seafloor undulation pattern on the adriatic shelf and comparison to deep water sediment waves abstract on the adriatic shelf a large field of seafloor and subsurface undulations typically 300 m wide 2 5 m high and several km long parallel to the bathymetric contour affects the progradational clinoforms of the late holocene prodelta wedge above a regional downlap surface that shows evidence of deformation and fluid escape the undulations are associated with mud reliefs that occur farther seaward in elongated swarms perpendicular to the regional slope and to the crests of the undulations a quantitative measurement of key morphobathymetric parameters such as wavelength height asymmetry and wave form indexes was performed on 13 selected seismic reflection profiles perpendicular to the undulations these measurements are determined with respect to water depth or downslope distance from the shallowest undulation the results highlight substantial differences from deep water sediment waves these differences include 1 most undulations show a staircase morphology with sub horizontal upslope limbs of 100 300 m delimited seaward by sharp edges and steep downslope limbs 2 landward or upslope dipping limbs do not develop 3 there is no consistent downslope decrease in wavelength or amplitude as opposed to most cases of sediment waves related to overflowing turbidity currents 4 there is a consistent downslope loss in crest continuity approaching areas where mud reliefs and sediment deformation are evident at the seafloor 5 many of the undulations show differences in angle of climb and in some cases a single undulation at the seafloor results from the burial and merger of more undulations in the underlying section these differences compared to bottom current or turbidity current sediment waves are augmented by the observation that the adriatic shallow water undulations are also typically associated with gas charged sediment fluid escape sediment deformation and localised failure planes it is therefore suggested that seafloor undulations evolved in response to sediment deformation and were successively amplified by differential deposition from bottom currents crossing an irregular seafloor in general we feel that case by case solutions should be found to explain the origin and evolution of seafloor wavy features based on the geologic stratigraphic setting the recognition of possible weak layers and the co existence of a variety of other deformation geometries that may occur within or adjacent to the field of wavy features the adriatic example can reinforce recent suggestions that besides purely depositional bedforms there exist also wave like deformation structures and multi process sediment waves faugeres et al 2002 multi process generated sediment waves on the landes plateau bay of biscay north atlantic marine geology 182 279 302

variability of el nino southern oscillation activity at millennial timescales during the holocene epoch the variability of el nino southern oscillation enso during the holocene epoch in particular on millennial timescales is poorly understood palaeoclimate studies have documented enso variability for selected intervals in the holocene but most records are either too short or insufficiently resolved to investigate variability on millennial scales1 2 3 here we present a record of sedimentation in laguna pallcacocha southern ecuador which is strongly influenced by enso variability and covers the past 12 000 years continuously we find that changes on a timescale of 2 8 years which we attribute to warm enso events become more frequent over the holocene until about 1 200 years ago and then decline towards the present periods of relatively high and low enso activity alternating at a timescale of about 2 000 years are superimposed on this long term trend we attribute the long term trend to orbitally induced changes in insolation and suggest internal enso dynamics as a possible cause of the millennial variability however the millennial oscillation will need to be confirmed in other enso proxy records

process studies on the po river plume north adriatic sea the coastal processes in the adriatic sea and in particular the development and evolution of the po river plume are studied with a three dimensional primitive equation model experiments are performed to examine the buoyancy driven flow and the interaction with topography wind stress and ambient stratification the pathways of particles released from the po are computed to simulate the transport of land drained materials in the absence of wind forcing the po river plume consists of an offshore bulge that occupies most of the north part of the basin and a southward coastal current that is confined within the narrow coastal region along the italian peninsula when all adriatic rivers are included basinwide buoyancy driven cyclonic coastal flow is established that diminishes the seaward removal of po waters and promotes their southward advection through the coastal current wind stress modifies the above winds that are downwelling favorable for the po discharge site like bora restrict offshore plume development enhance the southward coastal current and confine the plume within the narrow western adriatic shelf conversely upwelling favorable winds like scirocco eliminate the baroclinic coastal current and advect low salinity po waters toward the shallow parts of the northern adriatic when preexisting stratification of basin waters is described the density field is influenced by both temperature and salinity during winter when the coastal waters tend to be colder and fresher than offshore waters the cyclonic circulation is sustained owing to input from rivers and particularly the po the intense spatial and temporal variability of wind stress and river runoff and the resulting variability in the circulation of the coastal adriatic sea are elaborated through a realistic simulation during january 1994

late quaternary variation of lignin composition in core md01 2421 off central japan nw pacific abstract in order to understand the responses of terrestrial vegetation in central japan to global climate changes we have generated the record of lignin composition from core md01 2421 off central japan in the nw pacific during the last 145 000 years by tetramethylammonium hydroxide tmah pyrolysis gas chromatography mass spectrometry gc ms the relative abundance of lignin was significantly low in early mis 1 and mis 5e and higher in mis 5c to early mis 4 this reflects glacial interglacial changes in sea level and riverine runoff the ratio of syringyl s to vanillyl v phenols s v ratio which is a contribution index of angiosperms against gymnosperms was lower in mis 2 mis 4 and mis 6 reflecting the glacial interglacial variation of air temperature the ratio of cinnamyl c to vanillyl v phenols c v ratio which indicates the contribution of grasses was higher in late mis 2 early mid mis 3 and mis 6 the periods of higher c v ratio correspond to the periods of lower sea surface temperatures ssts suggesting a dry and cold climate in late mis 2 mid mis 3 and mis 6

role of orbital forcing in east asian monsoon climates during the last 350 kyr evidence from terrestrial and marine climate proxies from core rc14 99 proxy records of northeast asian precipitation marine pollen and northwest pacific sea surface temperatures marine fauna contain concentrations of variance frequency peaks coincident with those of orbital variations eccentricity obliquity and precession time series of these monitors of various components of the east asian monsoon system are coherent with changing solar insolation and climate boundary conditions ice volume snow cover albedo at 41 and 23 kyr frequencies winter sea surface temperature wsst maxima are in phase with global ice volume minima at all three milankovitch frequencies 100 41 and 23 kyr periods wsst maxima are also linearly related to summer insolation at 30 n lagging radiation maxima by 55 3 5 kyr across the precessional frequency band 23 kyr period our east asian monsoon rainfall indicator cryptomeria reaches highest values immediately following summer insolation maxima during periods of low ice volume interglacials across the eccentricity frequency band 100 kyr period cryptomeria maxima are in phase with ice volume minima at the higher frequency of orbital precession monsoon rainfall lags both summer radiation maxima 125 8 kyr and ice volume minima 60 3 8 kyr whereas much of the variation in northwest pacific wsst can be attributed to summer radiation forcing and changes in global climate mechanisms driving east asian monsoon precipitation are more complex involving other possibly internal factors

the dynamics of the coastal region of the northern adriatic sea abstract the northern half of the adriatic sea is constituted by the continental shelf with very shallow depths 20 m in the northernmost extremity in particular the new coastal region adjacent to the italian coastline forms a shallow strip with isobaths running parallel to the coast and a topography gently increasing towards the interior of the basin in the region immediately south of the po river delta the major source of fresh water input into the adriatic important eutrophication phenomena have recently occurred in summer the controversial question thus arises whether these eutrophication phenomena are to be ascribed to nutrient inputs from local sources or from the po river waters carried southward parallel to the italian coastline in the general cyclonic gyre characterizing the adriatic yearly average circulation the dynamically important question is then whether and how a localized source of freshwater drives the nearcoastal shelf circulation to answer this question a multi level hydrodyn

patterns of deglacial warming in the pacific ocean a review with emphasis on the time interval of heinrich event 1 abstract based on a compilation of currently available records of past sea surface temperature sst variability estimated from a variety of different proxies the regional scale deglacial sst development in the pacific ocean is tentatively classified into four endmember types the subtropical and tropical pacific is characterized by a continuous deglacial warming without marked interruption during the time interval of heinrich event 1 h1 whereas the subarctic north pacific exhibits centennial scale warm cold oscillations during this time interval sst records from marginal seas of the pacific show a deglacial warming interrupted by a cooling event coeval with h1 followed by a marked bolling sst increase a single sst record from the southwestern subantarctic pacific displays a continuous deglacial warming across h1 followed by an antarctic cold reversal type cooling during the allerod thus in contrast to the deglacial sst development in the atlantic which has been inferred to be overwhelmingly driven by the redistribution of heat through changes in the meridional overturning circulation moc none of the open oceanic pacific sst records reviewed here displays any obvious and or dominant response to the reduction of the moc and or the reorganization of atmospheric circulation during h1 within the limits of absolute chronologies all tropical and subtropical pacific sst records show an onset of deglacial warming at 19 1 ka coeval with the onset of the deglacial rise in sea level

