seasonal stratification shell flux and oxygen isotope dynamics of left coiling n pachyderma and t quinqueloba in the western subpolar north atlantic blooms this annual population overturning is marked by a 0 7 increase in d 18 o in both species the shell flux of n pachyderma peaks during the spring bloom and in late summer when stratification is close to its minimum and maximum respectively both export periods contribute about equally and account for 95 of the total annual flux shell fluxes of t quinqueloba show only a single broad pulse in summer thus following the seasonal stratification cycle the d 18 oo fn pachyderma reflects temperatures just below the base of the seasonal sml without offset from isotopic equilibrium the d 18 op attern oft quinqueloba shows a nearly identical amplitude and correlates highly with the d 18 oo fn pachyderma therefore t quinqueloba also reflects temperature near the base of the sml but with a positive offset from isotopic equilibrium these offsets contrast with observations elsewhere and suggest a variable offset from equilibrium calcification for both species in the irminger sea the species consistently show a contrast in their flux timings their flux weighted dd 18 o will thus dominantly be determined by seasonal temperature differences at the base of the sml rather than by differences in their depth habitat consequently their sedimentary dd 18 o may be used to infer the seasonal contrast in temperature at the base of the sml citation jonkers l g j a brummer f j c peeters h m van aken and m f de jong 2010 seasonal stratification shell flux and oxygen isotope dynamics of left coiling n pachyderma and t quinqueloba in the western subpolar north atlantic paleoceanography 25 pa2204 doi 10 1029 2009pa001849

benthonic foraminiferal distributions and quantitative transfer functions for the northwest european continental margin abstract a database of benthonic foraminiferal data from 298 sediment surface samples from the northwest european ireland to svalbard and iceland margin has been compiled samples deeper than 500 m on the continental slope and shallower than 30 m in coastal areas are not included bottom water temperatures at the sites range between 1 and 12 5 c and salinity between 33 5 and 35 5 detrended correspondence analyses of percentage values of 65 benthonic foraminifera taxa from 260 of the samples show a strong statistically significant relationship between modern foraminiferal assemblages and summer temperature and salinity utilising weighted averaging partial least square regression transfer functions for summer bottom water temperature ts and salinity ss have been developed the transfer functions have relatively low root mean square errors of prediction expressed as a percentage of the range of the modern environmental gradient sampled for ts 3 9 and for ss 9 02 compared to transfer functions developed for other proxies which commonly range from 8 to 20 the distributions of benthonic foraminifera species are dependent on other factors than salinity and temperature such as nutrients substrate turbidity current regime different biological factors different depth related factors etc the present analyses demonstrate that for this group as for most other groups there is an overall but not necessarily direct relationship with distribution and abundance and temperature and salinity conditions the transfer functions have been tested on a late glacial holocene data set and an eemian early weichselian data set from the eastern north sea region these experiments suggest that transfer functions on benthonic foraminifera can be a useful new tool in palaeoceanographic and palaeoenvironmental work along the european north atlantic seaboard

seismic instrumentation of landslides building a better model of dynamic landslide behavior although the geologic topographic and threshold shaking con ditions required to trigger landslides in earthquakes are probabilistically pre dictable models used to estimate the behavior of slopes under dynamic shaking conditions are overly simplistic because of the lack of direct measurement of landslide behavior during seismic shaking two permanent instrument arrays have been installed on seismically active landslides to simultaneously record acceleration pore pressure and permanent landslide displacement which will permit more accurate modeling of seismic landslide response

environmental impact of mud volcano inputs on the anthropogenically altered porong river and madura strait coastal waters java indonesia abstract increasing human modifications of the coastal zone are endangering the integrity of coastal ecosystems this is of particular importance in se asia where large parts of the population live in the coastal zone and are economically dependent on its resources the region is also affected by a high frequency of extreme natural events like storms earthquakes and volcanic eruptions the eruption of a mud volcano nicknamed lusi near the city of sidoarjo in eastern java indonesia on may 29 2006 represents such an event one of the measures to minimize the potential detrimental effects to the environment and the local population was to channelise part of the mud into the nearby porong river the major distributary of the brantas river which is affected by intensive land use and hydrological alterations in a densely populated catchment here we report for the first time on the effects of the mud volcano on the aquatic environment the lusi input more than doubled the suspended matter and particulate organic carbon load of the river moreover we found decomposition of the additional organic matter worsening oxygen depletion in the river and adjacent coastal waters that can severely affect the well being of aquatic organisms we conclude that the mud volcano input adds to the adverse effects of human activities in the river catchment on the ecology and biogeochemistry of the estuary and madura strait coastal waters

