the role of tropical atlantic sst anomalies in modulating western north pacific tropical cyclone genesis the connection between north tropical atlantic nta sea surface temperature sst anomalies and tropical cyclone tc genesis over the western north pacific wnp and associated physical mechanisms are investigated in this study we demonstrate a remarkable negative correlation of wnp tc genesis frequency with the preceding boreal spring nta sst anomalies our analysis suggests that major factors for tc genesis including distributions of large scale vorticity and midtropospheric humidity are rendered unfavorable by remote teleconnections while barotropic energy conversion from the large scale flow is suppressed as shown in recent studies the remote teleconnection from the atlantic is sustained and enhanced throughout the typhoon season through local air sea interactions these results suggest that boreal spring nta sst anomaly could be a new predictor for the seasonal wnp tc activity

latest quaternary oceanographic changes in the okhotsk sea based on diatom records abstract the okhotsk sea is a locus of the north pacific intermediate water formation today the formation of the okhotsk intermediate water is linked with seasonal sea ice cover diatom records from the okhotsk sea show the following 1 during the last glacial maximum between 21 000 yr b p and 18 000 yr b p sea ice covered the western side of the sea throughout the whole year but the eastern part was open this permitted more efficient heat exchange with the atmosphere than waters and hence ventilation of the glacial okhotsk sea waters which in turn caused a greater extent of intermediate water formation through the bussol strait 2 the perennial sea ice cover extended northward and sea ice was present throughout the whole year over a great part of the sea except for the eastern part between 18 000 yr b p and 17 000 yr b p 3 the ice free area extended greatly to the south during the interval between 17 000 yr b p and 11 000 yr b p 4 there was no perennial ice cover over the whole sea and the ice free area that appeared as the seasonal ice area began to extend to the western part between 11 000 yr b p and 8 000 yr b p 5 after 8000 yr b p the ice free waters contracted to the present extent

diatom derived ssts td ratio indicate warm seas off japan during the middle holocene 8 2 3 3 kyr bp abstract regression analysis was performed between the ratio of warm and cold water diatoms td ratio in 123 surface sediment samples in the northwest pacific ocean and the mean annual sea surface temperatures ssts c at the core sites in order to calibrate this proxy for paleo temperatures equations to derive annual sst c from diatom analysis were somewhat different for the tohoku area y 6 5711 0 273 r 0 89946 than for the japan sea y 5 4069 0 26841 r 0 89088 the annual paleo ssts c in the tohoku area were in general higher than in the japan sea despite lower td values because the warm water species fragilariopsis doliolus is abundant only in the tsushima warm current in the japan sea the reliability of the equations is supported by our understanding of the ecology of recent diatoms td derived annual paleo ssts c agree with alkenone derived summer paleo sst c at a site off central japan in the northwestern pacific in a south to north transect of cores around honshu and hokkaido paleo ssts c decreased when the kuroshio and tsushima warm currents weakened the middle holocene 8 2 3 3 cal kyr bp was warmer by 1 2 c than earlier and later parts of the holocene and mean annual paleo ssts c show rhythmic fluctuations with durations of 1000 years and 400 500 years these new data show that annual ssts were warm in the northwestern pacific at times that the northeastern pacific was cold in addition oceanic warm and cold water species defined by kanaya and koizumi kanaya t koizumi i 1966 interpretation of diatom thanatocoenoses from the north pacific applied to a study of core v20 130 studies of a deep sea core v20 130 part iv sci rep tohoku univ 2nd series geol 37 89 130 and koizumi et al koizumi i irino t oba t 2004 paleoceanography during the last 150 kyr off central japan based on diatom floras mar micropaleontol 53 293 365 are illustrated

monsoon gyres of the northwest pacific influences of enso the mjo and the pacific japan pattern abstractan objective definition of monsoon gyres in the northwest pacific was developed in order to construct a gyre climatology over a 31 yr period 53 gyres were identified with a median formation location at 16 5 n 135 e more than 80 formed during july september more than half of gyres developed during el nino periods at a median location 1200 km farther to the east southeast than during la nina cyclonic winds at 850 hpa extended across a diameter of more than 4000 km with maximum tangential wind near the 1000 km radius a precipitation maximum extended westward for several thousand kilometers south of the gyre typhoons were most common north and east of the gyre centers more than 70 of gyres developed during large amplitude mjo events with a strong preference for real time multivariate mjo rmm phases 5 7 in boreal summer these phases contain circulation and convective anomalies that coincide most closely with those of the climatological monsoon trough gyres are most likely to form when

paleoceanographic evolution of north pacific surface water off japan during the past 150 000years abstract hydrographic variability in the mixed water region of the northwest pacific ocean at latitudes 35 40 n between the kuroshio extension and oyashio front causes complex upwelling leading to large primary productivity and thus great fishery resources we reconstructed the periodicity of the variability in north pacific intermediate water upwelling and surface ocean hydrography based on the high resolution analysis of diatom assemblages in seven cores representing the last 150 000 years we derived annual sea surface temperatures ssts through a diatom based proxy td the td derived annual ssts c are controlled by orbital forcing and show a reversed saw tooth in southern cores in contrast to a normal saw tooth pattern in the northern cores oceanic diatom abundances along the northern margin of the mixed water region are twice times as high as beneath the axis of the kuroshio extension and fluctuated in a revised saw tooth pattern with higher overall abundances interglacials after the last deglaciation annual ssts declined markedly during heinrich and bond events in the northern north atlantic when ice rafted detritus transported by icebergs was abundant wavelet analyses of the record of oceanic diatom abundances show significant variability at 2 0 kyr 2 to 5 6 kyr and 3 2 to 9 6 kyr periods wavelet analyses of the annual sst records show significant periodicity at 1 4 to 2 6 kyr 3 3 to 4 0 kyr 7 2 to 12 8 kyr cycles

response of daily and annual shell growth patterns of the intertidal bivalve phacosoma japonicum to holocene coastal climate change in japan abstract it is well known that the latitudinal distribution of shallow marine mollusks around the japanese islands has changed episodically during the holocene in response to climate change however few studies have investigated the biotic response of individual species to holocene climate change at daily to annual scales of temporal resolution holocene shells of the venerid phacosoma japonicum recovered from various sites in japan preserve lunar daily and annual growth increments in the outer shell layer and hinge plate as also observed in modern shells sclerochronological analysis of 29 shells with known 14 c ages revealed that the life history traits e g length of the growth period and the mean lunar daily growth rate at a given age have changed markedly over the past 8000 years the intra annual patterns of lunar daily increments and shell oxygen isotope records of the fossil shells can be compared with those of modern specimens from various locations which are constrained by annual patterns of seawater temperature and summer autumn precipitation rates furthermore the temporal trends recorded in the fossil shells show a strong correlation with climate change in mid latitude parts of east asia over the past 8000 years indicating that p japonicum has changed its life history traits in response to holocene terrestrial and coastal climate change

interdecadal change in typhoon genesis condition over the western north pacific the interdecadal changes in typhoon categories 1 3 frequency and its genesis condition over the western north pacific during the period of 1979 2011 are investigated with consideration for discrepancies among best track datasets to tide over data uncertainty a detection produced dataset is utilized as a homogeneous dataset with five available best track datasets typhoon experienced interdecadal changes around the mid 1990s and the mid 2000s in their genesis conditions even under the oceanic warm state typhoon frequency has decreased since the mid 1990s showing a northwestward movement of its genesis location over the main formation region the eastward gradient of vertical wind shear is the most significant factor for the change in typhoon genesis condition in recent decades the vertical wind shear behavior is strongly linked with zonal asymmetry of local sst we demonstrate that a westward gradient of local sst is the most important modulator of the recent typhoon behavior through the movement of favorable genesis location the present results indicate that the horizontal distribution not magnitude of local sst can be a key factor for prediction of future typhoon activity thus contributing to natural disaster mitigation and climate change adaptation strategies