effect of moisture and temperature conditions on the decay rate of a purple mudstone in southwestern china soil formation and geomorphology are primarily influenced by the rock decay which in turn is strongly determined by moisture and temperature conditions however it remains unclear whether rock decay is dominated by thermal stresses or by hydration disintegration and there is little information on mudstone decay rate in southwestern china this study hypothesized that rock decay is dominated by hydration mechanism and focused on the physical decay characteristics of typical purple mudstones using a combination of field and laboratory based experiments the bedrock of a penglaizhen group j 3 p in yanting county sichuan province southwestern china was exposed and covered with nylon fabric in situ soil depths of 10 20 40 and 60 cm were laid on this nylon fabric in 2003 and the decay rate the quantity of clastic particles 2 mm that were decayed from the bedrock in t km 2 yr 1 under the nylon fabric was measured both in 2005 and 2009 in addition fresh mudstones sampled from the matoushan group k 2 m the tuodian group j 3 t and the lufeng group j 1 l in yuanmou county shuangbai county and lufeng county of yunnan province southwestern china respectively were subjected to alternating applications of moisture temperature and their interaction seven treatments in the laboratory and their decay ratios the mass of decayed rock of 2 mm clastic particles to sampled rock mass in percent were measured in 2010 in the field the decay rate of the bedrock showed a significant p 0 05 positive relationship with both the daily moisture and temperature variation at the interface between the soil and bedrock in the laboratory results showed that the effect of moisture variation but not temperature alternation on rock decay was apparent suggesting that purple rock decay is dominated by hydration mechanism freezing thawing in particular affects the sampled rocks because it causes more spalling and fracturing the j 3 t rock had the highest decay ratio because it had the highest clay mineral content and porosity of the three rock types hierarchical clustering analysis suggested that the variation of moisture content and h2o phase solid or liquid within rock plays a key role in rock decay processes both field and laboratory studies consistently showed that the alteration of wetting drying and freezing thawing as well as moisture content substantially influenced rock decay c 2012 elsevier b v all rights reserved

topographic control of wind driven circulation in the northern adriatic 1 two synoptic wind driven situations of the circulation in the northern adriatic were studied using the princeton ocean model over the northern adriatic sea napom in both situations the basin was driven by a relatively steady wind 8 m s along and across the basin over three days in the first situation 28 30 october 2008 the sse southern jugo or scirocco wind blew along the basin and in the second 19 21 march 2009 the ene bora wind blew across the basin cyclonic turn was present in the first situation while the cyclonic branch of a known double gyre circulation north of the strip of wind minima was evident in the second we show that during the jugo the model does not confirm quantitatively the simple topographic control of a wind driven circulation suitable for elongated basins while qualitatively the model meets expectations with downwind transport in shallow areas close to shorelines and upwind transport in places with greater depths during the bora wind however the wind driven circulation in the gulf of trieste is well explained by this topographic control 82 of the flux through the transect

space and time variability of the surface color field in the northern adriatic sea a time series of coastal zone color scanner images for the years 1979 and 1980 was used to observe the spatial and temporal variability of bio optical processes and circulation patterns of the northern adriatic sea on monthly seasonal and interannual scales the chlorophyll like pigment concentrations derived from satellite data exhibited a high correlation with sea truth measurements performed during seven surveys in the summer of both years comparison of the mean pigment fields indicates a general increase in concentration values and larger scales of coastal features from 1979 to 1980 this variability may be linked to the different patterns of nutrient influx due to coastal runoff in the 2 years the distribution of surface features is consistent with the general cyclonic circulation pattern the pigment heterogeneity appears to be governed by fluctuations of freshwater discharge while the dominant wind fields do not appear to have important direct effects the po river presents a plume spreading predominantly in a southeastern direction with scales positively correlated with its outflow the spatial scales of the western coastal layer in contrast are negatively correlated with this outflow and the plume scales both results are consistent with and may be rationalized by recent theoretical and experimental results involving a dynamical balance between nonlinear advection and bottom friction with alternate predominance of one of the two effects

coastal dynamics under conditions of rapid sea level rise late pleistocene to early holocene evolution of barrier lagoon systems on the northern adriatic shelf italy this multidisciplinary case study of two preserved barrier systems combined the analysis of radiocarbon datings grain size distributions high resolution seismics and shelf bathymetry with reconstructions of palaeo environmental conditions tides waves sea level change and forward modelling of barrier lagoon systems to provide an integrated view of the coastal transgressive evolution of a large sector of the northern adriatic shelf between 15 and 8 ka bp palaeoenvironmental reconstructions point to increased tidal amplitude low energy wave climate and high rates of sea level rise up to 60 mm a during the formation of the oldest preserved barrier system not vert similar90 m water depth 14 3 cal ka bp a younger barrier system 42 m water depth 10 5 cal ka bp formed under conditions of lower tidal amplitude higher wave energy and a lower rate of sealevel rise 10 mm a forward modelling suggests that the probability of barrier island overstepping during transgression is inversely proportional to tidal amplitude if all other factors are assumed equal the oldest barrier lagoon system developed under conditions of large tidal amplitude which permitted rapid transgression however this system apparently failed to keep up with the anomalously high rate of sea level rise resulting from melt water pulse 1a the youngest barrier system appears to have drowned in place due to antecedent topography as the barrier system transgressed over an ancient pleistocene alluvial plain the rapid increase in backbarrier accommodation caused an abrupt disequilibrium between shoreface and backbarrier sedimentation which led to barrier overstepping although barsim modelling indicates that tidal deposition can reduce the probability of barrier overstepping there are other driving mechanisms in our case extremely rapid sea level rise and antecedent topography which are more determinative in explaining the transgressive coastal evolution of barrier lagoon systems in the northern adriatic sea grain size analysis of shoreface deposits sampled above the transgressive ravinement surface across the northern adriatic shelf indicate a distinct relation between the sediment grain size and the rate of sea level rise during deposition which implies that progressive sorting must have been highly effective

sea surface temperature and salinity changes in the northwest pacific since the last glacial maximum the oxygen isotope records of both benthic and planktonic foraminifera in five piston cores collected from the region between the oyashio and kuroshio currents near japan clearly show the marked latitudinal shifts of these two currents during the past 25 kyr under the present hydrographic condition a clear relationship between the sea surface temperature sst and oxygen isotope differences from benthic to planktonic foraminifera is observed in this region using this relationship we find decreased ssts of 12 13 c maximum 15 c in the southernmost core site at the last glacial maximum lgm indicating the oyashio current shifted southward the ssts at the southern two core sites abruptly increased more than 10 c at 10 11 ka suggesting the kuroshio current shifted northward over these sites at 10 11 ka in contrast the northern two core sites have remained under the influence of the cold oyashio current for the past 25 kyr with the reasonable estimate of bottom water temperature decrease of 2 5 c at the lgm the ssts estimated by this new method give exactly the same sst values calculated from mg ca ratio of planktonic foraminifera allowing palaeosea surface salinities to be reconstructed the result suggests that the ice volume effect was 1 0 0 1 at the lgm copyright 2004 john wiley sons ltd

the late holocene gargano subaqueous delta adriatic shelf sediment pathways and supply fluctuations the gargano subaqueous delta formed on the eastern and southeastern sides of the gargano promontory in the western adriatic this subaqueous deposit represents the southernmost portion of the late holocene highstand systems tract hst growing along the western side of the adriatic as an extensive wedge of deltaic and shallow marine mud the late holocene hst rests above a regional downlap surface that marks the time of maximum landward shift of the shoreline attained around 5 5 cal kyr bp at the end of the late pleistocene holocene sea level rise high resolution seismic stratigraphic and tephra correlation indicate the presence of a thin basal unit recording condensed deposition between 5 5 and 3 7 cal kyr bp over much of the basin above this unit sediment accumulation rates increased to high values as much as 1 5 cm yr 1 reflecting the stabilisation of relative sea level and the forcing from high frequency climatic or anthropogenic changes affecting river dynamics the late holocene mud wedge of which the gargano subaqueous delta is a significant component reaches up to 35 m in thickness and has a volume of ca 180 km3 the shore parallel thickness distribution of the mud wedge reflects the dominant oceanographic regime of the basin and the asymmetric location of the mostly western sediment sources with a combined modern delivery of 51 7 106 t yr 1 of mean suspended load in sections perpendicular to the coast the late holocene mud wedge appears composed of forestepping clinoforms with gently dipping foresets typically 0 5 the gargano subaqueous delta is characterised by a submarine topset in water depths shallower than 25 28 m and accounts for about 1 7th of the total volume of the late holocene mud wedge despite the absence of direct river supply to the gargano area in the area of maximum interaction between shore parallel currents and basin morphology progradation occurs onto a flat and barren bedrock outcrop in about 50 80 m water depth the rapid transition from a thickness of 30 m of late holocene mud to nil is a good indication of the role of southward flowing bottom hugging shelf currents in causing the redistribution of sediment along the adriatic inner shelf additional evidence of this regime comes from 1 the most recent sigmoid defined at seismic stratigraphic scale deposited since the onset of the little ice age showing a shore parallel thickness distribution and a main depocentre to the southeast of the gargano promontory 2 the maximum values of sediment accumulation rates over the last century documented by 210pb measurements defining a narrow shore parallel belt immediately seaward of the depocentre of the most recent sigmoid the gargano subaqueous delta grows from the outbuilding of progressively younger progradational sigmoids that tend to parallel the previous ones the gargano subaqueous delta differs from other documented late holocene subaqueous deltas because its growth reflects 1 sediment transport dominated by bottom currents sub parallel to the strike of the composing clinoforms 2 a complex supply regime including the po delta 350 km to the north and several coalescing apennine rivers acting as line source 3 several alternating intervals of enhanced outbuilding and condensed deposition and 4 an in phase growth of the most recent sigmoid with the major progradation of the po delta during the little ice age

mapping turbidity patterns in the po river prodelta using multi temporal landsat 8 imagery abstract thirty meters resolution turbidity maps derived from landsat 8 l8 images were used to investigate spatial and temporal variations of suspended matter patterns and distribution in the area of po river prodelta italy in the period from april 2013 to october 2015 the main focus of the work was the study of small and sub mesoscale structures linking them to the main forcings that control the fate of suspended sediments in the northern adriatic sea a number of hydrologic and meteorological events of different extent and duration was captured by l8 data quantifying how river discharge and meteo marine conditions modulate the distribution of turbidity on and off shore at sub mesoscale peculiar patterns and smaller structures as multiple plumes and sand bars were identified thanks to the unprecedented spatial and radiometric resolution of l8 sensor the use of these satellite derived products provides interesting information particularly on turbidity distribution among the different delta distributaries in specific fluvial regimes that fills the knowledge gap of traditional studies based only on in situ data a novel approach using satellite data within model implementation is then suggested

