interannual modulation of eddy kinetic energy in the northeastern south china sea as revealed by an eddy resolving ogcm interannual modulation of eddy kinetic energy eke in the northeastern south china sea ne scs is investigated based on outputs of an eddy resolving oceanic general circulation model between 1980 and 2014 the eke displays distinct interannual modulations with periods between 1 5 and 7 years the maximum peak to trough amplitude of the interannual modulation occurred during period 2004 2005 which was about 1 5 fold the time mean eke level further analysis suggested that interannual variability of eke in the ne scs is primarily modulated by the luzon strait transport lst during high eke years the lst increases corresponding to a strengthened kuroshio intrusion the strengthened kuroshio intrusion enhances the baroclinic instability of current in the ne scs and thus leads to a strong eke the reverse is true during low eke years when lst is smaller influences of enso and pacific mesoscale eddies on the interannual modulation of lst are also discussed in this study

sediment dynamics over sand ridges on a tideless mid outer continental shelf abstract a sand ridge field with crests oriented ne sw 52 located between 55 and 85 m water depth on the valencia continental shelf spain was mapped with multibeam swath bathymetry and characterized with seismic profiling and sediment sampling boundary layer hydrodynamic measurements conducted over a sand ridge at 66 m depth show evidence of wave and current sediment resuspension during a major storm event with a three year recurrence period from the measured intrawave sediment concentration profiles it is shown that the suspended sediment time evolution is related not only to mean currents but also to the wave field the near bottom shear stress generated during storm conditions reached around 1 n m2 and was able to resuspend and transport sandy and muddy sediments for more than 32 h the total suspended sediment transport in a layer of 1 m above the bottom was around 4000 kg per meter width and directed 160 it is argued that these sand ridges were developed in a shallow environment and there is no evidence of present day ridge migration or morphological degradation it is hypothesized that sediment dynamics affecting sand ridges during storms favors the maintenance of their morphology

diffusion of ar in k feldspar present and absent the mechanisms of ar release from k feldspar samples in laboratory experiments and during their geological history are assessed here modern petrology clearly established that the chemical and isotopic record of minerals is normally dominated by aqueous recrystallization the laboratory critique is trickier which explains why so many conflicting approaches have been able to survive long past their expiration date current models are evaluated for self consistency especially arrhenian non linearity leads to paradoxes the models testable geological predictions suggest that temperature based downslope extrapolations often overestimate observed geological ar mobility substantially an updated interpretation is based on the unrelatedness of geological behaviour to laboratory experiments the isotopic record of k feldspar in geological samples is not a unique function of temperature as recrystallisation promoted by aqueous fluids is the predominant mechanism controlling isotope transport k feldspar should therefore be viewed as a hygrochronometer laboratory degassing proceeds from structural rearrangements and phase transitions such as are observed in situ at high temperature in na and pb feldspars these effects violate the mathematics of an inert fick s law matrix and preclude downslope extrapolation the similar upward concave non linear shapes of arrhenius trajectories of many silicates hydrous and anhydrous are likely common manifestations of structural rearrangements in silicate structures

anti cyclonic eddies northwest of luzon in summer fall observed by satellite altimeters anti cyclonic eddies northwest of luzon of the philippines in summer fall are identified in the merged data products of satellite altimeters of topex poseidon jason 1 and european research satellites the generation and propagation of the anti cyclonic eddies which are confirmed by satellite ocean color data are found to be a seasonal phenomenon that is phase locked to the onset of the southwesterly monsoon and the relaxation of the cyclonic wind curl in the northeastern south china sea the eddies originate from northwest of luzon in summer move across the northeastern south china sea to reach the china continental slope in fall and propagate southwestward along the continental slope in fall winter inducing shelfbreak current variations in the western south china sea in fall winter the anti cyclonic eddy discovered by li et al 1998 in the northern south china sea is found to originate from northwest of luzon and carry primarily the south china sea waters it does not appear to be an eddy shed from the kuroshio in the luzon strait area as alluded by li et al 1998 and others

sedimentary record of environmental evolution off the yangtze river estuary east china sea during the last 13 000 years with special reference to the influence of the yellow river on the yangtze river delta during the last 600 years abstract a 35 60 m long core ecs 0702 recovered from a water depth of 22 m in the muddy area off the yangtze river estuary was analyzed for sedimentary characteristics clay and detrital mineral components and element geochemistry as well as by ams 14 c dating to document sediment provenance changes and environmental evolution during the postglacial period in the study area on the basis of the lithology the benthic foraminiferal and ostracod assemblages and the ams 14 c ages we divided the core into four depositional units du1 du4 in descending order representing the postglacial sedimentary sequence during the last 13 000 years du 4 was deposited in a littoral to tidal flat environment during 13 000 11 500 cal yr bp du 3 in a nearshore subtidal environment upwards to the nearshore shelf with tidal influence in response to the postglacial sea level rise during 11 500 7400 cal yr bp du 2 in a tide affected nearshore shallow sea environment during 7400 540 cal yr bp on the delta front of the yangtze river when the delta was actively prograding and du 1 in a nearshore shallow sea environment during the last 540 years on the delta front under modern marine conditions in du 1 the depositional rate was much higher than in the underlying units and the sediment composition reflects more influence from the yellow river this unit can therefore be logically linked to the period when the yellow river last discharged into the south yellow sea from ad 1128 to 1855 according to historical records this period can be divided into an early stage ad 1128 1494 when the shoreline near the yellow river mouth was advancing slowly eastward and a late stage 1495 1855 when the shoreline was advancing rapidly the initiation of du 1 deposition corresponds to the latter part of the early stage suggesting that since that time a relatively large amount of sediment from the old yellow river mouth area has been transported to the offshore area of the yangtze river mouth our study has identified a high resolution sedimentary signature associated with the last course shift of the yellow river in the yangtze river delta front thus highlighting the intricate relationship between sediment sources and sinks in coastal areas a significant contribution of the old yellow river sediments to the yangtze subaqueous delta during the last 600 years must be considered when the evolutional history of the yangtze delta is examined and especially when the influence of the three gorge dam construction on the future changes of the yangtze estuary and ecological environments in the east china sea is estimated

routine characterization and interpretation of complex alkali feldspar intergrowths almost all alkali feldspar crystals contain a rich inventory of exsolution twin and domain microtextures that form subsequent to crystal growth and provide a record of the thermal history of the crystal and often of its involvement in replacement reactions sometimes multiple microtextures strongly influence the subsequent behavior of feldspars at low temperatures during diagenesis and weathering they are central to the retention or exchange of trace elements and of radiogenic and stable isotopes this review is aimed at petrologists and geochemists who wish to use alkali feldspar microtextures to solve geological problems or who need to understand how microtextures influence a particular process we suggest a systematic approach that employs methods available in most well founded laboratories the crystallographic relationships of complex feldspar intergrowths were established by the 1970s mainly using single crystal x ray diffraction but such methods give limited information on the spatial relationships of the different elements of the microtexture or of the mode and chronology of their formation which require the use of microscopy we suggest a combination of techniques with a range of spatial resolution and strongly recommend the use of orientated sections sections cut parallel to the perfect 001 and 010 cleavages are the easiest to locate and most informative techniques described are light microscopy scanning electron microscopy using both backscattered and secondary electrons including the use of surfaces etched in the laboratory electron probe microanalysis and analysis by energy dispersive spectrometry in a scanning electron microscope transmission electron microscopy we discuss the use of cathodoluminescence as an auxiliary technique but do not recommend electron backscattered diffraction for feldspar work we review recent publications that provide examples of the need for great care and attention to pre existing work in microtextural studies and suggest several topics for future work

monsoon surges trigger oceanic eddy formation and propagation in the lee of the philippine islands 1 two winter monsoon surge events northerly and easterly of january 2005 are captured in a one way coupled atmosphere 8 km resolution and ocean 3 km resolution simulation of the philippines region intensified wind jets and wakes in the lee of mindoro and luzon islands induce the generation and migration of a pair of counter rotating oceanic eddies in the model with propagation direction related to the orientation of the winds during each of the surges features shared by the eddies include size 100 200 km depth 300 m and propagation speed 0 1 0 15 m s 1 for cyclones mean wintertime model wind stress positive negative curl coincides with the climatological cyclone anticyclone distribution from a prior 8 year altimetry based census of eddies in the southeast quadrant of the south china sea during the winter monsoon moreover the simulation results agree with contemporaneous satellite and historical in situ data characterizing regional oceanic eddy and atmospheric surface jet properties

seasonal thermal fronts on the northern south china sea shelf satellite measurements and three repeated field surveys seasonal thermal fronts associated with wind driven coastal downwelling upwelling in the northern south china sea are investigated using satellite measurements and three repeated fine resolution mapping surveys in winter spring and summer the results show that vigorous thermal fronts develop over the broad shelf with variable widths and intensities in different seasons which tend to be approximately aligned with the 20 100 m isobaths driven by the prevailing winter summer monsoon the band shaped fronts were observed with a magnitude exceeding 0 1 degrees c km in the subsurface and accompanied by energetic coastal downwelling upwelling due to shoreward offshore ekman transport the downward upward tilting of seasonal thermoclines across the shelf exceeds 20 m significantly contributing to the development of thermal fronts over the shelf in addition the diagnostic analysis of potential vorticity pv suggests that the summer frontal activities induced by the coastal upwelling are more stable to convection and symmetric instabilities in comparison to the winter fronts associated with downwelling favorable monsoon forcing this is primarily due to their essential differences in the upper ocean stratification and horizontal buoyancy gradients arising from wind forcing at the same time the coastal currents are substantially regulated by the seasonal winds an expected lag correlation between the velocity from mooring measurements and alongshore wind stress is detected near the frontal region these results indicate that seasonal wind forcing plays an important role in the frontal activities and coastal water transport over the shelf

influence of an island on hysteresis of a western boundary current flowing across a gap abstractwe investigate impact of an island on hysteresis of a western boundary current wbc flowing across a gap using a nonlinear 1 5 layer ocean model the results of hysteresis curves show the

formation and dynamics of a long lived eddy train in the south china sea a modeling study abstracta process oriented numerical modeling study was conducted to investigate the formation and underlying forcing of an anticyclonic eddy train observed in the northern south china sea observations showed that long lived anticyclonic eddies formed an eddy train along an eastward separated jet across the northern south china sea in summer the eddy train plays a critical role in regulating ocean circulation in the region forced by the southwesterly monsoon and prevailing dipole wind stress curl in the summer the northward coastal jet separates from the west boundary of the south china sea basin and overshoots northeastward into the basin the anticyclonic recirculation of the separated jet forms the first anticyclonic eddy in the eddy train the jet meanders downstream with a strong negative shear vorticity that forms a second and a third anticyclonic eddy along the jet s path these three eddies form the eddy train these eddies weaken gradually with depth from surface but they can extend to appro

standing wave modes observed in the south china sea deep basin this study deals with standing wave or seiche events using cruise observations satellite altimeter data and theoretical analysis cruise missions in summer 2007 and 2009 detected internal oscillation signals in the south china sea scs deep basin the signals have average wavelengths of 320 and 390 km and the maximum amplitudes of 50 100 m at layers 500 700 m and 1500 1700 m satellite altimeter sea level anomaly sla images and the second intrinsic mode function imf2 images derived from the empirical mode decomposition emd analysis show that the observed internal oscillations are a portion of 2 d seiche modes which lasted for at least 2 weeks we recognize that the observed internal oscillation signals represent seiche modes h5 3 and h5 1 derived from a rectangular model ocean basin with a uniform depth a west east length of 1000 km and a north south width of 800 km statistical analysis of standing wave modes h4 0 h5 1 and h5 3 with the average wavelength of 500 390 and 320 km indicates that from 1993 to 2012 1045 weeks total 94 events with total temporal coverage of 218 weeks are affirmed the total occurrence frequency is 20 9 histograms of annual distributions of seiche events and timespans show an interannual variability of about 9 years with peak years 1993 1994 1998 2001 and 2011 while monthly distributions show an intraseasonal variability double peaked in may and october transit periods of east asia monsoon in the scs

paleotidal regime in the changjiang yangtze estuary the east china sea and the yellow sea at 6 ka and 10 ka estimated from a numerical model abstract two dimensional paleotidal simulations were carried out to investigate the paleotides and paleotidal currents in the changjiang yangtze estuary the east china sea and the yellow sea calculations were made for 10 ka 6 ka and the present an age of 10 ka corresponds to a period during the last deglaciation when the sea level was about 45 m below its present level at that time the changjiang estuary extended southeastward to the east china sea for about 400 km the second period 6 ka coincides with the maximum holocene transgression in eastern china the paleotopography around the changjiang estuary was reconstructed for 10 ka and 6 ka using available borehole datasets to remove the holocene strata at 10 ka the spatial distribution of m2 tides was different from today no amphidrome was present in the yellow sea and the current velocity was generally larger on the continental shelf strength and ellipticity of the simulated tidal currents indicated that the northern part of the moribund tidal sand ridge system in the east china sea might have been formed at around this period on the other hand the tidal field at 6 ka was similar to that at present except for the region within and adjacent to the paleo changjiang estuary a radial tidal flow pattern was originated from the estuary mouth which seemed to have enhanced tides and tidal currents in the estuary

a mesoscale eddy pair southwest of taiwan and its influence on deep circulation 1 a pair of mesoscale eddies namely an anticyclonic eddy ae and a cyclonic eddy ce generated southwest of taiwan was investigated using long term moored observations augmented with satellite and reanalysis data ae ce increased the upper ocean current to 100 cm s 50 cm s and generated temperature anomaly t up to 7 5 c 3 0 c the vertical structure of ae presented a phase difference between t and velocity with the core of t located south of the zero velocity line this phase difference induced a 28 5 12 0 tw 1 tw 1012 w westward eddy heat transport southwest of taiwan ae also presented strong nonlinearity in the upper ocean and yielded an annual mean volume transport of 0 86 0 15 sv energy analysis showed that both baroclinic and barotropic instabilities were important for the generation and growth of the eddy pair and contribution from wind work was relative small in the deep sea ae ce intensified the deep currents and generated large positive negative t the deep and surface currents flowed in opposite directions during the eddy events which is consistent with the interpretation that the eddy pair is dominated by the first baroclinic mode the observed deep penetrating eddy pair could greatly influence the deep circulation of the northeastern south china sea

magnetic characteristics of sediments from a radial sand ridge field in the south yellow sea eastern china and environmental implications during the mid to late holocene abstract proxy records from radial sand ridge fields are essential for understanding sedimentary environmental changes forced by climate driven coast and sea level variations that affect large river inlets we conducted a systematic environmental magnetic study on sediments from a radial sand ridge field in the south yellow sea eastern china from 41 6 to 0 m the sediments of core yz07 derive from river mouth littoral and modern tidal flat environments magnetic measurements indicate that magnetite and hematite dominate the studied magnetic mineral assemblages magnetic mineral contents are highest in the river mouth environment and lowest in the modern tidal flat environment the magnetic minerals in the core yz07 sediments can be attributed primarily to detrital inputs rather than biogenic sources the highest and sirm values and lowest arm sirm and arm values reflect relatively warm and humid climate conditions respectively during the period 7000 to 2900 a b p 41 6 24 73 m compared with the period 7000 to 2900 a b p 41 6 24 73 m the period between 2900 and 870 a b p 24 73 5 14 m is characterized by lower arm and sirm values and higher arm sirm and arm values which indicate cool and dry climatic conditions our results reconfirm known regional climatic events that demonstrate holocene climatic instability gradual decreases in and sirm and increases in arm sirm arm and fd characterize the sediments after 870 a b p 5 14 0 m as indicated in previous studies these changes were influenced by diversion of the yellow river additionally spectral analysis of the and arm sirm records reveals rapid climatic fluctuations on millennial and centennial scales that coincide with those recorded in marine sedimentary records from adjacent regional seas these results are important for investigations into the interactions between regional systems and global change in monsoonal climatic regions thus providing an example of the evolution of a large scale geomorphic feature resulting from river sea interaction

a census of eddy activities in the south china sea during 1993 2007 1 numerous mesoscale eddies occur each year in the south china sea scs but their statistical characteristics are still not well documented a pacific basin wide three dimensional physical biogeochemical model has been developed and the result in the scs subdomain is used to quantify the eddy activities during the period of 1993 2007 the modeled results are compared with a merged and gridded satellite product of sea level anomaly by using the same eddy identification and tracking method on average there are about 32 9 2 4 eddies predicted by the model and 32 8 3 4 eddies observed by satellite each year and about 52 of them are cyclonic eddies the radius of these eddies ranges from about 46 5 to 223 5 km with a mean value of 87 4 km more than 70 of the eddies have a radius smaller than 100 km the mean area covered by these eddies each year is around 160 170 km2 equivalent to 9 8 of the scs area with water depths greater than 1000 m linear relationships are found between eddy lifetime and eddy magnitude and between eddy vertical extent and eddy magnitude showing that strong eddies usually last longer and penetrate deeper than weak ones interannual variations in eddy numbers and the total eddy occupied area indicate that eddy activities in the scs do not directly correspond to the el nino southern oscillation events the wind stress curls are thought to be an important but not the only mechanism of eddy genesis in the scs

oceanic eddy formation and propagation southwest of taiwan 1 oceanic eddies are active and energetic southwest of taiwan the formation and propagation of eddies in this area were investigated using 17 year satellite altimeter data cyclonic eddies ces and anticyclonic eddies aces often coexisted but there were more ces than aces generated during the period from october 1992 to october 2009 aces were stronger and in general lived longer than ces aces occurred more often in winter than in other seasons while ces were more frequent in summer compared with the direct local wind forcing the kuroshio path variability appears to be a dominant factor for eddy formation in this area a conceptual model of an eddy kuroshio interaction is proposed in summer there exists an outflow northwest of luzon island and the kuroshio likely leaps across the luzon strait to the north of the outflow and left of the kuroshio axis ces are often formed which in turn induce aces to the west of ces in winter under the influence of northeasterly monsoon the kuroshio current loop kcl appears southwest of taiwan more frequently than in other seasons and aces are frequently shed from the kcl most of the aces propagate westward and as a result ces are often spun up to the east of the aces the surface south china sea outflow in summer and the kcl in winter are however likely related to the monsoons therefore the indirect effects of monsoon winds are also evident in the seasonal variations of eddy occurrence

upper layer circulation in the south china sea abstract upper layer circulation is investigated by using all available historical temperature profiles combined with climatological temperature salinity relationships in the south china sea two cyclonic eddies are revealed one is located east of vietnam called the east vietnam eddy and the other is off northwest luzon called the west luzon eddy both local ekman pumping and remotely forced basin scale circulation are important mechanisms controlling these two eddies the luzon strait transport relative to 400 db is estimated to be of the order 3 0 sv 1 sv 1 106 m3 s 1 in the mean and has a seasonal cycle dominated by the annual signal with a maximum 5 3 sv in january february and a minimum 0 2 sv in june july pressure gradients are also examined to explore the dynamics of the intrusion of waters from the pacific into the south china sea through the luzon strait

quaternary seismic stratigraphy and paleoenvironments on the continental shelf of the east china sea abstract paleoenvironments and stratigraphy have been interpreted from 4380 km of seismic profiling collected during a geological and geophysical cruise on the continental shelf of the east china sea ecs undertaken in 1996 the geophysical data are correlated with a borehole situated on the outer shelf obtained by shanghai marine geology bureau indicating that six seismic units have been preserved since oxygen isotope stage 6 including four regressive transgressive cycles seismic units u2 u3 u4 u5 u6 and u7 are interpreted to correspond respectively to oxygen isotope stages 1 3 5 and 6 implying that sediment partitioning and sequence architecture in the ecs have been controlled by glacio eustasy and global climate changes alternating continental and marine strata corresponding to glaciation and interglaciation are well preserved on the outer shelf of the ecs most of the cold environment strata which formed on the outer shelf during oxygen isotope stages 2 and 4 are too thin to be recognized on sig 600j because of resolution but corresponding erosion surfaces exist seismic unit u7 is widespread over the shelf extending to the continental edge and showing little variation in thickness as the regression was pronounced and lasted a long time thus u7 can be used as a marker layer for correlation of quaternary strata on the shelf of the ecs post glacial transgression is obvious in the ecs marine strata with varied thickness were developed in the shallow sea of the inner shelf thinning toward the outer shelf the continental shelf of the ecs has been influenced by pacific tide wave systems for a long time forming tidal sand ridge sequences developed during transgressions corresponding to oxygen isotope stages 7 or 9 5 3 and 1

using nd sr isotopes and rare earth elements to study sediment provenance of the modern radial sand ridges in the southwestern yellow sea abstract the radial sand ridges rsrs in the southwestern yellow sea off the jiangsu coast east china have been intensively studied at least since 1975 despite decades of studies the provenance of the rsr sediments remains uncertain in this study the nd sr isotopic and ree geochemical compositions of residual sediments i e the acid insoluble fractions were investigated to determine the provenance of the rsr sediments the nd isotopic composition paas normalized ree patterns and characteristic parameters e g sm nd la sm n gd yb n were merely associated with source rocks but not with particle sorting while the sr isotopic composition and ree contents of residual sediments were affected by particle sorting in addition to source rocks the onshore rsr sediments originated mainly from mixing of the fine grained sediments from various parts of the offshore rsr in terms of ree geochemical and isotopic analyses isotopic and ree geochemical comparison further reveals that the rsrs off the jiangsu coast were fed chiefly by the dispersal of surface sediments from the yangtze river mouth surface sediments from the yangtze river mouth were directly dispersed to the rsrs along the jiangsu coast and significantly affected the seaward part of the offshore rsr and the old yellow river delta area by a northward branch of the changjiang diluted freshwater plume only minor quantities of surface sediments from the modern yellow river mouth were introduced into the rsrs by the jiangsu coastal current and mainly contaminated the landward part of the offshore rsr area our findings highlighted the potential of the nd isotopes with ree geochemistry to trace the provenance of coastal sediments

geochemical constraints on the provenance of surface sediments of radial sand ridges off the jiangsu coastal zone east china abstract the jiang harbor centered radial sand ranges rsrs off the jiangsu coast are the largest in the yellow sea however the provenance of the rsrs remains controversial in this study we compare major and trace element geochemistry together with grain size and main mineral composition in carbonate free sediments from rsrs and potential sources onshore and offshore rsr sediments have different grain size characteristics onshore rsr sediments have mean grain sizes of 2 tio 2 li and partly in cs zn and some high field strength elements y zr nb pb and th while depleted in other elements offshore rsr sediments are complicated in geochemical compositions some of them have very high contents of high field strength elements and others are similar to onshore rsr sediments onshore and offshore rsr sediments have different controlling factors of geochemical compositions onshore rsr sediments are influenced by clay size minerals whereas offshore sediments are controlled by heavy minerals the identification of zr nb and ti zr vs k rb shows that onshore and offshore rsrs seem to have similar sources their differences in grain size are a result of hydrodynamic sorting the identification of elemental ratios reveals that sources of rsr sediments are variable in space and time and the inputs of the chinese rivers especially the old yellow river and the yangtze river are still dominant but the effect of the korean field cannot be neglected our findings also demonstrate the potential of elemental ratios such as zr nb and k rb as tracer pairs for provenance of sediments in the yellow sea

eddy heat and salt transports in the south china sea and their seasonal modulations this study describes characteristics of eddy turbulent heat and salt transports in the basin scale circulation as well as in the embedded mesoscale eddy found in the south china sea scs we first showed the features of turbulent heat and salt transports in mesoscale eddies using sea level anomaly sla data in situ hydrographic data and 375 argo profiles we found that the transports were horizontally variable due to asymmetric distributions of temperature and salinity anomalies and that they were vertically correlated with the thermocline and halocline depths in the eddies an existing barrier layer caused the halocline and eddy salt transport to be relatively shallow we then analyzed the transports in the basin scale circulation using an eddy diffusivity method and the sea surface height data the argo profiles and the climatological hydrographic data we found that relatively large poleward eddy heat transports occurred to the east of vietnam eov in summer and to the west of the luzon islands wol in winter while a large equatorward heat transport was located to the west of the luzon strait wls in winter the eddy salt transports were mostly similar to the heat transports but in the equatorward direction due to the fact that the mean salinity in the upper layer in the scs tended to decrease toward the equator using a 21 2 layer reduced gravity model we conducted a baroclinic instability study and showed that the baroclinic instability was critical to the seasonal variation of eddy kinetic energy eke and thus the eddy transports eov wls and wol were regions with strong baroclinic instability and thus with intensified eddy transports in the scs the combined effects of vertical velocity shear latitude and stratification determined the intensity of the baroclinic instability which intensified the eddy transports eov during summer and wls and wol during winter

three long lived anticyclonic eddies in the northern south china sea 1 in august 2007 three long lived anticyclonic eddies ace1 ace2 and ace3 were detected by both satellite sea level anomaly sla map and in situ measurements in the northern south china sea scs ace3 had a two core ace3 1 and ace3 2 structure in situ stations along 18 degrees n almost cut through the centers of ace2 and ace3 2 near the centers of ace2 and ace3 2 mean temperature and sound velocity are similar to 0 65 degrees c and similar to 2 m s 1 larger than those in their surrounding areas respectively while mean salinity and density are similar to 0 02 psu and similar to 0 15 m 3 s 1 smaller than those in their surrounding areas due to downwelling near the eddy cores the depths of maximum and minimum salinity near the eddy cores are similar to 65 m and similar to 35 m larger than those in their surrounding areas the vertical depth with current speed larger than 0 05 m s 1 can reach similar to 900 m their detailed evolutionary processes were depicted based on the variation of geostrophic currents and the trajectories of five drifting buoys ace1 lasted 147 days while ace2 and ace3 lasted 168 days and 210 days respectively ace1 had a smaller mean sla 18 8 cm in its lifetime than ace2 21 8 cm and ace3 25 3 cm but had a larger negative mean vorticity 7 7 x 10 6 s 1 than ace2 7 0 x 10 6 s 1 and ace3 7 0 x 10 6 s 1 one short lived anticyclonic eddy that split from ace2 and another one that merged with ace3 both had a smaller sla negative vorticity and diameter than ace2 and ace3 respectively

winter eddy genesis in the eastern south china sea due to orographic wind jets abstract generation of mesoscale eddies in the eastern south china sea scs in winters during august 1999 to july 2002 is studied with a reduced gravity model it is found that the orographic wind jets associated with the northeast winter monsoon and the gaps in the mountainous island chain along the eastern boundary of the scs can spin up cyclonic and anticyclonic eddies over the scs results suggest that direct wind forcing could be an important generation mechanism for the rich eddy activity in the scs and that to simulate this mechanism the resolution of the wind forcing has to be high enough to resolve the local wind jets induced by orographic effects

kuroshio intrusion and the circulation in the south china sea 1 the princeton ocean model is used to study the circulation in the south china sea scs and its seasonal transition kuroshio enters leaves the scs through the southern northern portion of the luzon strait the annually averaged net volume flux through the luzon strait is 2 sv into the scs with seasonal reversals the inflow season is from may to january with the maximum intrusion of kuroshio water reaching the western scs during fall in compensation of summertime surface offshore transport associated with coastal upwelling from february to april the net transport reverses from the scs to the pacific the intruded kuroshio often forms an anticyclonic current loop west of the luzon strait the current loop separates near the dongsha islands with the northward branch continuously feeding the south china sea warm current scswc near the shelf break and the westward branch becoming the south china sea branch of kuroshio on the slope which is most apparent in the fall the scswc appears from december to february on the seaward side of the shelf break flowing eastward against the prevailing wind diagnosis shows that the onshore ekman transport due to northeasterly monsoon generates upwelling when moving upslope and the particular distributions of the density and sea level associated with the cross shelf motion supports the scswc

sediment supply to the continental shelf by the major rivers of china the yalu luan the yellow changjiang and pearl rivers discharge 90 of china s total annual input of 20 14 10 8 t of sediment to the sea this huge volume of sediment is deposited in the river mouths and in the vicinity of the inner shelves in the form of deltas or submarine sandy ridges depending upon the dominant processes or dynamics of the area even though the continental shelves of the china seas were coastal plains during the late pleistocene modern river sediments rarely extend to the outer shelves except in response to changes in sea level

mesoscale eddies in the northern south china sea a fine grid resolution model with realistic bathymetry and forcing has been developed to study the characteristics of the mesoscale eddies for the northern south china sea scs the scs model derives its open boundary conditions from a larger scale model which minimizes errors related to the uncertainty of the kuroshio intrusion at the open boundaries the model results are consistent with previous observations model sea surface height anomaly demonstrates that the hydrography and circulation in the northern scs are modulated by westward propagating mesoscale eddies originating in the vicinity of the luzon strait this explains the observed intra seasonal fluctuations at the southeast asian time series study seats station the mesoscale eddies have the same propagation speed as baroclinic rossby waves 0 1 ms 1 the periods of eddy shedding estimated from strouhal number are around 40 50 days in december and 80 120 days in august respectively the seasonal variability of the kuroshio intrusion results in more eddies in winter than in summer r 2007 elsevier ltd all rights reserved

a gis based method for depicting the characteristics of mesoscale eddies a case study in the northern south china sea the paper presents a geographical information system gis based method for depicting the characteristics particularly the internal structures and evolutionary processes of mesoscale eddies this was done by examining topologic relations among closed sea surface height ssh contours that were reconstructed from the naval research laboratory navy layered ocean model nlom different scenarios of the topological relations among the contour lines permitted the identification of the outermost outline of eddies and the depiction of the number of cores in each mesoscale oceanic eddy with full consideration of the internal structure of the eddies we then reconstructed the evolutionary processes of these eddies and the results were compared with empirical observations on three long lived mesoscale eddies in the northern south china sea scs tracking results were similar thereby validating our method as being efficient and robust in reconstructing mesoscale ocean eddies especially their evolutionary processes based on their internal structures

seismic geomorphology architecture and genesis of miocene shelf sand ridges in the pearl river mouth basin northern south china sea abstract multiple stages of large scale shelf sand ridges including the shoreface attached and the offshore types have developed in the miocene successions on the mid shelf region of the pear river mouth basin northern south china sea utilizing a high quality 3d seismic data set accompanying 2d seismic profiles and well logs the morphology architecture and genesis of these shelf sand ridges have been systematically investigated in this study the ridges are of very large scale with the largest one having a maximum height of 64 m a width of more than 20 km and a length of 37 km within the 3d survey area being mound shaped they also display obvious asymmetry character with the ridge crest preferentially located on the se side three main internal components including the ridge front central ridge and the ridge tail have been recognized through careful anatomy analysis of the two most well imaged ridges each displaying distinct expressions on seismic amplitudes and geometries in the plan view most of the shelf sand ridges are generally ne sw oriented and widening to the sw direction scouring features can also be clearly observed along the sw direction including scour depressions and linear sandy remnants on well logs the shelf sand ridges are represented by an overall coarsening upward pattern intervals with blocky sandstones are preferentially present on higher locations due to a differential winnowing process controlled by shelf topography plenty of evidence indicates that these ridges were primarily formed by the reworking of forced regressive or lowstand deltaic deposits under a persistent southwesterly flowing current during the subsequent transgression this very current is a composite one which is speculated to consist of winter oceanic current scsbk south china sea branch of kuroshio intrusion onto the shelf and internal waves propagating from the luzon strait tidal currents might have contributed to the se growth of the ridge in response to the reglaciation of antarctic ice sheet and the closure of pacific indian ocean seaway in the middle miocene the intensification of the north pacific western boundary current was considered to have potential links to the initiation of the shelf sand ridges at 12 ma the development of shelf ridges was terminated and replaced by rapid deltaic progradation at 5 5 ma

generation and life cycle of the dipole in the south china sea summer circulation 1 the south china sea scs summer circulation often has a dipole structure associated with an eastward jet appearing off central vietnam the dipole has an anticyclonic eddy ae south of the jet and a cyclonic eddy ce north of it the life cycle of the dipole structure is analyzed using satellite altimetry data and a reduced gravity model on average the dipole structure begins in june peaks in strength in august or september and disappears in october the dipole evolution lags behind the basin scale wind by about 40 days and 40 days are exactly what it takes for baroclinic planetary waves to cross the southern scs our results show that the vorticity transports from the nonlinear effect of the western boundary currents are crucial for the generation of the dipole structure in addition the strength and direction of the offshore wind jet also play a significant role in determining the magnitudes and the core positions of the two concomitant eddies

the sand ridge field of the south yellow sea origin by river sea interaction abstract the origin of a large field of sand ridges offshore from the north jiangsu coast in the south yellow sea has been investigated on the basis of bathymetry seabed samples high resolution seismic profiles and 31 to 71 m deep boreholes sediment composition including heavy minerals and clay minerals sampled from surface sediments shows that most of the sand was derived from the changjiang yangtze river but in the northern part of the field particularly the clay came from the huanghe yellow river seismic profiles show late pleistocene distributary channels of the ancient changjiang river underlying much of the southern part of the sand ridge field the holocene transgression cut a widespread ravinement surface reworking abundant late pleistocene sandy sediment the available sand was reworked by tidal currents into large ridges the location of the ridges is strongly influenced by relict channels in the southern part of the field and by tidal currents in the northern and especially the northeastern part of the field resulting in a radiating ridge pattern these ridges provide an example of the evolution of a large scale geomorphic feature resulting from river sea interaction in which climatic and sea level changes played an important role

circulations and eddies over the south china sea derived from topex poseidon altimetry topex poseidon t p altimeter data were used to derive time varying circulation and eddies over the south china sea scs for 1993 1999 large variabilities of sea surface heights and dense distribution of eddies were found to occur along a band across the scs basin a cross over method is introduced to compute pointwise velocity components the t p derived circula tions and eddies are consistent with the drifter results from the world ocean circulation experi ment data center 1 because of monsoons the scs circulation is largely cyclonic in winter is largely anticyclonic in summer and is modulated interannually by el nifio southern oscillation 2 both cold and warm core eddies were found in the waters east of vietnam west of luzon and west of the luzon strait but their times of occurrence and the way they evolved vary interannually 3 the reversal of the alongshore currents east of vietnam was in complete accordance with wind stress the locations and kinematic properties of eddies over scs were estimated by the least squares method the averaged vorticities of the cold and warm core eddies are 1 684x 10 6 and 1 738x l0 6 tad s respectively and the shearing and stretching deformations are one thousandth of the vorticities the angular velocity of eddy decreases with increasing radius coherence analy sis suggests that the interannual and seasonal variations of circulation are largely due to wind stress and the semi annual variation is largely due to wind stress curl the angular velocities of eddies over the central scs basin are coherent with the magnitudes and signs of wind stress curl the seasonal steric anomaly was also computed and its spatial pattern and scale are quite different from those of circulation and eddy

curie temperatures of titanomagnetite in ignimbrites effects of emplacement temperatures cooling rates exsolution and cation ordering pumices ashes and tuffs from mt st helens and from novarupta contain two principal forms of titanomagnetite homogeneous grains with curie temperatures in the range 350 500 c and oxyexsolved grains with similar bulk composition containing ilmenite lamellae and having curie temperatures above 500 c thermomagnetic analyses and isothermal annealing experiments in combination with stratigraphic settings and thermal models show that emplacement temperatures and cooling history may have affected the relative proportions of homogeneous and exsolved grains and have clearly had a strong influence on the curie temperature of the homogeneous phase the exsolved grains are most common where emplacement temperatures exceeded 600 c and in laboratory experiments heating to over 600 c in air causes the homogeneous titanomagnetites to oxyexsolve rapidly where emplacement temperatures were lower curie temperatures of the homogeneous grains are systematically related to overburden thickness and cooling timescales and thermomagnetic curves are generally irreversible with lower curie temperatures measured during cooling but little or no change is observed in room temperature susceptibility we interpret this irreversible behavior as reflecting variations in the degree of cation ordering in the titanomagnetites although we cannot conclusively rule out an alternative interpretation involving fine scale subsolvus unmixing short range ordering within the octahedral sites may play a key role in the observed phenomena changes in the curie temperature have important implications for the acquisition stabilization and retention of natural remanence and may in some cases enable quantification of the emplacement temperatures or cooling rates of volcanic units containing homogeneous titanomagnetites

evolution of holocene ebb tidal clinoform off the shandong peninsula on east china sea shelf abstract studies of mud clinoforms in marine environments have documented a wide diversity in the behavior of depositional systems on continental margins with different sedimentary dynamics and spatiotemporal characteristics the mud clinoform associated with the bohia strait off the shandong peninsula has attracted the attention of marine geologists and sedimentologists after systematically reviewing the climatology oceanography and sedimentology as well as postglacial sea level change on the east china shelf and the changes in the strength of the east asian winter monsoon the aim of this paper is to provide a comprehensive explanation for the evolution of the clinoform and to establish a model of a tidal current controlled mud clinoform on the seaward side of a tidal inlet the bohai strait is a large tidal inlet linking the bohai sea a large bay and the yellow sea an open sea the yellow river delivers large amounts of fine grained sediments to the southern bohai sea under the action of the east asian monsoon the speed and duration of ebb currents are higher and longer than those of the flood currents in the southern bohai strait the stronger nnw wind in winter causes more powerful waves on the southern bohai sea inducing high suspended sediment concentrations ssc these suspended sediments are transported by ebb currents from the bohai sea to the yellow sea through the southern bohai strait particularly in winter and then deposited on the seaward side of the strait forming the ebb tidal clinoform off the shandong peninsula the evolution of the ebb tidal clinoform is controlled mainly by historical changes in the strength of the east asian winter monsoon and the spatial extent of the bohai sea the clinoform has been accumulating since 9600 cal bp it formed mainly from 8200 to 5000 cal bp when a strong east asian winter monsoon produced relatively strong ebb currents with high ssc in the southern bohai strait whilst the extent of the bohai sea was large the ebb currents from 9600 to 8200 cal a bp and during the last 5000 years were comparatively weak primarily as a result of the small area of the bohai sea in the former time interval and a weak east asian winter monsoon in the latter time interval these changes in the area of the bohai sea and monsoon strength also caused the deposition rates within this clinoform to differ from the rates during the period 8200 to 5000 cal bp i e when the area of the bohai sea was large and the east asian winter monsoon was relatively strong from 8200 to 5000 cal bp the deposition rates were 4 4 5 8 times the rates during the past 5000 years whilst it has been argued that the development of the clinoform could be associated with the evolution of the yellow river delta this hypothesis is not consistent with the ages of these features a significant portion of the clinoform formed before 7000 cal bp the point at which delta development was initiated the yellow river delta on the west coast of the bohai sea and the clinoform off the shandong peninsula are not coeval and do not belong to a compound clinoform system it is concluded that the clinoform off the shandong peninsula is substantially a large mud ebb tidal delta on the seaward side of the bohai strait the clinoform on the seaward side of the bohai strait and the flood tidal sand ridges and sand sheet on the landward side of the bohai strait constitute a complete tidal depositional system on both sides of this large inlet this new insight may enhance the understanding of the formation of mud clinoforms on other shelf environments and facilitate the analysis of tidal zone palaeofacies

the vertical structure of eddy heat transport simulated by an eddy resolving ogcm abstract the vertical structure of meridional eddy heat transport eht of the north pacific was investigated by analyzing the results from an eddy resolving ocean general circulation model ogcm with a horizontal resolution of while comparing with previous simulation results and observation data in particular the spatial and temporal variation of the effective depth of eht he was investigated which is defined by the depth integrated eht d eht divided by eht at the surface it was found that the annual mean value of he is proportional to the eddy kinetic energy eke level at the surface in general however its seasonal variation is controlled by the mixed layer depth mld in the extratropical ocean 20 n examination of the simulated eddy structures reveals that the temperature associated with mesoscale eddies is radically modified by the surface forcing in the mixed layer while the velocity field is not and the consequent enhanced misalignment of temperature and velocity anomalies leads to

the seasonal variation of the intrusion of the philippine sea water into the south china sea the seasonal variation of the intrusion of the philippine sea water into the south china sea was studied by analyzing the historical hydrographic station data in the northern south china sea and the philippine sea water masses at 150 200 and 250 m were classified by discriminant analysis according to their temperature salinity characteristics at each depth most water in the study region was classified into two groups representing the philippine sea water and the south china sea water respectively the geographic distribution of water masses in the south china sea shows that the philippine sea water was present along the continental margin south of china between october and january a westward current in the northern south china sea in winter was inferred from the distribution of the intrusion water

evolution of sedimentary mode since pleistocene in the central south yellow sea china based on seismic stratigraphy analysis abstract in order to investigate the distribution development and evolution of the strata in the south yellow sea basin sysb seismic and core data were analyzed fourteen 14 reflecting interfaces and 13 seismic units are identified and a stratigraphic framework since 1 81 ma b p is established the deposition rate has changed since 126 ka b p the stratigraphic model shows that the sysb responded to sea level changes during the same period 126 ka b p which suggests a model change of the development of regional strata between 1 81 ma b p and 126 ka b p the zhejiang minnan uplift zmu obstructed the intrusion of seawater into the sysb which is the main factor responsible for the development of regional strata while the sea level fluctuation and fluvial material input have dominated the formation of the strata since 126 ka b p

distribution pattern and controlling factors of heavy mineral assemblages in surficial seafloor sediments offshore of the eastern shandong peninsula yellow sea the source and processes controlling the deposition of the sand fraction of muddy seafloor sediments remain poorly understood surficial seafloor sediments were collected offshore of the eastern shandong peninsula and were analyzed regarding their detrital heavy mineral constituents and grain size distributions to determine their spatial distribution patterns sand fraction provenance and transport pathways five sediment types were identified in the study area clayey silt silt sandy silt silty sand and sand each of these sediment types displayed distinct grain size parameters of their corresponding sand fractions moreover three statistical clusters of sand grains were identified suggesting variations in provenances and sedimentary processes from one cluster to the next twenty five species of detrital heavy minerals in the sand fraction were identified and then assigned to four categories based on their mineral stability i e ultrastable stable moderately stable and unstable the sandy sediments were enriched in ultrastable and stable heavy minerals indicating that these sand grains mostly originated from coastal erosion of granitic and or metamorphic rocks in contrast the muddy sediments were characterized by unstable heavy minerals dominated by hornblende and epidote the results of principal component analysis further suggested that these sand grains are similar in terms of their provenance coastal erosion but have undergone complex sedimentary processes relative sea level changes during the late quaternary caused shifts in the sediment sources and supplies which were the primary factors controlling the grain sizes of the sand fractions and heavy mineral assemblages in the surficial sediments of the study area

exploratory morphodynamic modeling of the evolution of the jiangsu coast china since 1855 contributions of old yellow river derived sediment abstract in this study we aim to investigate the overall morphological evolution of the jiangsu coast after 1855 when the yellow river shifted northward we focus on fine sediment transport between two large scale geomorphological units i e the abandoned yellow river delta ayd and the radial sand ridges rsrs an existing morphodynamic model which was established for reproducing the development of the ayd before 1855 is modified and extended in addition to the tidal forcing waves and human interventions i e revetments are considered in the model the model results are compared with the existing data both the evolution trend of the jiangsu coast and the spatial distribution of the offshore shoals show good agreement the simulated fine sediment depositions in different periods are consistent with the geological measurements the results reveal that the old yellow river derived sediment not only contributes to the sedimentation in the rsrs but can also be transported to the adjacent zones especially farther south southeast moreover the spatial distribution of fine sediment deposits varies in the rsrs the different sedimentary environments in the dongsha and tiaozini ridges result in significant grain size differences in these two neighboring ridges a sensitivity analysis indicates that tides play a key role in dominating the long term morphological evolution of the jiangsu coast and the total erosion from the ayd on smaller scales the effect of revetments built since the 1930s on the evolution of the nearshore zone and the effect of wind waves on the erosion of offshore shoals are relatively important the effect of a gradual coarsening process of bottom sediment along the jiangsu coast which may be due to continuous fine sediment removal is identified fine sediment depositions in the tiaozini ridge and in the northern offshore zone of the rsrs are relatively more sensitive to the coarsening trend of bottom sediment than other areas

mesoscale eddies in the northwestern subtropical pacific ocean statistical characteristics and three dimensional structures mesoscale eddy properties in the northwestern subtropical pacific ocean are investigated by analyzing 22 567 cyclonic eddies ces and 26 365 anticyclonic eddies aes detected from 19 year altimetric sea level records eddy occurrence frequency and kinetic energy are prevailingly high in the subtropical countercurrent zonal band between 19 degrees n and 26 degrees n and further elevated near the luzon taiwan coast a general superiority of aes is observed at most latitudes except between 19 degrees n and 22 degrees n where the ce number is larger the modal radius and mean lifespan of the ces aes are 134km and 11 2weeks 121km and 10 9weeks respectively after generation most eddies propagate westward with a mean speed of 7 2cms 1 and deflect northward following the kuroshio along the luzon taiwan coast three dimensional eddy structures are further explored with composite eddy images in five subregions constructed by surfacing argo temperature salinity data into altimeter detected eddy areas due to the existence of mode waters in the main thermocline eddy induced temperature anomaly exhibits a double core vertical structure which is especially evident in ce images because of the vertical water mass distribution salinity anomaly features a sandwich like pattern which is more evident in ae images also revealed is the significant structure difference in these five subregions eddies are greatly intensified as they approach the western boundary inducing larger temperature and salinity anomalies and influencing deeper ocean along the luzon taiwan coast aes are preferentially strengthened by the northward background flow

silicon isotope constraints on sources and utilization of silicic acid in the northern south china sea the stable silicon isotopic composition 30si of waters and diatoms has increasingly been used to investigate the biogeochemical cycling of si in the major ocean basins here we present the first si isotope data set from the northern south china sea nscs a large marginal sea system in the western north pacific to examine sources and utilization of silicic acid si oh 4 during two cruises in july august 2009 summer and january 2010 winter samples for isotope measurements of dissolved si oh 4 30sisi oh 4 and of biogenic silica 30sibsi in suspended particles were collected along a transect perpendicular to the coast from the inner shelf to the deep water slope as well as at the south east asian time series study seats station located in the nscs basin surface 30sisi oh 4 generally increased from values 2 3 on the inner shelf to 2 8 above the deep basin suggesting an increasing utilization of dissolved si oh 4 reflecting the transition from eutrophic to oligotrophic conditions the 30sibsi values were systematically lower than the corresponding 30sisi oh 4 in the euphotic zone above 100 m on the shelf and slope in contrast at station seats in the nscs basin 30sibsi signatures in both seasons were within error equal to 30sisi oh 4 in the surface mixed layer above 50 m and 30sibsi in waters below were significantly higher than the corresponding 30sisi oh 4 by comparing the field data with the si isotope fractionation revealed by the rayleigh or the steady state models we demonstrate the existence of variable si oh 4 origins in different areas of the nscs surface waters on the inner shelf were largely fed by nutrients from the pearl river input while the primary source of si oh 4 for the euphotic zone on the outer shelf and slope was upwelling or vertical mixing from underlying waters the si oh 4 in the surface mixed layer of the nscs basin might have originated from horizontal mixing with other highly fractionated surface waters as a consequence the si isotope dynamics in the nscs are largely controlled by variable biological fractionation of si in waters from different sources with different initial si isotopic compositions rather than any single source water

the eddy mean flow interaction and the intrusion of western boundary current into the south china sea type basin in an idealized model abstractin this paper an ideal model of the role of mesoscale eddies in the kuroshio intruding into the south china sea scs is developed which represents the northwestern pacific and the scs as two rectangular basins connected by a gap in the case of considering only intrinsic ocean variability a time dependent western boundary current wbc driven by steady wind is modeled under both eddy resolving and noneddy resolving resolutions almost all simulated wbcs intrude into the adjacent sea in the form of the loop current with multiple state transitions and eddy shedding processes which have aperiodic variations on intraseasonal or interannual scales determined by the eddy induced wbc variation for the parameters considered in this paper the wbc intrusion exhibits a 30 90 day cycle in the presence of the subgrid scale eddy forcing ssef but a 300 500 day cycle in the absence of ssef moreover the roles of the grid scale and subgrid scale eddies in the wbc intrusion are studied by using the dynam

mesoscale dongsha cyclonic eddy in the northern south china sea by drifter and satellite observations 1 near the center of the northern south china sea nscs the dongsha atoll is situated on the continental slope that runs from taiwan to hainan a mesoscale cyclonic eddy south or southwest of dongsha seems to appear annually and has been identified as the dongsha cyclonic eddy dce historical drifter 1988 2005 and satellite altimeter 2000 2005 data were adopted to study the variations to and characteristics of the dce some typical features were derived such as mean tangential speed of 20 cm s moving speed of 8 km d i e 9 cm s eddy size of 22 103 km2 center sea surface lowering height difference dif of 6 cm and angular velocity of 9 d mean tangential speeds of 12 16 cm s in late spring and summer are slower than those of 16 31 cm s in winter and early spring moving speeds are of the order of the rossby wave at nscs latitudes variations in the time series of eddy size and dif are generally similar and show a positive linear relation between them the dce starts near dongsha and moves southwestward along the continental slope at a depth of 1000 2000 m the eddy peaks with maximum eddy size and dif when reaching 114 e and then diminishes south of hainan because of trapping of the underwater bay formed by the continental slope the dce typically exists 1 2 times per year and lasts 1 3 months roughly 90 of observed dces formed in winter or spring a unique dce was identified in the summer of 2000 and lasted for over 4 months its birth was associated with typhoon kai tak the positive linear relationship between eddy size and dif in this case was unique before reaching 114 e and then returned to the typical relationship of other dces the dif of this unique dce attained the highest of 24 cm right at the climax longitude according to avhhr and seawifs images such a dce is associated with a core of which sea surface temperature is 2 c lower and chlorophyll a concentration is 0 1 mg m3 higher than those of surrounding seas migration of the dce may be linked to tuna fish farms in the nscs

kuroshio intrusion into the south china sea a review the kuroshio carrying the northwestern pacific water intrudes into the south china sea scs through the luzon strait significantly affecting the temperature salinity circulation and eddy generation in the scs thus the kuroshio intrusion makes important contributions to the momentum heat and salt budgets in the scs in the past decades much work has been done on the kuroshio intrusion this paper reviews past efforts and summarizes our current understanding of the kuroshio intruding processes from observational evidence laboratory results theoretical analyses and a range of numerical model simulations in addition discrepancies between results simulated by models as well as those between simulations and observations are presented specifically this paper addresses the following topics 1 different types of the kuroshio intrusion into the scs and their identification 2 vertical structure of the kuroshio in the luzon strait 3 an overview of the luzon strait transport resulting from observations and numerical model simulations 4 seasonal and interannual variations of the kuroshio intrusion as well as eddy generation due to the kuroshio path variation and 5 dynamical mechanisms e g wind forcing interbasin pressure gradient beta effect and hysteresis potential vorticity eddy activity controlling the kuroshio intrusion into the scs finally several future research topics for gaining a better understanding of the kuroshio intruding processes are suggested c 2014 the authors published by elsevier ltd

late quaternary evolution of the yellow east china sea tidal regime and its impacts on sediments dispersal and seafloor morphology the evolution of a tidal current field in the yellow sea and east china sea yecs in response to the sea level rise since the last glacial maximum lgm was investigated using a two dimensional tidal model with special attention to changes in the sedimentary environment of the continental shelf region it was found that tidal currents on the yecs shelf have generally been semi diurnal throughout the post glacial stages with f ratio index of diurnal inequality and s2 m2 ratio index of spring neap cycle remaining similar to present on the other hand the spatial distribution of the tidal bottom stress associated with m2 and m4 tidal currents changed greatly during the transgression as the sea level rose two core regions showing high bottom stress values migrated shoreward from cheju island toward the west coast of korea and along the retreat path of the paleo changjiang estuary distribution of extremely intense tidal bottom stress suggested that intense tidal reworking may have occurred at sea levels from 90 to 45 m in the southeast yellow sea and at 75 to 60 m off the paleo changjiang estuary the latter of which agreed with the timing of a large terrigenous organic c flux observed on the shelf slope distribution of slightly weaker bottom stress indicated that the sand ridges off the changjiang estuary and in the southeast yellow sea also might have formed at during those periods on the other hand when the sea level was between 45 and 15 m the tidal bottom stress was generally not strong enough to invoke significant reworking even though the stress intensity may be stronger than present correlation with modern and relict sedimentary features suggested that the tidal process have played a significant role on the reworking and deposition of sediments on the yecs shelf

exploratory morphodynamic hindcast of the evolution of the abandoned yellow river delta 1578 1855 ce abstract the abandoned yellow river delta ayd which formed when the yellow river flowed into the southern yellow sea between 1128 and 1855 ce is a representative example of the sensitivity of deltas to modifications in their environments in this study we established a process based morphodynamic model to explore the morphological evolution of one such large scale fine grained delta the ayd before 1855 ce the uncertainties in the model settings which are inevitable when historical data are insufficient were assessed together with the corresponding influences on the evolution of the deltaic system by considering a series of scenarios the results indicate that the strength of local tidal forcing is the key factor that determines the shape and evolutionary trend of the delta sediment input discharge and the slope of the initial coastal profile have a considerable effect on the overall size of the delta and the relative ratio between subaerial and subaqueous parts of the delta respectively based on the evaluation of the uncertainties and a comparison with historical maps the simulated ayd was evaluated to be reliable through an analysis of the temporal delta evolution and residual sediment transport the morphological evolution of the ayd before 1855 ce was investigated the southern delta grew as the shoals merged with the mainland which is in agreement with an existing hypothesis zhang 1984 whereas the accretion of the northern delta was independent from the shoals in the northern part additionally suggestions are made regarding the distribution of the ayd at the end of its progradation stage which provides fundamental information for analyzing subsequent erosion processes since 1855 ce this study differs from existing studies on the ayd which are all based on geological approaches it provides insight into the evolution of the ayd through an alternative means viz a process based morphodynamic modeling approach

radiocarbon calibration curve spanning 0 to 50 000 years bp based on paired 230 th 234 u 238 u and 14 c dates on pristine corals abstract radiocarbon dating is the most widely used dating technique in the world recent advances in accelerator mass spectrometry ams and sample preparation techniques have reduced the sample size requirements by a factor of 1000 and decreased the measurement time from weeks to minutes today it is estimated that more than 90 percent of all measurements made on accelerator mass spectrometers are for radiocarbon age dates the production of 14 c in the atmosphere varies through time due to changes in the earth s geomagnetic field intensity and in its concentration which is regulated by the carbon cycle as a result of these two variables a radiocarbon age is not equivalent to a calendar age four decades of joint research by the dendrochronology and radiocarbon communities have produced a radiocarbon calibration data set of remarkable precision and accuracy extending from the present to approximately 12 000 calendar years before present this paper presents high precision paired 230 th 234 u 238 u and 14 c age determinations on pristine coral samples that enable us to extend the radiocarbon calibration curve from 12 000 to 50 000 years before present we developed a statistical model to properly estimate sample age conversion from radiocarbon years to calendar years taking full account of combined errors in input ages and calibration uncertainties our radiocarbon calibration program is publicly accessible at http www radiocarbon ldeo columbia edu along with full documentation of the samples data and our statistical calibration model

discrimination of geochemical compositions between the changjiang and the huanghe sediments and its application for the identification of sediment source in the jiangsu coastal plain china concentrations of 25 elements in the fine grained fraction 6 63 wm of bottom sediments of the changjiang and the huanghe were determined to characterize the geochemical compositions of each riverine origin most of the elements except for alkali and alkaline earth elements na ca sr and ba are highly enriched in the changjiang sediments compared to those in the huanghe sediments differences in source rocks and weathering mechanisms between the two drainage basins are the major factors controlling those compositional characteristics the provenance index of core sediments from the northern jiangsu coastal plain calculated with nine elements with distinct compositional differences between both river sediments indicates that the changjiang had prevailed in the coastal plain sedimentation during the early stage of holocene while the huanghe dominated over the area during the late holocene however neither of the signatures of the modern changjiang and huanghe derived sediments is remarkable in the present day coastal plain 5 2002 elsevier science b v all rights reserved

silicon self diffusion in single crystal natural quartz and feldspar abstract silicon diffusion was measured in natural quartz and anorthitic feldspar under dry low pressure 0 1 mpa conditions using a 30 si tracer sources of diffusant consisted of 30 si enriched silica powder for experiments on quartz and microcrystalline 30 si doped synthetic feldspar of composition comparable to the feldspar specimens distributions of 30 si were measured with rutherford backscattering spectrometry and nuclear reaction analysis using the reaction 30 si p 31 p the following arrhenius relations were obtained for anneals at 1 atm in air for quartz transport normal to c d qtz c 7 97 10 6 exp 447 31 kj mol 1 rt m 2 s 1 transport parallel to c d qtz c 6 40 10 6 exp 443 22 kj mol 1 rt m 2 s 1 for anorthitic feldspar an 93 d an 3 79 10 7 exp 465 50 kj mol 1 rt m 2 s 1 the few successful experiments on diffusion in plagioclase of more albitic compositions an 67 and an 23 reveal si diffusivities a few orders of magnitude faster than that in the anorthite the results for these feldspars bracket the determination of caal nasi interdiffusion under dry conditions by grove et al geochim cosmochim acta 48 1984 2113 2121 suggesting that the rate limiting process is indeed si diffusion si diffusion in quartz under more reducing conditions nno is slightly slower by about half an order of magnitude than diffusion in samples annealed in air this is consistent with observations made in studies of synthetic quartz bejina and jaoul phys earth planet inter 50 1988 240 250

enhanced crystal fabric analysis of a lava flow sample by neutron texture diffraction a case study from the castello d ischia dome 1 the crystal fabric of a lava has been analyzed for the first time by neutron texture diffraction in this study we quantitatively investigate the crystallographic preferred orientation of feldspars in the castello d ischia ischia island italy trachytic exogenous dome the crystallographic preferred orientation was measured with the monochromatic neutron texture diffractometer sv7 at the forschungszentrum julich in germany and a rietveld refinement was applied to the sum diffraction pattern the complementary thin section analysis showed that the three dimensional crystal shape and the corresponding shape preferred orientation are in agreement with the quantitative orientation distributions of the neutron texture data the 0k0 crystallographic planes of the feldspars are roughly parallel to the local flow bands whereas the other corresponding pole figures show that a pivotal rotation of the anorthoclase and sanidine crystals was active during the emplacement of this lava dome in combination with scanning electron microscopy investigations electron probe microanalysis xrf and x ray diffraction the rietveld refinement of the neutron diffraction data indicates a slow cooling dynamic on the order of several months during their crystallization under subaerial conditions results attained here demonstrate that neutron texture diffraction is a powerful tool that can be applied to lava flows

sediment characteristics floods and heavy metal pollution recorded in an overbank core from the lower reaches of the yangtze river overbank sediments contain abundant information about floods paleoenvironmental changes and recent pollution history of a river basin for the purpose of understanding modern overbank sediments and their environmental significance this multidisciplinary study sampled a core from the overbank and a short core from the overbank outcrop at nanjing in the lower reaches of the yangtze river the overbank deposit comprises fine grained discontinuous strata including silt sandy silt silty sand and sand layers field and laboratory observations indicated that the overbank sediment contained a series of layers of sandy silt coupled with thin silty sand layers each a few millimeters thick which formed muddy layers that were dozens of centimeters thick between the muddy layers were coarser sand layers grain size analyses 137cs dating and heavy metal measurements contained information on flood events and pollution history over the past 60 years the coarser sand layers corresponded with severe floods in 1954 and 1983 between the two severe floods the study area experienced an overbank building stage from the 1990s to the early 2000s the overbank sedimentation rate declined reflecting human activities especially the dams in the yangtze river basin that trapped more sediment the average heavy metal concentrations in the overbank sediments are higher than the background levels for suspended sediment in the yangtze river heavy metals in overbank sediments were assessed by enrichment factors and sediment quality assessment values for freshwater sediment cr and ni values were high especially from the early 1980s to the early 2000s the impacts of floods economic development and environmental management on these heavy metal variations were discussed

simulations of internal solitary wave interactions with mesoscale eddies in the northeastern south china sea abstractwith the combined analysis of synthetic aperture radar image and satellite altimeter data collected in the northeastern south china sea scs this study found one type of distorted phenomenon of internal solitary wave isw with the long front caused by the oceanic mesoscale eddy motivated by these satellite observations the authors carried out numerical experiments using the fully nonhydrostatic and nonlinear mitgcm to investigate the perturbation of isws by an isolated cyclonic or anticyclonic eddy the results show that the isw front is distorted by these oceanic eddies due to the retardation and acceleration effects at their two sides the isw energy along the front is focused onto scattered from the wave fragment where a concave convex pattern is formed and the previously accumulated energy in the focusing region is gradually released after the isw propagates away from the eddies the isw amplitude is modulated greatly by the eddies due to the energy redistribution along the front se

multibeam bathymetric investigations of the morphology of sand ridges and associated bedforms and their relation to storm processes sable island bank scotian shelf abstract storm formed sand ridges are important morphologic features occurring on many continental shelves of the world our understanding of the morphology migration and the controlling processes over this type of sand ridges under different environmental settings is still limited in the present study an integrated approach of combining multibeam bathymetry survey seabed sampling sidescan seismic surveys and seabed instrumentation measurements was used to characterize the surficial geology and morphology of offshore sand ridges on sable island bank scotian shelf and to evaluate the relationship between sand ridge morphology migration and the storm processes on this storm dominated outer shelf bank multibeam data obtained at selected sites demonstrated the series of ne sw oriented sand ridges with an average height of 4 3 m and wavelength of 1 5 km sand ridges attain maximum spacing height and steepness in the intermediate depths sand ridge size and steepness also decrease from west to east and this decrease is correlated with decreasing dynamic condition sediment grain size and depth sand ridge profiles show weak easterly asymmetry this morphological asymmetry augments the sediment texture and grain size asymmetry to suggest eastward long term sand ridge migration and net sediment transport in the study area sand ridge asymmetry also shows strong local variation and the number of sand ridges asymmetric to the west is nearly equal to that asymmetric to the east the likely cause is the nearly equal number of major storms passing to the south versus to the north of the island so that the westerly and easterly peak storm driven currents associated with these storm path scenarios affect equally the sand ridges on sable island bank a suite of smaller bedforms were found superimposed on the sand ridges sand waves widely superimposed on both flanks of sand ridges mixed 2d and 3d megaripples commonly occurring in the sand ridge troughs and on the lower western flanks and large wave ripples ubiquitously found in the troughs of all megaripples surficial sediment is coarsest coarse sand with shell fragments in the sand ridge trough and becomes progressively finer eastward toward the sand ridge crest and down the eastern flank while best sorting occurs near the sand ridge crest box cores collected across sand ridges reveal characteristic storm event bed structure that reflects the development and migration of bedforms with the evolution of storms

eddy effects on sea surface temperature and sea surface wind in the continental slope region of the northern south china sea 1 warm and cold sea surface temperature sst tongues on weather timescales are detected in the continental slope region of the northern south china sea nscs and their effects on sea surface wind are studied using satellite observations crossing the basin scale sst front geostrophic currents between cyclonic and anticyclonic eddies induce the warm and cold sst tongues during the northeast monsoon corresponding to the warm and cold sst tongues the sea surface wind is highly uneven in spatial distribution its speed is faster slower over the warm cold sst tongues than the surrounding areas the sst and sea surface wind non uniformity in space shifts southwestward with eddy motion along the continental slope these new findings from satellite observations give us an opportunity to study oceanic eddy s roles in ocean atmosphere interaction on weather timescales

mesoscale eddies in the south china sea observed with altimeter data 1 a composite time series 1993 2000 of sea surface height anomaly from several satellites is used to identify eddies in the south china sea scs the eddy lifetime radius strength and straight line travel distance are estimated altogether 58 anticyclonic eddies and 28 cyclonic eddies are identified for this period they are grouped into four geographical zones according to known eddy generation mechanisms and their statistics are discussed accordingly our geographical classification is a useful first step in gaining an overview of their generation

episodes of tidally forced swale erosion on the inner shelf interspersed with millennial fluviodeltaic progradational interludes insights from northern bohai bay china abstract erosional swales are common features on the seafloor with vigorous bottom flow s on continental shelves with energetical tidal currents and limited river discharge the initiation and evolution of tidally induced erosional depressions and bedforms have been extensively discussed but little is known about the evolution of such features when interspersed with active deltaic progradation over millennial timescales a recent boomer seismic investigation revealed a swale erosional complex within and proximal to the subaqueous delta in northern bohai bay nbhb china providing us with an opportunity to investigate such features here using the same seismic dataset we analyze the morphology reflective characteristics and evolution of the erosional and depositional structures the erosional swale complex consists of two episodes of tidally induced incised channels within a northern progradational system nps located in the northernmost bohai bay and prograde to the southeast followed by an episode of extensive trough and bump formation negative and positive relief within the middle and northern nbhb which are also erosional features these features are all highly lineated oriented wnw ese we attribute their formation to the similarly oriented tidal flows in this region the multi episode evolution of the swale erosional complex is predominately associated with progradation of the nps whose lobes cap the pre existing erosional features and provide substrate for new erosion the trough and bump complex was subject to long term erosion and may represent an evolution from the previous linear tidally forced marine incisions the complex was subsequently buried in part by the step wise progradation of a southern progradational system sps developed within the southern 2 3 bohai bay and prograde to the north northeast in addition we also observed clusters of longitudinal bedforms with convex internal reflectors superimposed on the erosional remnant bumps coeval with the erosion dominated environment they are observable on both sandy and muddy substrates

water and sediment movement in the vicinity of linear sandbanks the norfolk banks southern north sea geophysical surveys current meter measurements and fluorescent sand tracer experiments were undertaken in the vicinity of the broken bank the data are used to establish localised and regional patterns of water and sediment movement the results obtained confirm mechanisms proposed previously for sandbank growth with particular reference to the north sea these include the clockwise circulation of water and sand with convergence at the crestline secondary helical water circulations do not appear to be a dominant process influencing sandbank maintenance however such circulation may still be important in the initial formation of linear sandbanks and or at some stages in the bank development on a regional basis residual currents bedform asymmetries and tracer dispersion indicate an offshore sediment transport component this observation supports the hypothesis of other investigators formed on the basis of geomorphological observations and numerical model predictions concerning the movement of sand under extreme conditions moreover these transport pathways may persist under low wave and tidally dominated conditions as opposed to being restricted to storm activity

headland associated banner banks generated during the last deglaciation near the strait of gibraltar gulf of cadiz sw spain the inception and evolution of large scale bedforms on the barbate platform gulf of cadiz sw iberian peninsula are investigated based on a detailed study of multibeam bathymetric data high resolution seismic profiles and tidal current simulations elongated rocky outcrops and several large scale bedforms classified as sand banks were identified on the platform barbate zahara el palmar el varadero and canos de meca banks the barbate and zahara banks exhibit the most complex internal stratigraphic architecture which comprises five seismic units the basal unit u1 is interpreted as incised valley infill and is overlain by nearshore bars u2 two high energy growth phases u3 and u4 that combine progradation and accretion form the present day external bank shape superimposed bedforms covered these banks under the modern hydrodynamic regime u5 the multiphase accretion and progradation of u3 and u4 in the zahara and barbate banks were closely linked to the presence of a palaeo headland termed here as palaeo cape trafalgar and strong tidal current eddies that resulted from the progressive flooding of the barbate platform during the last deglaciation this configuration was relatively stable while the rocky outcrops were exposed to sub aerial conditions forming a palaeo coast with coastal bluffs we suggest that during this period of coastal stabilization u3 and u4 grew as banner banks on either side of the palaeo cape trafalgar the present study proposes that the configuration of palaeo headland associated with palaeo banner banks zahara and barbate banks along each side of the palaeo cape trafalgar represents a transgressive analogue model of headland associated tidal bank systems developed in funnel shaped coastal systems terminating in narrow straits

apparent enhancement of 234th based particle export associated with anticyclonic eddies national basic research program of china 973 program 2009cb421200 national natural science foundation of china nsfc 41121091 41130857

an exceptional anticyclonic eddy in the south china sea in 2010 the highest sea level near the xisha islands in recent 20 years occurred during august 2010 satellite altimeter data indicated that the extreme event was largely due to an anticyclonic eddy whose amplitude exceeded 20 cm and size exceeded 400 km on 11 august 2010 cruise observations showed the eddy raised the center temperature by 7 7 degrees c at 75 m and vertically extended to 500 m eddy tracking showed it had a life span of more than 8 months and propagated far from the south of xisha islands such strong and long lasting eddy that moved northward for such a long distance was observed for the first time in the south china sea scs observational data from ctd xbt and the reconstructed three dimensional temperature and salinity were used to explore the eddy s features and vertical structure our analyses show the 2010 summer monsoon and current in the western boundary of the scs were largely altered after the 09 10 el nino event from may onward the wind blew northward and strengthened over the northwestern scs such wind drove a strong northward current along the western boundary which carried the eddy northward by advection from may to july energy budget showed during the eddy northward propagation the boundary current passed energy to the eddy which led to the continuing growth of the eddy in both strength and size