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

intensified interannual relationship between tropical cyclone genesis frequency over the northwest pacific and the sst gradient between the southwest pacific and the western pacific warm pool since the mid 1970s abstractthe sea surface temperature gradient sstg between the southwest pacific swp 40 20 s 160 e 170 w and the western pacific warm pool wwp 0 16 n 125 165 e in boreal spring was revealed to contribute significantly to the interannual variability of tropical cyclone tc genesis frequency over the western north pacific wnp since 1980 the present study extends the analysis back to 1951 results show that the interannual relationship between the sstg and wnp tc genesis frequency is statistically significant only after the mid 1970s while insignificant prior to 1974 further analyses show that the sstg is strongly negatively correlated with the sst anomaly ssta in the central pacific cp in the recent period while with the ssta in the equatorial eastern pacific ep in the prior period in the prior period the spring positive negative ep ssta induces an anticyclonic cyclonic circulation over the wnp this partly offsets the impact of the sstg anomaly on the atmospheric circulation ov

decadal changes in tropical cyclone activity over the western north pacific in the late 1990s a pronounced decadal change in tropical cyclone tc activity over the western north pacific wnp in the late 1990s was identified based on a comparison of the two epochs that occurred before and after the late 1990s the tc genesis number exhibited an evident decrease over the southern wnp s wnp 5 20 n 105 170 e and an increase over the northern wnp n wnp 20 25 n 115 155 e which partly corresponded to a significant northward migration in the seasonal mean latitudinal location of tc genesis i e from 17 2 n to 18 7 n after the late 1990s the northwestward moving track became the most dominant track mode accompanied by the weakening of both the westward moving track and the northeastward recurving track meanwhile the tc occurrence frequency tcf experienced evident increases over southeastern china and the okinawa islands while prominent decreases occurred over the south china sea the philippine sea japan and east of japan changes in the tcf were determined by tc genesis changes tc track shifts and variations in regional tc durations which were all ascribed to the decadal change in tropical indo pacific sea surface temperature the full picture on the decadal changes in the wnp tc activity revealed in this study may provide useful guidance for regional tc seasonal forecasts and future projections

varieties of a single cosmopolitan diatom species associated with surface water masses in the north pacific abstract a time series of 65 sediment trap samples representing 48 month changes in diatom flora and 62 sediment core tops from the western north pacific ocean were analyzed varieties of a single diatom species were found to be characteristic of two surface water masses bounded by the kuroshio current thalassionema nitzschioides var incurvata var inflata and var parva dominate in warm saline waters in the subtropical gyre while t nitzschioides sensu stricto is abundant in less saline waters northwest of this current time series data on percent abundances for the three t nitzschioides varieties in the t nitzschioides complex are compared with path variations of the current south of japan inter annual fluctuations in percent abundance are linked to changes in surface water masses over the sediment traps in association with migration of the kuroshio paths this finding makes the percent abundance a useful tool for deciphering path migrations of the kuroshio current in the geologic past down core analyses of two sediment cores collected beneath the modern kuroshio current were performed a sharp increase in percent abundances from 12 to 9 kyr bp with an abrupt change around 11 kyr bp records the previously reported transition of the kuroshio current from a predominantly offshore path to its modern path path migrations of the kuroshio current may be inferred from percent abundances of these diatoms which comprise a new proxy for delineating the paleoclimate of the northwestern pacific in relation to changes in northward heat transport from the western equatorial pacific ocean by the western boundary current

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

tropical indian ocean influence on northwest pacific tropical cyclones in summer following strong el nino abstract in the summer following a strong el nino tropical cyclone tc number decreases over the northwest nw pacific despite little change in local sea surface temperature the authors analysis suggests el nino induced tropical indian ocean tio warming as the cause the tio warming forces a warm tropospheric kelvin wave that propagates into the western pacific inducing surface divergence off the equator the tropospheric kelvin wave suppresses convection and induces an anomalous anticyclone over the nw pacific both anomalies unfavorable for tcs the westerly vertical shear associated with the warm kelvin wave reduces the magnitude of vertical shear in the south china sea and strengthens it in the nw pacific an east west variation that causes tc activity to increase and decrease in respective regions these results help improve seasonal tc prediction

response of vegetation in central japan to precession during the last 147 000 years a lignin record from lake biwa core biw08 b abstract to understand the responses of terrestrial vegetation in central japan to global climate changes we generated a record of lignin composition from core biw08 b in lake biwa central japan during the last 147 000 years by tmah pyrolysis gc ms lignin abundance was intermittently elevated and associated with a high ratio of cinnamyl c to vanillyl v phenols c v ratio of lignin suggesting episodic inflows of herbaceous plant derived organic matter into lake biwa the largest inflow occurred during the last deglaciation variation in the ratio of syringyl s to vanillyl v phenols s v ratio which is a contribution index of angiosperms against gymnosperms showed a precession like cycle was consistent with a pollen record from lake biwa and showed a pattern similar to the s v record from an offshore marine site in the northwestern pacific the variation reflected the regional replacement of cool temperate deciduous broadleaf forests subalpine conifer forests and japanese cedar forests in central japan caused by the repetition of warmer dry and cooler wet climates on a precession cycle

pliocene pleistocene evolution of the north pacific ocean atmosphere system interpreted from fossil diatoms the relative abundance of diatom taxa in 216 core tops has been quantified and compared using cluster analysis with assemblages in six cores located beneath different water masses of the north pacific ocean all but one sequence span at least 1 5 m y early pleistocene to holocene and one extends to 2 6 ma the quantitative abundance of each taxon and the space time occurrence of each cluster are interpreted as tracers of oceanographic conditions in addition to high frequency glacial interglacial oscillations the records display rapid steplike changes at 2 4 ma 1 6 1 5 ma 1 0 ma 0 8 0 7 ma and 0 35 ma two secondary transitions recorded only in the northwestern cores occur at 2 0 ma and 1 1 ma we conclude that both the high frequency oscillations and the stepwise transitions reflect variations in extent of subarctic water masses under the influence of the siberian high pressure and aleutian low pressure atmospheric cells we further conclude that 1 the subarctic water mass has developed progressively and attained its modern structure only in the late pleistocene 2 some stages of this evolution may have occurred earlier in the eastern subarctic 3 the holocene is an atypical warm extreme so that the present is not a very good key to the past 4 there were several glaciations between 2 4 and 2 0 ma and 5 the subtropical gyre is more conservative than the subarctic gyre and major changes in the region have been due to forcing from the north we propose a conceptual model of oscillating metastable climatic modes maintained by internal feedback and suggest that steplike changes may occur when one set of boundary conditions is temporarily exceeded