the california current system during the last 136 000 years response of the north pacific high to precessional forcing abstract alkenone sea surface temperature sst records were generated from the ocean drilling program s odp sites 1014 and 1016 to examine the response of the california current system to global climate change during the last 136 ka the temperature differences between these sites sstnep sstodp1014 sstodp1016 reflected the intensity of the california current and varied between 0 4 and 6 1 c a high sstnep weaker california current was found for late marine isotope stage mis 2 and early mis 5e while a low sstnep stronger california current was detected for mid mis 5e and mis 1 spectral analysis indicated that this variation pattern dominated 23 precession and 30 ka periods comparison of the sstnep and sst based on data from core md01 2421 at the japan margin revealed anti phase variation the high sstnep weakening of the california current corresponded to the low sst at the japan margin the southward displacement of the nw pacific subarctic boundary and vice versa this variation was synchronous with a model prediction of the tropical el nino southern oscillation behavior these findings suggest that the intensity of the north pacific high varied in response to precessional forcing and also that the response has been linked with the changes of tropical ocean atmosphere interactions

northward and southward migrations of frontal zones during the past 40 kyr in the kuroshio oyashio transition area 1 the variation of sea surface temperature sst in the kuroshio oyashio transition area and the okhotsk sea during the last 40 kyr was estimated using long chain unsaturated alkyl ketones alkenones the temperature difference between the present and the last glacial period was about 5 6 c in the kuroshio oyashio transition area slightly larger than the 4 c previously reported moreover alkenones were not detected before 18 kyr b p in or near the okhotsk sea perhaps because of nearly year round sea ice expansion which would have prevented the growth of alkenone producers or because alkenones were less well preserved in surface sediments during the glacial period the northward and southward migrations of frontal zones were evaluated using differences in alkenone temperatures between stations located in the vicinity of the subarctic front saf subarctic boundary sab and kuroshio bifurcation front kbf all three frontal zones migrated southward during the glacial period compared with their present positions and their relative positions were different between the holocene and glacial periods in particular the distance between the saf and the sab was reduced during the glacial period compared with at present the northward and southward migration of the frontal zones may relate to both mid to low atmospheric circulation and polar atmospheric circulation

a three dimensional model of density driven circulation in the irish sea abstract a semi implicit version of the princeton ocean model ecomsi was used to simulate the cyclonic gyre that is found in the western irish sea during the spring and the summer mesoscale seasonal density driven circulations such as this are an important component of the long term flow in shelf seas and they pose a challenge to coastal ocean models extensive comparisons are made here with observational data to assess model performance the model successfully reproduced the development of the temperature field and the associated density driven currents throughout seasonal simulations the results demonstrate conclusively that the gyre is density driven and reinforce the dynamical importance of strong nearbed horizontal density gradients maximum baroclinic currents of 0 14 m s 1 were obtained and results showed that the regional kinetic energy due to the residual flow was 20 25 of that due to tidal flow during periods in which density gradients were strongest the model revealed important int

changes in biological production in the mixed water region mwr of the northwestern north pacific during the last 27 kyr abstract piston core pc6 40 n 143 e provides the first record of biological production and alkenone sea surface temperature sst in the mixed water region mwr off sanriku japan in the northwestern north pacific over the last 27 kyr biogenic opal content was low until the early holocene and rapidly increased at 6 calendar kiloyears before present cal kyr bp low biological production in the mwr resulted from the reduced duration of the phytoplankton bloom during the glacial period 27 18 cal kyr bp and from nutrient depletion especially silica during the deglaciation 15 9 5 cal kyr bp in spite of the decreased amount of nutrients in the oyashio water biological production increased in the late holocene 6 cal kyr bp present the data revealed that nutrients supplied from deeper levels by eddies played an important role in biological production in the mwr contrary to the conventional concept that the oyashio current has controlled productivity in this region alkenone sst during the glacial period was on average 13 6 c which is close to the modern sst 14 6 c in june but this timing is not consistent with the climap results 13 4 14 3 c in august this result indicates that alkenone sst recorded not late spring but summer temperatures owing to a bloom shift caused by surface water cooling during the last glacial period alkenone sst was even lower during the deglaciation than during the lgm and reached a minimum 9 4 c at 14 0 cal kyr bp 15 n was very high during the deglaciation implying that nutrients in the euphotic zone were depleted around the core site nutrient stress probably had a physiological impact on coccolithophorids and resulted in the apparent minimum alkenone sst these findings indicate that the reconstruction of sst by alkenones can sometimes be very complex and possibly misleading

response of mid latitude north pacific surface temperatures to orbital forcing and linkage to the east asian summer monsoon and tropical ocean atmosphere interactions we present a palaeoceanographic perspective of the north pacific during the last two glacial cycles based on u derived palaeotemperature records of images core md01 2421 off the coast of central japan and cores from the ocean drilling program odp sites 1014 and 1016 off the coast of california the sea surface temperature sst differences between odp sites 1014 and 1016 sstnortheastern pacific nep sstodp1014 sstodp1016 indicate the intensity of the california current comparison of sstnep and the sst from core md01 2421 revealed anti phase variation high sstnep indicating weakening of the california current corresponded to low sst at the japan margin indicating the southward displacement of the north western pacific subarctic boundary and weakening of the kuroshio extension and vice versa this finding suggests that the intensity of the north pacific subtropical gyre circulation has varied in response to precessional forcing and that this response has been linked with changes in tropical ocean atmosphere interactions in the precessional cycle the sst variation derived from core md01 2421 lags ca 2 5 4 ka behind the variations shown by hulu and sanbao stalagmite 18o records and by the pollen temperature index from core md01 2421 suggesting out of phase variations of the north pacific subtropical gyre circulation and the east asian summer monsoon these findings indicate that the behaviour of interactions between tropical ocean atmosphere dynamics and the east asian summer monsoon may have varied in response to the precessional cycle copyright 2009 john wiley sons ltd

geostrophic circulation patterns in the northeastern adriatic sea and the effects of air sea coupling may september 2003 1 ctd data were collected weekly during 20 cruises from may to september 2003 over a 19 station grid in a coastal region of the northeastern adriatic sea as part of the adriatic sea integrated coastal areas and river basin management system pilot project adricosm relative geostrophic velocities indicated fine scale circulation patterns in the area consisting of two pronounced circulation cells of cyclonic and anticyclonic character and that were present in the area for most of the investigated period these motions were induced primarily by spatial variations in the temperature field and may be strengthened during episodes of very strong northeasterly bora wind when the investigated region is not heated cooled uniformly

postglacial environmental change of the pacific ocean off the coasts of central japan abstract downcore changes in microfossil assemblages and oxygen isotope ratios in three piston cores recovered from the northwestern pacific off central japan show that the subtropical kuroshio front was located to the south of c 4 core site lat 33 n during the last glacial the front then advanced northward passing over the c 4 site and the c 6 site 34 6 n at about 13 ka and 10 ka respectively and reached the c 1 core site 36 n at about 7 ka after 5 5 ka it retreated to the area between the c 1 and c 6 sites a brief but significant cold event the readvance of the cold oyashio current is recognized between 11 and 10 ka in the two northern cores but the current did not reach the southern c 4 site a contemporaneous cold event is known in the north atlantic and the cooling was probably a global phenomenon likely to be associated with lowering of sea level contamination of isotopically light water is apparent between 14 and 11 ka in the marked change in isotopic composition of benthic foraminifers oxygen isotope ratios of planktonic foraminifers show that prior to the advance of the kuroshio front the surface water at these core sites was isotopically lighter than the kuroshio water at that time

biomarker temperature estimates for modern and last glacial surface waters of the california current system between 33 and 42 n sea surface temperature sst estimates were made using data for c37 39 alkenones analyzed in modern and glacial age intervals of sediment cores collected along an east west 42 n from 125 to 132 w and a north south 41 33 n transect of the california current system ccs the prymnesiophyte biomarker results suggest that surface waters warmed significantly throughout this region since the last glacial maximum lgm but the magnitude of warming varied spatially stratigraphic profiles from four sediment cores along the north south transect indicate the warming period was confined to the glacial interglacial transition 15 10 ka with sst reaching a maximum value at 10 ka and maintaining a uniformly high value throughout the holocene comparison of estimates derived from analysis of modern and lgm sediment intervals indicates the magnitude of the sst change was minimal for locations south of about 36 n 1 2 c and increased significantly 3 5 c north of this latitude using a simple heat balance model we calculate from the latitudinal gradient in sst that southward flow in the california current system during the lgm was about 60 of that measured today at 36 n our findings support the conclusion of others based on pollen data that coastal upwelling in the region of the northeast pacific off northern california was significantly reduced or even completely shutdown during the lgm

offshore stereo measurements of gravity waves stereo video techniques are effective for estimating the space time wave dynamics over an area of the ocean indeed a stereo camera view allows retrieval of both spatial and temporal data whose statistical content is richer than that of time series data retrieved from point wave probes to prove this we consider an application of the wave acquisition stereo system wass for the analysis of offshore video measurements of gravity waves in the northern adriatic sea in particular we deployed wass at the oceanographic platform acqua alta off the venice coast italy three experimental studies were performed and the overlapping field of view of the acquired stereo images covered an area of approximately 1100 m2 analysis of the wass measurements show that the sea surface can be accurately estimated in space and time together yielding associated directional spectra and wave statistics that agree well with theoretical models from the observed wavenumber frequency spectrum one can also predict the vertical profile of the current flow underneath the wave surface finally future improvements of wass and applications are discussed

on the structure and origin of major glaciation cycles 1 linear responses to milankovitch forcing time series of ocean properties provide a measure of global ice volume and monitor key features of the wind driven and density driven circulations over the past 400 000 years cycles with periods near 23 000 41 000 and 100 000 years dominate this climatic narrative when the narrative is examined in a geographic array of time series the phase of each climatic oscillation is seen to progress through the system in essentially the same geographic sequence in all three cycles we argue that the 23 000 and 41 000 year cycles of glaciation are continuous linear responses to orbitally driven changes in the arctic radiation budget and we use the phase progression in each climatic cycle to identify the main pathways along which the initial local responses to radiation are propagated by the atmosphere and ocean early in this progression deep waters of the southern ocean appear to act as a carbon trap to stimulate new observations and modeling efforts we offer a process model that gives a synoptic view of climate at the four end member states needed to describe the system s evolution and we propose a dynamic system model that explains the phase progression along causal pathways by specifying inertial constants in a chain of four subsystems solutions to problems involving systems of such complexity are not born full grown like athena from the head of zeus rather they evolve slowly in stages each of which requires a pause to examine data at great lengths in order to guarantee a sure footing and to properly choose the next step victor p starr

flocculation and sedimentation on the po river delta with the goal of improving understanding of the effect of flocculation on the formation of fine grained deposits on continental shelves hydrographic profiling in situ imaging of suspended matter and collection of surficial sediment samples were conducted at the po river delta in june 2001 these data show that during medium flow conditions 1920 m3 s sedimentation occurs rapidly immediately offshore of the main distributary po della pila rapid sedimentation is promoted by large rapidly sinking flocs forming in the river well upstream of the mouth the delivery of fine sediment to the seabed at the mouth of the po is sufficient to overwhelm the erosive effects of waves and currents leading to accumulation of mud in water depths as shallow as 4 m on cross shelf transects 2 km north and south of the mouth however suspended sediment supply from the river is reduced to the point that mud accumulates only seaward of the 8 m isobath along the central transect suspended sediment concentration decreases rapidly seaward of the 6 m isobath where the emergence of a more organic rich population of flocs along a mid water density interface is suggested energetic activity along the 15 m isobath likely promotes resuspension with the potential for removal of material from the delta further investigation of floc properties namely the relationship of floc size to settling velocity is necessary to establish the degree to which the suspension is flocculated during transport and deposition

planktonic foraminifera in the western north pacific during the past 150 000 years comparison of modern and fossil assemblages abstract planktonic foraminiferal abundance variations in 186 deep sea piston core tops from the western north pacific were used to create a calibration set to characterize the present day kuroshio gyre system q mode factor analysis helped identify six faunal assemblages 93 variance related to modern water masses two tropical assemblages differing in relative dissolution three assemblages representing subtropical subpolar and transitional conditions and a gyre margin assemblage lying between the kuroshio current and the mainland of asia multivariate regression produced transfer functions relating observed summer august and winter february sea surface temperatures sst to the assemblages with standard errors of estimate of 1 5 c and 2 5 c respectively data from 24 piston cores was used to interpret variations of the kuroshio gyre system during the past 150 000 yr stratigraphic control is based on oxygen isotopic measurements the extinction of pink pigmented globigerinoides ruber at 120 000 b p coiling direction changes in neogloboquadrina pachyderma north of 30 n and dissolution variations between resistant and fragile taxa major dynamic changes in the circulation of the kuroshio gyre occurred during the last two glacial maxima at 15 20 000 b p isotopic stage 2 and at 140 150 000 b p isotopic stage 6 these intervals are characterized by 1 lowered sea levels which reduced flow into the sea of japan and sea of okh okhotsk 2 advance of the polar front from its modern position at about 42 n to 35 38 n 3 southward penetration of the oyashio current along the pacific coast of japan to tokyo 4 2 3 c lowered sst in tropical areas little or no change in subtropical areas and a 4 6 c decrease in transitional areas and 5 an overall decrease in carbonate dissolution relative to interglacial stages the maximum interglacial at 120 000 b p isotopic substage 5e shows a retreat of the polar front north of its modern position and an overall relative increase in interglacial carbonate dissolution that does not become severe until substage 5d

variability of the path of the kuroshio ocean current over the past 25 000 years the kuroshio current is the strong northwestern component of the subtropical north pacific ocean gyre and advects a large amount of heat from the tropics to northern mid latitudes the kuroshio has bimodal stationary flow patterns with small and large meander paths east of central japan1 2 which switch on annual and decadal timescales3 4 these switches seem to be caused by changes in current velocity and volume transport of the north equatorial current that are associated with variations in the trade wind intensity in the eastern equatorial north pacific ocean5 6 here we present alkenone derived sea surface temperature records at multicentennial resolution from sediment cores from the nishishichitou ridge off central japan these 25 000 year records show that the kuroshio path has also fluctuated on millennial timescales this variability resembles that of the subtropical high pressure of the north pacific reconstructed from terrestrial pollen distributions water levels in north american lakes and marine micropalaeontological records7 together these data indicate that climate variability off central japan over the past 25 000 years may be part of a circum pacific phenomenon reflecting the rate of subtropical surface circulation in the north pacific ocean

tephra layers in late quaternary sediments of the central adriatic sea abstract magnetic susceptibility curves of ten cores collected in the western adriatic shelf and in the mid adriatic deep allowed us to recognize thirty tephra layers whose age based on physical and biostratigraphic data encompass a time interval ranging from less than 70 ka to the present chemical features of the tephra defined by sem eds analyses performed on glass shards indicate alkaline affinity mainly with k na 1 and trachytic compositions with two minor benmoreitic and phonolitic groups these characteristics are consistent with campanian and subordinate etnean provenances because of chemical and age constraints the glass shards can be referred to six tephra layers already described in the literature such as c20 c14 citara ischia c10 campanian ignimbrite c2 nyt neapolitan yellow tuff ams pf agnano monte spina phlegrean fields from campanian area and y1 from etna volcano indicating an age ranging from about 70 to 4 ka ams pf and c2 nyt dated 4 4 and 12 3 ka respectively are the most widespread tephra beds in the study cores the occurrence of ams pf never recorded in marine sequences up to now represents a very good marker for holocene adriatic sediments c2 nyt already recorded in the central tyrrhenian sea in lacustrine sediments from southern italy and in the campanian area is a good stratigraphic marker for inter sea and sea land correlations y1 tephra dated 14 2 ka also occurs in on land sediments of central italy and in marine sediments from the tyrrhenian and ionian seas it now represents one of the most widespread stratigraphic markers in the central mediterranean region

late quaternary paleoceanography deduced from coccolith assemblages in a piston core recovered off the central japan coast abstract nannofossil assemblages from the last 144 ka marine isotope stage mis6 were studied in a piston core md01 2421 from the nw pacific 36 01 4 n 141 46 8 e wd 2 224 m off the coast of central japan the site is influenced by both the subtropical kuroshio and the subarctic oyashio currents and is located just north of the kuroshio front this study attempted to reconstruct paleoceanographic changes in the region by illustrating the past migration patterns of the kuroshio current which is considered to be one of the strongest western boundary currents in the pacific in order to reconstruct the past migration patterns of the kuroshio current relative abundance values of several taxa classified as either kuroshio species or oyashio species were used as indices using these species a ratio tn nannofossils temperature index representing the mixing of the kuroshio and oyashio currents was calculated to express quantitatively the influence of the kuroshio current tn values fluctuated widely ranging from 1 45 135 ka to 86 9 115 3 ka and corresponds to the warm cold cycles obtained by oxygen isotope analysis the fluctuation pattern of percentage abundance of umbellosphaera spp shows a strong similarity to that of the precessional cycle it may indicate that subtropical water has influenced the japanese coast during these warm intervals possibly due to the expansion of subtropical divergence also the fluctuation pattern of tn shows a similar time transgressive trend to that of the precessional cycle this implies that latitudinal displacement of the kuroshio front was related to subtropical climatic variability the ratio between tn and tp planktonic foraminifera temperature index drastically increased at about 20 ka in mis2 with small peaks in mis6 this suggests that a thin layer of warm water may have covered the study area during these intervals an increased preservation of organic matter i e caco3 preservation possibly affected the absolute coccolith abundance coccolith g dry sediment although other factors controlling absolute coccolith abundance e g nutrient levels need to be taken into consideration

fine sediment mass balance in the western adriatic continental shelf over a century time scale abstract to obtain a quantitative estimate of the sediment accumulating on the muddy belt extending along the western adriatic continental shelf a budget was calculated based on the mass accumulation rates measured from more than one hundred activity depth profiles of 210 pb 137 cs depth distributions were used when possible to support 210 pb results 210 pb profiles show quasi monotonic declines in the foreset region of the central adriatic clinoform in the prodelta of the rivers po and isonzo 210 pb profiles are characterized by intervals of low and uniform activity which are thought to be produced by flood deposition since the north adriatic is shallow and occasionally affected by storms from bora wind sediments are not in steady state and their accumulation is the net result of recurring deposition resuspension and winnowing events in the western adriatic mass accumulation rates range between 0 04 and 6 6 g cm 2 yr 1 peak values were recorded in the po and isonzo prodeltas and along a narrow belt between pescara and the gargano promontory furthermore the latter depocentre is located immediately seaward of the offlap break 40 50 m water depth and parallels that of the most recent sigmoid of the hst the integration of mass accumulation rates throughout the mud wedge of the north and central adriatic gave a value of 42 0 tg yr 1 of sediment accumulating along the italian coast the balance between sediment accumulation and riverine sediment supply 46 6 tg yr 1 suggests an export of 4 6 tg yr 1 to the south adriatic basin and or the mediterranean sea the along shore sediment transport is very effective and in particular 16 2 tg yr 1 of sedimentary material 35 of the riverine supply is transferred from north to central adriatic through the ancona section

seasonal evolution of the cold pool gyre in the western irish sea an extensive cruise program during 1994 1995 and 1996 provided observations that describe the seasonal evolution of the three dimensional density field in the western irish sea a cold dense pool flanked by strong nearbed density gradients was present from may until october in spring salinity had a dominant influence on the density structure but from june until october temperature controlled the density stratification the trajectories of 55 satellite tracked argos drifters demonstrated the existence of the cyclonic circulation pattern that constitutes the western irish sea gyre and defined the gyre s spatial extent several distinct recirculation paths were observed and the implications for planktonic organisms of the seasonal variability in the recirculation are discussed drifter speeds were in good agreement with geostrophic calculations based on the observed density field and with de tided acoustic doppler current profiler adcp measurements the dynamical significance of strong nearbed gradients bottom fronts is highlighted the location of the dynamically significant baroclinicity below the level of wind mixing explains the persistence of the cold pool and cyclonic circulation until late october the dataset described here is valuable for environmental management purposes and it facilitates testing of the prognostic capabilities of the present generation of density advecting numerical models

surface current patterns in the northern adriatic extracted from high frequency radar data using self organizing map analysis 1 a network of high frequency hf radars was installed in the northern adriatic in the second half of 2007 aimed to measure surface currents in the framework of the north adriatic surface current mapping nascum project this study includes a detailed analysis of current measurements from february to august 2008 a period in which three radars were simultaneously operational current patterns and temporal evolutions of different physical processes were extracted by using self organizing map som analysis the analysis focused on subtidal frequency band and extracted 12 different circulation patterns on a 4 3 rectangular som grid the som was also applied on a joint data set that included contemporaneous surface wind data obtained from the operational hydrostatic mesoscale meteorological model aladin hr the strongest currents were recorded during energetic bora episodes being recognized by several current patterns and having the characteristic downwind flow with magnitudes exceeding 35 cm s at some grid points another characteristic wind the sirocco was represented by three current patterns while the remaining current structures were attributed to weak winds and the residual thermohaline circulation a strong resemblance has been found between som patterns extracted from hf radar data only and from combined hf radar and wind data sets revealing the predominant wind influence to the surface circulation structures and their temporal changes in the northern adriatic these results show the som analysis being a valuable tool for extracting characteristic surface current patterns and forcing functions

enso like forcing on oceanic primary production during the late pleistocene late pleistocene changes in oceanic primary productivity along the equator in the indian and pacific oceans are revealed by quantitative changes in nanoplankton communities preserved in nine deep sea cores we show that variations in equatorial productivity are primarily caused by glacial interglacial variability and by precession controlled changes in the east west thermocline slope of the indo pacific the precession controlled variations in productivity are linked to processes similar to the southern oscillation phenomenon and they precede changes in the oxygen isotopic ratio which indicates that they are not the result of ice sheet fluctuations the 30 000 year spectral peak in the tropical indo pacific ocean productivity records is also present in the antarctica atmospheric co2 record suggesting an important role for equatorial biological productivity in modifying atmospheric co2

recent deposits and suspended sediments off the po della pila po river main mouth italy abstract present sedimentary conditions in the prodeltaic marine area immediately in front of the po della pila po river main mouth are characterized by a maximum thickness of holocene muds of 10 12 m at a depth of 20 25 m and by two different sedimentary cycles with the more recent lens shaped unit 2 5 4 0 m thick probably deposited in the last 300 yrs the nearshore prodelta area is characterized by rapidly accumulating deposits 2 4 cm yr enriched in smectite gas organic material 1 2 and trace metals the water system presented well marked vertical stratification during the summer of 1985 revealing three distinct water bodies 1 riverine and diluted waters average depth of 3 m 2 middle depth waters 10 20 m and 3 bottom waters temperature oxygen and particulate organic carbon decrease with depth whilst total suspended matter yellow substances and total particulate carbon show maxima at the surface and in the bottom layers and minima in the intermediate waters where the organic fraction comprises 42 of the total

orbital controls on the el nino southern oscillation and the tropical climate the global synchroneity of glacial interglacial events is one of the major problems in understanding the link between milankovitch forcing and the climate of the late quaternary in this study we isolate a part of the climate system the tropical pacific and test its sensitivity to changes in solar forcing associated with changes in the earth s orbital parameters we use a simplified coupled ocean atmosphere model that is run for the past 150 000 years and forced with milankovitch changes in the solar insolation this system responds primarily to the precessional cycle in solar forcing and is capable of generating a mean response to the changes in the seasonal distribution of solar radiation even while the annual mean insolation is roughly constant the mean response to the precessional forcing is due to an interaction between an altered seasonal cycle and the el nifio southern oscillation enso changes in the enso behavior result in a mean tropical climate change the hypothesis is advanced that such a change in the tropical climate can generate a globally synchronous climate response to milankovitch forcing

fluctuations in the east asian monsoon over the last 144ka in the northwest pacific based on a high resolution pollen analysis of images core md01 2421 abstract a high resolution pollen analysis of images core md01 2421 45 83 m from the northwest pacific off central japan was used to clarify the vegetation history of central japan over the past 144 ka an age model was constructed using the oxygen isotope stratigraphy of benthic foraminifera 12 accelerator mass spectrometry ams 14c datings and two tephra layers with known eruption ages the pollen temperature index t p 1 0 0 t w t c t w where tw is the sum of temperate taxa and tc the sum of subalpine taxa values were high during 129 119 115 100 82 76 53 49 and 15 0 ka cool temperate broad leaved forests developed during the high tp periods and subalpine conifer forests grew during the low tp periods the tp fluctuated synchronously with summer insolation at 36 n where the core was collected during periods with abundant cryptomeria or sciadopitys 120 118 115 89 78 70 and 4 0 3 ka the east asian summer monsoon was stronger and the annual precipitation was greater in central japan than at present 2000 vs 1500 mm fluctuations in the sea surface temperature sst calculated from the oxygen isotopes of foraminifera in core md01 2421 and changes in the strength of the summer monsoon were synchronous the sst was determined by the currents passing over the core site rather than by the strength of summer insolation northward movement high sst of the kuroshio current which is under the influence of the summer okhotsk high pressure was strong near the summer insolation minima when precipitation was high particularly around 116 94 and 71 ka thus the strengths of both summer insolation and the east asian summer monsoon have determined the vegetation history of central japan for the last 144 ka

variability of the kuroshio extension jet recirculation gyre and mesoscale eddies on decadal time scales abstract twelve years of sea surface height ssh data from multiple satellite altimeters are used to investigate the low frequency changes and the interconnections of the kuroshio extension ke jet its southern recirculation gyre and their mesoscale eddy field the dominant signal is characterized by the steady weakening of the ke jet recirculation gyre from 1993 to 1996 followed by a gradual strengthening after 1997 during the weakening period of 1993 96 the ke path migrated southward in general and this path migration reversed in direction during the strengthening period of the ke jet and recirculation gyre after 1997 by hindcasting the ssh signals using linear vorticity dynamics it was found that weakening strengthening in the ke jet and recirculation gyre is consistent with westward propagation of negative positive ssh anomalies generating in the eastern north pacific and strengthening during their westward propagation when the ke jet and recirculation gyre were in a weak mode during 19

scales and variability of the sea surface temperature distribution in the adriatic sea 1 scales and variability of the adriatic sea surface temperature sst distribution in the period january 1991 to december 2000 are studied by means of 8 day composite 4 km resolution sst data scales of the sst are defined as scales of the sst autocorrelation function assuming an exponential correlation model scales of the sst are quantified as e folding times and distances of the sst autocorrelation function variability in the sst is analyzed through empirical orthogonal function eof analysis from summer to winter spatial scales of the sst in the along basin direction remain unchanged while in the across basin direction they decrease resulting in scales that are slightly shorter 10 15 in winter than in summer the spatial distribution of temporal scales displays two patterns the first characterized by low values is located in the northern part of the basin and along the italian coast and the second characterized by high values covers the rest of the basin the sst variability is dominated by the annual signal which explains 45 of the overall variance the main structures of the adriatic circulation leave their signature on the first three eofs whose spatial variability occurs on wavelengths longer than 200 km in the along basin direction and in the across basin direction in the band 25 50 km and at 80 and 100 km eof coefficients are characterized by oscillating components with periods of 20 days to 6 months

