assessment of sedimentary heterocyst glycolipids as tracers of freshwater input to the changjiang estuary and east china sea abstract heterocyst glycolipids hgs are biomarkers of important freshwater and marine diazotrophs known as heterocystous cyanobacteria recent research has found that hgs with hexose moieties c6 are derived from free living mostly freshwater species while those with pentose moieties c5 are derived from diatom symbiont mostly marine species here we analyzed 39 surface sediments from a study area ranging from the changjiang estuary to the offshore east china sea for hgs to investigate distribution patterns at this freshwater seawater interface we detected both c5 and c6 hgs in these samples however they had different spatial distributions the c6 hg abundance was highest at the freshwater end of the estuary and decease offshore whereas the abundance of c5 hgs displayed almost inverse pattern we hypothesized that such distributions were likely caused by the mixing of freshwater and seawater leading to a mixture of hgs derived from inland waters and or soils and the marine environment the proportion of c6 hgs to total hgs defined as the fhg index decreased with distance offshore possibly reflecting the delivery of freshwater into the ocean the fhg index changed curvilinearly with salinity likely resulting from concentration based weighting of end member contributions the fhg index correlated linearly r2 0 76 with 13corg suggesting that fhg could be used to indicate relative contributions of freshwater delivered terrestrial organic matter in this estuarine and coastal region however the fhg index did not linearly correlate with the branched and isoprenoid tetraether bit index another proxy used for terrestrial input likely because the bit index is predominantly controlled by variations in marine crenarchaeol production

holocene pool formation in oligotrophic fens from boreal quebec in northeastern canada at the biogeographical limit between the boreal and the subarctic domain in northeastern canada peatlands are mainly oligotrophic fens characterized by a dominance of aquatic microforms such as pools and wet hollows these peatlands present similar features as the appa mires in scandinavia they show evidence for recent water table rise indicated by tree mortality physical degradation of strings and pool expansion this study aims to evaluate the timing of pool inception and their impact on the long term dynamics of these microforms within two patterned oligotrophic fens in the laforge region northern quebec plant macrofossil and testate amoeba analyses from sediment underneath pools were used along with radiocarbon dating to reconstruct peatland pool dynamics over the holocene our data indicate that wet hollows or shallow pools developed at minimal ages between 4200 and 2500 cal a bp pool initiation in the peatlands of the laforge region corresponds to the climate shift toward cooler and wetter

seasonal exchanges of the kuroshio and shelf waters and their impacts on the shelf currents of the east china sea previous in situ observations and modeling studies have indicated that through mass and momentum exchanges across the shelf edge the kuroshio can significantly influence the shelf currents of the east china sea ecs here instead of localized observations this study uses 25yr of drifter data supported by satellite and other data to identify seasonal cross shelf exchanges along the entire shelf edge the authors show that kuroshiomeandersonshorefromfalltowinterandoffshorefromspringtosummer withthelargestamplitude northeast of taiwan the influence is limited to the shelf edge when the kuroshio meanders offshore in spring and summer by contrast strong onshelf intrusions and cross shelf exchanges occur when the kuroshio meanders onshore in fall and winter drifters intrude onshelf northeast of taiwan and spread as far north as 308n against the strong northeasterly wind the forcing on the shelf is identified as a northward downsloping of the sea level that is steepest north of taiwan at 258 288n but which is 3 times weaker farther north the vorticity budget computed from a numerical model indicates that intrusion during fall andwinter is primarily a result of balancebetweenonshelfadvectionofambientpotentialvorticityandvorticityproductionbythealong isobath pressure gradient acting on the changing mass of water column across the continental slope

upper ocean currents around taiwan abstract current velocity measured by shipboard acoustic doppler current profiler sb adcp during 1991 2000 was used to study the upper ocean the composite and moored currents revealed a branch of the kuroshio that intruded steadily and persistently into the south china sea part of the intruded kuroshio flowed out of the south china sea through the northern luzon strait and re united with the main stream kuroshio the kuroshio had two velocity maximum cores southeast of taiwan but gradually combined into one as the kuroshio flowed north the kuroshio was deflected by the i lan ridge east of taiwan and the zonal running shelf break northeast of taiwan at the shelf break the kuroshio split with one branch intruding onto the shelf west of the luzon strait the kuroshio intruded into the south china sea some water flowed northward into the taiwan strait and re joined the kuroshio currents in the taiwan strait flowed primarily in a northward direction except for the southward current near the coast of mainland china north of the taiwan strait a branch of the northward flow followed the northern coast of taiwan to join the kuroshio the composite current varied consistently from season to season there was generally poor correlation between currents and local winds especially in the deep water regime remote forces were important in the currents around taiwan