the role of shear and tensile failure in dynamically triggered landslides summary dynamic stresses generated by earthquakes can trigger landslides current methods of landslide analysis such as pseudo static analysis and newmark s method focus on the effects of earthquake accelerations on the landslide mass to characterize dynamic landslide behaviour one limitation of these methods is their use mohr coulomb failure criteria which only accounts for shear failure but the role of tensile failure is not accounted for we develop a limit equilibrium model to investigate the dynamic stresses generated by a given ground motion due to a plane wave and use this model to assess the role of shear and tensile failure in the initiation of slope instability we do so by incorporating a modified griffith failure envelope which combines shear and tensile failure into a single criterion tests of dynamic stresses in both homogeneous and layered slopes demonstrate that two modes of failure exist tensile failure in the uppermost meters of a slope and shear failure at greater depth further we derive equations that express the dynamic stress in the near surface in the acceleration measured at the surface these equations are used to approximately define the depth range for each mechanism of failure the depths at which these failure mechanisms occur suggest that shear and tensile failure might collaborate in generating slope failure

improving past sea surface temperature estimates based on planktonic fossil faunas a new method of past sea surface temperature sst reconstruction based on the modern analog technique prell 1985 and on the indirect approach bartlein et al 1986 has been developed the revised analog method ram applied to planktonic foraminifera this technique leads to significant improvements in modern sst reconstruction with respect to former methods our estimates are characterized by much lower residuals and a better coverage of the observed sst range moreover the error of ram estimates of past ssts is lower than that associated with former reconstructions particularly at middle and high latitudes in low latitudes cold season ssts reconstructed by ram during glacials are 1 3 c lower than previously estimated our results tend thus to reconcile paleoestimates of glacial temperatures based on planktonic microfossils and on continental data in the tropics

reconstruction of sea surface conditions at middle to high latitudes of the northern hemisphere during the last glacial maximum lgm based on dinoflagellate cyst assemblages abstract a new calibration database of census counts of organic walled dinoflagellate cyst dinocyst assemblages has been developed from the analyses of surface sediment samples collected at middle to high latitudes of the northern hemisphere after standardisation of taxonomy and laboratory procedures the database comprises 940 reference data points from the north atlantic arctic and north pacific oceans and their adjacent seas including the mediterranean sea as well as epicontinental environments such as the estuary and gulf of st lawrence the bering sea and the hudson bay the relative abundance of taxa was analysed to describe the distribution of assemblages the best analogue technique was used for the reconstruction of last glacial maximum lgm sea surface temperature and salinity during summer and winter in addition to sea ice cover extent at sites from the north atlantic n 63 mediterranean sea n 1 and eastern north pacific n 1 three of the north atlantic cores from the continental margin of eastern canada revealed a barren lgm interval probably because of quasi permanent sea ice six other cores from the greenland and norwegian seas were excluded from the compilation because of too sparse assemblages and poor analogue situation at the remaining sites n 54 relatively close modern analogues were found for most lgm samples which allowed reconstructions the new lgm results are consistent with previous reconstructions based on dinocyst data which show much cooler conditions than at present along the continental margins of canada and europe but sharp gradients of increasing temperature offshore the results also suggest low salinity and larger than present contrasts in seasonal temperatures with colder winters and more extensive sea ice cover whereas relatively warm conditions may have prevailed offshore in summer from these data we hypothesise low thermal inertia in a shallow and low density surface water layer