core top calibration of the lipid based u37k and tex86 temperature proxies on the southern italian shelf sw adriatic sea gulf of taranto abstract the mediterranean sea is at the transition between temperate and tropical air masses and as such of importance for studying climate change the gulf of taranto and adjacent sw adriatic sea are at the heart of this region their sediments are excellently suited for generating high quality environmental records for the last millennia with a sub decadal resolution the quality of these records is dependent on a careful calibration of the transfer functions used to translate the sedimentary lipid signals to the local environment here we examine and calibrate the u 37 k and tex 86 lipid based temperature proxies in 48 surface sediments and relate these to ambient sea surface temperatures and other environmental data the u 37 k based temperatures in surface sediments reflect winter spring sea surface temperatures in agreement with other studies demonstrating maximum haptophyte production during the colder season the tex 86 based temperatures for the nearshore sites also reflect winter sea surface temperatures however at the most offshore sites they correspond to summer sea surface temperatures additional lipid and environmental data including the distribution of the bit index and remote sensed chlorophyll a suggest a shoreward increase of the impact of seasonal and spatial variability in nutrients and control of planktonic archaeal abundance by primary productivity particle loading in surface waters and or overprint by a cold biased terrestrial tex 86 signal as such the offshore tex 86 values seem to reflect a true summer signal to the effect that offshore u 37 k and tex 86 reconstruct winter and summer temperature respectively and hence provide information on the annual temperature amplitude

analysis of the seasonal and interannual variability of the sea surface temperature field in the adriatic sea from avhrr data 1984 1992 seasonal and interannual variability of the sea surface temperature field in the adriatic sea is analyzed from the low resolution advanced very high resolution radiometer data the spatial resolution of 18 km allowed analysis of only basin and subbasin scale features average monthly and seasonal sea surface temperature fields for the entire studied period 1984 1992 are discussed the analysis shows the absence of any permanent sea surface thermal features in the adriatic sea the south adriatic sea surface temperature minimum presumably associated to the cyclonic gyre previously considered as one of the permanent features appears to be recurrent being prominent only in late autumn and early winter i e in the preconditioning and a deepwater formation phases the major ionian water inflow is documented in autumn while the thermal signature of the western surface outflow of adriatic water appears most prominent in winter the variability of the basin wide thermal pattern in the adriatic reveals four distinct seasons which is different from both the eastern and western mediterranean where only two major patterns are recognized a prominent interannual signal occurs in a northward extension of the warm water plume along the eastern coast which in some years reaches the northernmost corner of the adriatic while in other situations it remains trapped in the south adriatic cyclonic gyre the surface thermal signature of the south adriatic gyre also varies on an interannual timescale and it was weak or completely absent during the period 1984 1986 while it was rather prominent in the period 1987 1992 a constant trend of sea surface temperature decrease in the center of the south adriatic gyre and in the northernmost corner of the adriatic was evidenced over the studied period

mineral magnetism and geomagnetic secular variation of marine and lacustrine sediments from central italy timing and nature of local and regional holocene environmental change abstract sediment core palaeomagnetic and mineral magnetic records from two crater lakes in central italy and from the western margin of the adriatic sea have been used to evaluate local and regional responses to holocene environmental change in all cores sediment magnetism reflects the interplay between catchment material and the in situ production of bacterial magnetite magnetotactic bacteria in the lakes the earliest holocene sediments record a waning catchment input that we attribute to rising lake levels and increased tree cover in the catchment from 9000 to 5000 yr bp both lakes become anoxic a consequence of water mass stratification driven by high lake levels bottom water anoxia also developed in the adriatic with sapropel s1 produced between 9000 and 7000 yr bp subsequently the lake and adriatic mineral magnetic records show evidence for increased catchment delivery consistent with pollen evidence for bronze age deforestation in the lakes this evidence is first recorded at 4300 yr bp and a number of distinct clearance events are recorded in comparison at adriatic site rf93 30 lithogenic input increases abruptly at 3500 yr bp and is followed by a slowly changing record of waxing and waning sediment delivery inter site comparisons of palaeomagnetic data point to a possible link between the magnitude of the bacterial magnetite component and the recorded magnetic inclination the sites are at near identical latitudes and have similar sediment accumulation rates but the adriatic sites have a core average magnetic inclination that is some 10 steeper than the lake average values we suggest that the large dipole moment of the magnetosome chains which in life produce the passive alignment of the bacterium along the local geomagnetic field line produce a more faithful albeit smoothed record of the geomagnetic field

the adriatic sea hydrography and circulation in spring and autumn 1985 1987 abstract the adriatic basin wide circulation and its temporal variability are reviewed on the basis of results from the analysis of hydrographic data collected during four poem cruises major well known features in the circulation are revealed in the data set which covers the period from october 1985 to april 1987 a prominent signal associated with the seasonal variability is identified in the water outflowing along the italian coast differences between autumn and spring in the vein of cold and fresh water flowing along the italian shelf manifest mainly in the temperature field during the stratified season the fresh water spreads over the entire surface layer of the southern adriatic on the other hand during spring when the sea is vertically homogeneous the fresh water remains confined to the surface longshore boundary layer over the entire length of the italian coast layers below the seasonal thermocline at the eastern portion of the sea display very weak seasonal signals a strong signal associated with the inter annual variations also has been documented from the analysed data set it mainly appears in the salinity field it is shown that in spring 1986 the salinity averaged over the entire water column north of the palagruza sill is lower by 0 3 psu than in spring 1987 a similar but less prominent difference is noted in the southern adriatic an attempt is made to associate these differences with variations in climatic conditions over the area the river runoff and the mediterranean water inflow

characteristics of alkenone distributions in suspended and sinking particles in the northwestern north pacific abstract we investigated alkenones recorded in suspended particles and a settling particle time series collected at three stations 40n 40 n 165 e knot 44 n 155 e and 50n 50 n 165 e in the northwestern north pacific from december 1997 to may 1999 emiliania huxleyi the most abundant alkenone producer in this area is present in surface to subsurface to 50 m depth waters the alkenone concentrations recorded in the suspended particles indicated that the seasonal alkenone particle distribution differed significantly interannually alkenone export fluxes at the three sediment trap stations ranged from 0 16 to 49 3 g m 2 day 1 and the maximum export flux which occurred in summer to fall july november was associated with a high organic carbon export flux the amount of alkenone produced during the maximum export season accounted for 60 80 of the total annual amount of alkenone and the alkenones accumulated in the sediment below the traps had characteristics corresponding to subsurface waters during the summer autumn season alkenone derived temperatures recorded in suspended particles corresponded to the in situ temperature within 2 c although alkenone derived temperatures corresponded approximately to the temperatures observed in the stratified subsurface waters at the three trap stations during the high export season large differences were observed during the low export winter spring period for example the alkenone derived temperatures observed at stations knot and 50n were much higher than the in situ subsurface temperatures reported in the world ocean atlas 2001 relatively large differences between alkenone derived temperatures and in situ temperatures in the subarctic might be due to 1 a low light limitation or 2 contributions of allochthonous alkenones in particulate material transported from subtropical areas within a warm core ring

a 350 000 year summer monsoon multi proxy stack from the owen ridge northern arabian sea five summer monsoon proxies from the northern arabian sea are combined using stacking and principal components analysis pca to create two very similar multi proxy records of summer monsoon variability the five individual proxies all respond to monsoon variability but are largely independent in terms of the processes that complicate their interpretation as summer monsoon indicators e g preservation dissolution diagenesis sediment reworking as such stacking and pca average out non monsoon variance yielding a more pure monsoon signal these stacked and pca records hereafter summer monsoon stack and summer monsoon factor allow evaluation of relative monsoon strength through time as well as the relative concentration of variance within orbital bands these two parameters are less reliable when estimated from individual proxy records in fact the summer monsoon factor smf accounts for only 33 of the total variance in the five records suggesting that relative amplitude variations in each individual proxy time series are influenced by non monsoon processes the summer monsoon stack sms and smf are spectrally very similar dominated by variance in the 41 k y obliquity and 23 k y precession bands there is very little variance at the 100 k y eccentricity band associated with large scale changes in global ice volume indeed equally strong monsoons occur in both glacial and interglacial intervals within the 23 k y precession cycle monsoon maxima fall at 121 relative to precession minima june 21 perihelion maximum northern hemisphere nh summer insolation this phase falls midway between 18o minima 78 and december 21 perihelion 180 indicating that two mechanisms exert equal influence in determining the timing of strong summer monsoons within the precession band 1 sensible heating of the asian plateau which is maximized at times of ice volume minima 78 and 2 latent heat export from the southern subtropical indian ocean which is maximized at times of december 21 perihelion 180 the seasonal cycle at december 21 perihelion is characterized by warm southern hemisphere sh summers followed by cold sh winters a combination that preconditions the ocean to export latent heat during the boreal summer monsoon season summer monsoon winds transport this latent heat into asia where it is released during precipitation enhancing the asian monsoon low within the 41 k y obliquity cycle monsoon maxima are in phase with obliquity maxima this indicates that two mechanisms quite similar to those in the precession band influence the timing of strong summer monsoons in the obliquity band 1 sensible heating of the asian plateau but with no ice volume delay and 2 latent heat export from the southern subtropical indian ocean which is maximized at times of obliquity maxima again the seasonal cycle at obliquity maximum is characterized by warm sh summers followed by cold sh winters ideal for maximizing latent heat export during the boreal summer monsoon

tidal currents in the northwestern adriatic high frequency radio observations and numerical model predictions the results of a two year long deployment of high frequency radars along the italian coast of the northern adriatic are analyzed to characterize the surface tidal currents m2 and k1 ellipses are aligned with the basin axis and exhibit large eccentricities in the middle of the basin decreasing toward the italian coast comparisons are made with a 3d finite element non linear numerical model of the tides complex correlations between modeled and observed tidal currents show a remarkable agreement in the middle of the basin with magnitudes reaching 0 985 and average phases of 6 4 deg however the magnitudes drop to 0 5 within 20 30 km from the italian coast where the modeled currents amplitudes are underestimated by 2cm s and the phases lag the observed phases by 60 deg this shallow region less than 30 m deep is characterized by low salinity water originating at the po river and laterally sheared coastal flows the radars may have captured the influence of stratification or mean sheared flows both absent from the model the model parameterization of bottom friction may also inadequately represent the effects of real bottom friction on the vertical current shear

