mn crust in the Caroline Ridge Seamount in the Western Pacific and the variations of paleo-oceanographic environment clues borne by the Fe-Mn crusts.     

Zonal displacement of western Pacific warm pool and zonal wind anomaly over the Pacific Ocean

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.     

宝鸡黄土中的风化壳

根据野外调查,在宝鸡黄土中确定了五个时期的风化壳,它们分别为第1～5层古土壤与其下的风化黄土构成。根据X-射线衍射得知,这些风化壳为水云母和绿泥石等构成的粘土型风化壳。CaCO_3淀积深度和Fe_2O_3、Al_2O_3迁移特征表明第1和3～5层古土壤与其下黄土构成的风化壳发育时处于酸性风化阶段,当时年平均降水量在900mm以上;第2层古土壤与其下风化黄土构成的风化壳发育时处于中性风化阶段,当时年平均降水量为800mm左右。     

热带次表层海温对中国东部夏季气候的影响

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。     

Variation in joint mode of the tropical Indian-Pacific Ocean thermodynamic anomaly

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.     

Wind-forced equatorial wave dynamics of the Pacific Ocean during 2014/2015 and 2015/2016 E1 Ni?o events

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.     

Climate variability and predictability associated with the Indo-Pacific Oceanic Channel Dynamics in the CCSM4 Coupled System Model

An experiment using the Community Climate System Model (CCSM4), a participant of the Coupled Model Intercomparison Project phase-5 (CMIP5), is analyzed to assess the skills of this model in simulating and predicting the climate variabilities associated with the oceanic channel dynamics across the Indo-Pacific Oceans. The results of these analyses suggest that the model is able to reproduce the observed lag correlation between the oceanic anomalies in the southeastern tropical Indian Ocean and those in the cold tongue in the eastern equatorial Pacific Ocean at a time lag of 1 year. This success may be largely attributed to the successful simulation of the interannual variations of the Indonesian Throughflow, which carries the anomalies of the Indian Ocean Dipole (IOD) into the western equatorial Pacific Ocean to produce subsurface temperature anomalies, which in turn propagate to the eastern equatorial Pacific to generate ENSO. This connection is termed the “oceanic channel dynamics” and is shown to be consistent with the observational analyses. However, the model simulates a weaker connection between the IOD and the interannual variability of the Indonesian Throughflow transport than found in the observations. In addition, the model overestimates the westerly wind anomalies in the western-central equatorial Pacific in the year following the IOD, which forces unrealistic upwelling Rossby waves in the western equatorial Pacific and downwelling Kelvin waves in the east. This assessment suggests that the CCSM4 coupled climate system has underestimated the oceanic channel dynamics and overestimated the atmospheric bridge processes.     

Skewness of subsurface ocean temperature in the equatorial Pacific based on assimilated data

The skewness of subsurface temperature anomaly in the equatorial Pacific Ocean shows a significant asymmetry between the east and west.A positive temperature skewness appears in the equatorial eastern Pacific,while the temperature skewness in the western and central Pacific is primarily negative.There is also an asymmetry of the temperature skewness above and below the climatological mean thermocline in the central and western Pacific.A positive skewness appears below the thermocline,but the skewness is neg...     

Dynamic mechanism of interannual zonal displacements of the eastern edge of the western Pacific warm pool

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.     

Seasonal variation of the surface North Equatorial Countercurrent (NECC) in the western Pacific Ocean

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.     