simmax a modern analog technique to deduce atlantic sea surface temperatures from planktonic foraminifera in deep sea sediments we present a data set of 738 planktonic foraminiferal species counts from sediment surface samples of the eastern north atlantic and the south atlantic between 87 n and 40 s 35 e and 60 w including published climate long range investigation mapping and prediction climap data these species counts are linked to levitus s 1982 modern water temperature data for the four caloric seasons four depth ranges 0 30 50 and 75 m and the combined means of those depth ranges the relation between planktonic foraminiferal assemblages and sea surface temperature sst data is estimated using the newly developed simmax technique which is an acronym for a modern analog technique mat with a similarity index based on 1 the scalar product of the normalized faunal percentages and 2 a weighting procedure of the modern analog s ssts according to the inverse geographical distances of the most similar samples compared to the classical climap transfer technique and conventional mat techniques simmax provides a more confident reconstruction of paleo ssts correlation coefficient is 0 994 for the caloric winter and 0 993 for caloric summer the standard deviation of the residuals is 0 90 c for caloric winter and 0 96 c for caloric summer at 0 m water depth the sst estimates reach optimum stability standard deviation of the residuals is 0 88 c at the average 0 to 75 m water depth our extensive database provides sst estimates over a range of 1 4 to 27 2 c for caloric winter and 0 4 to 28 6 c for caloric summer allowing sst estimates which are especially valuable for the high latitude atlantic during glacial times an electronic supplement of this material may be obtained on adiskette or anonymous ftp from kosmos agu org login toagu s ftp account using anonymous as the username and guestas the password go to the right directory by typing cd append typels to see what files are available type get and the name of the file toget it finally type exit to leave the system paper 95pa01743 simmax a modern analog technique to deduce atlantic sea surfacetemperatures from planktonic foraminifera in deep sea sediments uwepflaumann josette duprat claude pujol and laurent d labeyrie diskette may be ordered from american geophysical union 2000florida avenue n w washington dc 20009 payment mustaccompany order

short term changes in seafloor character due to flood derived hyperpycnal discharge typhoon mindulle taiwan july 2004 during typhoon mindulle in early july 2004 the choshui river central western taiwan discharged similar to 72 mt of sediment to the eastern taiwan strait peak concentrations were g 200 g l similar to 35 40 of which was sand box core samples and chirp compressed high intensity radar pulse sonar records taken just before and after the typhoon indicate that the hyper pycnal sediment was first deposited adjacent to the mouth of the choshui subsequently resuspended and transported northward via the taiwan warm current and redeposited as a patchy coastal band of mud dominated sediment that reached thicknesses of 1 2 m within megaripples within a month most of the mud was gone probably continuing its northward transit but more mud appeared in late august in response to typhoon aere following autumn and winter storms the entire nearshore area was again sand dominated by early spring

lateglacial and early holocene climatic oscillations on the western svalbard margin european arctic abstract a multi proxy sediment core record on the continental margin off western svalbard european arctic reflects large climatic and oceanographic oscillations at the lateglacial early holocene transition based on studies of planktonic foraminifera their stable oxygen and carbon isotopic composition and ice rafted debris we have reconstructed the last 14 cal ka bp the period 14 13 5 cal ka bp was characterized by highly unstable climatic conditions short lived episodes of warming alternated with meltwater pulses and enhanced iceberg rafting this period correlates to a regional warming of the northern north atlantic an overall decrease in meltwater took place during the deglaciation 14 10 8 cal ka bp the late younger dryas and subsequent transition into the early holocene is characterized by a reduced flux of planktonic foraminifera and increased iceberg rafting a major warming took place from 10 8 to 9 7 cal ka bp the influence of meltwater ceased and the flux of warm atlantic water increased from 9 7 to 8 8 cal ka bp the western svalbard margin surface waters were significantly warmer than today this warm period the thermal maximum was followed by an abrupt cooling at 8 8 cal ka bp caused by an increased influence of arctic water from the arctic ocean the results document that the european arctic was very sensitive to climatic and oceanographic changes at the end of the last glacial and during the holocene

analysis of the seismic origin of landslides examples from the new madrid seismic zone by analyzing two landslides in the new madrid seismic zone we develop an approach for judging if a landslide or group of landslides of unknown origin was more likely to have formed as a result of earthquake shaking or in aseismic conditions the two landslides analyzed are representative of two groups of land slides that previous research on the geomorphology and regional distribution of landslides in this region indicates may have been triggered by the 1811 1812 new madrid earthquakes slope stability models of aseismic conditions show that neither landslide is likely to have formed aseismically even in unrealistically high ground water conditions dynamic stability analysis using newmark s method shows that both slides probably would have experienced large inertial displacements during earthquake shaking similar to that which occurred in 1811 1812 these displacements are large enough that catastrophic failure is highly probable thus the stability analyses are consistent with other lines of evidence that these landslides formed as a result of strong earthquake shaking during the 1811 1812 earthquakes our analysis yields a general relationship between newmark landslide displacement earthquake shaking intensity and the critical acceleration of a landslide using this relationship we estimate the minimum shaking intensities required to trigger the types of landslides studied an mb 5 8 or m 5 9 earthquake is the lower bound threshold at zero epicentral distance that could trigger catastrophic movement of typical block slides in the new madrid seismic zone for earth flows mb 5 4 or m 5 3 is the threshold earthquake

