relationships between extratropical sea level pressure variations and the central pacific and eastern pacific types of enso abstract this study examines the linkages between leading patterns of interannual sea level pressure slp variability over the extratropical pacific 20 60 n and the eastern pacific ep and central pacific cp types of el nino southern oscillation enso the first empirical orthogonal function eof mode of the extratropical slp anomalies represents variations of the aleutian low and the second eof mode represents the north pacific oscillation npo and is characterized by a meridional slp anomaly dipole with a nodal point near 50 n it is shown that a fraction of the first slp mode can be excited by both the ep and cp types of enso the slp response to the ep type is stronger and more immediate the tropical extratropical teleconnection appears to act more slowly for the cp enso during the decay phase of ep events the associated extratropical slp anomalies shift from the first slp mode to the second slp mode as the second slp mode grows subtropical sst anomalies are induced beneath via surface

importance of mean state in simulating different types of el nino revealed by snu coupled gcms abstract recent studies suggest that there are two types of el nino events which differ in terms of zonal distribution of sea surface temperature sst anomalies in this study we investigate mechanisms in controlling simulation of two types of el nino using three different versions of the seoul national university snu air sea coupled general circulation models the occurrences of two types of el nino are related to the simulated climatological sst over the eastern pacific it is found that a model with relatively less canonical or frequent warm pool or central pacific el nino occurrence has colder cold tongue in the equatorial central pacific due to the cold mean sst and associated dryness over the eastern pacific positive el nino related sst anomalies over the eastern pacific cannot trigger local convection effectively the eastern pacific dryness leads to the confinement of anomalous convective activity in the western pacific which results in weak canonical el nino and reduction in canonical el nino occurrence instead the confined convective activity in the western pacific can lead to strong sst anomalies over western central pacific through local air sea interaction which can increase warm pool wp el nino occurrence in addition we found that mean equatorial thermocline structure is also related to the occurrences of wp el nino and canonical el nino that is a model with deep thermocline depth simulates less wp el nino occurrence consistent with yeh et al 2009

the permo triassic transition in spitsbergen δ13corg chemostratigraphy fe and s geochemistry facies fauna and trace fossils new 13 c org analyses of two boundary sections between the late permian kapp starostin formation and the early triassic vardebukta formation of western spitsbergen confirm field evidence that their contact is a conformable one thus contrary to previous reports some spitsbergen sections contain a complete record of the environmental and faunal changes during the crisis interval of the end permian mass extinction no environmental deterioration is recorded in the late permian until near the end of the terminal changxingian stage whereupon the abundant siliceous sponge fauna of the kapp starostin formation disappears along with the deep burrowing fauna responsible for the zoophycus trace fossil a low diversity dysaerobic trace fossil assemblage is briefly developed before a transition to finely laminated pyritic facies immediately beneath the permo triassic boundary analysis of the s c ratios from the laminated strata suggests that free h 2 s was present in the water column euxinic conditions even in relatively nearshore settings subject to storm sandstone deposition the mass extinction crisis in spitsbergen is therefore coincident with the extensive development of oxygen poor conditions in the water column and compares closely both in timing and nature with the crisis seen in lower latitude tethyan settings however the subsequent aftermath and recovery in the boreal sections of spitsbergen was more rapid than in tethys thus a shoreface sandstone body within the dienerian stage contains an appreciable diversity of fauna by the standards of the early triassic including bryozoans calcareous algae and deep infaunal bivalves that suggests the marine ecosystem recovery began earliest in higher palaeolatitudes

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

the el nino southern oscillation enso modoki signal in the stratosphere el nino southern oscillation enso is known to be the largest source of interannual variability in the tropical troposphere however the variability in the tropical pacific since 1979 seems to be associated not only with canonical enso events but also with a variation thereof known as enso modoki which is characterized by warm anomalies in the central pacific west from those occurring during a typical enso this works analyzes the signal of enso modoki in the stratosphere and compares it to canonical enso by using the chemistry climate whole atmosphere community climate model waccm3 5 the results reveal a significant warming in the southern hemisphere polar stratosphere during boreal winter months which propagates downward in early spring this is absent during canonical warm enso events on the other hand in the northern hemisphere stratosphere the anomalous warming typical of canonical el nino episodes during boreal winter is not statistically significant during el nino modoki events these differences are related in waccm3 5 to changes in tropical convection and tropospheric teleconnections associated with each type of event in particular an enhancement and westward displacement of the anomalous convective area during el nino modoki episodes is related to an intensification of the pacific south american teleconnection pattern and a weakening of the aleutian low during cold enso modoki events a significant anomalous cooling is present in the model simulations

impacts of two types of la nina on the nao during boreal winter the present work identifies two types of la nina based on the spatial distribution of sea surface temperature sst anomaly in contrast to the eastern pacific ep la nina event a new type of la nina central pacific or cp la nina is featured by the sst cooling center over the cp these two types of la nina exhibit a fundamental difference in sst anomaly evolution the ep la nina shows a westward propagation feature while the cp la nina exhibits a standing feature over the cp the two types of la nina can give rise to a significantly different teleconnection around the globe as a response to the ep la nina the north atlantic na western european we region experiences the atmospheric anomaly resembling a negative north atlantic oscillation nao pattern accompanied by a weakening atlantic jet it leads to a cooler and drier than normal winter over western europe however the cp la nina has a roughly opposing impact on the na we climate a positive nao like climate anomaly is observed with a strengthening atlantic jet and there appears a warmer and wetter than normal winter over western europe modeling experiments indicate that the above contrasting atmospheric anomalies are mainly attributed to the different sst cooling patterns for the two types of la nina mixing up their signals would lead to difficulty in seasonal prediction of regional climate since the la nina related sst anomaly is clearly observed during the developing autumn the associated winter climate anomalies over western europe could be predicted a season in advance

formation processes of framboidal pyrite abstract pyrite framboid formation may be the result of four consecutive processes 1 nucleation and growth of initial iron monosulfide microcrystals 2 reaction of the microcrystals to greigite fe 3 s 4 3 aggregation of uniformly sized greigite microcrystals i e framboid growth and 4 replacement of greigite framboids by pyrite the uniform morphology uniform size range and ordering of the microcrystals in individual framboids as well as the range of observed framboid structures from irregular aggregates to densely packed spherical aggregates and polyframboids are consequences of these processes using dlvo theory derjaguin landau verwey and overbeek we have evaluated the stability of colloidal iron monosulfide suspensions with ionic strengths typical of marine and lacustrine waters in addition to van der waals attractive and double layer repulsive forces a term is included to account for the ferrimagnetic properties of greigite numerical models predict that magnetically saturated greigite particles 0 1 m in diameter will rapidly aggregate in either marine or fresh water the aggregation model is in agreement with the sequence of greigite formation followed by pyrite framboid formation established in a previous experimental study sweeney and kaplan 1973 and is consistent with the occurrence of framboids composed of other magnetic minerals e g greigite magnetite and magnesioferrite based on the temperature dependent magnetic properties of greigite and aging experiments in hydrothermal solutions this mechanism for framboid formation via precursor greigite could operate to temperatures of 200 c consistent with the occasional occurrence of pyrite framboids in the paragenesis of metalliferous ore deposits

how well do current climate models simulate two types of el nino in this study we evaluate the fidelity of current climate models in simulating the two types of el nino events using the pre industrial output in cmip3 archives it is shown that a few climate models simulate the two types of el nino events to some extent while most of the models have serious systematic problems in simulating distinctive patterns of sea surface temperature sst and precipitation anomaly associated with the two types of el nino that is they tend to simulate a single type of el nino it is shown that the ability of climate models in simulating the two types of el nino is related to the sensitivity of the atmospheric responses to the sst anomaly patterns models whose convective location is shifted to the east west as the sst anomaly center moves to the east west tends to simulate the two types of el nino events successfully on the other hand models whose location of convective anomaly is confined over the western or central pacific tends to simulate only the single type of el nino event it is also shown that the confinement of the convective anomaly over the western or central pacific is closely linked to the dry bias and the associated cold bias over the eastern pacific that is because positive el nino sst anomalies over the eastern pacific cannot increase local convection effectively when the total ssts are still too cold due to a cold bias this implies that the realistic simulation of climatology especially over the equatorial eastern pacific is essential to the successful simulation of the two types of el nino

analysis of the southward wind shift of enso in cmip5 models abstractduring the mature phase of el nino southern oscillation enso events there is a southward shift of anomalous zonal winds sws which has been suggested to play a role in the seasonal phase locking of enso motivated by the fact that coupled climate models tend to underestimate this feature this study examines the representation of the sws in phase 5 of the coupled model intercomparison project cmip5 it is found that most models successfully reproduce the observed sws although the magnitude of the zonal wind stress anomaly is underestimated several significant differences between the models with and without the sws are identified including biases in the magnitude and spatial distribution of precipitation and sea surface temperature sst anomalies during enso multiple linear regression analysis suggests that the climatological meridional sst gradient as well as anomalous enso driven convective activity over the northwest pacific both might play a role in controlling the sws while the mode