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

paleoceanographic history around the tsugaru strait between the japan sea and the northwest pacific ocean since 30 cal kyr bp abstract the paleoceanographic history around the tsugaru strait since 30 0 cal kyr bp was reconstructed using ecological and biogeographical habitats of diatom species and q mode factor analysis of diatom flora in six piston cores at 30 0 17 5 cal kyr bp a fall in sea level and the intensification of the oyashio current caused erosion of submarine sediments near the shore in the eastern area of the strait and led to deposition of the third and second sequences of thinly laminated layers tl3 and tl2 in the japan sea at 17 5 11 5 cal kyr bp cooling intensified around the strait producing an inflow of oyashio water into the japan sea through the strait at 15 5 14 5 cal kyr bp a cold water mass around the strait developed from subarctic sea ice to arctic waters at 13 0 11 2 cal kyr bp the younger dryas cooling was clearly recorded by the increasing of oceanic cold water diatom species in the eastern area of the tsugaru strait but not in the japan sea at 15 5 13 0 cal kyr bp and 11 25 10 25 cal kyr bp the warming around the younger dryas resulted in the deposition of thinly laminated layers off shimokita in the eastern area of the strait at 9 5 cal kyr bp the oyashio current water intruded into deep depths in the mixed water region off sanriku at 9 5 7 0 cal kyr bp the fluctuation of 1 5 kyr intervals in the strength of the tsushima warm current system in the japan sea was initiated

coastal paleo environment and sea level change at macassa bay southern mozambique since c 6600 cal bp changes in holocene coastal paleo environment and sea level variations have been recorded in estuary sediments from macassa bay southern mozambique methods include analysis of fossil diatoms sediment stratigraphy mineral magnetic properties stable carbon and nitrogen isotope composition and carbon and nitrogen content the chronology based on six ams c 14 dates suggests a basal age of the sediment core of c 6600 cal bp calibrated years before present the multi proxy dataset implies two phases when the site was experiencing marine conditions and tentative sea level high stands 1 between c 6600 6300 cal bp which is contemporary with the last phase of the global transgression and the holocene climatic optimum and 2 between c 4700 1000 cal bp a period when sea level curves from the region suggest occasional minor sea level high stands between these phases c 6300 4700 cal bp the environment within the macassa bay estuary was less influenced by marine processes and studied proxies indicate a freshwater phase associated with relatively low sea levels after c 1000 cal bp a terrestrial environment prevailed at the site probably as a result of a combined effect of sea level lowering and high accumulation of organic peat within the estuary c 2011 elsevier ltd and inqua all rights reserved

world wide delivery of river sediment to the oceans new data and new estimates from old data show that rivers with large sediment loads annual discharges greater than about 15 times 10 6 tons contribute about 7 times 10 9 tons of suspended sediment to the ocean yearly extrapolating available data for all drainage basins the total suspended sediment delivered by all rivers to the oceans is about 13 5 times 10 9 tons annually bedload and flood discharges may account for an additional 1 2 times 10 9 tons about 70 of this total is derived from southern asia and the larger islands in the pacific and indian oceans where sediment yields are much greater than for other drainage basins

exploring typhoon variability over the mid to late holocene evidence of extreme coastal flooding from kamikoshiki japan sediment cores from two coastal lakes located on the island of kamikoshiki in southwestern japan lake namakoike and lake kaiike provide evidence for the response of a backbarrier beach system to episodic coastal inundation over the last 6400 years sub bottom seismic surveys exhibit acoustically laminated parallel to subparallel seismic reflectors intermittently truncated by erosional unconformities sediment cores collected from targeted depocenters in both lakes contain finely laminated organic mud interbedded with coarse grained units with depths of coarse deposits concurrent with prominent seismic reflectors the timing of the youngest deposit at kamikoshiki correlates to the most recently documented breach in the barrier during a typhoon in 1951 ad assuming that this modern deposit provides an analog for identifying past events paleo typhoons may be reconstructed from layers exhibiting an increase in grain size a break in fine scale stratigraphy and elevated sr concentrations

interannual variation in the tropical cyclone formation over the western north pacific abstract the interannual variation in tropical cyclone genesis frequency over the western north pacific was examined for the active tropical cyclone including summer and fall during 1979 94 an emphasis was put on the possible effect of the interannual variation of atmospheric circulation and monsoon trough on tropical cyclone occurrence the major findings of this study are the following a distinct increase decrease of tropical cyclone genesis frequency occurs north of the climatological location of the monsoon trough in the philippine sea during summers june august with anomalous cold warm sea surface temperature sst over the nino3 region the interannual variation of tropical cyclone genesis in this region results from the appearance of an anomalous cyclonic anticyclonic cell situated in a summer teleconnection wave train emanating from the western tropical pacific and progressing along the rim of the north pacific in addition to the north south interannual variation there is also a long

a salinity related occurrence of a novel alkenone and alkenoate in late pleistocene sediments from the japan sea abstract the novel alkenoate ethyl tetratriacontadienoate c34 2ee has been found in late quaternary sediments of the japan sea by using gas chromatography mass spectrometry gc ms it accompanied hexatriacontadien 3 one c36 2ek previously found in black sea sediments a linear relationship between c36 2ek and c34 2ee concentrations points to both compounds being derived from the same source most likely a specific haptophyte the relative abundance of c34 2ee in total alkenones and alkenoates was significantly higher during the last glacial maximum when the 18o in planktonic foraminifera was anomalously light strongly suggesting that c34 2ee is associated with low salinity environments as samples with abundant c34 2ee also possessed anomalously high u 37 k values low salinity may have an ecological or physiological influence on both the unsaturation and carbon chain length of alkenones and alkenoates

composition of mineral fractions of the narbada and tapti estuarine particles and the adjacent arabian sea sediments off western india abstract thirty suspended and bottom sediment samples from the narbada and tapti river estuarine systems of western india were separated into magnetic clay and silt sand fractions the al fe mn zn cr co ni and cu concentrations of which have been determined by atomic absorption spectrophotometry on an average the silt sand fraction accounts for 90 of the suspended matter and bottom sediments of the rest clays are more abundant than the magnetic fraction for all fractions there are no major differences in the region of investigation in mineralogy between the estuarine suspended and the bottom sediments the magnetic fraction is enriched in all metals except al by a factor of 1 2 4 as compared to the other two fractions the clays in turn are enriched in all metals by a factor of 1 4 0 14 as compared to the silt sand the metal al ratios in the clay as well as in the silt sand fractions do not show any variations beyond 25 between the freshwater end member of the estuaries and the coastal arabian sea thus indicating that the effect of estuarine processes on the inorganic solids are within this limit in the magnetic fraction the metal al ratios vary by as much as an order of magnitude whereas the corresponding metal fe ratios do not vary by more than a factor of 2 the clay and silt sand fractions of sediments from the open shelf and slope regions of the arabian sea are enriched in ni and zn and depleted in mn by a factor of 2 as compared to the estuarine suspended and bottom sediments these enrichments are attributed to the reducing nature of the open marine environment the inter elemental correlations in the silt sand fractions are good the correlation coefficients for 28 observations ranging from 0 60 to 0 95 the highest value is for fe al the suspended fluxes of metals from the narbada and tapti rivers to the adjacent shelf and to the deep sea via clays are calculated on average 5 of the total flux to the shelf region reaches the deep sea

contrasting eastern pacific and central pacific types of enso abstract surface observations and subsurface ocean assimilation datasets are examined to contrast two distinct types of el nino southern oscillation enso in the tropical pacific an eastern pacific ep type and a central pacific cp type an analysis method combining empirical orthogonal function eof analysis and linear regression is used to separate these two types correlation and composite analyses based on the principal components of the eof were performed to examine the structure evolution and teleconnection of these two enso types the ep type of enso is found to have its sst anomaly center located in the eastern equatorial pacific attached to the coast of south america this type of enso is associated with basinwide thermocline and surface wind variations and shows a strong teleconnection with the tropical indian ocean in contrast the cp type of enso has most of its surface wind sst and subsurface anomalies confined in the central pacific and tends to onset develop and decay in situ