holocene paleoceanography and glacial history of the west spitsbergen area euro arctic margin two sediment cores from the west spitsbergen area euro arctic margin md99 2304 and md99 2305 have been investigated for paleoceanographic proxies including benthic and planktonic foraminifera benthic foraminiferal stable isotopes and ice rafted debris core md99 2304 is located on the upper continental margin reflecting variations in the influx of atlantic water in the west spitsbergen current core md99 2305 is located in van mijenfjord picturing variations in tidewater glacier activity as well as fjordocean circulation changes surface water warmer than today was present on the margin as soon as the van mijenfjord was deglaciated by 11 200 cal years bp relatively warm water invaded the fjord bottom almost immediately after the deglaciation a relatively warm early holocene was followedby an abrupt cooling at 8800 cal years bp on the continental margin another cooling in the fjord record 8000 4000 cal years bp is documented by an increase in ice rafted debris and an increase in benthic foraminiferal d 18 o the ird record indicates that central spitsbergen never was completely deglaciated during the holocene relatively cool andstable cond itions similar to the present were establishedabout 4000 cal years bp

geomorphic tectonic control of sediment discharge to the ocean the importance of small mountainous rivers analysis of data from 280 rivers discharging to the ocean indicates that sediment loads yields are a log linear function of basin area and maximum elevation of the river basin other factors controlling sediment discharge e g climate runoff appear to have secondary importance a notable exception is the influence of human activity climate and geology on the rivers draining southern asia and oceania sediment fluxes from small mountainous rivers many of which discharge directly onto active margins e g western south and north america and most high standing oceanic islands have been greatly underestimated in previous global sediment budgets perhaps by as much as a factor of three in contrast sediment fluxes to the ocean from large rivers nearly all of which discharge onto passive margins or marginal seas have been overestimated as some of the sediment load is subaerially sequestered in subsiding deltas before the proliferation of dam construction in the latter half of this century rivers

coseismic and postseismic motion of a landslide observations modeling and analogy with tectonic faults we document the first time series of a landslide reactivation by an earthquake using continuous gps measurements over the maca landslide peru our survey shows a coseismic response of the landslide of about 2 cm followed by a relaxation period of 5 weeks during which postseismic slip is 3 times greater than the coseismic displacement itself our results confirm the coseismic activation of landslides and provide the first observation of a postseismic displacement these observations are consistent with a mechanical model where slip on the landslide basal interface is governed by rate and state friction analogous to the mechanics of creeping tectonic faults opening new perspectives to study the mechanics of landslides and active faults

the gin sea a synthesis of its physical oceanography and literature review 1972 1985 abstract a synthesis and review of the physical oceanography of the gin sea greenland iceland and norwegian seas is presented an accompanying bibliography is included from 1972 through 1985 some 1986 works are also noted emphasis is placed on describing the gin sea as a major semi enclosed basin that plays a role unique among the world s oceans by providing a strong two way advective exchange between the ice covered polar sea and the north atlantic ocean and at the same time acting as the primary site for northern hemisphere bottom water formation the water masses for the gin sea are defined in a manner as consistent as possible with the literature the large scale oceanographic and meteorological factors influencing the water mass formation and circulation are described a sample calculation of the various horizontal and vertical thermohaline driven exchanges is given