high resolution mapping of bora winds in the northern adriatic sea using synthetic aperture radar 1 the adriatic sea is regularly subjected to strong bora wind events from the northeast during winter the events have a strong effect on the oceanography in the adriatic driving basin scale gyres that determine the transport of biogeochemical material and extracting large amounts of heat the bora is known to have multiple surface wind jets linked to the surrounding orography and have been the focus of many studies but it has not been possible to describe the detailed spatial structure of these jets by in situ observations using high resolution spaceborne radarsat 1 synthetic aperture radar sar images collected during an active bora period 23 january 16 february 2003 we created a series of high resolution 300 m maps of the wind field the obtained winds show reasonable agreement with several in situ wind observations with an rms wind speed error of 3 6 m s slightly higher than the 2 3 m s errors reported in previous studies these sar images reveal the spatial structure of the bora wind in unprecedented detail showing several new features in the senj region of croatia several images show rhythmic structure with wavelengths of 2 3 km that may reflect bora pulsation seen at fixed locations by previous investigators along the italian coast several images show a wide 20 30 km band of northwesterly winds that abruptly change to the northeasterly bora winds further offshore meteorological model results suggest that these northwesterly winds are consistent with those of a barrier jet forming along the italian apennine mountain chain

collapse of the california current during glacial maxima linked to climate change on land time series of alkenone unsaturation indices gathered along the california margin reveal large 4 to 8 c glacial interglacial changes in sea surface temperature sst over the past 550 000 years interglacial times with ssts equal to or exceeding that of the holocene contain peak abundances in the pollen of redwood the distinctive component of the temperate rainforest of the northwest coast of california in the region now dominated by the california current ssts warmed 10 000 to 15 000 years in advance of deglaciation at each of the past five glacial maxima ssts did not rise in advance of deglaciation south of the modern california current front glacial warming along the california margin therefore is a regional signal of the weakening of the california current during times when large ice sheets reorganized wind systems over the north pacific both the timing and magnitude of the sst estimates suggest that the devils hole nevada calcite record represents regional but not global paleotemperatures and hence does not pose a fundamental challenge to the orbital milankovitch theory of the ice ages

equatorward shift of the subarctic boundary in the northwestern pacific during the last deglaciation 1 we have generated a high resolution record of alkenone sea surface temperature sst between 10 24 ka from core md01 2421 off central japan in the northwestern pacific the cooling by 5 c from 21 ka to 12 8 ka implies the equatorward shift of the subarctic boundary in the northwestern pacific by 2 8 in latitude this shift was a result of the stronger summer okhotsk high the okhotsk high was likely enhanced by the combined effects of el nino like conditions in the tropical pacific and the heating of the land surface of northeastern siberia

sea surface temperature record off central japan since the last glacial maximum using planktonic foraminiferal mg ca thermometry we conducted paired measurements of the mg ca ratio and 18o of planktonic foraminifera globigerina bulloides from a sediment core md01 2420 off central japan in the northwest pacific to reconstruct current movements since the last glacial maximum lgm these methods make it possible to determine the magnitude and timing of the sea surface temperature sst changes and to reconstruct the variations of the past seawater 18o 18ow off central japan the amplitude of mg ca based sst changes between the holocene and the lgm was about 10 c the strong resemblance of the ssts estimated from both methods mg ca based and 18o based suggests that the sst changes were caused primarily by latitudinal displacement of the kuroshio oyashio currents and no distinct change in the carbonate dissolution of the core the southward migration of the water mass was 5 6 in latitude at the lgm the values for regional 18ow changes which were obtained by subtracting the ice volume contribution from the calculated 18ow describe the millennial scale water mass migration over the last 30 kyr copyright 2005 john wiley sons ltd

el nino like pattern in ice age tropical pacific sea surface temperature sea surface temperatures ssts in the cold tongue of the eastern equatorial pacific exert powerful controls on global atmospheric circulation patterns we examined climate variability in this region from the last glacial maximum lgm to the present using a sst record reconstructed from magnesium calcium ratios in foraminifera from sea floor sediments near the galapagos islands cold tongue sst varied coherently with precession induced changes in seasonality during the past 30 000 years observed lgm cooling of just 1 2 c implies a relaxation of tropical temperature gradients weakened hadley and walker circulation southward shift of the intertropical convergence zone and a persistent el nino like pattern in the tropical pacific this is contrasted with mid holocene cooling suggestive of a la nina like pattern with enhanced sst gradients and strengthened trade winds our results support a potent role for altered tropical pacific sst gradients in global climate variations

organic matter origin and distribution in suspended particulate materials and surficial sediments from the western adriatic sea italy abstract in this study organic carbon oc total nitrogen tn stable carbon isotopic 13 c oc and cuo reaction product compositions were used to identify the sources of organic matter om and to quantify the relative importance of allochthonous and autochthonous contributions to the western adriatic sea italy suspended particulate material 195 samples and surficial sediments 0 1 cm 70 samples from shallow cross shelf transects were collected in february and may 2003 respectively vertical water column profiles were acquired along the same transects data include depth potential temperature salinity density and chlorophyll fluorimetry along the western adriatic shelf in the near shore region the phytoplankton growth was influenced by dynamics of the buoyant plumes from the po and appennine rivers a small amount of very fine terrigenous material remained suspended within the coastal current and was exported southward along the shelf to the slope high variability in the bulk composition was detected in the po prodelta surficial sediments whereas the western adriatic shelf although a larger area exhibited a narrower range of values a significant decoupling was observed between suspended particles in the water column and surficial deposits the organic material collected in the water column was compositionally heterogeneous with contributions from marine phytoplankton riverine estuarine phytoplankton and soil derived om frequent physical reworking of surficial sediments likely leads to the efficient oxidation of marine oc resulting in the observed accumulation and preservation of refractory soil derived oc delivered by the po and appennine rivers

a high resolution absolute dated late pleistocene monsoon record from hulu cave china oxygen isotope records of five stalagmites from hulu cave near nanjing bear a remarkable resemblance to oxygen isotope records from greenland ice cores suggesting that east asian monsoon intensity changed in concert with greenland temperature between 11 000 and 75 000 years before the present yr b p between 11 000 and 30 000 yr b p the timing of changes in the monsoon as established with 230th dates generally agrees with the timing of temperature changes from the greenland ice sheet project two gisp2 core which supports gisp2 s chronology in this interval our record links north atlantic climate with the meridional transport of heat and moisture from the warmest part of the ocean where the summer east asian monsoon originates

millennial pulsing of environmental change in southern california from the past 24 k y a record of indo pacific enso events century long variations in coastal california vegetation inferred from polliniferous sediments deposited in the santa barbara basin record a succession of brief 14 c yr b p ka these millennial scale pulses many of which correspond with western great basin hydrological fluctuations are also linked to events of southwest monsoon intensification in southern asia we suggest that these correlative high frequency variations in the asian summer and northeast pacific winter climates may reflect submillennial scale el nino southern oscillation enso type forcing involving water vapor transport over the indian and pacific oceans

paleoenvironmental changes in the northern area of the east china sea during the past 42 000 years a 33 65 m long images md982195 core with very high sedimentation rate ca 80 cm kyr retrieved from the northern part of the east china sea was analyzed at 10 cm intervals about 125 years for oxygen carbon isotope of globigerinoides ruber sensu stricto sea surface temperature sst from alkenones u37 k and principal component analysis of planktonic foraminiferal assemblage the general pattern of the 18o curve resembling the alkenone sst curve is similar to the standard open ocean oxygen isotope curve it reveals many light 18o peaks apparently corresponding to dansgaard oeschger d o cycles as observed in greenland ice cores for the last 42 ka the alkenone sst at the core top is 24 c which is close to the modern annual mean sst around the core site on the other hand sst during the last glacial maximum lgm was about 5 c lower than that in the present day alkenone derived sst does not correlate with the light negative 18o peaks corresponding to the d o cycles the oxygen isotope ratios for the surface waters based on oxygen isotopes of g ruber and alkenone ssts indicate approximately 1 0 increase on average during the lgm and many light peaks at the warm d o events this suggests that fresh water was supplied to the core site during these events the meandering of the westerlies during the cold and warm d o cycles would have caused an atmospheric tele connection between east asia and greenland the core was divided into four periods based on q mode factor analysis of the planktonic foraminiferal assemblage i e 1 a strong upwelling period from 42 to 24 ka indicated by abundant occurrence of globigerina bulloides 2 a cold and low salinity water mass period from 24 to 14 ka suggested by increase of neogloboquadrina pachyderma neogloboquadrina incompta and globigerina quinqueloba 3 a transitional period from cold to warm water masses from 14 to 8 ka as indicated by the increase of warm water species such as pulleniatina obliquiloculata and globigerinoides ruber and 4 the present day warm kuroshio current condition after 8 ka the kuroshio current flowed into the ecs since the last 42 ka and weakened during the last glacial maximum lgm due to the expansion of the coastal water in the northern part of the ecs