interannual variability of the south pacific convergence zone and implications for tropical cyclone genesis the interannual variability of the south pacific convergence zone spcz and its influence on tropical cyclone tc genesis in the south pacific are investigated using observations and era40 reanalysis over the 1979 2002 period in austral summer the spcz displays four typical structures at interannual timescales the first three are characterized by a diagonal orientation of the spcz and account for 85 of the summer seasons one is close to climatology and the other two exhibit a 3 northward or southward departure from the spcz climatological position in contrast the fourth one that only encompasses three austral summer seasons the extreme 1982 1983 and 1997 1998 el nino events and the moderate 1991 1992 el nino event displays very peculiar behaviour where the spcz largely departs from its climatological position and is zonally oriented variability of the western central pacific equatorial sea surface temperature sst is shown to modulate moisture transport south of the equator thereby strongly constraining the location of the spcz the spcz location is also shown to strongly modulate the atmospheric circulation variability in the south pacific with specific patterns for each class however independently of its wide year to year excursions the spcz is always collocated with the zero relative vorticity at low levels while the maximum vorticity axis lies 6 to the south of the spcz position this coherent atmospheric organisation in the spcz region is shown to constrain tropical cyclogenesis to occur preferentially within 10 south of the spcz location as this region combines all the large scale atmospheric conditions that favour the breeding of tcs this analysis also reveals that cyclogenesis in the central pacific in the vicinity of french polynesia only occurs when the spcz displays a zonal orientation while this observation was previously attributed to el nino years in general different characteristics of el nino southern oscillation enso related pacific equatorial warming are shown to impact differently on the spcz position suggesting that for regional scales such as the south pacific the spcz classification is more appropriate than a simple enso index to characterize tc interannual variability these findings suggest that forecasting the strength of el nino through sst variations in the eastern pacific may not be sufficient to accurately predict cyclogenesis in the south pacific especially east of the dateline

constraining the cause of the end guadalupian extinction with coupled records of carbon and calcium isotopes abstract a negative c 13 excursion in carbonate sediments near the guadalupian lopingian middle late permian boundary has been interpreted to have resulted from a large carbon cycle disturbance during the end guadalupian extinction event ca 260 ma however the carbon isotope data alone are insufficient to uniquely determine the type and magnitude of perturbation to the global carbon cycle calcium isotopes can be used to further constrain the cause of a carbon isotope excursion because the carbon and calcium cycles are coupled via caco3 burial in this study we present coupled carbon and calcium isotope records from three guadalupian lopingian g l sections in china penglaitan and chaotian and turkey koserelik tepe the c 13 and ca 44 40 records differ among our studied sections and do not co vary in the same manner no section shows c 13 and ca 44 40 changes consistent with massive rapid volcanic co2 emissions or methane clathrate destabilization additionally many sections with large 3 changes in c 13 exhibit o 18 evidence for diagenetic alteration only one section exhibits a large excursion in the ca 44 40 of limestone but the absence of a similar excursion in the ca 44 40 of conodont apatite suggests that the limestone excursion reflects a mineralogical control rather than a perturbation to the global calcium cycle hence we interpret the large isotopic changes observed in some sections to have resulted from local burial conditions or diagenetic effects rather than from a large carbon and calcium cycle disturbance perturbations to the global carbon and calcium cycles across the g l transition were much less intense than the disturbances that occurred across the subsequent permian triassic boundary this finding is consistent with the much smaller magnitude of the end guadalupian extinction relative to the end permian

seawater strontium isotopic perturbation at the permian triassic boundary west spitsbergen and its implications for the interpretation of strontium isotopic data brachiopod shell samples from the kapp starostin formation west spitsbergen provide evidence for a large and rapid drop in seawater strontium isotopic ratios close to the permian triassic boundary the strontium isotopic shift is associated with similarly dramatic declines in carbon and oxygen isotope curves recorded in the same samples this pattern can be explained by a paleoceanographic model that we have proposed previously a model in which there is replacement of a largely stagnant stratified ocean by a vigorously mixed one at the permian triassic boundary

facies analysis and sea level change at the guadalupian lopingian global stratotype laibin south china and its bearing on the end guadalupian mass extinction abstract the guadalupian lopingian boundary stratotype at penglaitan and the nearby tieqiao section near laibin south china record a series of major environmental changes within the jiangnan basin during a mid permian biotic crisis the sequence stratigraphic petrographic and palaeontological record of these sections has been studied and the associated strontium isotopic fluctuations have been assayed mass extinction of fusulinid foraminifers is most clearly associated in time with onset of volcanism and a relative sea level fall that led to the establishment of mid ramp conditions laibin limestone in settings that were previously dominated by radiolarian mudstones the regression also coincides with a low point of 87 sr 86 sr ratios the lowstand deposits contain mafic scoriaceous grains that record pyroclastic volcanism probably centred in the emeishan flood basalt province 800 km to the west of laibin thus unusually violent eruptions associated with flood basalts in this province may have contributed to the environmental stresses responsible for the extinction event subsequent environmental changes included transgression spread of dysoxic waters indicated by populations of small pyrite framboids and a major negative c isotope excursion all these phenomena have been previously related to the end guadalupian extinction but they in fact post date the crisis because a post extinction fauna of foraminifers is encountered at this time

abrupt breakdown of the predictability of early season typhoon frequency at the beginning of the twenty first century maintenance of the anomalous anticyclone cyclone over the philippine sea following strong peak el nino la nina leads to a negative correlation between the pre winter october december el nino southern oscillation enso index and the tropical cyclone tc genesis frequency in the ensuing early tc season january june this negative lead lag correlation has established the predictability of the western north pacific wnp tc genesis frequency in the early season however little is known about whether this relationship remains steady to date especially in the context of evolving features of enso in recent decades here we show that the negative relationship experiences an abrupt breakdown around the early 2000s 1999 2006 which primarily occurs in the southeastern quadrant of the wnp during the breakdown period the anomalous anti cyclone shifts westward to the south china sea and an anomalous cyclonic circulation occupies the southeastern quadrant of the wnp causing enhanced tc formation we further reveal that the westward displacement of the wnp anticyclonic anomaly during 1999 2006 is induced by the westward shift of sea surface temperature sst and associated precipitation anomalies during the decaying phase of enso which increases cyclonic circulation and ascending motion while reduces vertical wind shear and thereby enhances tc formation over the southeastern wnp the results suggest that the frequent occurrence of decaying enso events with sst anomaly center over the central pacific cp accounts for the abrupt breakdown of predictability and the impacts of enso on tc formation in the early tc season are sensitive to the location of the maximum sst anomaly distinguishing eastern pacific ep and cp types of enso and or strong and weak enso events may help to improve the early season tc genesis forecast over the wnp the results also have important implications for understanding the future projection of tc changes under global warming scenarios

atlantic seasonal hurricane frequency part i el nino and 30 mb quasi biennial oscillation influences abstract this is the first of two papers on atlantic seasonal hurricane frequency in this paper seasonal hurricane frequency as related to e1 nino events during 1900 82 and to the equatorial quasi biennial oscillation qbo of stratospheric zonal wind from 1950 to 1982 is discussed it is shown that a substantial negative correlation is typically present between the seasonal number of hurricanes hurricane days and tropical storms and moderate or strong 15 cases el nin off the south american west coast a similar negative anomaly in hurricane activity occurs when equatorial winds at 30 mb are from an easterly direction and or are becoming more easterly with time during the hurricane season this association of atlantic hurricane activity with el nino can also be made with the southern oscillation index by contrast seasonal hurricane frequency is slightly above normal in non el nino years and substantially above normal when equatorial stratospheric winds blow from a westerly direction and or are bec

a new paradigm for the predominance of standing central pacific warming after the late 1990s canonical el nino has a warming center in the eastern pacific ep but in recent decades el nino warming center tends to occur more frequently in the central pacific cp the definitions and names of this new type of el nino however have been notoriously diverse which makes it difficult to understand why the warming center shifts here we show that the new type of el nino events is characterized by 1 the maximum warming standing and persisting in the cp and 2 the warming extending to the ep only briefly during its peak phase for this reason we refer to it as standing cp warming cpw global warming has been blamed for the westward shift of maximum warming as well as more frequent occurrence of cpw however we find that since the late 1990s the standing cpw becomes a dominant mode in the pacific meanwhile the epochal mean trade winds have strengthened and the equatorial thermocline slope has increased contrary to the global warming induced weakening trades and flattening thermocline we propose that the recent predominance of standing cpw arises from a dramatic decadal change characterized by a grand la nina like background pattern and strong divergence in the cp atmospheric boundary layer after the late 1990s the anomalous mean cp wind divergence tends to weaken the anomalous convection and shift it westward from the underlying sst warming due to the suppressed low level convergence feedback this leads to a westward shift of anomalous westerly response and thus a zonally in phase sst tendency preventing eastward propagation of the sst anomaly we anticipate more cpw events will occur in the coming decade provided the grand la nina like background state persists