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

late holocene 1500 yr climatic periodicities and their implications fourier and nonlinear regression analysis of a 4000 yr paleoclimate proxy record in western canada shows strong periodicities of 1500 yr and several weaker century to millenial scale periodicities in conjunction with the 23 708 yr milankovitch periodicity these produce a model of climate fluctuation through the postglacial consistent with recognized paleoclimatic fluctuations of the past 15 000 yr in the northern mid latitudes these results suggest that postglacial climatic anomalies such as the little ice age and the younger dryas were at least in part periodic phenomena rather than the result of unique aperiodic events projecting these periodicities into the future suggests that even in the absence of anthropogenic climate forcing a natural warming trend will continue until ca a d 2400

last glacial emplacement of methane derived authigenic carbonates in the sea of japan constrained by diatom assemblage carbon 14 and carbonate content abstract we studied diatom assemblages and caco 3 contents of methane derived authigenic carbonates from the eastern margin of the sea of japan and assessed the formation time of these samples radioactive 14 c date was determined in selected samples to obtain the maximum age of the time the results of our study suggest mass formation of carbonate nodules in a glacial period within 40 ky consistent with a published u th dating result of carbonate nodules in the study area diatom assemblages and contents in the carbonate nodules abundance of 10 6 g dominance of neritic littoral species warm cold water species ratio lower than 25 differ from the near seafloor sediments in the study area which have characteristics of holocene sediments in the sea of japan and suggest cementation of glacial sediments laminated sediments in some nodule samples are glacial sediments because laminations are records of a low sea level period in the semi enclosed ocean similarity of diatom assemblages and contents in all carbonate samples is another evidence of glacial sediments in nodules glacial sediments with oceanic cold water species as low as holocene sediments restricts the sediment age to before 20 cal ky bp carbonate contents higher than 78 wt suggest the cementation of poorly compacted sediments near the seafloor and the date of carbonate cementation is therefore close to that of the cemented sediments most carbonate nodule samples in this study were formed in a glacial period and detection of 14 c restricts this period to within 40 ky

the relationship between the southern oscillation index and tropical cyclone tracks in the eastern north pacific points of origin and downgradation of tropical cyclones in the eastern north pacific enp east of 160 w are related to the southern oscillation index soi during the hurricane season all enp tropical storms and hurricanes from 1966 through 1997 were grouped into three soi based categories those occurring during strong el nino events mean soi 0 6 or near zero periods 0 6 mean soi 0 6 during el nino storm seasons enp tropical cyclones originated approximately 5 7 617 km west and downgraded 7 5 780 km west of the long term mean longitudes for the positive soi group near zero group storms also followed more northerly tracks than the negative soi group storms however no significant differences in storm track are evident between the positive soi and near zero groups and the track length is not significantly different for any storm group

groundwater δ18o and δd from central indian peninsula influence of the arabian sea and the bay of bengal branches of the summer monsoon abstract results of oxygen and hydrogen isotopic investigations of shallow groundwater and river water samples from the central indian peninsula are reported the study was undertaken to isotopically characterise the near surface water sources and identify the influence of the two branches of the indian summer monsoon june september in this region the western part of the study area receives vapour flux largely from the arabian sea branch whereas the eastern part receives significant vapour flux from the bay of bengal branch no significant rainfall occurs in the study area during northeast winter monsoon period of october december or the remaining part of the year therefore the isotopic character of shallow groundwater from this region could be used to study the relative influence of the vapour sources from the arabian sea and the bay of bengal the study shows that i the northeast part receiving significant rainfall from the bay of bengal branch has a distinctly depleted isotopic composition 18 o 5 2 compared to areas receiving dominant rain from the arabian sea branch 18 o 1 1 ii in the west coastal belt the average 18 o in groundwater is close to the average 18 o of precipitation at bombay 1 4 1 1 but groundwater samples in the entire deccan plateau region show signatures of evaporative enrichment in the form of a low slope 6 5 of 18 o d regression line b low d excess 0 5 and c slightly enriched 18 o values 1 1 compared to those expected from the limited precipitation data from stations in maner basin approximately in the middle of the study area iii depleted ground waters along the central indian east coast could arise due to continental rainout of the arabian sea vapour source as the moisture laden monsoon winds crossover to the bay of bengal alternatively it is necessary to postulate that the surface waters of the bay of bengal contributing to inland vapour flux are significantly more depleted during the monsoon period than the known depletion of 1 it is also possible that both factors are operative

diatom records in the quaternary marine sequences around the japanese islands abstract understanding the quaternary is a key to estimating what the earth s climate will be like in the future such studies demand high resolution analyses based on paleoclimatic proxy records of changing earth s orbital forcing and solar insolation that affect the climate system quaternary diatom biostratigraphy and paleoceanography have been well established based on the quaternary marine sequences obtained by piston coring and deep sea drilling around the japanese islands this paper firstly reviews the quaternary diatom datum levels that are directly tied to magnetic polarity and then the late pleistocene and holocene rhythmic fluctuations in td derived ssts c which correlate with the earth s orbital parameters and finally reveals the large and abrupt climatic changes that have occurred around the japanese islands on centennial to millennial time scales the main aim is to provide the results of td ssts c based on the late pliocene to pleistocene sequences from three holes obtained by deep sea drilling dsdp odp the main difference between td and twt is that twt gives 0 5 values to xt warm transitional taxa thalassiosira oestrupii is grouped with xt in twt but with warm water species in td differences between the twt and td ssts c curves at hole 436 are unremarkable the remarkable variations of paleo temperatures based on td ssts c show four conspicuous episodes which correspond to the double precession cycle of mis 11 in the japan sea the twt ratio remarkably decreases at 2 6 ma due to a large increase in cold water taxa and indicates the beginning of the glacial age defined as the pliocene pleistocene boundary both twt and td ssts c increase at 2 60 2 0 ma and coincide with the lithologic change from diatom bearing clay with few dark colored layers to fine grained sediments with distinct dark light colored cycles wavelet analysis of td ssts c at site 798 indicates a reversed saw tooth pattern of 48 to 24 ky periods during 1 2 0 7 ma and 24 to 12 ky periods during 0 7 0 ma resulting in a change from longer to shorter cycles these fluctuations correlate with the earth s orbital parameters and climatic changes on a millennial time scale