paleoproductivity and carbon burial across the california current the multitracers transect 42 n the multitracers experiment studied a transect of water column sediment trap and sediment data taken across the california current to develop quantitative methods for hindcasting paleoproductivity the experiment used three sediment trap moorings located 120 km 270 km and 630 km from shore at the oregon california border in north america we report here about the sedimentation and burial of particulate organic carbon corg and caco3 in order to observe how the integrated caco3 and corg burial across the transect has changed since the last glacial maximum we have correlated core from the three sites using time scales constrained by both radiocarbon and oxygen isotopes by comparing surface sediments to a two and a half year sediment trap record we have also defined the modern preservation rates for many of the labile sedimentary materials our analysis of the corg data indicates that significant amounts 20 40 of the total corg being buried today in surface sediments is terrestrial at the last glacial maximum the terrestrial corg fraction within 300 km of the coast was about twice as large such large fluxes of terrestrial corg obscure the marine corg record which can be interpreted as productivity when we corrected for the terrestrial organic matter we found that the mass accumulation rate of marine corg roughly doubled from the glacial maximum to the present because preservation rates of organic carbon are high in the high sedimentation rate cores corrections for degradation are straightforward and we can be confident that organic carbon rain rate new productivity also doubled as confirmation the highest burial fluxes of other biogenic components opal and ba also occur in the holocene productivity off oregon has thus increased dramatically since the last glacial maximum caco3 fluxes also changed radically through the deglaciation however they are linked not to caco3 production but rather to changes in deepwater carbonate chemistry between 18 ka and now

the modern po delta system lobe switching and asymmetric prodelta growth the modern po delta system comprising five main delta lobes has been investigated by integrating vhr seismic surveys recorded offshore from water depths as shallow as 5 m to the toe of the prodelta in about 30 m with accurate historical cartography extending back several centuries previous studies give sedimentological and geochronological information from precisely positioned sediment cores this combined historical and stratigraphic reconstruction of the modern po prodelta allows volumetric reconstructions indicating an average sediment load of 9 4 10 6 ty r 1 for po di pila and po di goro gnocca lobes this estimate is remarkably consistent with the total sediment load of 11 5 10 6 ty r 1 available for parts of the last century from a gauge station at the apex of the delta plain in pontelagoscuro these integrated stratigraphic studies allow to explain the key characters of the po delta system a the marked asymmetry of the whole delta prodelta system reflecting prevailing sediment dispersal to the south of each individual delta outlet b the shoreparallel overlapping of successive prodelta lobes fed by distinct river outlets of ever changing relative importance c the delta outlets being artificially forced in a fixed position so that natural avulsion is prevented and delta lobes undergo headland retreat leaving a marked erosion on the prodelta d the presence of prodelta lobes showing widespread bcut and fillq features ranging from 100 to 300 m and depths up to 4 5 m filled with massive silt to very fine sand offshore of short lived very active distributary channels e g po di tolle lobe and suggesting that in some particular interval short lived episodes of submarine erosion are induced by catastrophic increases in river discharge of natural origin or induced by human maintenance the seismic stratigraphy of the modern po delta documents that markedly distinct prodelta architectures form when a newly activated lobe is located updrift north in this case or downdrift south of the one that is retreating in the first case the abandoned lobe becomes sheltered by the new rapidly advancing one in the opposite case the retreating lobe is updrift and a substantial portion of the sediment is cannibalized and transported to the new lobe downdrift d 2005 elsevier b v all rights reserved

climatic and oceanographic variations on the california continental margin during the last 160 kyr organic matter in sediment samples from three odp sites ocean drilling program leg 167 that form a south north transect was investigated to reconstruct the paleoclimatic and oceanographic conditions on the california continental margin during the last 160 kyr alkenone derived paleosea surface temperatures sst are 3 to 6 c colder in glacial stages and reveal a clear relationship with global climate changes the differences are greater in the north latitudinal sst comparison exhibits water mixing of the colder california current with warmer waters from the south particularly in the southern central california borderland area organic matter accumulation on the california continental margin indicates an interplay between climatic and atmospheric glacial interglacial variations and spatially and temporally changing nutrient availability along the california coastline climatic and atmospheric dependent circulations apparently caused variations in the intensity of coastal upwelling along the southern central california margin and this suggests due to the close connection of the california current to the local wind patterns that the california current was weaker during glacial and stronger during interglacial periods

paleoceanography during the last 150 kyr off central japan based on diatom floras abstract the paleoceanographic history of the area above the northern boundary of the warm kuroshio current during the last two glacial interglacial cycles was reconstructed based on high resolution records of the diatom flora in core md01 2421 ecological categories of the diatom flora were extracted using q mode factor analysis the four most prominent factors explained 91 4 of the total variance cross spectral analyses were performed on temperature estimates derived from diatom data td the relative abundance of littoral neritic diatom associations and the oxygen isotope record of benthic foraminifera diatom derived temperatures show a 50 23 and 17 kyr periodicity with only the 23 kyr band coherent with that of benthic foraminiferal oxygen isotope values littoral neritic associations show a periodicity at 62 and 17 kyr coherent with td species composition and relative abundance of the diatom flora changed at the marine isotope stage boundaries when cold water and warm water mixed over the core site due to hydrographic disturbances by changes in transport trajectory of the kuroshio current transport and global climatic changes

quantitative model prediction of the combined effect of moisture content and temperature on purple mudstone decay in south western china abstract rock decay is mainly the result of the combined effects of moisture content and temperature but little is known about the quantitative relationship between these variables and the rate of rock decay in this study we develop quantitative calculation models of rock decay rate under laboratory conditions and validate the efficiency of these models by comparing the predicted rock decay mass and that measured for rock exposed in the field rainfall and temperature data in the field were standardised to a dimensionless moisture content and temperature variables respectively and then the predicted rock decay mass was calculated by the models the measured rock decay mass was determined by manual sieving based on our previously determined relationship between a single factor moisture content or temperature and the rate of rock decay in the laboratory power function models are developed results show that the rock decay mass calculated by the model was comparable with field data with averaged relative errors of 1 53 9 00 and 11 82 for the tuodian group j 3 t matoushan group k 2 m and lufeng group j 1 l respectively which are mainly due to inaccurate transformation of field rainfall into the rock moisture content and artificial disturbance when the samples were sieved in the field our results show that the developed models based on laboratory derived rates can accurately predict the decay rates of mudstones exposed in the field

transport properties in the adriatic sea as deduced from drifter data abstract the surface transport properties in the adriatic sea a semienclosed subbasin of the mediterranean sea have been studied using a drifter dataset in the period december 1994 march 1996 three main points have been addressed first the exchange between southern and northern regions and between deep and coastal areas have been studied focusing on the role of topography a significant cross topography or cross shelf exchange has been found probably due to the direct wind forcing and to the influence of stratification that isolates the surface flow from bottom effects especially in the open sea second a lagrangian transport model with parameters derived from the data has been implemented simulated particles have been compared with drifter data with positive results the model is found to be able to reproduce reality with good approximation except for a specific advective event during the late summer season finally the residence timescale t that is the average time spent by a surface parti

evolution and variability of the asian monsoon system state of the art and outstanding issues the asian monsoon is comprised of the indian and east asian subsystems these two components are linked to one another in varying degrees by regions of strong sensible heating indo asian landmass and strong latent heat export the western pacific warm pool and the southern subtropical indian ocean variability within the indian and east asian subsystems interactions among them and the extent to which they interact with other climate phenomena e g enso are current topics of modern and paleoclimate research this work provides an overview of past and current paleomonsoon research on tectonic to interannual time scales with a primary focus on marine sediment records while past and current work has contributed greatly to our understanding of paleomonsoon variability at all time scales additional efforts are required to make further progress in two critical areas 1 additional efforts are needed in terms of proxy development and evaluation requiring concerted efforts at long term sediment trap deployments in key monsoon influenced regions as well as development of adequate and widely available core top databases these are necessary to assess the impact of modern oceanographic and seafloor processes on potential monsoon proxies 2 additional effort is also needed in acquiring a sufficient geographic distribution of downcore records to assess linkages among the subsystems and their role in the context of extratropical climate change these records should have high sedimentation rates including varved sections this requires substantial survey support to identify the most appropriate coring and drilling targets c 2004 elsevier ltd all rights reserved

simulation of the climate of 18 000 years bp results for the north american north atlantic european sector and comparison with the geologic record of north america abstract the large ice sheets in north america and europe and the extensive sea ice cover in the north atlantic at the time of the last glacial maximum must have greatly modified the surface temperature patterns and in turn the location and intensity of the surface winds and jet streams a general circulation model was used to simulate the january and july patterns of temperature precipitation and wind for 18 ka bp boundary conditions for the model consisting of ice sheet location and height sea ice location and sea surface temperature were prescribed from climap 1981 the model results are illustrated and described for the north american north atlantic european sector the jet stream splits around the north american ice sheet and the southern branch strengthens considerably compared to present over the southern portion of the united states the sea ice margin of the north atlantic and the southern edge of the european ice sheet geologic evidence principally from north america of wind temperature and moisture conditions is assessed from sand dune and loess records estimates of snowline depression pollen records and lake level studies the geologic evidence is generally compatible with the model simulation

orbital scale anti phase variation of sea surface temperature in mid latitude north pacific margins during the last 145 000 years 1 the late quaternary records of alkenone sea surface temperature sst in the japan and california margins showed orbital scale anti phase sst variations between the two margins this east west seesaw like change agreed well with the long term el nino southern oscillation enso behavior predicted by the zebiak cane enso model clement et al 1999 as regards both the timing and frequency during 0 60 ka and 120 145 ka and is attributed to the precession controlled change in tropical enso behavior this anti phase sst change was not clearly demonstrated during 60 120 ka this finding suggests that the influence of tropical climatic dynamics on the mid latitude north pacific varied in response to glacial interglacial cycles