modulation of north pacific tropical cyclone activity by three phases of enso abstract tropical pacific ocean warming has been separated into two modes based on the spatial distribution of the maximum sea surface temperature sst anomaly an east pacific warming epw and a central pacific warming cpw when combined with east pacific cooling epc these three regimes are shown to have different impacts on tropical cyclone tc activity over the north pacific by differential modulation of both local thermodynamic factors and large scale circulation patterns in epw years the genesis and the track density of tcs tend to be enhanced over the southeastern part and suppressed in the northwestern part of the western pacific by strong westerly wind shear the extension of the monsoon trough and the weak wind shear over the central pacific increases the likelihood of tc activity to the east of the climatological mean tc genesis location in cpw years the tc activity is shifted to the west and is extended through the northwestern part of the western pacific the westward shifting of c

faunal migration into the late permian zechstein basin evidence from bryozoan palaeobiogeography abstract late permian bryozoans from the wegener halvo ravnefjeld and schuchert formations in east greenland have been investigated 14 genera are recognised integration of the new bryozoan data from the upper permian of east greenland with data on the distribution of permian bryozoans along the northern margin of pangea is used to test hypotheses concerning late palaeozoic evolution of the north atlantic region during the permian the atlantic rift system formed a seaway between norway and greenland from the boreal barents shelf to the warm and arid zechstein basin this seaway is considered to be the only marine connection to the zechstein basin and therefore the only possible migration route for bryozoans to enter the basin the distribution of permian bryozoans is largely in keeping with such a connection from the cool barents shelf past the east greenland basin to the warm zechstein basin and also corroborates the change in temperature through this connection

recharge oscillator mechanisms in two types of enso the el ni oscillation enso tends to behave arguably as two different types or flavors in recent decades one is the canonical cold tongue type enso with major sea surface temperature anomalies ssta positionedoverthe easternpacific theotheris awarm pool typeensowith sstacenteredin the central pacific near the edge of the warm pool in this study the basic features and main feedback processes of these two types of enso are examined it is shown that the interannual variability of upper ocean heat content exhibits recharge discharge processes throughout the life cycles of both the cold tongue ct and warm pool wp enso types through a heat budget analysis with focus on the interannual frequency band the authors further demonstrate that the thermocline feedback plays a dominant role in contributing to the growth and phase transitions of both enso types whereas the zonal advective feedback contributes mainly to their phase transitions the westward shift of the ssta center of the wp enso and the presence of significant surface easterly wind anomalies over the far eastern equatorial pacific during its mature warm phase are the two main factors that lead to a reduced positive feedback for the eastern pacific ssta nevertheless both the wp and ct enso can be understood to a large extent by the recharge oscillator mechanism

the paleozoic minimum of 87sr 86sr ratio in the capitanian permian mid oceanic carbonates a critical turning point in the late paleozoic abstract the secular change in 87sr 86sr ratio of the paleozoic recorded the lowest value below 0 7070 in late middle permian i e the permian minimum suggesting that a major reform in oceanography occurred before the paleozoic mesozoic transition we have detected the correlative lowest 87sr 86sr value 0 706914 0 000012 from the middle upper permian paleo atoll limestone in japan formed primarily on an ancient seamount in mid panthalassa the stratigraphic horizon of the minimum was constrained to the capitanian interval 265 8 260 4 ma middle permian by fusulines as the mid oceanic data represent the global average the present study confirmed the chemostratigraphical utility of the capitanian minimum of 87sr 86sr ratio in global correlation after the long term nearly 280 million years decrease throughout the paleozoic since the cambrian a remarkable turnover of seawater 87sr 86sr values appeared in the capitanian immediately before the guadalupian lopingian middle late permian boundary a major global change likely appeared in the capitanian to change the sr isotope balance in seawater from a mantle flux dominated to a continental flux dominated regime the initial rifting of pangea probably started in the capitanian and the rifting induced new connection of many intra supercontinental drainage systems to the superocean may have caused the overturn in global sr isotopic trend

impact of resolution and downscaling technique in simulating recent atlantic tropical cylone activity using the global environmental multiscale gem model we investigate the impact of increasing model resolution from 2 to 0 3 on atlantic tropical cyclone activity there is a clear improvement in the realism of atlantic storms with increased resolution in part linked to a better representation of african easterly waves the geographical distribution of a genesis potential index composed of large scales fields known to impact cyclone formation coincides closely in the model with areas of high cyclogenesis the geographical distribution of this index also improves with resolution we then compare two techniques for achieving local high resolution over the tropical atlantic a limited area model driven at the boundaries by the global 2 gem simulation and a global variable resolution model gvar the limited area domain and high resolution part of the gvar model coincide geographically allowing a direct comparison between these two downscaling options these integrations are further compared with a set of limited area simulations employing the same domain and resolution but driven at the boundaries by reanalysis the limited area model driven by reanalysis produces the most realistic atlantic tropical cyclone variability the gvar simulation is clearly more accurate than the limited area version driven by gem global degradation in the simulated interannual variability is partly linked to the models failure to accurately reproduce the impact of atmospheric teleconnections from the equatorial pacific and sahel on atlantic cyclogenesis through the use of a smaller limited area grid driven by gem global 2 we show that an accurate representation of african easterly waves is crucial for simulating atlantic tropical cyclone variability

small to medium sized glacitectonic structures in till and in its substratum and their comparison with mass movement structures abstract ductile and brittle deformation structures have been observed in till of various origins particularly in subglacial till and flowtill and in the substratum beneath subglacial till although some of the glacitectonic structures have been claimed to be palimpsest structures from debris rich glacier ice such a preservation is not proven to be very common however deformation structures are found in megablocks and other clasts that occur in melt out till and in deformation till most glacitectonic deformation structures are formed in the substratum or in the already deposited subglacial till by an actively moving glacier for instance recumbent folds shears boudins thrusts hook folds diapirs tension fractures till wedges fissility glacitectonic breccia conjugate sets of fractures structures similar to those reported from subglacial primary till and its substratum occur also in flowtill and other mass movement deposits but deformations are less common in the substratum beneath them the orientation of the deformations in flowtill is unrelated to the direction of glacial movement the shapes of some shears and folds are different in flowtill when compared with those in subglacial till and its substratum still the flow and shear structures alone are not sufficient to distinguish certain varieties of till fir instance subglacial primary till from flowtill but they are useful as local directional indicators of stress and as genetic criteria in combination with other features particularly with directional glacial erosion marks and fabric

lack of westerly wind bursts in unmaterialized el nino years abstractthe lack of westerly wind bursts wwbs when atmospheric intraseasonal variability isv events occur from boreal spring to autumn is investigated by comparing two types of el nino years with unmaterialized el nino uen years although high ocean heat content buildup and several isv events propagating eastward are observed in all three types of years few wwbs accompany these in the uen years the eddy kinetic energy budget analysis based on isv shows that mean westerly winds in the lower troposphere facilitate the development of eddy disturbances including wwbs through convergence and meridional shear of zonal winds in the uen years these westerly winds are retracted westward and do not reach the equatorial central pacific mainly due to interannual components in addition positive sea surface temperature anomalies in the western pacific which are conducive to active convection spread widely in a meridional direction centered on 15 n both westward retracted mean westerlies and off equator

evolution of the madden julian oscillation in two types of el nino abstractevolution characteristics of the madden julian oscillation mjo during the eastern pacific ep and central pacific cp types of el nino have been investigated mjo activities are strengthened over the western pacific during the predeveloping and developing phases of ep el nino but suppressed during the mature and decaying phases in contrast mjo activities do not show a clear relationship with cp el nino before their occurrence over the western pacific but they increase over the central pacific during the mature and decaying phases of cp el nino lag correlation analyses further confirm that mjo activities over the western pacific in boreal spring and early summer are closely related to ep el nino up to 2 11 months later but not for cp el nino ep el nino tends to weaken the mjo and lead to a much shorter range of its eastward propagation anomalous descending motions over the maritime continent and western pacific related to el nino can suppress convection and moisture flux convergence the