全球海洋初级生产力时空异常变化对ENSO事件的响应

海洋初级生产力在海洋环境要素的驱动下,在不同海域呈现出不同的时空变化特征,这种时空演变特征在不同的ENSO事件类型下差异更为显著。本文基于1998年1月至2017年12月全球海洋初级生产力的卫星遥感数据集,通过改进海洋时空双约束聚类挖掘方法,挖掘了近20年海洋初级生产力的时空聚簇模式,并从时空分布和空间移动2个方面对比分析了海洋初级生产力时空演变簇与ENSO（El Niño-Southern Oscillation）事件之间的关系。结果表明：① 在EP（Eastern-Pacific）型El Niño事件期间,海洋初级生产力异常低值时空簇主要分布在赤道太平洋东部或中东部海域,异常高值时空簇主要分布在西太平洋和南太平洋中部海域;在CP（Central-Pacific）型El Niño事件期间,异常低值时空簇分布在太平洋中部,而异常高值时空簇分布在南太平洋与西太平洋海域;② 在EP型La Niña事件期间,赤道太平洋中部及东部、赤道大西洋与印度洋海域出现异常高值时空簇,南太平洋中东部海域出现异常低值时空簇;在CP型La Niña事件期间,赤道太平洋中部出现异常高值时空簇;南太平洋中西部海域出现异常低值时空簇;③ 发生在赤道太平洋的海洋初级生产力时空演变簇,在EP型ENSO事件期间具有东移特征,而在CP型ENSO事件期间,时空演变簇在赤道太平洋中部海域产生并消亡;④ ENSO事件中海洋初级生产力时空演变簇面积与MEI具有较强相关性。     

Variations of the Eco-Hydro-Climatic Environment Response to the 2015/2016 Super El Niño Event in the Mindanao Dome Upwelling System

A super El Ni?o event occurred in the equatorial Pacific during 2015-2016,accompanied by considerable regional eco-hydro-climatic variations within the Mindanao Dome(MD)upwelling system in the tropical western Pacific.Using timeseries of various oceanic data from 2013 to 2017,the variability of eco-hydro-climatic conditions response to the 2015/2016 super El Ni?o in the upper 300 m of the MD region are analyzed in this paper.Results showed that during the 2015/2016 super El Ni?o event,the upwelling in the MD region was greatly enhanced compared to those before and after this El Ni?o event.Upwelling Rossby waves and the massive loss of surface water in the western Pacific were suggested to be the main reasons for this enhanced upwelling.De-creased precipitation caused by changes in large-scale air-sea interaction led to the increased surface salinities.Changes in the struc-tures of the thermohaline and nutrient distribution in deep waters contributed to the increased surface chlorophyll a,suggesting a po-sitive effect of El Ni?o on surface carbon storage in the MD region.Based on the above analysis,the synopsis mechanism illustrating the eco-hydro-climatic changing processes over the MD upwelling system responding to the El Ni?o event was proposed.It high-lights the prospect for the role played by El Ni?o in local eco-hydro-climatic effects,which has further profound implications for understanding the influence of the global climate changes on the ocean carbon cycle.     

AN ENSO-LIKE OSCILLATION SYSTEM

INTRODUCTIONElNi no SouthernOscillation (ENSO)istheinterannualinteractionofocean atmosphereinthetropical (especiallyequatorial)Pacific,andisconsideredtobethedominantmechanismoftheearth’sinterannualclimatechange.ThereareseveralparadigmsproposedforinterpretingENSO .Bjerknes’ (1 966,1 969)pio neeringworkvisualizedacloseassociationbetweenoceanandatmosphereandexplainedhowthedis turbancecoulddevelopthroughtheocean atmosphereinteraction .Heproposedapositivefeedbackmechanism .ButENSOisan…     

Fe-Si-Mn-Oxyhydroxide Encrustations on Basalts at East Pacific Rise near 13°N:An SEM-EDS Study

Fe-Si-Mn-oxyhydroxide encrustations at the East Pacific Rise(EPR) near 13°N were analyzed using the scanning electron microscope(SEM) with an energy dispersive spectrometer(EDS). These encrustations are mainly composed of amorphous FeSi-Mn-oxyhydroxides forming laminated, spherical, porous aggregates with some biodetritus, anhydrite, nontronite, and feldspar particles. Anhydrite particles and nontronite crystals in the Fe-Si-Mn-oxyhydroxide encrustations imply that the Fe-Si-Mn- oxyhydroxide may have formed under relatively low- to high-temperature hydrothermal conditions. The Fe-Si-Mn-oxyhydroxide encrustations on pillow basalts are 1–2 mm thick. The growth rate of ferromanganese crusts in the survey area suggests that these encrustations are an unlikely result of hydrogenic deposition alone having a hydrothermal and(Fe/Mn ratio up to 7.7 and Fe/(Fe+Mn+Al) ratio exceeding 0.78) hydrogenic origin(0.22 Fe/Mn ratio close to the mean value of 0.7 for open-ocean seamount crusts). The varying Fe/Mn ratios indicate that the Fe-Si-Mn-oxyhydroxide encrustations have formed through several stages of seafloor hydrothermalism. It is suggested that, at the initial formation stage, dense Fe-Si-oxyhydroxides with low Mn content deposit from a relatively reducing hydrothermal fluid, and then the loose Fe-Si-Mn-oxyhydroxides deposit on the Fe-Si-oxyhydroxides. As the oxidation degree of hydrothermal fluid increases and Si-oxide is inhibited, Mn-oxide will precipitate with Fe-oxyhydroxides.     