intensified impact of east indian ocean sst anomaly on tropical cyclone genesis frequency over the western north pacific abstracta recent finding is the significant impact of the sea surface temperature anomaly ssta over the east indian ocean eio on the genesis frequency of tropical cyclones tcs over the western north pacific wnp in this study it is shown that such an impact is significant only after the late 1970s the results based on both data analysis and numerical model experiments demonstrate that prior to the late 1970s the eio ssta is positively correlated with the equatorial central pacific ssta and the latter produces an opposite atmospheric circulation response over the wnp to the former as a result the impact of the eio ssta on the tc genesis over the wnp is largely suppressed by the latter after the late 1970s the area coverage of the eio ssta is expanding this considerably enhances the large scale circulation response over the wnp to the eio ssta and significantly intensifies the impact of the eio ssta on tc genesis frequency over the wnp the results from this study have great implications for s

paleoceanographic history of the northwest pacific ocean over the past 740kyr discerned from radiolarian fauna abstract the northwest pacific ocean is characterized by a strong mixing of water masses due to the interplay of three distinct currents i e the kuroshio the tsugaru and the oyashio the c9001c drill core site located east of the shimokita peninsula and directly influenced by the tsugaru warm current and the oyashio subarctic current was used here to reconstruct the paleoceanographical history of this region especially focusing on the mid brunhes event mbe and its consequences this core provides a continuous record from marine isotope stage mis 18 740 ka to the present polycystine radiolarian assemblages were analyzed to highlight paleoceanographic and sea surface temperature changes at this site based on the radiolarian fauna seven time periods are defined which coincide with changes in the dynamics of the tsugaru and oyashio currents respectively the oldest time interval covered by our analysis i e vii 740 621 ka was marked by generally sluggish ocean circulation the tsugaru current influence increased during the following interval vi 621 478 ka which encompasses interglacials mis 15 and 13 while the oyashio current strengthened during the interval v 478 337 i e from glacials mis 12 to 10 these latter intervals vi to v constitute a long climatic transitional period where tsugaru current and oyashio current influences are strengthened in the time period from interval iv to interval i 0 337 ka the warming intensity of interglacials mis 9 mis 5 appears to be close to the modern one however several unusually warm glacials associated with a relatively strong tsugaru current flow were identified during this interval e g mis 8 and mis 6 radiolarian productivity data suggest that during intervals vii to v deep water masses are rich in nutrient content however a high vertical mixing event is recorded after interval iv when high nutrient concentrations appear to shift to the surface layer

oceanographic variations over the last 150 000 yr in the japan sea and synchronous holocene with the northern hemisphere abstract the paleo hydrography in the japan sea called a mini ocean was reconstructed based on the high resolution analysis of diatom assemblages over the period of 150 000 yr the decrease of diatom fertilization in the japan sea when it was isolated from surrounding seas due to the drop of sea level during the glacial to stadial phase resulted in dissolution and or extremely low diatom production in the northern cores in the subarctic water masses the annual td derived paleo ssts c were controlled by the fluctuations of 2 kyr and 4 kyr periods at intervals of 20 kyr and 40 kyr over the last 160 kyr bp respectively a 23 kyr cycle is recognized during the periods from 140 ka to 100 ka according to the wavelet analysis after temperature and sea level increased both at 133 128 ka 60 53 ka and 15 10 ka oceanic warm water diatom species predominated at 127 119 ka and after 9 cal ka in the interstadial phase at 21 3 16 9 ka and 12 9 9 8 ka sea level and salinity increased as the transgression developed at 10 0 7 0 ka the oceanic association shifted from cold water species in the stadial period to warm water ones in the interstadial phase the fluctuations of td derived ssts c on century to millennial time scales during the holocene are well correlated with abrupt climatic events that different paleoclimatic proxies record in many regions of the northern hemisphere

contributions of sst anomalies in the indo pacific ocean to the interannual variability of tropical cyclone genesis frequency over the western north pacific abstractthis study attempts to evaluate quantitatively the contributions of sea surface temperature sst anomalies in the indo pacific ocean to the interannual variability of tropical cyclone tc

attribution of decadal variability in tropical cyclone passage frequency over the western north pacific a new approach emphasizing the genesis location of cyclones abstractvariability in tropical cyclone tc activity is a matter of direct concern for affected populations on interannual and longer time scales variability in tc passage frequency can be associated with total tc frequency over the concerned ocean basin basinwide frequency bf the spatial distribution of tc genesis in the basin genesis distribution gd and the preferable track pt that can be considered as a function of genesis locations to facilitate investigation of mechanisms responsible for the variability the authors propose an approach of decomposing anomalies in the passage frequency into contributions of variability in bf gd and pt which is named the integration of statistics on tc activity by genesis location istagl analysis application of this approach to tc best track data in the western north pacific wnp basin reveals that overall distribution of the passage frequency trends over the 1961 2010 period is mainly due to the pt trends on decadal time scales passage frequen

slow physics of large continental ice sheets and underlying bedrock and its relation to the pleistocene ice ages very simple two component models of the earth s cryosphere lithosphere system are analyzed the models consist of a continental ice sheet coupled to a responding earth model because of relatively long response times of the bedrock at least over shorter wavelengths long period of the order of 50 000 years internal or free oscillations in the system occur over a wide range of parameters and parameterizations the oscillatory mechanism operates primarily in the ablation zone and in particular at the firn line these free oscillations could play a dynamic role in the response of the climate system to eccentricity forcing a simple analysis presented strongly suggests that for the simplest rheological models of the earth response to pleistocence ice sheets elastic response is confined to a layer considerably less than the thermal thickness of the lithosphere furthermore because of the striking lack of geological evidence for large depressions of bedrock at the leading edge of growing continental ice sheets predicted by viscoelastic models of the earth more sophisticated rheological models of the earth s uppermost layer appear necessary

environmental fluctuations in the northwestern pacific ocean during the last interglacial period evidence from radiolarian assemblages abstract the last interglacial period from 130 to 117 ka was as warm as or warmer than the present and thus it is relevant for our understanding of the possible effects of recent global warming in this study we used radiolarian assemblages in a sediment core to reconstruct environmental fluctuations in the northwestern pacific ocean during the last interglacial period the sediment core md012421 was collected where the warm kuroshio current meets the cold oyashio current we used the ratio of warm water to the total of warm and cool water radiolarian species tr as an indicator of the dominant surface water masses relative importance of the warm kuroshio and cool oyashio currents and we used the relative abundance of cycladophora davisiana as an indicator of cold oxygen rich intermediate waters related to seasonal sea ice formation at high latitudes tr results indicated that a transitional surface water mass off kashima was replaced by a subtropical water mass between 131 ka late marine isotope stage mis 6 and 125 ka last interglacial period mis 5e furthermore the relative abundance of c davisiana changed from 19 6 at 133 ka late mis 6 to 0 at 126 ka mis 5e this change suggests a reduction of cold oxygen rich waters at intermediate depths off kashima in association with weakened ventilation at high latitudes in the north pacific as this reduction took place 1 kyr earlier than the shift of surface water masses at the core site we inferred that changes of insolation the main driver of glacial interglacial cycles controlling the variation of sea ice formation at high latitudes occurred earlier than the lower latitude change in the atmospheric pressure pattern controlling the surface water shifts high resolution time series analysis indicated that fluctuations in the surface water mass occurred cyclically with a periodicity of approximately 500 years during the second half of the last interglacial period this periodicity may be attributable to fluctuations in solar radiation