glacial north atlantic sea surface conditions reconstructed by glamap 2000 the response of the tropical ocean to global climate change and the extent of sea ice in the glacial nordic seas belong to the great controversies in paleoclimatology our new reconstruction of peak glacial sea surface temperatures ssts in the atlantic is based on census counts of planktic foraminifera using the maximum similarity technique version 28 simmax 28 modern analog technique with 947 modern analog samples and 119 well dated sediment cores our study compares two slightly different scenarios of the last glacial maximum lgm the environmental processes of the ice age land oceans glaciers epilog and glacial atlantic ocean mapping glamap 2000 time slices the comparison shows that the maximum lgm cooling in the southern hemisphere slightly preceeded that in the north in both time slices sea ice was restricted to the north western margin of the nordic seas during glacial northern summer while the central and eastern parts were ice free during northern glacial winter sea ice advanced to the south of iceland and faeroe in the central northern north atlantic an anticyclonic gyre formed between 45degrees and 60degreesn with a cool water mass centered west of ireland where glacial cooling reached a maximum of 12degreesc in the subtropical ocean gyres the new reconstruction supports the glacial to interglacial stability of sst as shown by climap project members climap 1981 the zonal belt of minimum sst seasonality between 2degrees and 6degreesn suggests that the lgm caloric equator occupied the same latitude as today in contrast to the climap reconstruction the glacial cooling of the tropical east atlantic upwelling belt reached up to 6degrees 8degreesc during northern hemisphere summer differences between these simmax based and published u37 k and mg ca based equatorial sst records are ascribed to strong sst seasonalities and sst signals that were produced by different planktic species groups during different seasons

distribution of planktic foraminifera at the ice margin in the arctic fram strait planktic foraminifera were collected in net tows 63 m along two east west transects at 78 and 80 n in the fram strait northern nordic seas at five concurrent depth intervals in the upper 200 m of the water column in the ice free zone absolute abundances in the upper 200 m of the water column up to 500 individuals m3 were obtained along the ice margin the absolute abundances reached up to 1250 ind m3 while in the ice covered areas not more than 50 ind m3 have been found surprisingly these strong variations in abundance are not accompanied by significant changes in faunal assemblages between the ice free and the ice covered regions neogloboquadrina pachyderma is the dominant species in most samples making up to 60 of the total faunal assemblage globigerina quinqueloba contributes 38 and all other species combined make up only 2 of the total fauna both absolute and relative abundances of the collected foraminifera are strongly dependent on the mesh size used using smaller mesh sizes provides a wider species spectrum which is of special interest for paleoceanographic reconstructions in the nordic seas where fossil assemblages 150 m often consist of only one species the specific hydrographic conditions in the fram strait with warm atlantic waters underlying cold polar surface waters result in a rather atypical depth distribution of the planktic foraminifera all species seem to prefer the temperate atlantic waters between 50 m and 200 m thus the species composition as well as geochemical tracers do not reflect the surface ocean conditions which again has potentially interesting implications for paleoceanographic reconstructions

comparison of statistical and artificial neural network techniques for estimating past sea surface temperatures from planktonic foraminifer census data we present the first detailed and rigorous comparison of six different computational techniques used to reconstruct sea surface temperatures sst from planktonic foraminifer census data these include the imbrie kipp transfer functions iktf the modern analog technique mat the modern analog technique with similarity index simmax the revised analog method ram and for the first time a set of back propagation artificial neural networks ann trained on a large faunal data set including a modification where geographical information was added among the input variables annd by training the techniques on an identical database we were able to explore the differences in sst reconstructions resulting solely from the use of different mathematical methods the comparison indicates that while the iktf technique consistently shows the worst performance ann and ram perform slightly better than mat and that the inclusion of the geographical information into the training database simmax and annd further improves the accuracy of modern sst estimates however when applied to an independent validation data set and an additional fossil data set the results did not conform to this ranking the largest differences in the reconstructed sst values occurred between groups of techniques with different approaches to sst reconstruction that is ann and annd produced sst reconstructions significantly different from those produced by ram simmax and mat the application of the various techniques to the validation data set which allowed comparison of sst reconstructions with instrumental records suggests that artificial neural networks might provide better paleo sst estimates than the other techniques

significance of variability in turborotalita quinqueloba natland test size and abundance for paleoceanographic interpretations in the norwegian greenland sea biometric analyses on shells of turborotalita quinqueloba natland reflect the paleoceanographic conditions in the norwegian greenland sea ngs both median and mean size variations exhibit a steady increase after the last glacial maximum lgm after termination i the size eventually reaches a constant level with only minor fluctuation in contrast peak abundances of specimens occur somewhat later during the holocene climatic optimum and rapidly decrease again in the youngest sediments test sizes are larger at the voring plateau in the vicinity of incoming atlantic water than in water further to the west turborotalita quinqueloba first appeared in the southwestern part of the ngs with a preliminary major peak in abundance and size well below the younger dryas this species was present in sizes 125 m in this area during almost entire oxygen isotopic stage 2 this was not observed in the more easterly located cores it seems likely that size variations as a tool for ngs paleoceanographic interpretations are not only valuable for the time since the lgm but can also be applied to older isotopic stages where abundances of t quinqueloba are low or absent in the 125 m size fractions but are high in the 63 125 m fraction e g stages 7 9 and 11

engineering geological mapping of earthquake induced landslides in south lefkada island greece evaluation of the type and characteristics of the slope failures a moderate shallow depth earthquake mw 6 5 occurred onshore lefkada island on november 17 2015 with the focal depth estimated at 11 km the seismic fault is a near vertical strike slip fault running along the western coast part of the cephalonia transform fault landslides and ground cracks were mainly reported at the western part of the island inducing structural damages high severity slope failures occurred at egremnoi and gialos areas that both are located at coastal regions this study aims to investigate the engineering geological conditions at these areas and assess the characteristics and physical quantities e g type area m2 and volume m3 of the instabilities to achieve this engineering geological mapping was implemented in egremnoi and gialos area aiming to a classify the geological units mapped on the heavily damaged areas and b to correlate them with the type of slope failures furthermore type and dimensions of slope failures were evaluated to estimate the total volume of the mass movement all the data originated from the engineering geological mapping have been digitized and rasterized at 5 m grid spacing using the arc info gis software to perform a newmark s sliding block analysis the outcome arisen by this analysis is that the generated by the earthquake peak ground acceleration at these areas should be at least 0 45 g to trigger these kinds of slope failures

variations in temperature and extent of atlantic water in the northern north atlantic during the holocene we compare six high resolution holocene sediment cores along a s n transect on the norwegian svalbard continental margin from ca 601n to 77 41n northern north atlantic planktonic foraminifera in the cores were investigated to show the changes in upper surface and subsurface water mass distribution and properties including summer sea surface temperatures sst the cores are located below the axis of the norwegian current and the west spitsbergen current which today transport warm atlantic water to the arctic sediment accumulation rates are generally high at all the core sites allowing for a temporal resolution of 10 10 2 years sst is reconstructed using different types of transfer functions resulting in very similar sst trends with deviations of no more than 71 0 1 51c a transfer function based on the maximum likelihood statistical approach is found to be most relevant the reconstruction documents an abrupt change in planktonic foraminiferal faunal composition and an associated warming at the younger dryas preboreal transition the earliest part of the holocene was characterized by large temperature variability including the preboreal oscillations and the 8 2 k event in general the early holocene was characterized by ssts similar to those of today in the south and warmer than today in the north and a smaller s n temperature gradient 0 231c 1n compared to the present temperature gradient 0 461c 1n the southern proxy records 60 691n were more strongly influenced by slightly cooler subsurface water probably due to the seasonality of the orbital forcing and increased stratification due to freshening the northern records 72 77 41n display a millennial scale change associated with reduced insolation and a gradual weakening of the north atlantic thermohaline circulation thc the observed northwards amplification of the early holocene warming is comparable to the pattern of recent global warming and future climate modelling which predicts greater warming at higher latitudes the overall trend during mid and late holocene was a cooling in the north stable or weak warming in the south and a maximum s n sst gradient of ca 0 71c 1n at 5000 cal years bp superimposed on this trend were several abrupt temperature shifts four of these shifts dated to 9000 8000 5500 3000 and 1000 and 400 cal years bp appear to be global as they correlate with periods of global climate change in general there is a good correlation between the northern north atlantic temperature records and climate records from norway and svalbard r 2007 elsevier ltd all rights reserved

variability of the mixed layer heat budget in the eastern equatorial atlantic during 2005 2007 as inferred using argo floats we examine the variability of the sea surface temperatures in the eastern equatorial atlantic during 2005 2007 by using argo profiling floats prediction and research moored array in the atlantic buoys and satellite in situ and atmospheric data sets the eastern equatorial atlantic characterized by shallow mixed layers all yearlong is divided into nine boxes of nearly equal surface area with respect to the dynamics and thermodynamics in this region monthly mixed layer heat budgets are computed in each box from 10 day argo profiles in all the boxes the net surface heat flux is one of the main causes of the seasonal evolution of sea surface temperatures for the 3 studied years the amount of short wave radiation penetrating through the base of the mixed layer and horizontal heat advection may locally contribute to the temperature variability while entrainment has a weaker contribution to balance the heat budget a residual term exists which includes all processes that cannot be calculated with observations as well as the possible errors in the other terms this residual is more intense in the cold tongue and the northern region and exhibits a clear seasonal cycle with minimum negative values in boreal summer and maximum values in winter this residual compares well with available observations of vertical turbulent mixing collected during etude de la circulation oceanique et des echanges ocean atmosphere dans le golfe de guinee campaigns 2005 2007 in the eastern equatorial atlantic when assuming that the residual is mostly associated with vertical turbulent mixing it can be conjectured that turbulent mixing is a significant cooling source in the cold tongue and north of the equator