Archaeal community structure in sediments from a seamount in the Mariana Volcanic Arc

Seamounts are subsurface mountains in the ocean.Examination of the abundance and distribution of Archaea in seamount ecosystems may provide a better understanding of their ecological functions.Most studies of marine archaeal assemblages in seamount area have focused on hydrothermal vents or ferromanganese crusts.We investigated the archaeal communities from a seamount of the Mariana Volcanic Arc,in the tropical western Pacific Ocean by using high-throughput sequencing.Thaumarchaeota was dominant in the sediments of all sample stations.Community diversity and species richness were greatest at stations near the top of the seamount,and lowest at the deepest station.One sample station on the steep southeast slope that faced the Yap-Mariana trench had a unique composition of Archaea.In summary,depth has an important influence on archaeal community structure,and the geographic properties and sediment characteristics may explain the unique distribution patterns of Archaea in this seamount.This study provides a foundation for future research on Archaea in seamounts.     

Early development of grateloupia turuturu (Halymeniaceae, Rhodophyta)

Grateloupia turuturu is a commercial red alga with potential value in nutraceuticals and pharmaceuticals. To supplement information on its life history and verify whether carpospores can be used for seedling culture, early development of G. turuturu was investigated under culture conditions (27°C, 10-13 mol/(m2.s) in irradiance, photoperiod 10:14 h L:D). Three physiological stages were recognized by continuous microscopic observation: division stage, discoid crust stage, and juvenile seedling stage. At the beginning of the division stage, the carpospores developed germ tubes into which the carpospore protoplasm was evacuated, and then the carpospore protoplasm in the germ tubes began to divide continuously until discoid crusts formed. Finally, upright thalli appeared on the discoid crusts and developed into juvenile seedlings. It took about 60 days for carpospores to develop into juvenile seedlings. The growth parameters, including germination rate for carpospores and discoid crust diameter, were recorded. These results contribute more information on the life cycle, and at the same time are of great significance in the scaling-up of artificial seedling cultures of G. turuturu.     

Impacts of SST anomalies in the Indian-Pacific basin on Northwest Pacific tropical cyclone activities during three super El Ni?o years

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.     

The Relation between Tectonic Movement and Climatic Change

1SeesawphenomenonofoceaniccrustSince 1996, Yoshino etal.(2002) have been us-ing the space geodetic techniques to observe crustal deformation at four sites in Tokyo metropolitan area. It is called Keystone project (KSP). At the end of June in 2000, volcanic and seismic events star-ted at Izu islands, south of Tokyo. Following the ev-ent, extraordinary crustal deformation was observed not only around the Izu islands, but also at the Key-stone network, where the closest site is over 100…     

The Relation between Tectonic Movement and Climatic Change

Climate and tectonics are two interactive factors in the earth's system. They are controlled by astronomical cycles. It has been unheeded for a long time that large-scale material motion caused by global climatic change is one of the powers for tectonic movement. Tectonic movement makes the distributional pattern of continent and ocean change and makes global climate type change strongly in large scale. It is a good example that the change of the sea-ice around Antarctic Continent and in the Drake Passage has the switch process for global climatic changes. Tide makes the oceanic crust of the East Pacific Ocean and the West Pacific Ocean rise or fall 60 cm oppositely. Before and after El Nino events,the oceanic level of the East Pacific Ocean and the West Pacific Ocean may rise or fall 40 cm oppositely. Because of isostasy, oceanic crust may fall or rise 13 or 20 cm. They are the reasons why El Nino events are interrelated with the earthquakes and volcanoes. This is so called seesaw phenomenon of oceanic crust.