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

u mo ratios and δ98 95mo as local and global redox proxies during mass extinction events abstract when used in conjunction with trace metal redox proxies the use of u mo ratios and 98 95 mo values can considerably enhance the interpretation of ocean oxygenation trends both locally and globally this is illustrated with studies from two biogenic chert dominated records of mass extinction the ordovician silurian boundary and the late permian in sections from the yangtze block in south china the latest ordovician mass extinction is well known to coincide with oxygenation episode in the hirnantian stage here revealed by trace metal proxies v v ni v cr ni co that show it sandwiched between anoxic euxinic black shales the predominantly anoxic euxinic ordovician silurian strata provide a record of seawater 98 95 mo values that are seen to gradually rise during the interval from 0 5 to 1 0 the exception to the 98 95 mo stability is the datum of the slight negatively 98 95 mo associated with decreasing of v cr and v v ni ratio suggesting the hirnantian oxygenation event the upper permian chert succession at shangsi reveals an overall better ventilated record in which the best oxygenated strata show the highest u mo values that is interpreted as relative enrichment of u in suboxic conditions at a few levels anoxic euxinic conditions show the 98 95 mo values to be 2 close to modern values implying that latest permian oceans were as well ventilated as those today the well known end permian oceanic anoxic event is therefore suggested to only develop at the end of this period

changes in atmospheric rivers and moisture transport over the northeast pacific and western north america in response to enso diversity the year to year changes in atmospheric rivers ars and moisture transport over the northeast pacific and western north america are investigated during december to february djf from 1979 80 to 2015 16 changes in ar frequency intensity and landfall characteristics are compared between three enso phases central pacific el nino cpen eastern pacific el nino epen and la nina nina during epen events the subtropical jet extends to the south and east with an anomalous cyclonic flow around a deeper aleutian low more moisture is transported towards north america and ar frequency is increased over western north america in cpen events the aleutian low shifts further southward relative to its position in epen resulting in an increase in the frequency and intensity of landfalling ars over the southwestern us in nina events the landfalling ar frequency is reduced associated with anomalous anticyclonic circulation over the eastern north pacific we diagnose the contribution of multiple factors to the seasonal mean moisture transport using moisture budgets during the three enso phases the change in low frequency circulation dynamical process is the leading contributor to the seasonal mean moisture flux divergence while the contributions of the synoptic anomalies and the change in moisture anomaly thermodynamic process are not significant along the west coast of north america

the carbon isotope excursion on gssp candidate section of lopingian guadalupian boundary an isotopic stratigraphically well documented outcrop in penglaitan guangxi province south china has been proposed as a candidate gssp for the lopingian guadalupian boundary correlatable outcrops from the west wing tieqiao section and east wing penglaitan section of the laibin syncline exhibit synchronous excursions in carbon isotopes the isotopic excursions 13c show the best placement of the boundary may lie at the base of bed 6k which coincides with the clarkina postbitteri conodont zone and with eustatic change 13c increases during the uppermost guadalupian jinogondolella granti conodont zone from the top of 3c to the base of 6i a 13c peak value of 5 is located at the transition between these two conodont zones and is suggested as a proxy for the transition from transgression to regression a gradual depletion of carbon isotopes occurs in the c postbitteri zone from bed 6e to 7b and this gradual 13c excursion also suggests the sequences around the guadalupian lopingian boundary at the candidate section are conformable during the middle later c postbitteri zone a 3 5 dramatic 13c depletion is recorded at the tieqiao section but only a 2 depletion at the deeper facies penglaitan section synchronous with conodont zones that mark eustatic changes

illawarra reversal the fingerprint of a superplume that triggered pangean breakup and the end guadalupian permian mass extinction abstract the permian magnetostratigraphic record demonstrates that a remarkable change in geomagnetism occurred in the late guadalupian middle permian ca 265 ma from the long term stable kiaman reverse superchron throughout the late carboniferous and early middle permian to the permian triassic mixed superchron with frequent polarity changes in the late permian and triassic this unique episode called the illawarra reversal probably reflects a significant change in the geodynamo in the outer core of the planet after a 50 million years of stable geomagnetism the illawarra reversal was likely led by the appearance of a thermal instability at the 2900 km deep core mantle boundary in connection with mantle superplume activity the illawarra reversal and the guadalupian lopingian boundary event record the significant transition processes from the paleozoic to mesozoic modern world one of the major global environmental changes in the phanerozoic occurred almost simultaneously in the latest guadalupian as recorded in 1 mass extinction 2 ocean redox change 3 sharp isotopic excursions c and sr 4 sea level drop and 5 plume related volcanism in addition to the claimed possible links between the above listed environmental changes and mantle superplume activity i propose here an extra explanation that a change in the core s geodynamo may have played an important role in determining the course of the earth s surface climate and biotic extinction evolution when a superplume is launched from the core mantle boundary the resultant thermal instability makes the geodynamo s dipole of the outer core unstable and lowers the geomagnetic intensity being modulated by the geo and heliomagnetism the galactic cosmic ray flux into the earth s atmosphere changes with time the more cosmic rays penetrate through the atmosphere the more clouds develop to increase the albedo thus enhancing cooling of the earth s surface the illawarra reversal the kamura cooling event and other unique geologic phenomena in the late guadalupian are all concordantly explained as consequences of the superplume activity that initially triggered the breakup of pangea the secular change in cosmic radiation may explain not only the extinction related global climatic changes in the end guadalupian but also the long term global warming cooling trend in earth s history in terms of cloud coverage over the planet

the middle permian capitanian mass extinction on land and in the oceans abstract a middle permian mass extinction first discovered in 1994 has become known as the end guadalupian event in the literature however recent studies of foraminifera and brachiopod range truncations in conodont dated sections on the south china block have shown that the losses occur below this level in the middle of the capitanian stage extinctions were suffered by several other groups notably the corals whilst the mollusc record is more enigmatic a major bivalve crisis has been reported in some studies the giant alatoconchids being notable victims but not others gastropods were unaffected by the crisis whilst a roughly contemporaneous ammonoid mass extinction may have occurred in the early wuchiapingian a few million years after the main marine losses compilation of data from plant species in south china reveals a significant 24 loss suggesting that the capitanian crisis also occurred on land an intra capitanian extinction of 56 of plant species in north china block sequences may also have coincided with these losses correlation of these marine and terrestrial extinction events using the palaeomagnetic record provides two alternatives either turnover amongst plant species is contemporaneous with the marine extinction and the eruption of the emeishan flood basalt province in southwest china or plant losses post date the marine extinction and instead coincide with the waning phase of the igneous province current understanding of the major dinocephalian extinction suggests this event occurred during the preceding stage the wordian but future improvements in both sampling and dating this tetrapod crisis may reveal a synchronicity of plant animal and marine invertebrate extinctions the clear temporal link of the capitanian marine extinction with emeishan volcanism suggests that these flood basalt eruptions triggered the crisis a contemporaneous major negative c isotope excursion suggests that like many other mass extinction events methane release from hydrates may also be implicated however in the best dated chinese sections the main excursion is found to slightly post date the extinction which occurs at the end of an unusual and unexplained interval of exceptionally heavy 13c values other usual suspects for mass extinctions either lack geological and palaeontological evidence e g marine anoxia and global cooling or do not precisely correlate with the extinction e g major eustatic regression

87sr 86sr record of permian seawater abstract a population of 169 permian articulate brachiopod shells was analysed for their 87 sr 86 sr ratios 51 of these characterised as well preserved and stratigraphically well defined are utilized for delineation of the permian seawater strontium isotope trend the 87 sr 86 sr curve shows values of about 0 7080 in the lowermost permian asselian followed by a gradual decline to 0 70685 in the capitanian and a minor rise in the dzhulfian and lower dorashamian to values of 0 70715 just below the permian triassic boundary the early permian decrease in the strontium isotope curve that commences in the early sakmarian is coincident with the advancing deglaciation of the gondwana and with the increased aridity in large parts of the pangaea these factors may have led to a reduced continental weathering of rb rich silicate rocks and thus to the decline in seawater 87 sr 86 sr starting with the artinskian the opening of the neotethys and the associated widespread basaltic volcanism supplied low radiogenic strontium to seawater from an enhanced hydrothermal flux in the capitanian basaltic volcanism in the entire palaeotethys ceased and this may have been the reason for a slightly more radiogenic seawater isotopic composition during the lopingian higher input of riverine sr due to expansion of humid areas may have been a contributory factor

the annual cycle modulation of meridional asymmetry in enso s atmospheric response and its dependence on enso zonal structure previous studies documented that a distinct southward shift of central pacific low level wind anomalies occurringduringtheensodecayingphaseiscausedbyaninteractionbetweenthewesternpacificannualcycleand el nino southern oscillation enso variability the present study finds that the meridional movement of the central pacificwindanomalies appears only duringtraditional eastern pacific el nino ep el nino eventsrather than in central pacific el nino cp el nino events in which sea surface temperature sst anomalies are confined to the central pacific the zonal structure of enso related sst anomalies therefore has an important effectonmeridionalasymmetryintheassociatedatmosphericresponseanditsmodulationbytheannualcycle in contrasttoepelninoevents thesstanomaliesofcpelninoeventsextendfartherwesttowardthewarmpool regionwithitsclimatological warmssts inthewarmpool region relativelysmallsstanomaliesarethusable to excite convection anomalies on both sides of the equator even with a meridionally asymmetric sst background state therefore almost meridionally symmetric precipitation and wind anomalies are observed over the central pacific during the decaying phase of cp el nino events the sst anomaly pattern of la nina events is similar to cp el nino events with a reversed sign accordingly no distinct southward displacement of the atmospheric response occurs over the central pacific during the la nina decaying phase these results have important implications for enso climate impacts over east asia since the anomalous low level anticyclone over the western north pacific is an integral part of the annual cycle modulated enso response