mud bottom hollows exceptional features in carbon accumulating bogs mud bottom hollows are depressions on the bog surface where sphagnum mosses have died and peat accumulation is retarded or even replaced with loss by oxidation results of measurements carried out at mannikjarve bog central estonia cone rmed that peat accumulation has stopped and that in 1999 2001 the uppermost 2 3 cm thick surface layer of mud bottom hollows became thinner by 1 95 6 0 75 mm yr 21

dual isotope measurements reveal zoning of nitrate processing in the summer changjiang yangtze river plume riverine nitrogen input into the coastal zone has increased remarkably in recent decades yet its transformation and recycling within hydrodynamically active regions remains unclear using observations of nitrate concentration and dual isotopic composition across the changjiang river plume within a three end member mixing model we found deviations between the observed and expected values for mixing alone revealing the nonconservative behavior of nitrate using cross correlations between concentrations and dual isotope deviations we identified three nitrogen transformation zones which correspond to separate portions of the plume nitrification and sedimentary denitrification occurred near the river mouth nitrification prevailed further offshore under the plume and finally phytoplankton assimilation occurred in the outer surface plume 100 km offshore where it was fueled by nitrate that had already been strongly modified by microbial processes information was assembled into a conceptual model offering an overview of nitrogen transformations in a large river plume

characterizing errors in airborne laser altimetry data to extract soil roughness airborne laser altimetry has the potential to make frequent detailed observations that are important for many aspects of studying land surface processes however the uncertainties inherent in airborne laser altimetry data have rarely been well measured uncertainty is often specified as generally as 20 cm in elevation and 40 cm planimetric to better constrain these uncertainties we present an analysis of several datasets acquired specifically to study the temporal consistency of laser altimetry data and thus assess its operational value the error budget has three main components each with a time regime for measurements acquired less than 50 ms apart elevations have a local standard deviation in height of 3 5 cm enabling the local measurement of surface roughness of the order of 5 cm points acquired seconds apart acquire an additional random error due to differential geographic positioning system fluctuation measurements made up to an hour apart show an elevation drift of 7 cm over a half hour over months this drift gives rise to a random elevation offset between swathes with an average of 6 4 cm the root mean square planimetric error in point location was derived as 37 4 cm we conclude by considering the consequences of these uncertainties on the principle application of laser altimetry in the u k intertidal zone monitoring

upwelling induced by the frictional stress curl and vertical squeezing of the vortex tube over a submerged valley in the east china sea we conducted a process oriented modeling study to investigate the characteristics and dynamics of the prominent upwelling over a vast submerged valley in the east china sea ecs the valley is inversely funnel shaped with the west bank and the east bank oriented in the north south direction a cross bank upward transport occurred along the west bank it intensified northward and peaked around the head of the valley an along bank southward pressure gradient force pgf formed the cross bank geostrophic transport for the upwelling over the valley the pgf reached its maxima at the head of the valley our momentum and vorticity dynamic analyses revealed that a bottom stress curl mainly contributed the pgf along the west bank at the same time both the bottom stress curl and the nonlinear vorticity advection contributed to the pgf around the head the bottom stress curl was due to the bottom shear vorticity of the coastal current and the curvature vorticity around the head the nonlinear vorticity advection formed because of the vertical squeezing of vortex tube as the current flowed over the valley the nonlinearity mainly affected the pgf around the head whereas the bottom stress curl contributed to the pgf over the entire valley the ratio of the nonlinear to frictional contributions to the pgf increased as the coastal current intensified our study demonstrates that the pgf that drives the upwelling over the valley is the combined result of the nonlinearity due to vertical squeezing of vortex tube and bottom frictional effects