uranium isotopes in rivers estuaries and adjacent coastal sediments of western india their weathering transport and oceanic budget the two major river systems on the west coast of india narbada and tapti their estuaries and the coastal arabian sea sediments have been extensively studied for their uranium concentrations and 238u238u activity ratios the 238u concentrations in the aqueous phase of these river systems exhibit a strong positive correlation with the sum of the major cations na k mg ca and with the hco3 ion contents the abundance ratio of dissolved u to the sum of the major cations in these waters is similar to their ratio in typical crustal rocks these findings lead us to conclude that 238u is brought into the aqueous phase along with major cations and bicarbonate the strong positive correlation between 238u and total dissolved salts for selected rivers of the world yield an annual dissolved 238u flux of 0 88 1010g yr to the oceans a value very similar to its removal rate from the oceans 1 05 1010g yr estimated based on its correlation with hco3 contents of rivers in the estuaries both 238u and its great grand daughter 234u behave conservatively beyond chlorosities 0 14 g l these data confirm our earlier findings in other indian estuaries the behavior of uranium isotopes in the chlorosity zone 0 02 0 14 g l was studied in the narbada estuary in some detail the results though not conclusive seem to indicate a minor removal of these isotopes in this region reexamination of the results for the gironde and zaire estuaries martin et al 1978a and b also appear to confirm the conservative behavior of u isotopes in unpolluted estuaries it is borne out from all the available data that estuaries beyond 0 14 g l chlorosities act neither as a sink nor as a source for uranium isotopes the behavior in the low chlorosity zones warrants further detailed investigation a review of the uranium isotope measurements in river waters yield a discharge weighted average 238u concentration of 0 22 g l with a 234u238u activity ratio of 1 20 0 06ismissing the residence time of uranium isotopes in the oceans estimated from the 238u concentration and the 234u238u a r of the rivers yield conflicting results the material balance of uranium isotopes in the marine environment still remains a paradox if the disparity between the results is real then an additional 234u flux of about 0 25 dpm cm2 103 yr into the oceans about 20 of its river supply is necessitated

changes in the distribution of uvigerinidae species over the past 775 kyr implications for the paleoceanographic evolution of the japan sea abstract the distribution of benthic foraminifera of the uvigerinidae family which are abundant in middle to upper pleistocene samples from the yamoto basin in the japan sea have been analyzed quantitatively and used for paleoceanographic interpretations twenty three uvigerinidae species are reported from iodp site u1426 6 of which are present in at least three or more samples with 10 or more abundance and considered as dominant species the abundance and ecological preferences of dominant uvigerinidae species comprised of uvigerina mediterranea uvigerina yabei uvigerina sp 1 uvigerina peregrina suggest dysoxic conditions with high influx of organic matter between 775 and 475 ka in response to the enhanced flow of the tsushima warm current the end of mis 13 marked the onset of more extreme glacial interglacial climate cycles in the japan sea glacial interglacial alternations of uvigerina peregrina and trifarina angulosa from 475 ka to the holocene indicate major fluctuations in circulation and productivity within this semi enclosed basin both u peregrina and t angulosa respond to 100 kyr variability reflecting the paleoclimatic shift and global ice volume changes associated with the middle pleistocene transition

marine diatom assemblage variation across pleistocene glacial interglacial transitions from integrated ocean drilling program site c9001 northwest pacific abstract in 2006 d v chikyu cruise ck06 06 drilled hole c9001c at site c9001 in the northwest pacific ocean 80 km east of the shimokita peninsula japan an existing chronostratigraphic framework provides a continuous glacial interglacial g i climate record from which a diatom record of paleoenvironmental changes was developed across several g i cycles species counts diatom temperature values and calculated sea surface temperatures sst were produced for each sample and calibrated to prior diatom studies in this region these features were used to characterize and compare interglacial maxima of marine isotope stages mis 1 5e 9 and 11 and transitions from the preceding glacial maxima mis 9 was the longest and warmest of the four interglacials examined with a peak calculated temperature of 20 2 c maximum temperature for mis 1 of 14 9 c is only 1 c cooler than peak ssts calculated for mis 11 and 5e however the temperature trend for mis 1 continues on a linear trajectory toward warmer modern temperatures to the top of the section a lead lag relationship between sst and the benthic oxygen isotope record of ice volume was observed at the onset and reversals of major g i cycles

tropical cyclone activity in the northwest pacific in relation to the el nino southern oscillation phenomenon abstract the interannual variations in tropical cyclone activity in the northwest pacific nwpac and their relationships with the el nino southern oscillation enso phenomenon were studied using the method of spectral analyses time series of a southern oscillation index soi defined as the sea level pressure difference between easter island and darwin and tropical cyclone activity in the entire nwpac ocean basin as well as in different regions of the nwpac were analyzed two spectral peaks are apparent in all these time series one corresponds to the generally accepted southern oscillation with a period of 3 to 3 5 years and another at the quasi biennial oscillation qbo frequency cross spectral analyses between the soi and tropical cyclone activity show significant coherence in these two spectral peaks the dominant peak is at the southern oscillation frequency with the soi leading typhoon activity by almost a year at the qbo frequency the two series are almost in phase cyclone activity in t

modulation of tropical cyclogenesis location and frequency over the indo western north pacific by the intraseasonal indo western pacific convection oscillation during the boreal extended summer abstractthe influence of the intraseasonal indo western pacific convection oscillation ipco on tropical cyclone tc genesis location and frequency over the indo western north pacific wnp during the boreal extended summer may october is explored observational analysis shows that the impacts of the intraseasonal ipco on tcs over the indo wnp include an evident phase lock of tc genesis location and distinct differences in tc frequency in the wnp in the positive intraseasonal ipco phase the atmosphere gains heat through the release of latent heat in cumulus convective condensation and the anomalous cyclonic circulation weakens the western pacific subtropical high wpsh and enhances tc genesis thereby tending to produce many more tcs moreover the diminished wpsh and the westward shift of the centers of anomalous cyclonic circulations lock tc genesis locations to the west wnp and lower latitudes around 5 20 n especially in the south china sea the almost opposite situation occurs in a nega

impact of shifting patterns of pacific ocean warming on north atlantic tropical cyclones two distinctly different forms of tropical pacific ocean warming are shown to have substantially different impacts on the frequency and tracks of north atlantic tropical cyclones the eastern pacific warming epw is identical to that of the conventional el nino whereas the central pacific warming cpw has maximum temperature anomalies located near the dateline in contrast to epw events cpw episodes are associated with a greater than average frequency and increasing landfall potential along the gulf of mexico coast and central america differences are shown to be associated with the modulation of vertical wind shear in the main development region forced by differential teleconnection patterns emanating from the pacific the cpw is more predictable than the epw potentially increasing the predictability of cyclones on seasonal time scales