relationship between el nino southern oscillation and the symmetry of the hadley circulation role of the sea surface temperature annual cycle abstractel nino southern oscillation enso which features an equatorial quasi symmetric sea surface temperature anomaly ssta is related to both the symmetric and asymmetric components of the h

simulated impacts of two types of enso events on tropical cyclone activity in the western north pacific large scale atmospheric response the present paper uses an atmospheric general circulation model to explore large scale atmospheric response to various el nino southern oscillation events associated with tropical cyclone tc activity in the western north pacific the simulated response is basically consistent with and confirms the observed results for eastern pacific warm epw event anomalously wet ascent occurs over the tropical central eastern pacific and dry descent is over the western pacific this walker circulation is associated with anomalous low level convergence reduced vertical wind shear vws and enhanced genesis potential index gpi in the southeast sub region these are consistent with the observed increase of the tc formation in the southeast sub region but decrease in the northwest sub region during july september jas and the increase in the southwest and northwest sub regions during october december ond in addition the strong westerly anomalies of the tc steering flow prevail in the east asian coast suppressing the tc northwestward or westward tracks for eastern pacific cold epc event all of the simulated variables show almost a mirror image of epw for central pacific warm event the anomalous walker circulation shifts westward because of the westward shift of the maximum sst anomaly forcing the anomalous subsidence associated with the western branch of the walker circulation during ond shifts northward to the south china seas resulting in a decrease of the tc genesis there the tc steering flow patterns during jas are favorable for tcs to make landfall over japan and korea compared with epc the descending motion in the central eastern pacific is much stronger for central pacific cold cpc event accompanied by more enhanced vws and reduced gpi in the southeast sub region therefore cpc provides a more adverse environment to the tc formation there during jas and ond consistent with the observed decrease of tc formation there moreover the easterly anomalies of the tc steering flow dominate the tropics during jas enhancing tc activity in the east coast of china additionally the convection over the western pacific moves to the south china sea during ond favoring the tc genesis there

nonlinearities in the evolutional distinctions between el nino and la nina types using the hadisst soda reanalysis and various other observed and reanalyzed data sets for the period 1950 2010 we explore nonlinearities in the subsurface evolutional distinctions between el nino types and la nina types from a few seasons before the onset cluster analysis carried out over both summer and winter suggests that while the warm phased events of both types are distinguishable several cold phased events are clustered together further we apply a joint self organizing map som analysis using the monthly sea surface temperature anomaly ssta and thermocline depth anomalies in tropical pacific tp results reveal that the evolutionary paths of el nino modoki em and el nino el are broadly different subsurface temperature composites of el and em show different onset characteristics during an el warm anomaly in the west spreads eastward along the thermocline and reaches the surface in the east in march may of year 0 during an em warm anomaly already exists in the central tropical pacific and then reaches the surface in the east in september november of year 0 composited sstas during la nina ln and la nina modoki lm are distinguishable only at 80 confidence level but the composited subsurface temperature anomalies show differences in the location of the coldest anomaly as well as evolution at 90 confidence level thus the el nino flavor distinction is potentially predictable at longer leads

marine ingressions into the middle late permian saline lake of the southern permian basin rotliegend northern germany possibly linked to sea level highstands in the arctic rift system abstract a huge saline lake existed in the southern permian basin spb of northwest europe during late wordian to early wuchiapingian more than 2500 m thick continental siliciclastics and evaporites of the upper rotliegend ii were deposited before the marine zechstein transgression flooded the basin marine deposition took place in the arctic rift system between east greenland and the fennoscandian shield at that time interval sediments of the foldvik creek group reflect relative sea level fluctuations short termed pre zechstein ingressions from the boreal realm into the spb are known by the marine lamellibranch liebea reichei however sedimentological analysis of different saline lake horizons show that the marine influenced saline lake horizon does not differ lithologically from other saline lake claystone layers in the rotliegend succession the 87 sr 86 sr ratios of anhydrite 0 7089 0 7100 reflect deposition in a continental setting in contrast to this s isotopic values more than 11 7 cdt reflect marine pre zechstein ingressions into the spb in the middle niendorf and munster members s isotopic values of anhydrite can be used as an indicator for marine influence in the spb the pre zechstein ingressions superimpose the climatic triggered lake level fluctuations of the rotliegend saline lake two marine ingressions can be integrated into a set of regularly recurring abnormities in the depositional evolution these important evolutionary steps the saline lake formation the garlstorf ingression the p ameland and bahnsen lake level highstands the niendorf ingression and the zechstein transgression show a periodicity of more or less 1 ma one million year cyclicity is also known from deposits of the arctic rift system in east greenland wegener halvo and ravnefjeld formations a correlation of the upper rotliegend ii deposits with the succession of east greenland is proposed based on the assumption that the marine ingressions as well as the exceptionally intensive saline lake expansions could be linked to sea level highstands in the arctic rift system the result is the first correlation of upper rotliegend ii deposits with marine strata

the mid capitanian middle permian mass extinction and carbon isotope record of south china abstract conodont c isotope and fossil and facies data are presented for the capitanian middle permian mass extinction record seen in platform carbonates maokou and wuchiaping formations of south china where limestones interdigitate with the volcanic succession of the emeishan large igneous province the maokou formation provides an extinction record marked by the loss of keriothecal walled fusulinaceans and a turnover in calcareous algae in sections within the emeishan province this crisis occurs at the base of the oldest record of volcanism from the jinogondolella altudaensis conodont zone of mid capitanian age around the periphery of the emeishan province this extinction level lies within the upper part of the maokou formation at a level where platform carbonate deposition was frequently interrupted by thick volcanic ash depositional events the assemblages of the uppermost maokou formation are characterised by typical late permian taxa although these levels still lie within the middle permian guadalupian series disaster taxa such as earlandia and diplosphaerina are locally prolifically abundant in the aftermath of the mass extinction the crisis is particularly noteworthy amongst photosynthetic taxa such as calcareous algae and fusulinaceans that probably harboured photosymbionts therefore a kill mechanism involving cooling from explosive volcanism and potentially acid rain from sulphate aerosols appears appropriate a composite 13ccarb curve calibrated against a high resolution conodont biostratigraphy reveals a major intra capitanian negative excursion of 5 superimposed on typically heavy 4 5 middle permian values this curve can also be recognised in panthalassan seamount carbonates of japan although this requires reassignment of apparently upper permian limestones to the middle permian in both china and japan the capitanian mass extinction occurs during the early stage of this major intra capitanian negative excursion assuming typical platform carbonate accumulation rates the records of the maokou formation suggest 13ccarb values fell at 0 01 kyr suggesting a catastrophic origin such as gas hydrate destabilisation is unlikely although a volcanic source is possible

sea surface chlorophyll signature in the tropical pacific during eastern and central pacific enso events 1 recent analyses of physical measurements show the existence of a central pacific type of el nino cpen with a sea surface temperature warming pattern distinct from that of the classical eastern pacific el nino epen in this study we analyze the surface chlorophyll signature of el nino southern oscillation enso using monthly maps of satellite derived chlorophyll anomalies between september 1997 and december 2010 we identify five typical enso structures the first structure describes the lonely 1997 1998 epen of the period the second and third represent la nina the fourth illustrates intermediate conditions and the fifth characterizes cpen during the 1997 1998 epen a large eastward shift of the oligotrophic warm pool and a reduction of equatorial upwelling result in negative chlorophyll anomalies east of 170 e between 10 s and 10 n during the four cpen events a reduced eastward shift yields negative chlorophyll anomalies in the equatorial band within about 160 e and 160 w only westward surface current in the central basin limits the expansion of the anomaly core negative chlorophyll anomalies that extend eastward from the equatorial anomaly core probably result from reduced upward iron fluxes linked to the deepening of the equatorial undercurrent during la nina the westward expansion of the equatorial upwelling results in positive chlorophyll anomalies west of the date line away from the equatorial band advection of oligotrophic warm pool waters by enhanced eastward countercurrents drives negative anomalies within 8 10 n and toward the marquesas islands during cpen while reduced countercurrents lead to positive chlorophyll anomaly during la nina

capitanian late guadalupian permian global brachiopod palaeobiogeography and latitudinal diversity pattern a global database containing 3365 occurrences 821 species and 251 genera of the capitanian late guadalupian permian brachiopod faunas from 24 stations has been analyzed by cluster analysis using the jaccard and otsuka coefficients and the probabilistic index of similarity nonmetric multidimensional scaling and minimum spanning tree two supergroups three groups and six subgroups are revealed and interpreted as representing respectively two biotic realms the palaeoequatorial and gondwanan realms two regions and six provinces an additional realm the boreal realm based on the fauna from spitsbergen also appears recognizable although it also shows considerable similarities with southwestern north america and the northern margin of gondwana as revealed by the statistical analysis the palaeoequatorial realm can be further subdivided into the north america region and the asian tethyan region the six biotic provinces are the cathaysian province in the palaeotethys and mesotethys the greenland svalbard province in the arctic region the austrazean province in eastern australia and new zealand the grandian province in western north america and the two transitional zones the himalayan province in the southern temperate zone and the sino mongolian japanese province in the northern temperate zone polynomial regression analysis and rarefaction analysis indicate that the generic diversities of brachiopod faunas during the capitanian peaked in the palaeoequatorial cathaysian province and the two transitional zones himalayan province and sino mongolian japanese province but fell dramatically in the polar regions the generic diversity of the palaeoequatorial grandian province is apparently lower than in the two transitional zones of temperate palaeolatitudes suggesting that the generic diversity of capitanian brachiopod faunas does not exhibit a strict negative correlation with palaeolatitudes this in turn would suggest that biogeographical determinants such as geographical barriers inhabitable area and ocean currents other than latitude related temperature control may also have played an important role in the dispersal of some brachiopods and the characterization of some local provinces and high diversities the capitanian global brachiopod palaeobiogeography is generally comparable with those in the wuchiapingian and changhsingian but with some notable differences these include 1 that the grandian province of the capitanian in western north america vanished after the end guadalupian regression 2 that the western tethyan province of the lopingian could not be distinguished in the capitanian and 3 that the austrazean province was larger in area than either in the wuchiapingian or in the changhsingian

on the relationship between indian ocean sea surface temperature and the transition from el nino to la nina the relationship between indian ocean sea surface temperature and the transition of el nino events into either la nina or el nino southern oscillation neutral conditions is examined in both observations and the retrospective ensemble hindcasts of the national center for environmental prediction climate forecast system the southern indian ocean is shown to demonstrate a particularly robust and consistent relationship with the evolution of these transitions these associations are described and a physical mechanism involving air sea interaction in the indian and western pacific oceans is proposed observations suggest that easterly surface wind anomalies in the western pacific ocean are associated with the emergence of la nina during boreal summer and fall here it is shown that these winds are significantly correlated to southern indian ocean sea surface temperature in the preceding spring that is characterized by a large scale zonal dipole of cool and warm anomalies in the southwestern and southeastern indian oceans respectively these associations are particularly pronounced for strong el nino conditions during the dissipation of which a pronounced wavetrain like atmospheric pattern accompanies sea surface temperature anomalies in the southern indian ocean together the circulation and sea surface temperature anomalies increase the meridional cross equatorial temperature gradient in the western indian ocean and mute intraseasonal variability while strengthening surface equatorial easterly winds in the indo pacific warm pool collectively these anomalies favor subsequent la nina development on the basis of these observed associations a predictive model that demonstrates skill in anticipating the nature of el nino transitions involving the southern indian ocean asian monsoon and el nino southern oscillation is proposed in the national center for environmental prediction climate forecast system the relationships described above are simulated both consistently and realistically despite model weaknesses further bolstering a key role of southern indian ocean and predictive relationship comparison of fully coupled and sea surface temperature forced simulations suggests a key role for air sea interaction in the observed associations moreover it is demonstrated that coupled simulations of el nino southern oscillation may benefit substantially from improved representation of indian ocean variability and indo pacific interaction

linear trends in sea surface temperature of the tropical pacific ocean and implications for the el nino southern oscillation a principal component decomposition of monthly sea surface temperature sst variability in the tropical pacific ocean demonstrates that nearly all of the linear trends during 1950 2010 are found in two leading patterns the first sst pattern is strongly related to the canonical el nino southern oscillation enso pattern the second pattern shares characteristics with the first pattern and its existence solely depends on the presence of linear trends across the tropical pacific ocean the decomposition also uncovers a third pattern often referred to as enso modoki but the linear trend is small and dataset dependent over the full 61 year record and is insignificant within each season enso modoki is also reflected in the equatorial zonal sst gradient between the nino 4 region located in the west central pacific and the nino 3 region in the eastern pacific it is only in this zonal sst gradient that a marginally significant trend arises early in the northern hemisphere spring march may during el nino and la nina and also in the late summer july september during el nino yet these sst trends in the zonal gradient do not unequivocally represent an enso modoki like dipole because they are exclusively associated with significant positive sst trends in either the eastern or western pacific with no corresponding significant negative trends insignificant trends in the zonal sst gradient are evident during the boreal wintertime months when enso events typically mature given the presence of positive sst trends across much of the equatorial pacific ocean using fixed sst anomaly thresholds to define enso events likely needs to be reconsidered

contrasting the flavors of el nino southern oscillation using sea surface salinity observations 1 the recent detection of a central pacific type of el nino has added a new dimension to the el nino southern oscillation climatic puzzle sea surface salinity sss observations collected during 1977 2008 in the tropical pacific are used to contrast the three eastern pacific ep 1982 1983 1991 1992 1997 1998 and seven central pacific cp 1977 1978 1986 1988 1990 1991 1992 1995 2002 2003 2004 2005 2006 2007 types of el nino events as well as the six ep 1985 1986 1988 1989 1995 1996 1999 2001 2005 2006 2007 2008 and two cp 1983 1984 1998 1999 types of la nina events the ep el nino events result in large 30 longitude eastward displacements of the eastern edge of the low salinity warm pool waters in the equatorial band a resulting well marked sss freshening 1 near the dateline and a sss increase 1 below the mean position of the south pacific convergence zone spcz the cp el nino events are characterized by smaller 50 eastward displacements of the eastern edge a 15 longitude westward shift of the equatorial sss freshening and a comparatively reduced 50 sss increase in the spcz a qualitative analysis indicates that changes in zonal currents and precipitation can account for the observed contrasted signature in sss eastward current anomalies appear over most of the equatorial band during ep el nino events in contrast there is a tendency for zonal current convergence slightly west of the dateline during cp el nino events consistent with the confinement of the warm fresh pool in the western central equatorial basin the related quasi inexistent northeastward migration of the spcz and associated heavy precipitation regime

two types of el nino events cold tongue el nino and warm pool el nino abstract in this study two types of el nino events are classified based on spatial patterns of the sea surface temperature sst anomaly one is the cold tongue ct el nino which can be regarded as the conventional el nino and the other the warm pool wp el nino the ct el nino is characterized by relatively large sst anomalies in the nino 3 region 5 s 5 n 150 90 w while the wp el nino is associated with sst anomalies mostly confined to the nino 4 region 5 s 5 n 160 e 150 w in addition spatial patterns of many atmospheric and oceanic variables are also distinctively different for the two types of el nino events furthermore the difference in the transition mechanism between the two types of el nino is clearly identified that is the discharge process of the equatorial heat content associated with the wp el nino is not efficient owing to the spatial structure of sst anomaly as a result it cannot trigger a cold event it is also demonstrated that zonal advective feedback i e zonal adve

el nino phases embedded in asian and north american drought reconstructions abstract the amplitude of el nino southern oscillation enso varies substantially at each phase of its evolution affecting the timing and patterns of atmospheric teleconnections around the globe instrumental records are too short to capture the full behavior of enso variability here we use the well validated monsoon asia drought atlas mada and north america drought atlas nada for the past 700 years and show that tree ring records from different regions represent tropical sea surface temperature sst conditions at various phases of enso three modes of tree ring based summer drought variability are found to be correlated with enso summer droughts over the maritime continent and southwest north america na and a dipole mode between central and south asia a lagged correlation analysis is performed to determine the time when precipitation and temperature anomaly imprints on summer droughts as recorded in tree rings drought anomalies in the maritime continent and southwest na represent enso at the developing and peak phases respectively while those over central south asia are associated with tropical wide sst anomalies including the indian ocean at the decay phase of enso thus proxy records from different regions can provide valuable information on long term behavior of enso at different phases

combined impacts of pdo and two types of la nina on climate anomalies in europe abstractcombined impacts of the pacific decadal oscillation pdo and two types of la nina on climate anomalies in europe are studied particularly the conjunction of the negative pdo phase and two different types of la nina events favors strong and significant north atlantic oscillation nao pattern anomalies with opposite polarity for the central pacific cp la nina a clear positive nao signal can be detected which is accompanied by positive surface air temperature sat anomaly and a dipolar structure of precipitation anomalies in europe in addition a typical negative pacific north america pna teleconnection pattern forms including a high pressure anomaly over the southeastern united states which may contribute to the development and maintenance of the nao anomaly by strengthening the baroclinicity and the local eddy mean flow interaction however for the eastern pacific ep la nina a zonal wave train in the high latitudes can be observed which is quite different from the typical pna st

the response of enso flavors to mid holocene climate implications for proxy interpretation the response of el nino southern oscillation enso to mid holocene boundary conditions remains an open question paleoclimate proxies and climate model simulations do not agree in the magnitude of the reduction of enso variability while recent proxy evidence from fossil corals from the central pacific show that the reduction in mid holocene enso variability compared to the end of the twentieth century is not different from the reduction during other holocene time intervals this is inconsistent with the interpretation of lake and ocean sediment records from the eastern pacific which show a significant reduction compared to all other holocene periods in order to reconcile the seemingly conflicting proxy evidence from the eastern and central pacific we hypothesize that enso remained active during the mid holocene however there was a change in the spatial pattern of the sea surface temperature anomalies also known as enso flavors using national center for atmospheric research s community climate system model version 4 forced with mid holocene orbital conditions we find that the frequency of occurrence of the strongest eastern pacific ep events decreases in the mid holocene and their variance is reduced by 30 while the frequency of central pacific cp events slightly increases and their variance does not change we also find a shift in the seasonality of ep events but not in that of cp events lastly mid holocene ep events develop more slowly and decay faster the differential response of enso flavors to mid holocene forcing is remotely forced by the west pacific where a weakening of the trade winds in early boreal spring in the mid holocene initiates an anomalous downwelling annual kelvin wave which reaches the eastern pacific during the enso development season weakens the upper ocean stratification and results in reduced enso upwelling feedback the simulated reduction in the ep flavor versus the cp flavor in the mid holocene is consistent with proxy evidence the teleconnection patterns of the two flavors with temperature precipitation and salinity are distinct and proxies from different regions of the pacific might be recording variability associated with only one of the flavors or some combination of their relative effects

evidence for sulfidic deep water during the late permian in the east greenland basin a detailed study of the size distribution of framboidal pyrites in the black shales of the upper permian ravnefjeld formation was performed to evaluate the redox state of the late permian ocean in contrast to framboidal pyrites in bioturbated sediments the smaller and less variable size distribution of pyrite framboids in the laminated shales of the ravnefjeld formation provides persuasive evidence for sulfidic h 2 s rich bottom water conditions in the east greenland basin however the s isotope compositions of both pyrite populations show a similar distribution the widespread 3 4 s values of pyrites 41 2 to 28 2 in the black shales of the ravnefjeld formation indicate a large fractionation up to 52 7 relative to seawater sulfate and may record different pathways of sulfur cycling in sulfidic water columns as well as within sediments the new data from the east greenland basin indicate that environmental stress such as widespread sulfidic conditions could have caused the biotic crisis in the late permian

the two types of el nino and their impacts on the length of day at the interannual to decadal timescale the changes in the earth rotation rate are linked with the el nin o southern oscillation phenomena through changes in the atmospheric angular momentum as climatic studies demonstrate that there were two types of el nin o events namely eastern pacific ep and central pacific cp events we investigate how each of them affect the atmospheric angular momentum we show in particular that ep events are associated with stronger variations of the atmospheric angular momentum and length of day we explain this difference by the stronger pressure gradient over the major mountain ranges due to a stronger and more efficiently localized pressure dipole over the pacific ocean in the case of ep events

interdecadal change in the tropical pacific precipitation anomaly pattern around the late 1990s during boreal spring abstractthe leading mode of boreal spring precipitation variability over the tropical pacific experienced a pronounced interdecadal change around the late 1990s the pattern before 1998 features positive precipitation anomalies over the equatorial eastern pacific ep with positive principle component years the counterpart after 1998 exhibits a westward shift of the positive center to the equatorial central pacific cp observational evidence shows that this interdecadal change in the leading mode of precipitation variability is closely associated with a distinctive sea surface temperature sst anomaly pattern the westward shift of the anomalous precipitation center after 1998 is in tandem with a similar shift of maximum warming from the ep to cp diagnostic analyses based on a linear equation of the mixed layer temperature anomaly exhibit that an interdecadal enhancement of zonal advection za feedback process plays a vital role in the shift in the leading mode of both the tropical pacific sst and t

interdecadal variability of el nino onset and its impact on monsoon systems over areas encircling the pacific ocean based on previous study by xu and chan j clim 14 418 433 2001 two types of el nino distinguished by the onset time a spring sp type and a summer su type have been investigated from 1871 through 2011 as can be classified by the spatial patterns of sea surface temperature anomaly into the warm pool wp and cold tongue ct el nino the temporal features of the ct are dominated by the sp events whereas the su events mostly display the spatial pattern of wp or mixed events the approximate 140 year data analysis shows that the frequency of sp events tends to increase in the most recent 30 years 1980 2009 while the su events show very strong activity in the beginning of the twentieth century 1900 1929 which are closely associated with the decadal changes in oceanic and atmospheric background conditions the air sea processes indicate that the pattern of sea surface temperature sst gradient between tropical and extratropical pacific ocean on decadal time scales is related to the sea level pressure distribution which tends to produce wind anomalies the wind anomalies in turn affect the sst anomalies on inter annual time scales over the equatorial areas and finally result in the early onset of el nino in sp time or late onset of el nino in su time a spring onset el nino favors a kelvin wave that propagates across the basin and a summer onset favors a kelvin wave that does not traverse the basin or the related effects are not strong enough the early or late onset of el nino significantly impacts the precipitation distribution correlated with the monsoon systems including the asian australian monsoon and north south american monsoon the el nino monsoon relationship is modulated by decadal changes in atmospheric and oceanic background conditions the precipitation in the monsoonal area circling the pacific ocean exhibits characteristic quasi biennial variations that are closely associated with the onset time of el nino events especially with the early onset of el nino for the spring sp type drought is observed over the central china australia southwestern north america and northern south america in boreal summer but the opposite pattern appears in the subsequent summer of the following year

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

three evolution patterns of central pacific el nino 1 three evolution patterns are identified for the central pacific cp type of el nino based on events that occurred during 1958 2007 1 a symmetric decaying pattern whose sea surface temperature anomalies grow and decay symmetrically with respect to a peak phase 2 a prolonged decaying pattern that decays slowly and is followed by a warm event in the eastern pacific ep and 3 an abrupt decaying pattern that terminates rapidly after the peak and is followed by a cold event in the ep the depth of the equatorial thermocline is found to determine which evolution pattern occurs if the cp el nino occurs in a recharged thermocline state i e deeper than normal depth an ep warming may appear in the decaying phase of the cp event to slow down the decay giving rise to the prolonged decaying pattern if the thermocline is in a discharged state i e shallower than normal depth an ep cooling may occur to abruptly terminate the cp el nino if the thermocline is in a neutral state i e normal depth the cp event may have a symmetric pattern of growth and decay although a few exceptions exist these results indicate that the equatorial thermocline state at the peak phase of a cp el nino event can be a potential predictor of the way the event may decay

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

an abrupt extinction in the middle permian capitanian of the boreal realm spitsbergen and its link to anoxia and acidification the controversial capitanian middle permian 262 ma extinction event is only known from equatorial latitudes and consequently its global extent is poorly resolved we demonstrate that there were two severe extinctions amongst brachiopods in northern boreal latitudes spitsbergen in the middle to late permian separated by a recovery phase new age dating of the spitsbergen strata belonging to the kapp starostin formation using strontium isotopes and d 13 c trends and comparison with better dated sections in greenland suggests that the first crisis occurred in the capitanian this age assignment indicates that this middle permian extinction is manifested at higher latitudes redox proxies pyrite framboids and trace metals show that the boreal crisis coincided with an intensification of oxygen depletion implicating anoxia in the extinction scenario the widespread and near total loss of carbonates across the boreal realm also suggests a role for acidification in the crisis the recovery interval saw the appearance of new brachiopod and bivalve taxa alongside survivors and an increased mollusk dominance resulting in an assemblage reminiscent of younger mesozoic assemblages the subsequent end permian mass extinction terminated this late permian radiation

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

volcanism mass extinction and carbon isotope fluctuations in the middle permian of china the 260 million year old emeishan volcanic province of southwest china overlies and is interbedded with middle permian carbonates that contain a record of the guadalupian mass extinction sections in the region thus provide an opportunity to directly monitor the relative timing of extinction and volcanism within the same locations these show that the onset of volcanism was marked by both large phreatomagmatic eruptions and extinctions amongst fusulinacean foraminifers and calcareous algae the temporal coincidence of these two phenomena supports the idea of a cause and effect relationship the crisis predates the onset of a major negative carbon isotope excursion that points to subsequent severe disturbance of the ocean atmosphere carbon cycle

the extreme el nino of 2015 2016 the role of westerly and easterly wind bursts and preconditioning by the failed 2014 event at the beginning of 2015 as one year earlier in 2014 the scientific community anticipated that el nino conditions could develop in the tropical pacific by year end such projections were related to the occurrence of westerly wind bursts during winter spring of each year that generated strong downwelling kelvin waves indicative of an emerging el nino however the event s progression quickly stalled in 2014 but actively continued in 2015 leading to an extreme warm event comparable to 1997 or 1982 here we compare climate evolution during these two years using satellite observations and numerical simulations we show that during 2014 el nino development was interrupted mid year by an exceptionally strong easterly wind burst whereas during the second year it continued through the summer further we show that the failed 2014 event created favorable conditions for el nino development during the next year as it kept ocean heat content recharged and the western pacific warm pool extended eastward subsequently the winter spring westerly wind bursts in 2015 were followed by a series of state dependent westerly bursts as part of a strong positive bjerknes feedback analogue simulations with a coupled gcm wherein we superimpose the observed sequences of westerly and easterly wind bursts support these conclusions stressing the role of the failed 2014 event in preconditioning the ocean atmosphere system for the development of an extreme el nino in our simulations the probability of an extreme event following early year westerly wind bursts increases from 14 to nearly 60 due to this preconditioning thus the interplay between westerly and easterly wind bursts shapes el nino development and diversity

a depositional and sequence stratigraphic model for cold water spiculitic strata based on the kapp starostin formation permian of spitsbergen and equivalent deposits from the barents sea this article summarizes the lithostratigraphy of two sections through the kapp starostin formation on spitsbergen having contrasting distal and proximal depositional settings these outcrop sections are compared with an approximately age equivalent spiculitic unit penetrated in two exploration wells 800 km to the southeast on the finnmark platform eight main facies associations comprise these strata including limestones matrix rich matrix poor and mudstone siliciclastics shale and sandstone spiculite dark tight and light colored porous and phosphatized surfaces a sequence stratigraphic model is proposed wherein siliciclastic limestone intervals represent lowstands of relative sea level and the spiculites are mainly highstand deposits based on this model seven depositional cycles sequences are recognized in the distal high accommodation locality on spitsbergen akseloya four in the proximal locality dickson land and two on the finnmark platform a speculative model for correlation between these localities is presented wherein lateral amalgamation of sequences due to landward pinch out of some lowstand intervals results in recognition of fewer sequences in areas of lower accommodation on both dickson land and the finnmark platform an upward change in spiculite lithology from dark tight to light porous is shown and dickson land also shows an upward change in siliciclastic lithology from shale to glauconitic sandstone these changes record a long term shoaling trend approaching the permian triassic boundary this model provides a basis for interpreting the basin scale begin page 2062 distribution of lithofacies and predicting the occurrence of porous zones representing potential hydrocarbon reservoirs

el nino variability in simple ocean data assimilation soda 1871 2008 1 a new ocean reanalysis that covers the period from 1871 to 2008 is used to explore the time evolving characteristics of el nino the new reanalysis assimilates all available hydrographic and sea surface temperature data into a model of the global ocean forced with surface boundary conditions from an atmospheric reanalysis that also covers the period from 1871 through 2008 using traditional measures of el nino our reanalysis shows that the timing of el nino events is in agreement with sea surface temperature reconstructions but el nino in the reanalysis is stronger particularly from 1871 to 1920 a new index based on the first moment of the temperature anomaly is introduced the new index is used to characterize the strength and location of el nino events and has the advantage that it is independent of the location of el nino using the new index el nino in the reanalysis shows prominent decadal variability of strength but relatively little long term trend el nino events were strong in the last part of the 19th century and first part of the 20th century and again in the latter part of the 20th century with weak el nino events in the middle of the 20th century the location of el nino also varies considerably ranging from the western to the eastern pacific near the coast of south america however the null hypothesis that the location of el nino can be represented as a random distribution about a central longitude of about 140 w cannot be rejected

permo triassic boundary superanoxia and stratified superocean records from lost deep sea pelagic cherts of japan and british columbia canada recorded a long term and worldwide deep sea anoxic oxygen depleted event across the permo triassic or paleozoic and mesozoic boundary 251 2 million years ago the symmetry in lithostratigraphy and redox condition of the boundary sections suggest that the superocean panthalassa became totally stratified for nearly 20 million years across the boundary the timing of onset climax and termination of the oceanic stratification correspond to global biotic events including the end guadalupian decline the end permian extinction and mid triassic recovery

different pacific ocean warming decaying types and northwest pacific tropical cyclone activity abstractthis study focuses on statistical analysis of anomalous tropical cyclone tc activities and the physical mechanisms behind these anomalies different patterns of decaying of the warm sea surface temperature anomaly ssta over the equatorial central eastern pacific are categorized into three types eastern pacific warming decaying to la nina epwdl eastern pacific warming decaying to a neutral phase epwdn and a central pacific warming decaying year cpwd differences in tc activity over the western north pacific wnp corresponding to the above three types are discussed and possible mechanisms are proposed for epwdl tc genesis shows a significant positive negative anomaly over the northwestern southeastern wnp and more tcs move westward and make landfall over the southern east asian coast this is attributed primarily to the combined modulation of la nina and the warm equatorial east indian ocean ssta for epwdn enhanced tc genesis is observed over the northeastern wnp and suppress

different evolutions of the philippine sea anticyclone between the eastern and central pacific el nino possible effects of indian ocean sst abstractthe authors examine different evolution features of the low level anticyclone over the tropical northwestern pacific between eastern pacific ep el nino events and central pacific cp el nino events during ep el nino the low level anticyclone shows an eastward movement from the northern indian ocean to the east of the philippines during cp el nino however the anticyclone is mostly confined to the west of the philippines it is weaker exhibits a shorter lifetime and lacks eastward movement compared to the philippine sea anticyclone psac during ep el nino investigation into the possible impact of indian ocean io sea surface temperature sst on the evolution of the low level anticyclone during ep and cp el nino indicates that both sst and low level atmospheric circulation over the io are related more strongly with ep el nino than with cp el nino the io sst tends to exert a more prominent influence on psac during ep el nino than during cp el nino during the developing summer and autum

the capitanian permian minimum of 87sr 86sr ratio in the mid panthalassan paleo atoll carbonates and its demise by the deglaciation and continental doming abstract the capitanian minimum in the permian represents one of the most significant features in the phanerozoic seawater 87 sr 86 sr history in order to establish the detailed sr chemostratigraphy around the guadalupian minimum 87 sr 86 sr ratios were measured for the capitanian upper middle permian paleo atoll limestones at akasaka in japan the limestone was primarily deposited on a paleo seamount in the low latitude mid panthalassa and was secondarily accreted to japan south china block margin in the jurassic as being free from local continental influences the akasaka limestone recorded well mixed seawater isotope composition of the permian low latitude mid superocean we detected extremely low 87 sr 86 sr ratios ca 0 7068 0 7069 in the 70 m thick capitanian interval immediately below the guadalupian lopingian middle late permian boundary g lb of the akasaka limestone this sr isotopic profile at akasaka suggests that the global seawater was least affected by radiogenic continental flux throughout the capitanian as these values correspond to the lowest in the paleozoic this interval with low 87 sr 86 sr ratios lasted for at least some milllion years represents the capitanian minimum which marks the significant turning point from the late paleozoic decrease to early mesozoic increase in seawater 87 sr 86 sr ratio the geological lines of evidence indicate that the capitanian minimum was caused likely by the mid permian cooling that may have driven extensive ice cover over continental crusts to suppress continental flux enriched in radiogenic sr into the superocean the rapid increase in 87 sr 86 sr values after the minimum can be explained either by the deglaciation or by the pangean rifting

strontium isotope profile of the early toarcian jurassic oceanic anoxic event the duration of ammonite biozones and belemnite palaeotemperatures we profile 87sr 86sr 13c 18o sr ca mg ca and na ca in belemnites through pliensbachian and toarcian strata on the yorkshire coast uk which include the early jurassic oceanic anoxic event the 87sr 86sr profile shows that the relative duration of ammonite subzones differ by a factor of up to 30 the lower jurassic exaratum subzone is 30 times longer than the clevelandicum subzone because the exaratum subzone in yorkshire which contains the anoxic event is condensed by a factor of between 6 5 and 12 2 times relative to adjacent strata using our 87sr 86sr profile the resolution in correlation and dating attainable in the interval is between 1 5 m and 15 m of section and better than 0 25 myr in parts of the sequence this stratigraphic resolution equals that attainable with ammonites a new age model is provided for late pliensbachian and early toarcian time that is based on the 87sr 86sr profile through the sequence the sr ca mg ca na ca and 18o of belemnite carbonate covary suggesting that elemental ratios may be useful for palaeotemperature measurement our 13cbelemnite data splits into three the previously reported positive isotope excursion to 6 5 in the early toarcian we speculate that the excursion s resulted from addition to surface waters of isotopically heavy co2 via ebullition of methanogenic co2 from the sediment during early burial of organic rich 10 toc sediments