numerical study of the ocean circulation on the east china sea shelf and a kuroshio bottom branch northeast of taiwan in summer using the regional ocean model system the ocean circulation on the east china sea ecs shelf was examined by a fine resolution model which was nested in a coarse resolution pacific ocean model the high resolution simulation shows an accurate volume transport of 2 70 sv sv 10 6 m 3 s 1 through the tsushima strait which is more consistent with the previous 5 5 year observation value 2 64 sv than former model results for the taiwan strait it also shows a close volume transport 1 03 sv to a recent estimate 1 20 sv at the same time the model results reproduced almost all of the known circulation structure on the ecs shelf in addition the hindcast of 2009 shows a kuroshio bottom branch current to the northeast of taiwan kbbcnt the kbbcnt is confirmed by the observational bottom high salinity water from 15 august to 2 september 2009 whose distribution is also reproduced by the model results tracer and particle experiments were carried out to elucidate the formation of the high salinity water and the pathway of the kbbcnt in light of the field observation and numerical experiments a new pathway of the kbbcnt is proposed bifurcated from the subsurface water of kuroshio northeast of taiwan it upwells northwestward gradually from 300 to 60 m then turns to northeast in the region around 27 5 degrees n 122 degrees e and finally reaches 31 degrees n off the mouth of the changjiang river along similar to 60 m isobaths forming the bottom saline water off the coast of zhejiang province china

microplaty hematite ore in the yilgarn province of western australia the geology and genesis of the wiluna west iron ore deposits abstract the wiluna west small 130 mt high grade bedded hematite ore deposits consisting of anhedral hematite mesobands interbedded with porous layers of acicular hematite show similar textural and mineralogical properties to the premium high grade low phosphorous direct shipping ore from pilbara sites such as mt tom price mt whaleback etc in the hamersley province and goldsworthy shay gap and yarrie on the northern margin of the pilbara craton both margins of the pilbara craton and the northern margin of the yilgarn craton were subjected to sub aerial erosion in the paleoproterozoic era followed by marine transgressions but unlike the hamersley basin the jfgb was covered by comparatively thin epeirogenic sediments and not subjected to proterozoic deformation or burial metamorphism the joyner s find greenstone belt jfgb in the yilgarn region of western australia was exhumed by middle to late cenozoic erosion of a cover of unmetamorphosed and relatively undeformed paleoproterozoic epeirogenic sedimentary rocks that preserved the jfgb unaltered for nearly 2 ga thus providing a unique snapshot of the early proterozoic environment acicular hematite pseudomorphous after acicular iron silicate is only found in iron ore and bif that was exposed to subaerial deep weathering in early paleoproterozoic times pre 2 2 ga and in the overlying unconformable paleoproterozoic conglomerate derived from these rocks and is absent from unweathered rocks lascelles 2002 high grade ore and bif weathered during later subaerial erosion cycles contain anhedral hematite and acicular pseudomorphous goethite the acicular hematite was formed from goethite pseudomorphs of silicate minerals by dehydration in the vadose zone under extreme aridity during early paleoproterozoic subaerial weathering the principal high grade hematite deposits at wiluna west are interpreted as bedded ore bodies that formed from bif by loss of chert bands during diagenesis and have been locally enriched to massive hematite by the introduction of hydrothermal specular hematite no trace of chert bands are present in the deep saprolitic hematite and hematite goethite ore in direct contrast to shallow supergene ore in which the trace of chert bands is clearly defined by goethite replacement voids and detrital fill abundant hydrothermal microplaty hematite at wiluna west is readily distinguished by its crystallinity the genesis of the premium ore from the pilbara region has been much discussed in the literature and the discovery at wiluna west provides a unique opportunity to compare the features that are common to both districts and to test genetic models

continental slope flow northeast of taiwan abstract hydrographic observations and current measurements with a shipboard acoustic doppler current profiler over the continental shelf slope junction northeast of taiwan during 10 17 august 1994 allow the construction of the mesoscale flow pattern generated by the collision of the kuroshio and a stretch of the continental shelf that has turned to run nearly east west the pattern is made up of a deflected kuroshio mainstream to the east an intrusion of kuroshio water onto the continental shelf region a counterclockwise circulation over mien hwa canyon mhc immediately northeast of taiwan a deep southwestward countercurrent along the northern wall of mhc and a seaward outflow of continental shelf water around the northern coast of taiwan the hydrography features a cold dome over the west side of mhc that consisted of subsurface kuroshio water a temperature salinity plot of all the station data shows the incorporation in the neighborhood of taiwan of continental shelf water into the kuroshio