geochemical and geophysical implications of the radiocarbon calibration abstract a precise and accurate chronological framework is crucial to study the dynamics of a variety of phenomena which occurred during the last 45 000 years although the 14 c dating method has been widely applied since the 1950s it is recognized that the atmospheric 14 c 12 c ratio has not been stable during the past in order to calculate accurate ages these fluctuations have to be corrected by means of a calibration curve obtained by comparing raw 14 c measurements with true calendar ages provided by independent dating methods the calibration curve obtained so far is characterized by a long term trend with raw 14 c ages being significantly younger than calendar ages during most of the last 45 000 years abrupt 14 c shifts which occurred over centuries to millennia are superimposed on this long term trend of decreasing atmospheric 14 c 12 c ratio to a certain extent it is possible to outline the different causes of atmospheric 14 c variations by considering complementary information obtained from other cosmogenic nuclides studied at different latitudes 1 most high frequency changes in the atmospheric 14 c 12 c ratio are linked to magnetic fluctuations of solar origin as revealed by studying the last three centuries for which direct observations of the sun are available a similar conclusion is derived by comparing 14 c 12 c events with 10 be and 36 cl concentration maxima in polar ice cores 2 the long term trend shift of 14 c ages is due to a long period of decreased shielding effect of the geomagnetic dipole field which occurred over the interval between 10 000 and 40 000 years bp this interpretation is supported by paleomagnetic measurements performed on volcanic and sedimentary rocks and by 10 be and 36 cl analysed in low and high latitude records 3 a prominent and rapid atmospheric 14 c 12 c excursion occurred between 13 000 and 11 500 cal yr bp thus corresponding to the younger dryas cold period by contrast with the 14 c variability mentioned above which is linked to 14 c production changes this so called 14 c age plateau is probably due to an abrupt variation in the rates of exchange within the global carbon cycle this interpretation is supported by independent geochemical proxies and by numerical modelling of the carbon cycle

the sst gradient between the southwestern pacific and the western pacific warm pool a new factor controlling the northwestern pacific tropical cyclone genesis frequency abstractthe sea surface temperature gradient sstg between the southwestern pacific ocean 40 20 s 160 e 170 w and the western pacific warm pool 0 16 n 125 165 e in boreal spring has been identified as a new factor that controls the interannual variability of tropical cyclone tc frequency over the western north pacific ocean wnp this sstg can explain 53 of the total variance of the wnp tc genesis frequency during the typhoon season for the period 1980 2011 the positive sstg anomaly produces an anomalous cross equatorial pressure gradient and thus anomalies in low level southward cross equatorial flow and tropical easterlies over the central western pacific the anomalous easterlies further produce local equatorial upwelling and seasonal cooling in the central pacific which in turn maintains the easterly anomalies throughout the typhoon season these dynamical thermodynamical effects induced by the positive sstg anomaly lead to a reduced low level cyclonic shear increased vertical wind sh

solar influences on holocene climatic changes illustrated by correlations between past lake level fluctuations and the atmospheric 14c record chronological correlations established at different time scales among the lake level fluctuations in the jura and french subalpine ranges glacier movements in the swiss and austrian alps and the atmospheric 14c record during the last 7 millennia show coincidences between lake level rises glacier advances and high 14c production and vice versa these correspondences suggest that the short term 14c variations may be an empirical indicator of holocene palaeoclimates and argue for possible origins of holocene climatic oscillations 1 the varying solar activity refers to secular climatic oscillations and to major climatic deteriorations showing a ca 2300 yr periodicity 2 a question is raised about a relationship between the earth s magnetic field and climate first the weak strength periods of the earth s dipole magnetic field between 3800 and ca 2500 b c coincide with higher climate variability and vice versa second the ca 2300 yr periods revealed by the 14c record and also by the major climatic deteriorations re corded in jurassian lakes ca 1500 a d ca 800 b c and ca 3500 b c coincide with the ca 2300 yr periods revealed by the earth s nondipole geomagnetic field the present warming induced by anthropogenic factors should be intensified during the next few centuries by natural factors of climate evolution

record of a mid pleistocene depositional anomaly in west antarctic continental margin sediments an indicator for ice sheet collapse abstract modern global warming is likely to cause future melting of earth s polar ice sheets that may result in dramatic sea level rise a possible collapse of the west antarctic ice sheet wais alone which is considered highly vulnerable as it is mainly based below sea level may raise global sea level by up to 5 6 m despite the importance of the wais for changes in global sea level its response to the glacial interglacial cycles of the quaternary is poorly constrained moreover the geological evidence for the disintegration of the wais at some time within the last ca 750 kyr possibly during marine isotope stage mis 11 424 374 ka is ambiguous here we present physical properties palaeomagnetic geochemical and clay mineralogical data from a glaciomarine sedimentary sequence that was recovered from the west antarctic continental margin in the amundsen sea and spans more than the last 1 myr within the sedimentary sequence proxies for biological productivity such as biogenic opal and the barium aluminum ratio and the supply of lithogenic detritus from the west antarctic hinterland such as ice rafted debris and clay minerals exhibit cyclic fluctuations in accordance with the glacial interglacial cycles of the quaternary a prominent depositional anomaly spans mis 15 mis 13 621 478 ka the proxies for biological productivity and lithogenic sediment supply indicate that this interval has the characteristics of a single prolonged interglacial period even though no proxy suggests environmental conditions much different from today we conclude that if the wais collapsed during the last 800 kyr then mis 15 mis 13 was the most likely time period apparently the duration rather than the strength of interglacial conditions was the crucial factor for the wais drawdown a comparison with various marine and terrestrial climate archives from around the world corroborates that unusual environmental conditions prevailed throughout mis 15 mis 13 some of these anomalies are observed in the pelagic southern ocean and the south atlantic and might originate in major ice sheet drawdown in antarctica but further research is required to test this hypothesis

el nino modoki and its possible teleconnection 1 using observed data sets mainly for the period 1979 2005 we find that anomalous warming events different from conventional el nino events occur in the central equatorial pacific this unique warming in the central equatorial pacific associated with a horseshoe pattern is flanked by a colder sea surface temperature anomaly ssta on both sides along the equator empirical orthogonal function eof analysis of monthly tropical pacific ssta shows that these events are represented by the second mode that explains 12 of the variance since a majority of such events are not part of el nino evolution the phenomenon is named as el nino modoki pseudo el nino modoki is a classical japanese word which means a similar but different thing the el nino modoki involves ocean atmosphere coupled processes which include a unique tripolar sea level pressure pattern during the evolution analogous to the southern oscillation in the case of el nino hence the total entity is named as el nino southern oscillation enso modoki the enso modoki events significantly influence the temperature and precipitation over many parts of the globe depending on the season the impacts over regions such as the far east including japan new zealand western coast of united states etc are opposite to those of the conventional enso the difference maps between the two periods of 1979 2004 and 1958 1978 for various oceanic atmospheric variables suggest that the recent weakening of equatorial easterlies related to weakened zonal sea surface temperature gradient led to more flattening of the thermocline this appears to be a cause of more frequent and persistent occurrence of the enso modoki event during recent decades