reconstruction of sea surface temperatures from assemblages of planktonic foraminifera multi technique approach based on geographically constrained calibration data sets and its application to glacial atlantic and pacific oceans abstract we present a conceptual framework for a new approach to environmental calibration of planktonic foraminifer census counts this approach is based on simultaneous application of a variety of transfer function techniques which are trained on geographically constrained calibration data sets it serves to minimise bias associated with the presence of cryptic species of planktonic foraminifera and provides an objective tool for assessing reliability of environmental estimates in fossil samples allowing identification of adverse effects of no analog faunas and technique specific bias we have compiled new calibration data sets for the north n 862 and south n 321 atlantic and the pacific ocean n 1111 we show evidence that these data sets offer adequate coverage of the sea surface temperature sst and faunal variation range and that they are not affected by the presence of pre holocene samples and or calcite dissolution we have applied four transfer function techniques including artificial neural networks revised analog method and simmax with and without distance weighting on faunal counts in a last glacial maximum lgm data set for the atlantic ocean 748 samples in 167 cores based on the glamap 2000 compilation and a new data set for the pacific ocean 265 samples in 82 cores and show that three of these techniques provide adequate degree of independence for the advantage of a multi technique approach to be realised the application of our new approach to the glacial pacific lends support to the contraction and perhaps even a cooling of the western pacific warm pool and a substantial 3 c cooling of the eastern equatorial pacific and the eastern boundary currents our results do not provide conclusive evidence for lgm warming anywhere in the pacific the atlantic reconstruction shows a number of robust patterns including substantial cooling of eastern boundary currents with considerable advection of subpolar waters into the benguela current a cooling of the equatorial atlantic by 5 c and steep sst gradients in the mid latitude north atlantic the transfer function techniques generally agree that subtropical gyre areas in both hemispheres did not change significantly since the lgm although the ann technique produced glacial sst in the southern gyre 1 2 c warmer than today we have revisited the issue of sea ice occurrence in the nordic seas and using the distribution of subpolar species of planktonic foraminifera in glacial samples we conclude that the norwegian sea must have been ice free during the summer

assessing the performance of a foraminifera based transfer function to estimate sea level changes in northern portugal a b s t r a c t a r t i c l e i n f o article history received 14 april 2010 available online 15 december 2010 we assessed the performance of a transfer function model for sea level studies using salt marsh foraminifera from two estuaries of northern portugal an independent data set of 12 samples and 13 sub fossil samples from a core were used to evaluate if reconstructions and errors derived from current models are adequate initial transfer function models provided very strong results as indicated by cross validation component 2 r 2 0 80 0 82 rmsep ranged from 10 7 to 12 3 cm and improved its performance by ca 10 when sample size reached ca 50 results derived using an independent test data set indicate that cross validation is a very effective approach and produces conservative errors when compared to observed errors we additionally explored the possible effect of transforming the concentration data into percent in the error estimations by comparing the results obtained based on the use of both concentration and compositional data results indicate that this type of transformation does not affect the performance of the transfer function results derived from a reconstruction of sub fossil samples from a core indicate that high resolution sea level reconstructions are possible but show that depositional environments have to be selected carefully in order to minimize the impact of possible taphonomical loss

earthquake triggered increase in sediment delivery from an active mountain belt in tectonically active mountain belts earthquake triggered landslides deliver large amounts of sediment to rivers we quantify the geomorphic impact of the 1999 mw 7 6 chi chi earthquake in taiwan which triggered 20 000 landslides coseismic weakening of substrate material caused increased landsliding during subsequent typhoons most coseismic landslides remained confined to hillslopes downslope transport of sediment into the channel network occurred during later storms the sequential processes have led to a factor of four increase in unit sediment concentration in rivers draining the epicentral area and increased the magnitude and frequency of hyperpycnal sediment delivery to the ocean four years after the earthquake rates of hillslope mass wasting remain elevated in the epicentral area

reprint of arctic planktic foraminiferal assemblages implications for subsurface temperature reconstructions abstract earlier reconstructions of the inflow of atlantic water to arctic and subarctic oceans based on foraminiferal proxy data have been obstructed by uncertain quantitative reconstructions of sea surface and subsurface temperatures in this study surface sediment samples with undisturbed sediment water interface from polar north atlantic and barents sea were retrieved and prepared at the size fractions from 100 m to 1000 m the foraminiferal analyses show that neogloboquadrina pachyderma constitutes 96 99 of the fauna in arctic and polar surface water masses the same result is obtained when investigating the 150 m size fraction however in arctic areas influenced by atlantic water additional faunal information is obtained when using the smaller 100 m size fraction in these areas n pachyderma is reduced to about 50 and the relatively small species turborotalita quinqueloba becomes very frequent this also applies to the coastal water masses which are dominated by neogloboquadrina incompta and globigerinita uvula transfer functions using the current dataset based on the 100 m size fraction were developed and assessed different statistical models were tested using both seasonal and annual temperature data from 0 m 10 m 50 m and 100 m water depth the most precise reconstructions of subsurface temperatures were found when using summer temperatures from the 100 m depth level the transfer function was tested on holocene foraminiferal records and compared to previous reconstructions the results show that our new transfer function based on the 100 m fraction generally yields lower temperatures at both 10 and 100 m water depth than earlier reconstructions e g hald et al 2007 this could be due to the increased number of samples containing both small species and or the presence of more small specimens representing cold conditions

dynamic analysis of a slope failure from the 6 august 1979 coyote lake california earthquake abstract the coyote lake california earthquake of 6 august 1979 m l 5 7 provided a rare opportunity to perform a dynamic numerical analysis of a seismically induced slope failure using actual strong motion records the earthquake displaced a preexisting slump on the northeast shore of lake anderson and formed a fissure 20 m long offsets of 9 mm vertically and 18 mm horizontally were measured across the fissure the slump is 9 km northwest of the located epicenter but within 100 m of the mapped trace of the calaveras fault two strong motion records were written in the vicinity of the slump coyote creek 5 km to the southeast and gilroy 6 15 km to the southeast these records combined with field measurements of the slope estimates of the material properties and a dynamic numerical model based on the newmark analysis of seismic slope stability to calculate a predicted displacement for the landslide a displacement of 27 mm calculated using the n50 e component of the gilroy 6 record is in excellent agreement with the displacement measured in the field 21 mm however displacements of only 0 12 mm calculated using the 250 component of the coyote creek strong motion record reflect significant local variations in seismic shaking intensity because strong motion records and slope failures rarely coincide this landslide provides an important test case for our understanding of the dynamics of seismically induced landslides as well as a warning that local seismologic variations need to be considered in any design applications

paleoceanographic reconstructions of surface ocean conditions in the greenland iceland and norwegian seas through the last 14 ka based on diatoms prior reconstructions of the last glacial maximum and the holocene did not include detailed paleoclimate data from the greenland iceland and norwegian gin seas which cover sensitive areas for oceanographic boundaries sea ice distribution and deep water formation in order to fill this gap we studied nine well dated sediment cores from this area and reconstructed the paleoceanographic conditions of the surface gin seas at 2000 year intervals since 13 400 bp based on the diatom record results show that a n s extending sea ice free corridor had opened along norway already at 13 400 bp indicating a northward flow of a branch of the north atlantic drift possibly caused by a change in the jet stream flow due to the decreased height of the north american ice sheet a major change of climatic conditions occurred over the gin seas as the insolation anomaly reached its maximum around 9000 bp when the sea ice cover and the oceanic fronts retreated to a northwesterly position along greenland and the ocean temperatures rose the first half of the holocene is recorded as the warmest period during the last 13 400 bp in the gin seas the duration of this climatic optimum decreased both toward the north and toward the margins of the area the second half of the holocene is characterized by a cooling trend in step with the decreasing insolation these results support the proposal of imbrie et al 1992 that the gin seas region acts as an initial responder to insolation changes