coral record of variability in the upstream kuroshio current during 1953 2004 the kuroshio current kc one of the most important western boundary currents in the north pacific ocean strongly affects regional hydroclimate in east asia and upper ocean thermal structure limited by few on site observations the responses of the kc to regional and remote climate forcings are still poorly understood here we use monthly coral 18o data to reconstruct a kc transport record with annual to interannual resolution for the interval 1953 2004 the field site is located in southern taiwan on the western flank of the upstream kc increased reduced kc transport would generate strong weak upwelling resulting in relatively high low local coral 18o the upstream kc transport and downstream transport off tatsukushi bay japan covary on interannual and decadal timescales this suggests common forcings such as meridional drift of the north equatorial current bifurcation or zonal climatic oscillations in the pacific the intensities of kc transport off southeastern and northeastern taiwan are in phase before 1990 and anti phase after 1990 this difference may be due to a poleward shift of the subtropical western boundary current as a response to global warming

interannual variability of the kuroshio onshore intrusion along the east china sea shelf break effect of the kuroshio volume transport the interannual variability of the kuroshio onshore intrusion koi across the east china sea ecs shelf break and its response to the ecs kuroshio volume transport kvt during 1993 approximate to 2010 are studied based on a high resolution real time and global ocean general circulation model since variability of kvt is mainly determined in the interior pacific it is rather a remote than a local factor for the local ecs koi on interannual time scales kvt affects koi not only in the net volume transport across the entire shelf break but also in the spatial pattern along the shelf break when kvt increases the intrusion decreases increases upstream downstream of the major intrusion region northeast of taiwan the retreating increases decreases upstream downstream of the main veering region southwest of kyushu these patterns are caused by cyclonic eddies induced by the seaward deflection of the kuroshio axis from the shelf break which ultimately results from the kvt increase a diagnostic mechanism of koi approximate to msin delta h 1 is proposed where h is the bottom depth is the angle between isobaths and the vertically averaged current and m is the absolute volume transport at the shelf break is large in the major intrusion retreating regions and stable on interannual time scales while m changes with opposite signs between upstream and downstream of the major intrusion retreating regions the mechanism explains well the relation of local kvt and the spatial pattern of koi along the shelf break in both the mean state and the interannual variations

driving mechanism of band structure of mean current over the continental shelf abstract a two layer numerical model is used to investigate the continental shelf circulation forced by western boundary currents along shelf edges emphasis is placed on an effect by frontal eddies or frontal waves which are reproduced in the model with the shelf edge along which a western boundary current is imposed after long term integration the model reaches the equilibrium state in which alternating bands of long term mean currents are found over the continental shelf the generation of the band structure is consistent with the observational results obtained by acoustic doppler current profilers on the shelf of the east china sea the western boundary current is accompanied by frontal waves and so vertical momentum transfer occurs because of the diffusive stretching topographic rossby waves are excited on the shelf slope by the vertical momentum transfer thereafter energy of the waves proceeds to flow toward the lower frequency limit by resonant interactions the along shelf wavenumber also

numerical study on the pattern and origins of kuroshio branches in the bottom water of southern east china sea in summer pattern and origins of kuroshio branches in the bottom water of southern east china sea ecs were carefully examined by numerical simulations based on the regional ocean modeling system roms together with observations model results show that in the bottom water of ecs the intrusion pattern of kuroshio is mainly composed of an offshore kuroshio branch current okbc which bifurcated from the kuroshio northeast of taiwan flows nearly along the isobath of similar to 100 m and a nearshore kuroshio branch current nkbc which originated from the kuroshio northeast of taiwan upwells northwestward gradually from similar to 250 m to similar to 60 m then turns to northeast around 27 5 degrees n 122 e thereafter flows northeastward along the isobath of similar to 60 m and finally reaches at 30 5 degrees n where it turns to east furthermore we found that the nkbc mostly originated in the kuroshio subsurface water 120 250 m east of taiwan whereas the okbc mainly stemmed from the kuroshio water 60 120 m east of taiwan this pattern and origins of okbc and nkbc well addressed the observational phenomena that off the coast of zhejiang province china there were colder less saline and more phosphate rich bottom water near the isobath of similar to 60 m rather than near the isobath of similar to 100 m in august 2009 finally it is proposed that on southern ecs continental shelf kuroshio exhibits its intrusion branches by an anticyclonical stair structure bottom stair nkbc middle stair okbc and top stair kuroshio surface branch kbc

anisotropy and depth related heterogeneity of hydraulic conductivity in a bog peat i laboratory measurements anisotropy and heterogeneity of hydraulic conductivity k are suspected of greatly affecting rates and patterns of ground water seepage in peats a new laboratory method termed here the modified cube method was used to measure horizontal and vertical hydraulic conductivity kh and kv of 400 samples of bog peat the new method avoids many of the problems associated with existing field and laboratory methods and is shown to give relatively precise measurements of k in the majority of samples tested kh was much greater than kv indicating that the bog peat was strongly anisotropic log10kh log10kv and log10 kh kv were found to vary significantly with depth although none of the relationships was simple we comment on the scale dependency of our measurements

do peatland microforms move through time examining the developmental history of a patterned peatland using ground penetrating radar using ground penetrating radar gpr to map subsurface patterns in peat physical properties we investigated the developmental history of meso scale surface patterning of microforms within a raised bog common offset gpr measurements were obtained along a 45 m transect at frequencies ranging from 100 to 900 mhz we found that low frequency central frequency 240 mhz showed a striking pattern of subsurface reflections that dip consistently in a northerly direction the angle of these dipping reflectors is calculated using a semblance algorithm and was shown to average 3 9 degrees between a depth of 1 0 and 2 5 m these dipping reflectors may indicate downslope migration of surface microforms during the development of the peatland based on the estimated angle and the rate of peat accumulation the average rate of downslope propagation of these surface microforms is calculated at 9 8 mm per year further survey work is required to establish whether the downslope migration is common across the peatland

dissolved silicon isotopic compositions in the east china sea water mass mixing vs biological fractionation we present the first set of dissolved silicon isotope data in seawater delta si 30 si oh 4 from the east china sea a large and productive marginal sea significantly influenced by the kuroshio current and freshwater inputs from the changjiang yangtze river in summer august 2009 the lowest surface delta si 30 si oh 4 signatures of 2 1 parts per thousand corresponding to the highest si oh 4 concentrations similar to 30 0 mu mol l 1 were observed nearshore in changjiang diluted water during advection on the east china sea inner shelf surface delta si 30 si oh 4 increased rapidly to 3 2 parts per thousand while si oh 4 became depleted indicating increasing biological utilization of the si oh 4 originating from the changjiang diluted water this is also reflected in the water column profiles characterized by a general decrease of delta si 30 si oh 4 and an increase of si oh 4 with depth on the east china sea mid shelf and slope in winter december 2009 january 2010 however the delta si 30 si oh 4 was nearly constant at 1 9 parts per thousand throughout the water column on the east china sea shelf beyond the nearshore which was a consequence of enhanced vertical mixing of the kuroshio subsurface water horizontal admixture of kuroshio surface water which is highly fractionated in si isotopes was observed only beyond the shelf break significant seasonal differences in delta si 30 si oh 4 were detected in the surface waters beyond the changjiang diluted water influenced region on the east china sea shelf where the winter values were similar to 1 0 parts per thousand lower than those in summer despite the same primary si oh 4 supply from the kuroshio subsurface water during both seasons this demonstrates significantly higher biological consumption and utilization of si oh 4 in summer than in winter

the onshore intrusion of kuroshio subsurface water from february to july and a mechanism for the intrusion variation abstract to examine the variation of kuroshio subsurface water kssw off the coast of zhejiang province china we carried out six monthly cruises from february to july 2015 observations show that the kssw appears in a frequently reported algal bloom area near the coast as early as in april and persists until july however the kssw was absent in february we set up a fine resolution 4 km model which can reproduce most of the observed features model results and cruise data suggest that a nearshore kuroshio branch current nkbc originated from the kssw northeast of taiwan can emerge as early as in april which is responsible for the observed kssw from april to july however in february nkbc turns seaward before reaching this algal bloom area and thus the kssw is absent in addition to the traditional mechanisms of wind bottom stress and cooling we suggest a new mechanism of this nkbc variation in the origin area of the nkbc the kssw is more shoreward squeezed and flows more westward flowing northward in february while northwestward in april in april than february the change of flow direction caused different meeting point between the shelf break and the kuroshio current according to topographic beta spiral different meeting points will induce different upwelling velocity and then contribute to the different intrusion pattern of nkbc this direction change is one of the essential ingredients which enable nkbc to reach as far as the algal bloom area hence algal blooms in april may be potentially influenced by this nkbc whose water properties are significantly different to the coastal water

intrusion of the kuroshio subsurface water in the southern east china sea and its variation in 2014 and 2015 traced by dissolved inorganic iodine species abstract the circulation systems and ecological environment of the east china sea ecs are greatly influenced by the kuroshio the nutrient rich kuroshio subsurface water kssw has been subject to considerable research attention but the intrusion pathway extent and variation of the kssw over the entire southern ecs shelf are still debated in june 2015 the dissolved inorganic iodine species diis were determined and hydrographic data were collected and analyzed in the southern ecs analysis of the collected data suggests that the kssw mainly intrudes onto the ecs shelf from northeast of taiwan and bifurcates into a nearshore branch and an offshore branch the nearshore branch ultimately appears in the subsurface layer within the 50 m isobath off the zhejiang coast north of 30 n and the offshore branch flows along the 100 m isobath and covers the area outside the 80 m isobath another kssw intrusion along the shelf edge is located at 28 n this additional kssw intrusion is weaker and the offshore area in the southern ecs is mainly influenced by the kssw intrusion northeast of taiwan compared with the kssw intrusion on the ecs continental shelf depth

the kuroshio east of taiwan moored transport observations from the woce pcm 1 array observations from the woce pcm 1 moored current meter array east of taiwan for the period september 1994 to may 1996 are used to derive estimates of the kuroshio transport at the entrance to the east china sea three different methods of calculating the kuroshio transport are employed and compared these methods include 1 a direct method that uses conventional interpolation of the measured currents and extrapolation to the surface and bottom to estimate the current structure 2 a dynamic height method in which moored temperature measurements from moorings on opposite sides of the channel are used to estimate dynamic height differences across the current and spatially averaged baroclinic transport profiles and 3 an adjusted geostrophic method in which all moored temperature measurements within the array are used to estimate a relative geostrophic velocity field that is referenced and adjusted by the available direct current measurements the first two methods are largely independent and are shown to produce very similar transport results the latter two methods are particularly useful in situations where direct current measurements may have marginal resolution for accurate transport estimates these methods should be generally applicable in other settings and illustrate the benefits of including a dynamic height measuring capability as a backup for conventional direct transport calculations the mean transport of the kuroshio over the 20 month duration of the experiment ranges from 20 7 to 22 1 sv 1 sv 106 m3 s 1 for the three methods or within 1 3 sv of each other the overall mean transport for the kuroshio is estimated to be 21 5 sv with an uncertainty of 2 5 sv all methods show a similar range of variability of 10 sv with dominant timescales of several months fluctuations in the transport are shown to have a robust vertical structure with over 90 of the transport variance explained by a single vertical mode the moored transports are used to determine the relationship between kuroshio transport and sea level difference between taiwan and the southern ryukyu islands allowing for long term monitoring of the kuroshio inflow to the east china sea

impact of mesoscale eddies on kuroshio intrusion variability northeast of taiwan abundant mesoscale eddies propagate to the east of taiwan and affect the kuroshio current and its onshore intrusion northeast of taiwan but the dynamical process of how eddy activities modulate the kuroshio intrusion is still unclear in this study in situ ocean velocity observations drifter trajectories tide gauge measurements satellite sea surface height data and assimilative hybrid coordinate ocean model hycom reanalysis outputs were used to analyze a cyclonic eddy induced large kuroshio onshore intrusion during late autumn 2008 along with nine anticyclonic eddy events and seven cyclonic eddy events extracted from long term hycom reanalysis outputs the variability of the eddy induced intrusion were quantified the impacts of the cyclonic eddy and the anticyclonic eddy were opposite under the impact of cyclonic anticyclonic eddy the total onshore intrusion between 122 e and 124 e across the 200 m isobaths was decreased increased by 15 7 7 3 while the onshore intrusion west of 122 6 e and the northeastward current on the outer shelf was increased decreased by 30 6 4 7 and 31 10 1 respectively the arrival of cyclonic anticyclonic eddy brought positive negative potential vorticity pv flux and modulated the local ocean vertical stratification which weakened enhanced the cross slope pv gradient and the shelf slope constraint on the upper layer current therefore favored inhibited the kuroshio onshore intrusion this article is protected by copyright all rights reserved

nepartak typhoon influenced bottom sediments from the yangtze river estuary and adjacent east china sea foraminiferal evidence foraminiferal taphocoenose characteristics notably allochthonous tests in surface sediment samples from the yangtze river estuary and adjacent areas in the east china sea were examined during july 2016 and after typhoon nepartak february 2017 crossed this region a comparison of transport indices from five sample stations reveals that this typhoon significantly strengthened sediment transport although the transport in predominate direction twcnorth branch occurs all year moreover findings from a comprehensive impact of currents topography test size and shape as well as other abiotic factors show that transport occurs in the order from stronger to weaker south north path southeast northwest path nearshore northeast path along the south north path the twcnorth branch transports larger tests of taxa ammonia compressiuscula and cavarotalia annectens as bed load along the gentle seabed in a rolling or saltating process results from the southeast northwest path show smaller and bulging tests of the dominant species epistominella naraensis and bolivina robusta may be transported as suspension load along the steep submarine valley by the twcnorthwest branch on the nearshore northeast path only part of allochthonous tests ammonia beccarii vars was transported probably due to distance travelled and weakening of the typhoon furthermore we also infer the northeastern area as a sink zone that accumulates grains of allochthonous tests predominantly from the southern source zone and a selection of tests from littoral species originating from the nearshore source zone it is important to identify and independently count allochthonous test samples if a large number of these tests are recorded findings from this study provide a reference to identify and investigate typhoon modern effects in areas with complex currents and frequent strong physical dynamic events as well as their geological records

the tsushima warm current through tsushima straits estimated from ferryboat adcp data abstract current structures across the tsushima straits are studied using results from long term acoustic doppler current profiler adcp observations by a ferryboat between hakata and pusan conducted since february 1997 two maxima of the northeastward current are observed in the central parts of the eastern and western channels and the maximum velocity in the western channel is stronger than that of the eastern channel downstream of the tsushima islands a southwestward countercurrent is observed associated with a pair of cyclonic and anticyclonic eddies in the western channel the deep countercurrent is observed pronouncedly on the bottom slope of the korean side from summer to winter the volume transport of the tsushima warm current through the straits has strong seasonal variation with a minimum in january and two maxima from spring to autumn double peaks the spring peak of the volume transport through the eastern channel is more pronounced than the autumn peak and the autumn peak of the west

kuroshio subsurface water feeds the wintertime taiwan warm current on the inner east china sea shelf the taiwan warm current twc has an overwhelming influence on the heat salt and nutrients balance on one of the broadest shelf in the world the east china sea shelf in winter the twc flows in an unusual upwind direction and reaches the changjiang yangtze river estuary but its origin and pathway are intensely debated here combined evidences from current measurement hydrographic and stable isotopic data all suggest that the wintertime twc intrusion off the changjiang estuary mainly originates from the kuroshio subsurface water northeast of taiwan rather than from the taiwan strait warm water the kuroshio branched water northeast of taiwan can intrude into the inner shelf near the zhe min coast via bottom layer manifesting by a pronounced boundary at 50 m isobath around 28 n and thereby feeds the twc intrusion into the changjiang estuary the intrusion complicates the hydrological process in the estuary and shelf sea and its impact on marine environment deserves more research attentions

climatic and topographic limits to the abundance of bog pools on patterned peatlands open water pools develop within a matrix of terrestrial vegetation ridges regional patterns in the distribution of ridge pool complexes suggest that the relative cover of these two surface types is controlled in part by climate wetness but landscape topography must also be an important controlling factor in this paper a functional model that relates relative cover of ridges and pools to climate and surface gradient was developed and tested the model was formulated in terms of a water budget based on the differential effects of ridges and pools on losses by evapotranspiration and subsurface flow it predicts a positive relationship between surface gradient and ridge proportion with a linear effect related to water supply and ridge hydraulic conductivity modified at high ridge proportion by differences in evapotranspiration between ridges and pools the limit to patterned peatland distribution occurs where the surface is completely covered by ridges the model may be sensitive or insensitive to climate differences between localities depending on whether hydraulic characteristics of ridge peat co vary with water supply to distinguish between these alternative hypotheses surface gradient and ridge proportion were surveyed along 20 transects in each of three localities in scotland that differ threefold in net precipitation to pools the results of the field survey served to reject the climate sensitive hypothesis but were consistent with the climate insensitive hypothesis analysis of the residuals suggested that variation within localities was related more to topographic control of water supply than to ridge hydraulic conductivity or developmental stage hence within this maritime climate region the distribution of ridge pool complexes and the relative abundance of pools are controlled mainly by topographic variables field surveys across both maritime and continental regions are required to confirm a subtle climatic effect that allows pools to occur on higher gradients in drier climates than in wetter climates further development and testing of the functional model will provide a stronger basis for assessing potential feedback between climate change peatland surface structure and methane emission from pools copyright 2006 john wiley sons ltd