improved extended reconstruction of sst 1854 1997 abstract an improved sst reconstruction for the 1854 1997 period is developed compared to the version 1 analysis in the western tropical pacific the tropical atlantic and indian oceans more variance is resolved in the new analysis this improved analysis also uses sea ice concentrations to improve the high latitude sst analysis and a modified historical bias correction for the 1939 41 period in addition the new analysis includes an improved error estimate analysis uncertainty is largest in the nineteenth century and during the two world wars due to sparse sampling the near global average sst in the new analysis is consistent with the version 1 reconstruction the 95 confidence uncertainty for the near global average is 0 4 c or more in the nineteenth century near 0 2 c for the first half of the twentieth century and 0 1 c or less after 1950

mid holocene sea level fluctuation inferred from diatom analysis from sediments on the west coast of korea diatoms from the ks2009 core sediment on the coast of the west sea kunsan si and the kr07 trench sediment collected from the neighboring sabsi island korea were analyzed for holocene sea level fluctuations in ks2009 core sediment results of ams 14c dating identified five stratigraphic horizons ranging from 2200 to 9100 bp the results obtained by measuring the radiocarbon dating from the kr07 were as follows 0 34 m a s l 6108 bp 0 74 m 6488 bp 1 46 m 6838 bp and 1 58 m 7208 bp diatom assemblages from ks2009 indicated facies a barren zone ks2009 23 5 to 20 3 m facies b high tidal flat ks2009 20 3 to 14 6 m holocene marine transgression facies c mid tidal flat ks2009 14 6 to 2 0 m falling sea level rising sea level facies d high tidal flat ks2009 2 to 2 m rising sea level thus after seawater influx started at 8300 bp seawater rose with fluctuations rising and falling the kr 07 trench deposit of sabsi island showed facies a barren zone kr07 1 58 to 1 18 m facies b bog kr07 1 18 to 0 76 m facies c tidal marsh kr07 0 76 to 0 52 m facies d tidal flat kr07 0 52 to 0 28 m facies e tidal marsh kr07 0 28 to 0 08 m facies f tidal flat kr07 0 08 to 0 06 m transgression occurred first about 8 300 bp at the west coast of korea around 6300 6000 bp there was a drop in the sea level and around 6000 4000 bp there was a rapid rise also repetition of falling and rising occurred since 4500 bp

a comprehensive mass flux scheme for cumulus parameterization in large scale models abstract observational studies indicate that a mass flux approach may provide a realistic framework for cumulus parameterization in large scale models but this approach through the introduction of a spectral cloud ensemble leads normally to rather complex schemes in this paper the question is addressed whether much simpler schemes can already provide realistic values of the thermal forcing by convection under various synoptic conditions this is done through verifying such a scheme first on data from field experiments for periods of tropical penetrative convection gate marshall islands tradewind cumuli atex bomex and extratropical organized convection sesame 79 and then in a nwp model the scheme considers a population of clouds where the cloud ensemble is described by a one dimensional bulk model as earlier applied by yanai et al in a diagnostic study of tropical convection cumulus scale downdrafts are included various types of convection are represented i e penetrative convection in c

contribution of the interdecadal pacific oscillation to the recent abrupt decrease in tropical cyclone genesis frequency over the western north pacific since 1998 abstractprevious studies have documented an abrupt decrease of tropical cyclone tc genesis frequency over the western north pacific wnp since 1998 in this study results from an objective clus

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

manganese fluxes from mississippi delta sediments abstract massive sediment deposition on the mississippi river delta establishes reducing conditions sufficient to bring about mn dissolution in the top millimeters of sediment as a result significant fluxes of dissolved mn pass from the delta sediments to the overlying water column this process is examined by study of chemical partitioning of mn in river particulates and delta sediments and from interstitial water chemistry remobilized mn is actively transported away from the delta area with aluminosilicate detritus thereby providing excess mn to the deep gulf of mexico at the expense of the delta sediments

successive oceanic and solar forcing indicated by younger dryas and early holocene climatic oscillations in the jura abstract the recent extension of 1 the residual 14 c curve back to 11 400 cal yr b p and 2 the lake level reconstruction in the jura back to ca 13 500 cal yr b p offers the opportunity of testing by proxy data the relationships between climate atmospheric 14 c the sun and the ocean recently suggested from the atmospheric 14 c record the climatic significance of the jura record is supported by correlations with climatic oscillations reconstructed in the alps from glaciers and timberline movements correspondence between the 14 c and paleoclimatic record from the jura suggests a working hypothesis two intervals within the holocene can be distinguished in the middle latitudes of western and central europe an early holocene period shows abrupt climatic oscillations linked to ocean forcing major colder climate phases developed between ca 9000 and 8800 and between ca 8000 and 7000 cal yr b c that coincide with higher 14 c values after 6000 cal yr b c a second period is characterized by smoother multicentury climatic oscillations linked to solar forcing

age and significance of miocene diatoms and diatomaceous sediments from northeast japan abstract neogene diatomaceous floras collected from marine sediments exposed in northeastern japan provide evidence of diatom evolution stratigraphic correlation and the geologic and paleoceanographic history of this region middle to late miocene diatom zones younger than the early middle miocene denticulopsis lauta zone have been established in the oga peninsula section an onshore sequence regarded as the neogene reference section for northeast japan correlative middle and late miocene diatom floras are not preserved in sediments recovered by ocean drilling program legs 127 and 128 in the japan sea emphasizing the importance of the time equivalent onshore deposits initial marine sedimentation is represented by lower middle miocene 16 15 ma littoral and shelf deposits exposed along the southern and eastern margins of the japan sea subsequent middle and late miocene deposition was marked by widespread deposition of bathyal diatomaceous sediments as recorded in the onnagawa and correlative formations in onshore sequences the major global cooling event at 13 ma is signaled in the japan sea area by the disappearance of subtropical warm water diatoms and the appearance of subarctic cold water floras an event coincident with a period of rapid subsidence in the japan sea the zonal marker species and the species mentioned in the text are illustrated

the last 100 000 years palaeoenvironmental changes inferred from the diatom assemblages of core md012404 from the okinawa trough east china sea the diatom assemblage records preserved in a sedimentary core md012404 retrieved from the okinawa trough in the east china sea ecs imply palaeoenvironmental changes of the last 100 ka our statistical analyses of diatom species abundance data indicate that the assemblages dominate open ocean and warm water coastal water and freshwater masses in the ecs these proxy species were used to infer the long term variation in surface hydrological conditions and palaeoclimate cycles of ca 23 ka observed in the relative abundance of the tychopelagic species paralia sulcata indicate that the increases in precipitation driven by solar insolation might have controlled the diatom assemblages in the ecs the diatom records also indicate relatively low abundances of tropical tychopelagic and freshwater species during millennial scale cold events such as the younger dryas and heinrich events which have been well expressed in the high latitude northern hemisphere climate the floral patterns are interpreted as synchronous cooling and more saline sea surface conditions in the ecs caused by the enhanced asian winter monsoon during the northern hemisphere cold events the higher abundances of tropical species during deglaciation and the holocene might have been linked to gradual increases in the inflow of the kuroshio into the okinawa trough the records also suggest a temporary reduction in tropical species from 5 to 3 ka corresponding to the pulleniatina minimum event during which the warm water planktic foraminifer pulleniatina obliquiloculata was rare copyright 2009 john wiley sons ltd

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr