subsurface energetics of the gulf stream near the charleston bump abstract the energy budgets of the eddies and the mean flow in the gulf stream near a topographic feature known as the charleston bump are computed first we consider these results in the context of the amplification hypothesis for the development of gulf stream meanders according to this hypothesis the finite amplitude gulf stream fluctuations observed offshore of onslow bay are the result of the destabilizing effect of the bump on the stream the present dataset was obtained both immediately upstream and downstream of the bump and the results of our analysis suggest 1 immediately south of the charleston bump the eddies perform net work on the gulf stream at a rate of 1 02 66 10 2 ergs cm 3 s 1 by transporting momentum offshore 2 the net work performed by the eddies south of the bump is not used locally to accelerate the mean rather it is exported to the rest of the ocean at a rate of 1 58 1 39 10 2 ergs cm 3 s 1 3 in spite of the net work performed by the eddies south of the bu

the global mesoscale eddy available potential energy field in models and observations global maps of the mesoscale eddy available potential energy eape field at a depth of 500m are created using potential density anomalies in a high resolution 112 5 global ocean model maps made from both a free running simulation and a data assimilative reanalysis of the hybrid coordinate ocean model hycom are compared with maps made by other researchers from density anomalies in argo profiles the hycom and argo maps display similar features especially in the dominance of western boundary currents the reanalysis maps match the argo maps more closely demonstrating the added value of data assimilation global averages of the simulation reanalysis and argo eape all agree to within about 10 the model and argo eape fields are compared to eape computed from temperature anomalies in a dataset of moored historical observations mho in conjunction with buoyancy frequencies computed from a global climatology the mho dataset allows for an estimate of the eape in high frequency motions that is aliased into the argo eape values at mho locations 15 32 of the eape in the argo estimates is due to aliased motions having periods of 10 days or less spatial averages of eape in hycom argo and mho data agree to within 50 at mho locations with both model estimates lying within error bars observations analysis of the eape field in an idealized model in conjunction with published theory suggests that much of the scatter seen in comparisons of different eape estimates is to be expected given the chaotic unpredictable nature of mesoscale eddies

ice sheet sources of sea level rise and freshwater discharge during the last deglaciation we review and synthesize the geologic record that constrains the sources of sea level rise and freshwater discharge to the global oceans associated with retreat of ice sheets during the last deglaciation the last glacial maximum 26 19 ka was terminated by a rapid 5 10 m sea level rise at 19 0 19 5 ka sourced largely from northern hemisphere ice sheet retreat in response to high northern latitude insolation forcing sea level rise of 8 20 m from 19 to 14 5 ka can be attributed to continued retreat of the laurentide and eurasian ice sheets with an additional freshwater forcing of uncertain amount delivered by heinrich event 1 the source of the abrupt acceleration in sea level rise at 14 6 ka meltwater pulse 1a 14 15 m includes contributions of 6 5 10 m from northern hemisphere ice sheets of which 2 7 m represents an excess contribution above that derived from ongoing ice sheet retreat widespread retreat of antarctic ice sheets began at 14 0 15 0 ka which together with geophysical modeling of far field sea level records suggests an antarctic contribution to this meltwater pulse as well the cause of the subsequent younger dryas cold event can be attributed to eastward freshwater runoff from the lake agassiz basin to the st lawrence estuary that agrees with existing lake agassiz outlet radiocarbon dates much of the early holocene sea level rise can be explained by laurentide and scandinavian ice sheet retreat with collapse of laurentide ice over hudson bay and drainage of lake agassiz basin runoff at 8 4 8 2 ka to the labrador sea causing the 8 2 ka event

non trionychid turtles from the paleocene of alberta canada turtle fossils of paleocene age have been recovered from four formations in alberta canada the upper paleocene part of the scollard formation the upper paleocene portion of the willow creek formation and the exclusively paleocene porcupine hills and paskapoo formations at least three non trionychid turtle taxa can be recognized definitely present are a generically indeterminate baenid the macrobaenid judithemys backmani and the chelydrid protochelydra zangerli the carapace of a juvenile chelydrid could be either a juvenile of p zangerli or a fourth distinct taxon the macrobaenid j backmani and the chelydrid p zangerli are the most abundant non trionychid turtles from the paleocene of alberta the turtles from the paleocene of alberta differ from those of comparable age in new mexico usa and other more southern localities in the north american western interior in i the presence of macrobaenids and chelydrids and ii the absence of kinosternoids these differences mirror those of the

constant holocene southern ocean 14c reservoir ages and ice shelf flow rates article i nfo southern ocean radiocarbon reservoir ages i e non zero radiocarbon ages in seawater are the highest in the world s surface ocean constraining these reservoir ages at present and in the past is important not only because unknown reservoir ages limit the interpretation of antarctic radiocarbon chronologies but also because reservoir ages provide information about ocean circulation as a recorder of past circulation and as an end member for major deep water masses in today s ocean in this study we use paired u th and 14 c ages of an unusual set of solitary coral samples trapped by fringing ice shelves in the ross sea to provide the first detailed study of holocene reservoir ages for the southern ocean our results indicate a relatively constant marine radiocarbon reservoir age of 1144 120 years for the past 6000 years these results are consistent with extrapolation of the relationship between 14 c and alkalinity seen elsewhere supporting the use of this empirical relationship in high latitudes the results also suggest constant deep ocean circulation and air sea exchange during the holocene and provide a good target for tuning ocean models of modern circulation combining the new ages for corals with their distance from the modern day ice shelf grounding line provides some of the first long term records of ice shelf velocities for any region and indicates constant flow of the mcmurdo ice shelf during the holocene at a rate similar to that observed today

taphonomy of a mass death layer of fishes in the paleocene paskapoo formation at joffre bridge alberta canada a layer of silty mudstone only a few centimetres thick in the lower part of the mainly fluvial paskapoo formation contains thousands of complete skeletons of fossil fish and is tiffanian late paleocene ti3 in age the diversity represented in the layer is low with thousands of specimens of a species in the trout perch family percopsidae tens of specimens of a species in the smelt family osmeridae and just two specimens of a species of osteoglossomorph in the family osteoglossidae recovered to date although the fishes occur without other kinds of fossils in the fish layer other layers in the same outcrop have yielded abundant remains of plants insects mollusks and mammals taphonomic features of the fish layer are used to test the hypothesis that it represents a mass death event and to evaluate mechanisms of formation there is little disarticulation and no sign of scavenging fish occur in distinct size classes individuals of the smelt species demonstrate breeding tubercles fish tend

glacial interglacial ice stream stability in the weddell sea embayment antarctica the resilience of the antarctic ice sheet and its effect on global sea level depends on the dynamics of ice streams antarctic ice streams are known to be responsive to changes at the ocean interface and as expected most have thinned in response to ocean warming and sea level rise since the last glacial maximum lgm here we provide direct and unexpected evidence that points toward the glacial interglacial stability of the slessor and recovery glaciers ice streams of the east antarctic ice sheet eais which merge with the west antarctic ice sheet wais to form the filchner ice shelf in the weddell sea embayment cosmogenic nuclide measurements in the shackleton range suggest that the slessor and recovery ice streams were not significantly thicker than today during the lgm we hypothesise that the glaciers did not thicken because the grounding line was not able to migrate seaward beyond the deep thiel crary trough beneath the filchner ice shelf immediately offshore this discovery reveals how a topographic threshold can affect the dynamics of ice streams it also reduces uncertainties on the thickness extent and volume of the antarctic ice sheet in a large but unknown sector of the antarctic ice sheet it constrains the potential sea level rise from antarctica it helps explain observed anomalies in glacio isostatic adjustment above all it suggests that the behaviour of the atlantic facing weddell sea sector of the wais contrasts with that of the pacific facing ross and amundsen sea sectors

global sea level rise published values for the long term global mean sea level rise determined from tide gauge records exhibit considerable scatter from about 1 mm to 3 mm yr this disparity is not attributable to instrument error long term trends computed at adjacent sites often agree to within a few tenths of a millimeter per year instead the differing estimates of global sea level rise appear to be in large part due to authors using data from gauges located at convergent tectonic plate boundaries where changes of land elevation give fictitious sea level trends in addition virtually all gauges undergo subsidence or uplift due to postglacial rebound pgr from the last deglaciation at a rate comparable to or greater than the secular rise of sea level modeling pgr by the ice 3g model of tushingham and peltier 1991 and avoiding tide gauge records in areas of converging tectonic plates produces a highly consistent set of long sea level records the value for mean sea level rise obtained from a global set of 21 such stations in nine oceanic regions with an average record length of 76 years during the period 1880 1980 is 1 8 mm yr 0 1 this result provides confidence that carefully selected long tide gauge records measure the same underlying trend of sea level and that many old tide gauge records are of very high quality

normal polarity magnetosubchrons in 24r and the age of the paleocene eocene boundary a late paleocene to early eocene sequence of flat lying continental strata occurs in an area known as obed mountain west central alberta the upper 110 m consist of interbedded fluvial channel sandstones and overbank mudrocks containing five back swamp coal seams two coreholes 3 5 km apart that extend through the entire coal zone were sampled for magnetostratigraphy and 13c isotope analysis bentonites in the no 1 lowest and no 5 coal seams and a tuff in the no 3 coal seam were sampled for u pb and or rb sr dating of zircon and biotite respectively magnetostratigraphic analysis of 520 samples identified the younger part of chron 25r the whole of chron 25n and the older half of chron 24r we find six normal polarity subzones in this part of chron 24r which we correlate to tiny wiggles 6 to11 in marine magnetic profiles carbon isotope analysis of 14 samples from two cores revealed a negative shift of about 2 peaking near the base of 24r 8r we interpret this as the carbon isotope excursion

faunal assemblages from the upper horseshoe canyon formation an early maastrichtian cool climate assemblage from alberta with special reference to the albertosaurus sarcophagus bonebed the faunal assemblage from the early maastrichtian portion of the horseshoe canyon formation is described on the basis of four new vertebrate microfossil localities and remains from the albertosaurus bonebed all of the localities sampled were deposited during a cool dry climate at a palaeolatitude of 58 n thus these assemblages provide insight into a northern cool climate assemblage in the early maastrichtian of western north america this fauna is characterized by the presence of taxa with more northern affinities such as holostean a champsosaurs troodon and toothed birds warm climate taxa such as crocodylians large and diverse turtles and albanerpetontids are notable in their absence the albertosaurus bonebed locality at the top of unit 4 of the horseshoe canyon formation was deposited during the initial stages of a trend to a warmer and wetter climate that is represented in unit 5 the bonebed shares many taxa with the underlying vertebrate microfossil localities however a notable diffe

rapid flooding of the sunda shelf a late glacial sea level record the increase in sea level from the last glacial maximum has been derived from a siliciclastic system on the tectonically stable sunda shelf in southeast asia the time from 21 to 14 thousand calendar years before the present has been poorly covered in other records the record generally confirms sea level reconstructions from coral reefs the rise of sea level during meltwater pulse 1a was as much as 16 meters within 300 years 14 6 to 14 3 thousand years ago

selective glacial erosion and weathering zones in the coastal mountains of marie byrd land antarctica in the coastal mountains of marie byrd land antarctica there is a juxtaposition of ice moulded landforms at lower altitudes and upstanding summits with weathered surfaces bearing tors this paper uses geomorphological mapping and exposure dating to test two hypotheses commonly used to explain such a landscape contrast either the pattern reflects contrasts in glacial erosion related to the basal thermal regime beneath a former ice sheet or it represents a periglacial trimline marking the upper limit of ice cover during the last glacial maximum lgm cosmogenic nuclide measurements on erratics show that the mountains were covered by ice on several occasions most recently during the lgm similar measurements on bedrock show that fragile landforms on weathered surfaces survived many glaciations nuclide concentrations in bedrock indicate both that subglacial erosion is insignificant and that ice free periods of periglacial weathering are longer at higher elevations we conclude that the pattern of landscape modification reflects both topographically controlled contrasts in the basal thermal regime of overriding ice and the longer exposure to periglacial conditions at higher elevations in addition the combination of nuclide data and the wider pattern of striations shows that the lgm ice cover was thinner than predicted by ice sheet models assuming equilibrium conditions that ice sheet thinning has occurred from 10 400 years ago to the present and that regional flow by overriding ice has been replaced by radial ice flow from local glaciers centred on individual mountain massifs

seasonal mesoscale and submesoscale eddy variability along the north pacific subtropical countercurrent abstractlocated at the center of the western north pacific subtropical gyre the subtropical countercurrent stcc is not only abundant in mesoscale eddies but also exhibits prominent submesoscale eddy features output from a high resolution ogcm simulation and a gridded satellite altimetry product are analyzed to contrast the seasonal stcc variability in the mesoscale versus submesoscale ranges resolving the eddy scales of 150 km the altimetry product reveals that the stcc eddy kinetic energy and rms vorticity have a seasonal maximum in may and april respectively a weak positive vorticity skewness without seasonal dependence and an inverse forward kinetic energy cascade for wavelengths larger shorter than 250 km in contrast the submesoscale resolving ogcm simulation detects that the stcc eddy kinetic energy and rms vorticity both appear in march a large positive vorticity skewness with strong seasonality and an intense inverse kinetic energy cascade whose short wave cutoff migrates seaso

ross sea paleo ice sheet drainage and deglacial history during and since the lgm onshore and offshore studies show that an expanded grounded ice sheet occupied the ross sea embayment during the last glacial maximum lgm results from studies of till provenance and the orienta

a new ambystomatid salamander dicamptodon antiquus n sp from the paleocene of alberta canada the discovery of a skull and partial postcranial skeleton of dicamptodon from northern alberta is the earliest certain record of the subfamily dicamptodontinae the specimen comes from late paleocene lake sediments which also contain the remains of fish and plants the close resemblance of the specimen to larvae or neotenes of extant dicamptodon shows that this family exhibits the common trend of extreme conservatism known from other salamanders the specimen is found in association with floral assemblages confirming nussbaum s hypothesis of the origin of the genus in northwestern north america

ice age paleotopography a gravitationally self consistent theory of postglacial relative sea level change is used to infer the variation of surface ice and water cover since the last glacial maximum lgm the results show that lgm ice volume was approximately 35 percent lower than suggested by the climap reconstruction and the maximum heights of the main laurentian and fennoscandian ice complexes are inferred to have been commensurately lower with respect to sea level use of these ice age boundary conditions in atmospheric general circulation models will yield climates that differ significantly from those previously inferred on the basis of the climap data set

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

deglacial sea level record from tahiti corals and the timing of global meltwater discharge the timing of the last deglaciation is important to our understanding of the dynamics of large ice sheets1 and their effects on the earth s surface2 3 moreover the disappearance of the glacial ice sheets was responsible for dramatic increases in freshwater fluxes to the oceans which probably disturbed the ocean s thermohaline circulation and hence global climate4 7 sea level increases bear witness to the melting of continental ice sheets but only two such records from barbados8 9 and new guinea10 11 corals have been accurately dated but these corals overlie active subduction zones where tectonic movements are large and often discontinuous especially in new guinea so the apparent sea level records may be contaminated by a complex tectonic component here we date fossil corals from tahiti which is far from plate boundaries and thus is likely to be tectonically relatively stable and remote from the locations of large former ice sheets the resulting record indicates a large sea level jump shortly before 13 800 calendar years bp which corresponds to meltwater pulse 1a in the barbados coral records8 9 the timing of this event is more accurately constrained in the tahiti record revealing that the meltwater pulse coincides with a short and intense climate cooling event12 15 that followed the initiation of the bolling allerod warm period12 16 but preceded the younger dryas cold event by about 1 000 years

skeletal and isotopic composition and paleoclimatic significance of late pleistocene carbonates ross sea antarctica abstract carbonates cover an extensive area of the northwestern ross sea continental shelf radiocarbon dates yield late pleistocene stage 3 ages for these deposits hence the carbonates appear to be correlative with widespread tills and glacial marine deposits in the region four carbonate facies are recognized on the basis of skeletal composition a barnacle foraminifer facies a muddy bryozoan facies a bryozoan barnacle pelecypod foraminifer facies and a planktonic foraminiferal facies these deposits occur on the shelf and upper slope while carbonate turbidites derived from them occur on the adjacent continental slope and rise compositional analyses of ross sea carbonates lend support to previously recognized criteria for identifying cold water carbonates these include 1 the presence of an associated ice rafted component including dropstones 2 a dominance of calcite relative to other carbonate minerals the remaining fraction consists solely of aragonite 3 allochems that are entirely skeletal and 4 heavy oxygen isotopic compositions in the range of 3 0 to 5 1 pdb

kindleia fragosa jordan and stylomyleodon lacus russell two amiid fishes from the late cretaceous and the paleocene of alberta canada detailed study of the type specimens and of new materials collected in the upper maastrichtian and paleocene of alberta canada leads one to propose new diagnoses of kindleia fragosa jordan and stylomyleodon lacus russell which are two different species of amiid fishes bearing styliform teeth on the vomers and coronoids comparison with some amiid fishes from the european cenozoic shows that both species belong to the genus cyclurus agassiz which was widely distributed in europe from the paleocene to the oligocene

a new crocodylian archosauria from the basal paleocene of the red deer river valley southern alberta borealosuchus griffithi sp nov is described on the basis of an incomplete skeleton from the basal paleocene southern alberta this new species records one of a few basal cenozoic occurrences o

cosmogenic nuclide exposure ages from the pensacola mountains adjacent to the foundation ice stream antarctica we describe glacial geological observations and cosmogenic nuclide exposure ages from the schmidt williams and thomas hills in the pensacola mountains of antarctica adjacent to the foundation ice stream fis our aim is to learn about changes in the thickness and grounding line position of the antarctic ice sheet in the weddell sea embayment between the last glacial maximum lgm and the present glacial geological observations from all three regions indicate that currently ice free areas were covered by ice during one or more past ice sheet expansions and that this ice was typically frozen to its bed and thus non erosive permitting the accumulation of multiple generations of glacial drift cosmogenic nuclide exposure age data from glacially transported erratics are consistent with this interpretation in that we observe both i samples with holocene exposure ages that display a systematic age elevation relationship recording lgm to present deglaciation and ii samples with older and highly scattered apparent exposure ages that were deposited in previous glacial interglacial cycles and have experienced multiple periods of surface exposure and ice cover holocene exposure ages at the thomas and williams hills upstream of the present grounding line of the fis show that the fis was at least 500 m thicker prior to 11 ka and that 500 m of thinning took place between 11 and 4 ka however exposure age data from the schmidt hills downstream of the present grounding line of the fis show no evidence for lgm thickening of the fis and in fact provide some evidence that the fis could have been no more than 200 m thicker than present at the lgm if all these observations are correct they imply that the lgm and early holocene ice surface slope in the vicinity of the present grounding line was steeper than present which is inconsistent with glaciological model predictions of possible lgm ice sheet configurations specifically scenarios in which the lgm grounding line of the fis advanced to the outer continental shelf appear inconsistent with exposure age data from the schmidt hills whereas scenarios in which the fis grounding line did not advance at the lgm appear inconsistent with exposure age data from the williams and thomas hills

eddy kuroshio interactions local and remote effects quasi geostrophic mesoscale eddies regularly impinge on the kuroshio in the western north pacific but the processes underlying the evolution of these eddy kuroshio interactions have not yet been thoroughly investigated in the literature here this interaction is examined with results from a semi idealized three dimensional numerical model and observations from four pressure sensor equipped inverted echo sounders piess in a zonal section east of taiwan and satellite altimeters both the observations and numerical simulations suggest that during the interaction of a cyclonic eddy with the kuroshio the circular eddy is deformed into an elliptic shape with the major axis in the northwest southeast direction before being dissipated the poleward velocity and associated kuroshio transport decrease and the sea level and pycnocline slopes across the kuroshio weaken in contrast for an anticyclonic eddy during the eddy kuroshio interaction variations in the velocity sea level and isopycnal depth are reversed the circular eddy is also deformed to an ellipse but with the major axis parallel to the kuroshio the model results also demonstrate that the velocity field is modified first and consequently the ssh and isopycnal depth evolve during the interaction furthermore due to the combined effect of impingement latitude and realistic topography some eddy kuroshio interactions east of taiwan are found to have remote effects both in the luzon strait and on the east china sea shelf northeast of taiwan

eddy induced heat transport in the subtropical north pacific from argo tmi and altimetry measurements basin scale heat transport induced by mesoscale oceanic eddies is estimated by combining satellite derived sea surface height and temperature temperature data are from the trmm microwave imager tmi data with argo float temperature salinity data in the north pacific ocean subtropical gyre warm cold temperature anomalies of mesoscale eddies are found to be consistently located to the west of high low ssh anomalies the phase misalignment between the temperature and velocity anomalies however is largely confined to the seasonal thermocline causing most of the eddy induced heat transport to be carried in the surface 200 m layer by establishing a statistical relationship between the surface and depth integrated values of the eddy heat transport the basin scale eddy heat transport is derived from the concurrent satellite ssh sst data of the past six years in the kuroshio extension region the meandering zonal jet is found to generate oppositely signed eddy heat fluxes as a result the zonally integrated poleward heat transport associated with the kuroshio extension is at a level o 0 1 pw smaller than the previous estimates based on turbulent closure schemes large poleward eddy heat transport is also found in the subtropical north pacific along a southwest northeast tilting band between taiwan and the midway islands this band corresponds to the region of the subtropical front and it is argued that the relevant temperature field for identifying this band in the turbulent closure scheme models should be that averaged over the seasonal thermocline

a description of local and nonlocal eddy mean flow interaction in a global eddy permitting state estimate abstractthe assumption that local baroclinic instability dominates eddy mean flow interactions is tested on a global scale using a dynamically consistent eddy permitting state estimate interactions are divided into local and nonlocal if all the energy released from the mean flow through eddy mean flow interaction is used to support eddy growth in the same region or if all the energy released from eddies through eddy mean flow interaction is used to feed back to the mean flow in the same region eddy mean flow interaction is local otherwise it is nonlocal different regions have different characters in the subtropical region studied in detail interactions are dominantly local in the southern ocean and kuroshio and gulf stream extension regions they are mainly nonlocal geographical variability of dominant eddy eddy and eddy mean flow processes is a dominant factor in understanding ocean energetics

on the seasonal eddy variability in the kuroshio extension abstractusing a recently developed tool multiscale window transform mwt and the mwt based canonical energy transfer theory this study investigates the seasonal eddy variability in the kuroshio

eddy kuroshio interaction processes revealed by mooring observations off taiwan and luzon the influence and fate of westward propagating eddies that impinge on the kuroshio were observed with pressure sensor equipped inverted echo sounders piess deployed east of taiwan and northeast of luzon zero lag correlations between pies measured acoustic travel times and satellite measured sea surface height anomalies ssha which are normally negative have lower magnitude toward the west suggesting the eddy influence is weakened across the kuroshio the observational data reveal that impinging eddies lead to seesaw like ssha and pycnocline depth changes across the kuroshio east of taiwan whereas analogous responses are not found in the kuroshio northeast of luzon anticyclones intensify sea surface and pycnocline slopes across the kuroshio while cyclones weaken these slopes particularly east of taiwan during the 6 month period of overlap between the two pies arrays only one anticyclone affected the pycnocline depth first at the array northeast of luzon and 21 days later in the downstream kuroshio east of taiwan

ice sheets and sea level of the last glacial maximum this paper outlines the general issues regarding ice sheets and sea level of the last glacial maximum lgm which formed the basis of an epilog project workshop papers in this special issue of quaternary science reviews provide a comprehensive assessment of these issues from the perspective of geological reconstructions of ice sheet extent records of sea level change ice sheet modelling geophysical models of glacial isostatic adjustment and geochemical proxies of ice volume this new assessment has substantially narrowed the uncertainties in the total changes in ice sheets and sea level and their proxies suggesting a net decrease in eustatic sea level at the lgm ranging from 120 to 135 m r 2001 elsevier science ltd all rights reserved

energetics of eddy mean flow interactions along the western boundary currents in the north pacific abstractthe energetics of eddy mean flow interactions along two western boundary currents of the north pacific the kuroshio and ryukyu currents are systematically investigated using 22 years of n

energetics of eddy mean flow interactions in the brazil current between 20 s and 36 s the energetics of eddy mean flow interactions in the brazil current bc between 20 s and 36 s are investigated in nineteen transects perpendicular to the 200 m isobath ten years 2000 2009 of output data from the hybrid coordinate ocean model hycom ncoda reanalysis with a spatial resolution of 1 12 5 and five day averages are used the mean kinetic energy mke and eddy kinetic energy eke fields presented the same subsurface spatial pattern but with reduced values the eke increases southward with high values along the bc path and the offshore portion of the jet the values of the barotropic conversion term btc are highest in the surface layers and decreased with depth whereas the values of the baroclinic conversion term bcc and the vertical eddy heat flux vehf are highest in the subsurface despite the vertical thickening of the bc the highest energy conversion rates are confined to the upper 700 m of the water column the energetic analysis showed that the current features mixed instability processes the vertical weighted mean of the btc and bcc presented an oscillatory pattern related to the bathymetry the eddy field accelerates the time mean flow upstream and downstream of bathymetric features and drains energy from the time mean flow over the features the bc is baroclinically unstable south of 28 s and the highest energy conversion rates occur in cabo de sao tome cabo frio and the cone do rio grande

a review of nonmarine turtles from the late cretaceous of alberta the late cretaceous of alberta preserves one of the most complete records of fossil turtles within a single geographic area in north america the cenomanian dunvegan formation contains the earliest record of the family trionychidae in north america the santonian milk river formation contains a minimum of ten taxa with adocus a small trionychid and a member of the solemydidae being the most abundant diversity remains high in the mid campanian judith river group the solemyidid last occurs in the basal beds of the judith river group a member of the macrobaenidae first occurs in the dinosaur park formation the uppermost formation in the judith river group turtles diversity is low in the late campanian lower horseshoe canyon formation and they are absent in the early maastrichtian upper horseshoe canyon formation diversity increases in the late maastrichtian scollard formation although it is much less than in the contemporaneous hell creek formation of montana two of the taxa present in the scollar

on postglacial geoid subsidence over the equatorial oceans we develop two new spectral formalisms for the gravitationally self consistent solution of the sea level equation which governs the redistribution of glacial meltwater on a visco elastic earth the first is a purely spectral technique based on an extension of theory outlined by dahlen 1976 for determining the equilibrium oceanic tide on an elastic planet using this technique with a feasible spherical harmonic truncation level l 30 we can obtain convergence in the computed sea level variations within the degree range l 10 we also develop a second pseudospectral technique however which permits the construction of gravitationally self consistent solutions to much higher degree and order l 100 the pseudospectral formalism is employed here to develop a comprehensive physical explanation for the global pattern of present day sea level variations due to ongoing glacial isostatic adjustment in particular we focus upon a mechanism which we term equatorial ocean syphoning that acts to draw water toward the oceanic portion of the collapsing peripheral bulge that encircles previously glaciated regions the collapse of the forebulge induces a flow of water which is required to maintain hydrostatic equilibrium the syphoning mechanism dominates the relative sea level rsl variation in oceans in the far field of the ice sheets that is beyond the peripheral bulge during periods such as the interglacial of the past 4000 years during which the volume of the ice sheets has not apparently changed appreciably while at the same time isostatic adjustment persists the rsl change in the near field is in contrast dominated by the local vertical displacement of the solid surface finally comparison of gravitationally self consistent predictions of rsl change in the far field with the observational data at small pacific island sites has provided an upper bound of 1 to 2 m for the eustatic sea level rise produced by any recent last 3000 years melting of the antarctic ice sheet

late quaternary evolution of reedy glacier antarctica abstract fresh deposits above the margins of reedy glacier show that maximum ice levels during the last glaciation were several hundred meters above present near the glacier mouth and converged to less than 60 m above the present day surface at the head of the glacier exposure ages of samples from five sites along its margin show that reedy glacier and its tributaries thickened asynchronously between 17 and 7 kyr bp at the quartz hills located midway along the glacier maximum ice levels were reached during the period 17 14 kyr bp farther up glacier the ice surface reached its maximum elevation more recently 14 7 10 2 kyr bp at the caloplaca hills 9 1 7 7 kyr bp at mims spur and around 7 kyr bp at hatcher bluffs we attribute this time transgressive behavior to two different processes at the glacier mouth growth of grounded ice and subsequent deglaciation in the ross sea embayment caused a wave of thickening and then thinning to propagate up glacier during the lateglacial and holocene increased snow accumulation on the east antarctic ice sheet caused transient thickening at the head of the glacier an important result of this work is that moraines deposited along reedy glacier during the last ice age cannot be correlated to reconstruct a single glacial maximum longitudinal profile the profile steepened during deglaciation of the ross sea thinning at the quartz hills after 13 kyr bp while thickening upstream near its confluence with mercer ice stream rapid thinning beginning prior to 7 8 kyr bp reduced the level of reedy glacier to close to its present level thinning over the past 1000 years has lowered the glacier by less than 20 m

deglacial meltwater discharge north atlantic deep circulation and abrupt climate change high resolution paleogeochemical data from the north atlantic ocean indicate that in the interval 15 000 to 10 000 14c years before present b p north atlantic deep water nadw production was decreased or eliminated four times at about 14 500 and probably older 13 500 12 000 and 10 500 years b p each of these changes occurred at the same time as abrupt events of meltwater discharge to the surface ocean inferred from oxygen isotope studies of planktonic foraminifera and from glacial geological studies on land in addition each of these times may be associated with brief episodes of cooler climate in the north atlantic region the best example of which is the younger dryas cooling of 10 500 years ago these results support models linking meltwater discharge decreased nadw production and decreased north atlantic heat flux

subthermocline eddies in the western equatorial pacific as shown by an eddy resolving ogcm abstractsporadic in situ observations have shown evidence that subthermocline eddies exist off the mindanao coast these subthermocline eddies are believed to play an important role in the heat freshwater and other ocean property transports of the region but their characteristics and in particular their pathway and source of energy are poorly explored because of the lack of long term observations analysis of results from an eddy resolving general ocean circulation model has revealed that most subthermocline eddies off the mindanao coast originate from the equatorial south pacific ocean to the west of the ninigo group these eddies propagate northward along the new guinea coast cross the equator in the far western pacific and reach the mindanao coast at a typical propagation speed of 0 12 m s 1 the dominant time scales of these eddies range between 50 and 60 days

contributions and unrealized potential contributions of cosmogenic nuclide exposure dating to glacier chronology 1990 2010 abstract this paper reviews the application of cosmogenic nuclide exposure dating to glacier chronology exposure dating of glacial landforms has made an outsize impact on this field because the technique filled an obvious need that had already been recognized by glacial geologists by now hundreds of studies have used cosmogenic nuclide exposure dating to date glacial deposits and in fact it is rare to find a study of glacial geology or glacier chronology or any paleoclimate synthesis that makes use of such studies that does not involve exposure dating these developments have resulted in major contributions to glacier chronology and paleoclimate in particular i reconstructing antarctic ice sheet change ii establishing the chronology of late pleistocene and holocene glacier change in mountain regions where it was previously unknown iii establishing the broad chronological outlines of mountain glaciations prior to the last glacial maximum and iv gaining insight into subglacial erosional processes through the observation that many glaciated surfaces preserve cosmogenic nuclide inventories from long past ice free periods as well as the present one an important potential future contribution will be the application of the large data set of exposure dated glacier chronologies to better understand global and regional climate dynamics during lateglacial and holocene millennial scale climate changes however this contribution cannot be realized without significant progress in two areas i understanding and accounting for geologic processes that cause apparent exposure ages on glacial landforms to differ from the true age of the landform and ii minimizing systematic uncertainties in exposure ages that stem from cosmogenic nuclide production rate estimates and scaling schemes at present there exists an enormous data set of exposure ages on glacial deposits but these data cannot be used to their full potential in paleoclimate syntheses due to an inadequate understanding of geologic scatter and production rate uncertainties the intent of this paper is to highlight this situation and suggest some strategies for realizing this potential

late quaternary stage 2 and 3 meltwater and heinrich events northwest labrador sea two major meltwater events are documented in cores from the nw labrador sea one occurred ca 20 000 14c yr b p in association with deposition of a major detrital carbonate unit both prior to and after this event 18o values of near surface planktonic foraminifera were 4 5 indicating fully enriched glacial values a younger event ca 14 000 14 c yr b p is characterized by a dramatic change in 18o from 4 5 to 2 0 and coincided with the retreat of ice from the outer se baffin shelf possibly into hudson strait these meltwater events coincide with heinrich h layers 1 and 2 from north atlantic sediments the 14 000 14c yr b p meltwater event indicates that the eastern margin of the laurentide ice sheet also underwent rapid retreat at approximately the same time as other ice sheet margins around the ne north atlantic a third major detrital carbonate event at the base of hu87 033 009 possibly correlative with heinrich layer 3 occurred ca 33 960 675 14 c yr b p however this is older than the accepted date for h 3 of 27 000 14c yr b p and may be h 4

the marine record of deglaciation from the continental margin off nova scotia continental margin sediments off nova scotia accumulate at high rates up to 360 cm kyr 1 and contain a history of millennial scale environmental changes which are dominated by the proximity of the laurentide ice sheet during the latest quaternary using stable isotope ratios of oxygen accelerator mass spectrometer radiocarbon dating micropaleontology and sedimentology we document these changes in six piston cores ranging in water depth from 450 to 4300 m we find that maximum 18o in n pachyderma occurred about 15 ka and preceded the maximum abundance of this species in these cores by 1000 years between 13 and 14 ka we find a second peak in abundance of n pachyderma minimum 18o and two pulses of ice rafting the sediment lithology supports terrestrial studies which indicate that there was a general withdrawal of ice beyond the upper paleozoic and mesozoic red beds by 14 ka in southeastern canada so the ice rafting events between 13 and 14 ka probably reflect ice stream activity in the st lawrence valley the younger dry as event is recognized as a peak in abundance of n pachyderma and ice rafting dated as 11 3 ka but meltwater discharge to the gulf of st lawrence was either too small or occurred over too long a time to leave a distinct 18o minimum off nova scotia at 7 1 ka in the middle of holocene warming we find a third peak in abundance of n pachyderma and another 18o minimum but no ice rafting we interpret these data as evidence of a late occurring meltwater event which if correct could have originated in the great lakes in the labrador ungava region or in both the final millennial scale phenomenon off nova scotia is the onset of neoglaciation marked by increased ice rafting and increased n pachyderma beginning about 5 kyr ago

holocene deglaciation of marie byrd land west antarctica surface exposure ages of glacial deposits in the ford ranges of western marie byrd land indicate continuous thinning of the west antarctic ice sheet by more than 700 meters near the coast throughout the past 10 000 years deglaciation lagged the disappearance of ice sheets in the northern hemisphere by thousands of years and may still be under way these results provide further evidence that parts of the west antarctic ice sheet are on a long term trajectory of decline west antarctic melting contributed water to the oceans in the late holocene and may continue to do so in the future

late pleistocene oxygen isotope records of biogenic silica from the atlantic sector of the southern ocean we determined the isotopic composition of oxygen in marine diatoms in eight deep sea cores recovered from the atlantic sector of the southern ocean the analytical reproducibility and core to core consistency of the isotopic signal suggests that diatom 18o can be used as a new paleocenographic tool to reconstruct past variations in surface water characteristics and to generate 18o isotope based stratigraphy for the southern ocean the data indicate that diatom 18o reflects sea surface temperature and seawater isotopic composition and that diatoms retain their isotopic signal on timescales of a least 430 ka the 18o analyses of different diatom assemblages reveal that the isotopic signal is free of species effects and that the common antarctic species have the same water opal fractionation the transition from the last glacial maximum lgm to the holocene is fully recorded in high sedimentation rate cores an 18o enrichment during the lgm a post lgm meltwater spike and an input of meltwater during the late holocene are the main isotopic features observed in down core records the origin of this meltwater was very likely melting icebergs and or continental ice or by melting sea ice that had accumulated snow the most pronounced meltwater effects are recorded in cores that are associated with the weddel gyre our results provide the basis for extending isotope studies to oceanic regions devoid of carbonate further isotopic stratigraphies may be constructed for records and regions where they were previously not possible

the ross sea s contribution to eustatic sea level during meltwater pulse 1a abstract radiocarbon dates obtained from ross sea sediments combined with constraints on maximum ice extent based on sedimentological data and ice sheet modeling results indicate that the ross embayment antarctica is unlikely to have been a substantial contributor to meltwater pulse mwp 1a at 12 5 14c ka the ice sheet in the ross embayment during the last glacial maximum is estimated to have contained ice volume equivalent to 3 6 m eustatic sea level rise and does not show evidence of rapid retreat grounded ice advance occurred during initial late pleistocene eustatic rise and ice sheet retreat began coeval with or subsequent to mwp 1a chronological and sedimentological data from the ross embayment indicate that deglaciation in this region has occurred throughout the holocene and the maximum possible contribution of eustatic rise from the ross embayment is

abrupt bolling warming and ice saddle collapse contributions to the meltwater pulse 1a rapid sea level rise elucidating the source s of meltwater pulse 1a the largest rapid sea level rise caused by ice melt 14 18 m in less than 340 years 14 600 years ago is important for understanding mechanisms of rapid ice melt and the links with abrupt climate change here we quantify how much and by what mechanisms the north american ice sheet could have contributed to meltwater pulse 1a by driving an ice sheet model with two transient climate simulations of the last 21 000 years ice sheet perturbed physics ensembles were run to account for model uncertainties constraining ice extent and volume with reconstructions of 21 000 years ago to present we determine that the north american ice sheet produced 3 4 m global mean sea level rise in 340 years due to the abrupt bolling warming but this response is amplified to 5 6 m when it triggers the ice sheet saddle collapse

calibration of the c 14 timescale over the past 30 000 years using mass spectrometric u th ages from barbados corals uranium thorium ages obtained by mass spectrometry from corals raised off the island of barbados confirm the high precision of this technique over at least the past 30 000 years comparison of the u th ages with 14c ages obtained on the holocene samples shows that the u th ages are accurate because they accord with the dendrochronological calibration before 9 000 yr bp the 14c ages are systematically younger than the u th ages with a maximum difference of 3 500 yr at 20 000 yrbp the u th technique thus provides a way of calibrating the radiocarbon timescale beyond the range of dendrochronological calibration

rapid early holocene deglaciation in the ross sea antarctica deglaciation of the ross sea following the last ice age provides an important opportunity to examine the stability of marine ice sheets and their susceptibility to changing environmental conditions insufficient chronology for ross sea deglaciation has helped sustain i the theory that this region contributed significantly to meltwater pulse 1a mwp 1a and ii the idea that ross sea grounding line retreat occurred in a swinging gate pattern hinged north of roosevelt island we present deglaciation records from southern transantarctic mountain glaciers which delivered ice to the central ross sea abrupt thinning of these glaciers 9 8 kyr bp coincided with deglaciation of the scott coast 800 km to the north and ended with the ross sea grounding line near shackleton glacier this deglaciation removed grounded ice from most of the central and western ross sea in less than 2 kyr the ross sea sector neither contributed nor responded significantly to mwp 1a

regolith transport quantified by braking block mcmurdo dry valleys antarctica abstract the mcmurdo dry valleys of antarctica are today a hyper arid polar desert prior work has identified several in situ volcanic ashes 6 11 myr old resting on the surface regolith that suggests the persistent stability of the regolith surfaces and climate however our field observations of characteristic regolith bulges above and cavities below boulders that are lodged in the hillslope braking blocks contradict the apparent preservation of the regolith surfaces to quantify the regolith mobility we modeled the downslope regolith transport around large boulders in the dry valleys using a finite difference regolith transport model to guide our modeling effort we surveyed the detailed topography around one large boulder in the field model results fit the observed topography well and allow for the calculation of the minimum volume of regolith per unit width of slope that was mobilized 4 m3 1 m width to assess the general applicability of the braking block analysis on random boulders on hillslope we surveyed the topographic characteristics adjacent to 997 boulders on 10 separate hillslopes the bulge cavity development appears to be sensitive to 1 the adjacent obstructions that restrict the free movement of the regolith around the given boulder and 2 the inherent surface roughness even though theoretically boulders of all sizes should have a cavity bulge pair surrounding them the signal to noise ratio prevented us from extracting such measurements reliably on boulders whose diameter was smaller than about 1 m on boulders that sat on bedrock covered by a thin veneer of regolith and on boulders that were part of an actively aggrading talus the limiting minimum topographic diffusivity was found to be 10 6 m2 yr over time periods of millions of years this is enough to rework the surfaces and highlights the intriguing contradiction between the preserved ashes and the observed regolith transport

retreat signature of a polar ice stream sub glacial geomorphic features and sediments from the ross sea antarctica abstract three research expeditions to the ross sea antarctica resulted in collection of a dataset of more than 270 km of side scan and chirp sonar data more than 330 km of swath bathymetry and 3 5 khz data and 24 cores within a glacially carved trough the former ice stream flow path is divided into six zones covering a distance of approximately 370 km distinguished by unique stratigraphic signatures and geomorphic features an erosional surface with thin patchy lodgement till characterizes zone 1 this region is interpreted as having experienced relatively high basal shear stress conditions zones 2 3 and 4 are characterized by an erosional surface and thin time transgressive subglacial and grounding line proximal deposits that include back stepping moraines flutes transverse moraines and corrugation moraines these zones represent the transition between erosional and depositional regimes under the expanded lgm ice sheet material eroded from the inner shelf was transported toward the outer shelf possibly as a thin deforming till layer the two outer zones are depositional and include maximum grounding line zone 5 and pro glacial deposits that were overridden subsequently by the ice sheet zone 6 surface features include mega scale glacial lineations corrugation moraines and iceberg furrows ice in these zones is interpreted as having experienced relatively lower basal shear stress an extensional regime and faster flow this advance may have destabilized the ice sheet initiating local draw down and production of icebergs that furrowed the sea floor corrugation moraines are thought to represent annual retreat moraines constraining the retreat rate of the ice sheet across the continental shelf to a consistent 40 to 100 m a 1

antarctic grounding line mapping from differential satellite radar interferometry 1 the delineation of an ice sheet grounding line i e the transition boundary where ice detaches from the bed and becomes afloat in the ocean is critical to ice sheet mass budget calculations numerical modeling of ice sheet dynamics ice ocean interactions oceanic tides and subglacial environments here we present 15 years of comprehensive high resolution mapping of grounding lines in antarctica using differential satellite synthetic aperture radar interferometry dinsar data from the earth remote sensing satellites 1 2 ers 1 2 radarsat 1 and 2 and the advanced land observing system alos palsar for years 1994 to 2009 dinsar directly measures the vertical motion of floating ice shelves in response to tidal oceanic forcing with millimeter precision at a sample spacing better than 50 m simultaneously over areas several 100 km wide in contrast with earlier methods that detect abrupt changes in surface slope in satellite visible imagery or altimetry data on stagnant and slow moving areas we find that breaks in surface slope are reliable indicators of grounding lines but on most fast moving glaciers and ice streams our dinsar results reveal that prior mappings have positioning errors ranging from a few km to over 100 km a better agreement is found with icesat s data also based on measurements of vertical motion but with a detection noise one order of magnitude larger than with dinsar overall the dinsar mapping of antarctic grounding lines completely redefines the coastline of antarctica

sea level rise during past 40 years determined from satellite and in situ observations the 3 2 0 2 millimeter per year global mean sea level rise observed by the topex poseidon satellite over 1993 98 is fully explained by thermal expansion of the oceans for the period 1955 96 sea level rise derived from tide gauge data agrees well with thermal expansion computed at the same locations however we find that subsampling the thermosteric sea level at usual tide gauge positions leads to a thermosteric sea level rise twice as large as the true global mean as a possible consequence the 20th century sea level rise estimated from tide gauge records may have been overestimated

implications of two holocene time dependent geomagnetic models for cosmogenic nuclide production rate scaling abstract the geomagnetic field is a major influence on in situ cosmogenic nuclide production rates at a given location in addition to atmospheric pressure and to a lesser extent solar modulation effects a better understanding of how past fluctuations in these influences affected production rates should allow more accurate application of cosmogenic nuclides as such this work explores the cosmogenic nuclide production rate scaling implications of two recent time dependent spherical harmonic geomagnetic models spanning the holocene korte and constable 2011 phys earth planet inter 188 247 259 and korte et al 2011 earth planet sci lett 312 497 505 recently updated earlier spherical harmonic paleomagnetic models with new paleomagnetic data from sediment cores in addition to new archeomagnetic and volcanic data these updated models offer improved resolution and accuracy over the previous versions in part due to increased temporal and spatial data coverage in addition pavon carrasco et al 2014 earth planet sci lett 388 98 109 developed another time dependent spherical harmonic model of the holocene geomagnetic field based solely on archeomagnetic and volcanic paleomagnetic data from the same underlying paleomagnetic database as the korte et al models but extending to 14 ka with the new models as input trajectory traced estimates of effective vertical cutoff rigidity r c the standard method for ordering cosmic ray data yield significantly different time integrated scaling predictions when compared to each other and to results using the earlier models in addition predictions of each new model using r c are tested empirically using recently published production rate calibration data for both 10be and 3he and compared to predictions using corresponding time varying geocentric dipolar r c formulations and a static geocentric axial dipole gad model results for the few calibration sites from geomagnetically sensitive regions suggest that the pavon carrasco et al 2014 time varying dipolar model tends to predict sea level high latitude production rates more in line with those from calibration sites not affected by geomagnetic variations this suggests that uncertainties arising from hemispheric and temporal sampling biases in the holocene spherical harmonic models considered here combined with the currently limited spatial and temporal distribution of production rate calibration sites as empirical tests limit the robustness of the non dipole aspects of these models for production rate scaling these analyses should be revisited as such models improve and additional calibration sites become available

antarctic contribution to sea level rise observed by grace with improved gia correction antarctic volume changes during the past 21 thousand years are smaller than previously thought and here we construct an ice sheet history that drives a forward model prediction of the glacial isostatic adjustment gia gravity signal the new model in turn should give predictions that are constrained with recent uplift data the impact of the gia signal on a gravity recovery and climate experiment grace antarctic mass balance estimate depends on the specific grace analysis method used for the method described in this paper the gia contribution to the apparent surface mass change is re evaluated to be 55 13 gt yr by considering a revised ice history model and a parameter search for vertical motion predictions that best fit the gps observations at 18 high quality stations although the gia model spans a range of possible earth rheological structure values the data are not yet sufficient for solving for a preferred value of upper and lower mantle viscosity nor for a preferred lithospheric thickness grace monthly solutions from the center for space research release 04 csr rl04 release time series from january 2003 to the beginning of january 2012 uncorrected for gia yield an ice mass rate of 2 9 29 gt yr the new gia correction increases the solved for ice mass imbalance of antarctica to 57 34 gt yr the revised gia correction is smaller than past grace estimates by about 50 to 90 gt yr the new upper bound to the sea level rise from the antarctic ice sheet averaged over the time span 2003 0 2012 0 is about 0 16 0 09 mm yr

volume of antarctic ice at the last glacial maximum and its impact on global sea level change abstract the volume of antarctic ice at the last glacial maximum is a key factor for calculating the past contribution of melting ice sheets to late pleistocene global sea level change at present there are large uncertainties in our knowledge of the extent and thickness of the formerly expanded antarctic ice sheets and in the timing of their release as meltwater into the world s oceans this paper reviews the four main approaches to determining former antarctic ice volume namely glacial geology glacio isostatic studies glaciological modelling and ice core analysis and attempts to reconcile these to give a best estimate for ice volume in the ross sea there was a major expansion of grounded ice at the last glacial maximum accounting for 2 3 3 2 m of global sea level at some time in the weddell sea a large grounded ice sheet corresponding to c 2 7 m of global sea level extended to the shelf break however this ice expansion has not yet been confidently dated and may not relate to the last glacial maximum around east antarctica there was thickening and advance offshore of ice in coastal regions ice core evidence suggests that the interior of east antarctica was either close to its present elevation or thinner during the last glacial so the effect of east antarctica on sea level depends on the net balance between marginal thickening and interior thinning suggested east antarctic contributions vary from a 3 5 5 m lowering to a 0 64 m rise in global sea level the antarctic peninsula ice sheet thickened and extended offshore at the last glacial maximum with a sea level equivalent contribution of c 1 7 m thus the antarctic ice sheets accounted for between 6 1 and 13 1 m of global sea level fall at the last glacial maximum this is substantially less than has been suggested by most previous studies but the maximum figure matches well with one modelling estimate the timing of antarctic deglaciation is not well known in the ross sea terrestrial evidence suggests deglaciation may have begun at c 13 000 yr bp 1 but that grounded ice persisted until c 6 500 yr bp marine evidence suggests the western ross sea was deglaciated by c 11 500 yr bp deglaciation of the weddell sea is poorly constrained grounded ice in the northern antarctic peninsula had retreated by c 13 000 yr bp and further south deglaciation occurred sometime prior to c 6 000 yr bp many parts of coastal east antarctica apparently escaped glaciation at the lgm but in those areas that were ice covered deglaciation was underway by 10 000 yr bp with existing data the timing of deglaciation shows no firm relation to northern hemisphere driven sea level rise this is probably due partly to lack of antarctic dating evidence but also to the combined influence of several forcing mechanisms acting during deglaciation

a new palaeocene genus and species of percopsiform teleostei paracanthopterygii from the paskapoo formation smoky tower alberta a new genus and species of teleostean fish lateopisciculus turrifumosus fossil taxon from the palaeocene paskapoo formation at smoky tower alberta is described this new species is classified in the family percopsidae paracanthopterygii percopsiformes based on the presence of a dorsal process on the maxilla the presence of this fish extends the earliest known age of this family from the eocene amphiplaga and erismatopterus fossil taxa to the late palaeocene the fossil assemblage at the smoky tower locality includes pike esocidae an osteoglossomorph and two salamanders as well as the new species of percopsid the site was likely an oxbow lake or shallow swamp a mass death event is indicated by the multiple species and size and age class distribution of the specimens

ice sheet and solid earth influences on far field sea level histories previous predictions of sea level change subsequent to the last glacial maximum show significant systematic discrepancies between observations at tahiti huon peninsula and sunda shelf during lateglacial time 14 000 to 9000 calibrated years before the present we demonstrate that a model of glacial isostatic adjustment characterized by both a high viscosity lower mantle 4 1022 pa s and a large contribution from the antarctic ice sheet to meltwater pulse ia 15 meters eustatic equivalent resolves these discrepancies this result supports arguments that an early and rapid antarctic deglaciation contributed to a sequence of climatic events that ended the most recent glacial period of the current ice age

ice 3g a new global model of late pleistocene deglaciation based upon geophysical predictions of post glacial relative sea level change a new high resolution global model of late pleistocene deglaciation is inferred on the basis of geophysical predictions of postglacial relative sea level variations in which the ice ocean solid earth interaction is treated in a gravitationally self consistent fashion for the purpose of these analyses the radial viscoelastic structure of the planet is assumed known on the basis of previously published sensitivity tests on solutions of the forward problem only radiocarbon controlled relative sea level histories from sites that were actually ice covered with one or two additions are employed to constrain the model leaving relative sea level rsl data from sites that were not ice covered to be employed to confirm its consistency results for these confirmatory analyses are reported elsewhere here the new deglaciation model referred to as ice 3g is compared to previous models derived by several independent means and tested against a number of additional observations other than sea level histories including geologically controlled retreat isochrones oxygen isotope data from deep sea sedimentary cores and coral terrace elevations the latter two observations strongly constrain the net sea level rise that has occurred since the onset of deglaciation and therefore the mass of ice that melted during the last glacial interglacial transition

mesoscale eddies in the northwestern subtropical pacific ocean statistical characteristics and three dimensional structures mesoscale eddy properties in the northwestern subtropical pacific ocean are investigated by analyzing 22 567 cyclonic eddies ces and 26 365 anticyclonic eddies aes detected from 19 year altimetric sea level records eddy occurrence frequency and kinetic energy are prevailingly high in the subtropical countercurrent zonal band between 19 degrees n and 26 degrees n and further elevated near the luzon taiwan coast a general superiority of aes is observed at most latitudes except between 19 degrees n and 22 degrees n where the ce number is larger the modal radius and mean lifespan of the ces aes are 134km and 11 2weeks 121km and 10 9weeks respectively after generation most eddies propagate westward with a mean speed of 7 2cms 1 and deflect northward following the kuroshio along the luzon taiwan coast three dimensional eddy structures are further explored with composite eddy images in five subregions constructed by surfacing argo temperature salinity data into altimeter detected eddy areas due to the existence of mode waters in the main thermocline eddy induced temperature anomaly exhibits a double core vertical structure which is especially evident in ce images because of the vertical water mass distribution salinity anomaly features a sandwich like pattern which is more evident in ae images also revealed is the significant structure difference in these five subregions eddies are greatly intensified as they approach the western boundary inducing larger temperature and salinity anomalies and influencing deeper ocean along the luzon taiwan coast aes are preferentially strengthened by the northward background flow

glacial geology and cosmogenic nuclide exposure ages from the tucker glacier whitehall glacier confluence northern victoria land antarctica we describe glacial geological observations and cosmogenic nuclide exposure ages from the vicinity of the present grounding line of tucker glacier a large alpine glacier flowing from the mountains of northern victoria land east antarctica into the outer ross sea these data are relevant for constraining the extent of ice sheet expansion and retreat in the ross sea and associated eustatic sea level impact between the last glacial maximum lgm and the present in addition a terrestrial geological record of ice thickness change from this region could provide evidence for or against the hypothesis that rapid eustatic sea level rise during meltwater pulse 1a mwp 1a at 14 6 ka was in part the result of rapid large scale thinning or breakup of a marine based portion of the lgm ice sheet in the outer ross sea glacial geological observations exposure ages on glacial deposits and a novel application of in situ produced cosmogenic 14c in quartz bearing bedrock to identify the limits of lgm ice cover in the absence of direct geomorphic evidence show that tucker glacier near its present grounding line was 300 to 350 m thicker than present during the lgm and thinned steadily between 17 to 5 ka the largest possible rapid thickness change in the time period 14 to 15 ka that could be accommodated by the exposure age data is 50 m which is a small fraction of that predicted for the western ross sea by model simulations of the antarctic contribution to mwp 1a there do exist possible scenarios in which hypothesized marine ice sheet collapse in the outer ross sea during mwp 1a might not be recorded by ice thickness changes at tucker glacier however our record of ice thickness changes spanning this time period is the closest such record to the outer ross sea that is likely to exist and it agrees with all exposure age deglaciation chronologies from other regions of the ross embayment in providing no evidence for such an event

sea level fingerprinting as a direct test for the source of global meltwater pulse ia the ice reservoir that served as the source for the meltwater pulse ia remains enigmatic and controversial we show that each of the melting scenarios that have been proposed for the event produces a distinct variation or fingerprint in the global distribution of meltwater we compare sea level fingerprints associated with various melting scenarios to existing sea level records from barbados and the sunda shelf and conclude that the southern laurentide ice sheet could not have been the sole source of the meltwater pulse whereas a substantial contribution from the antarctic ice sheet is consistent with these records

current system east of the ryukyu islands 1 the ryukyu current system rcs is a northeastward current southeast of the ryukyu islands the variation of current structure in the rcs region was investigated on the basis of the absolute geostrophic velocity estimated by inverse calculation using hydrographic data three realizations of the rcs are examined from cruises in may september and october 2002 it was found that the current structure in the rcs region is divided into upper and lower layers by an isopycnal surface of 26 the currents in both layers proceed northeastward along the eastern slope east of the ryukyu islands the current in the upper layer merges with the inflow from the interior region resulting in larger northeastward volume transport southeast of amami oshima island than southeast of okinawa island the volume transport from the east reaches more than 40 of that southeast of amami oshima island on the other hand the current in the lower layer is not affected by inflow from the east it is also found that the upper rcs gains heat mainly through the advection of warm water from the east resulting in an increase in the downstream temperature by about 0 5 c on average

a systematic reappraisal and quantitative study of the non marine teleost fishes from the late maastrichtian of the western interior of north america evidence from vertebrate microfossil localities the diversity and distribution of non marine teleost fishes in the western interior of north america during the late maastrichtian is documented based on isolated elements from vertebrate microfoss

introduction to the special issue commemorating the 30th anniversary of the royal tyrrell museum of palaeontology with a summary of the museum s early history and its research contributions located just west of drumheller in southern alberta canada the royal tyrrell museum of palaeontology rtmp is nestled among outcrops of the upper cretaceous horseshoe canyon formation exposed along the red deer river valley fig 1 since it officially opened on 25 september 19851 the museum has become one of alberta s must see tourist attractions a significant contributor to the local economy and earned an international reputation for the quality of its palaeontological collections and the research conducted by its scientists the rtmp is unique within canada in being the only government supported museum dedicated to palaeontology and it is one of the few such institutions in the world fig 1 the royal tyrrell museum of palaeontology a front of museum and main entrance circa 2010 looking westwards and with horizontal beds of the upper cretaceous horseshoe canyon formation exposed in the walls of the red deer river valley in the distance b aerial photograph oblique angle and looking to the north northeast the museum sits on top of the number 7 coal seam sensu gibson 1977 and at the base of the horsethief member of the horseshoe canyon formation d a eberth pers comm 2015 that stratigraphic position correlates with an age of about 71 5 ma i e late campanian and lies within the upper part of the edmontosaurus regalis pachyrhinosaurus canadensis dinosaur assemblage zone see eberth et al 2013 fig 6 c the iconic running theropod logo that until recently graced the exterior of the museum below a life sized tyrannosaurid sculpture by brian cooley one of many such sculptures by cooley that have been featured at the museum since its opening in 1985 and with the education wing opened in 2003 as the atco tyrrell learning centre in the background d the cretaceous alberta life sized diorama opened in 2007 an example of a rtmp exhibit that relies heavily on discoveries and interpretations by museum researchers in this case work done in the albertosaurus bonebed and at other localities throughout the horseshoe canyon formation all photographs courtesy of the royal tyrrell museum of palaeontology this special issue of the canadian journal of earth sciences presents a collection of papers commemorating the rtmp s 30th or pearl anniversary our rationale for doing a 30th anniversary volume was two fold first it is an opportunity to showcase the breadth of research conducted by current and former museum scientists as well as by some colleagues having a history of collaboration with the rtmp the 13 invited papers included in this volume are a mix of review and original research papers all thematically focused on the geology and palaeontology of alberta to varying degrees each contribution is the result of work supported by the rtmp and relies on specimens housed in the museum s collections second the 30th anniversary is an opportunity to reflect on the rtmp s history and its research program as is typical for most institutions the rtmp has done little to formally document its own history this year likely will be the last major milestone for which the original generation of museum staff are still working and available to share their recollections about the museum fieldwork and research already deaths and departures have winnowed away part of the original

diversity of turtles across the cretaceous tertiary boundary in northeastern montana abstract the abundant chelonian faunas of the hell creek and tullock formations of mccone and garfield counties montana span the cretaceous tertiary boundary and provide a basis for assessing extinction and changes in diversity over three thousand specimens were counted on a modified minimum number basis from 510 localities the lancian maastrichtian part of the hell creek formation contains at least 19 genera and subgenera of turtles and probably a greater but undetermined number of species and comprises the most diverse fossil turtle fauna known from a single rock unit at least 15 generic level taxa survive into the puercan early paleocene part of the overlying tullock formation and only one new genus appears the magnitude of the change in diversity across the cretaceous tertiary boundary is less than or compaable to examples within the tertiary and is readily explained by moderate ecological changes

spatial variations in the rate of sea level rise caused by the present day melting of glaciers and ice sheets the redistribution of surface water mass associated with the melting of glacial ice causes uplift near areas of mass depletion depression of the seafloors and changes in the earth s gravitational field which perturb the ocean surface as a result local spatial variations exist in the rate of sea level rise tide gauges on continental coastlines measure a sea level rise 5 smaller than the global average tide gauges in the hemisphere opposite a source of continental mass depletion measure sea level rise 10 to 20 greater than the global average produced by that source while satellites make measurements 10 too low because most long duration tide gauges are in the northern hemisphere if the sources of sea level rise are unbalanced between the two hemispheres estimates of global sea level rise could be in error by 10 to 20 individual tide gauges could be more seriously unrepresentative if they are near regions of significant present day mass depletion

origin of the first global meltwater pulse following the last glacial maximum well dated sea level records show that the glacioeustatic rise following the last glacial maximum was characterized by two or possibly three brief intervals of rapid sea level rise separating periods with much lower rates these very high rates of sea level rise indicate periods of exceptionally rapid deglaciation of remaining ice sheets the laurentide ice sheet is commonly targeted as the source of the first and largest of the meltwater pulses mwp ia between 14 200 12 200 14c years b p and 13 700 years ago 11 700 14c years b p in all oceanic records of deglaciation of the former northern hemisphere ice sheets that we review only those from the gulf of mexico and the bermuda rise show evidence of low 18o values at the time of mwp ia identifying the southern laurentide ice sheet as a potential source for mwp ia we question this source for mwp ia however because 1 ice sheet models suggest that this sector of the ice sheet contributed only a fraction 10 of the sea level needed for mwp ia 2 melting this sector of the ice sheet at the necessary rate to explain mwp ia is physically implausible and 3 ocean models predict a much stronger thermohaline response to the inferred freshwater pulse out of the mississippi river into the north atlantic than is recorded this leaves the antarctic ice sheet as the only other ice sheet capable of delivering enough sea level to explain mwp ia but there are currently no well dated high resolution records to document this hypothesis these conclusions suggest that reconstructions of the laurentide ice sheet in the ice 4g model which are constrained to match the sea level record may be too low for time periods younger than 15 000 years ago furthermore 18o records from the gulf of mexico show variable fluxes of meltwater from the southern margin of the laurentide ice sheet which can be traced to the opening and closing of eastward draining glacial lake outlets associated with surging ice sheet behavior these variable fluxes through eastern outlets were apparently sufficient to affect formation of north atlantic deep water thus underscoring the sensitivity of this process to changes in freshwater forcing

energetics of eddy mean flow interactions in the gulf stream region a detailed energetics analysis of the gulf stream gs and associated eddies is performed using a highresolution multidecadal regional ocean model simulation the energy equations for the time mean and timevaryingflowsarederivedasatheoreticalframeworkfortheanalysis theeddy meanflowenergycomponents and their conversions show complex spatial distributions in the along coast region the cross stream and cross bump variations are seen in the eddy mean flow energy conversions whereas in the off coast region a mixed positive negative conversion pattern is observed the local variations of the eddy mean flow interaction are influenced by the varying bottom topography when considering the domain averaged energetics theeddy meanflowinteractionshowssignificantalong streamvariability upstreamofcapehatteras the energy is mainly transferred from the mean flow to the eddy field through barotropic and baroclinic instabilities upon separating from the coast the gs becomes highly unstable and both energy conversions intensify when the gs flows into the off coast region an inverse conversion from the eddy field to the mean flow dominates the power transfer for the entire gs region the mean current is intrinsically unstable and transfers 28 26gw of kinetic energy and 26 80gw of available potential energy to the eddy field the mesoscaleeddykineticenergyisgeneratedbymixedbarotropicandbaroclinicinstabilities contributing28 26 and 9 15gw respectively beyond directly supplying the barotropic pathway mean kinetic energy also provides 11 55gw of power to mean available potential energy and subsequently facilitates the baroclinic instability pathway

amia cf pattersoni from the paleocene paskapoo formation of alberta a well prepared anterior half of an amiid skull from the late paleocene paskapoo formation of south central alberta is described the specimen is either very closely related to or conspecific with amia pattersoni grande and bemis 1998 from the early eocene green river formation of wyoming we leave the specimen as amia cf pattersoni until additional material is found to further clarify its relationships amia cf pattersoni is the oldest known specimen clearly identifiable as belonging to the genus amia sensu grande and bemis 1998 and the paskapoo species extends the known geographic range of amia both northward and westward the fish assemblage of the paskapoo formation represents the most diverse freshwater paleocene fish fauna known from north america based on comparisons of sample size and relative taxonomic diversity to the better known green river formation localities of wyoming we predict that further collecting will substantially increase the known diversity of the paskapoo fauna the p

the current system east of the ryukyu islands as revealed by a global ocean reanalysis abstract the structure and variability of the ryukyu current system rcs which forms the western boundary current along the eastern slope of the ryukyu islands are studied using results from a 32 layer 1 12 5 global hybrid coordinate ocean model hycom and navy coupled ocean data assimilation ncoda reanalysis for the period 1993 2012 it is confirmed that the reanalysis realistically reproduces salient features of the observed currents at three sections southeast of miyakojima okinawa and amami ohshima the mean velocity sections show well developed subsurface velocity maxima between 700 and 900 m the current core southeast of amami ohshima shows year to year variations with cyclonic anticyclonic circulation east of amami ohshima generating weak strong velocity cores interaction of the rcs with an anticyclonic eddy often produces a two core velocity structure with a surface core in the upper 300 m and a deeper core near 700 900 m the horizontal structure of the rcs at 15 m depth shows a well developed northeastward current northeast of okinawa which is partly fed by the southwestward extension of the anticyclonic recirculation gyre the rcs forms a continuous northeastward current from miyakojima to amami ohshima below 500 m with shoreward intensification the circulation at 2000 m shows a seasonal flow reversal which is northeastward from december to june and southwestward from august to october with july and november being the transition months the volume transports across these three sections have respective mean values of 0 6 6 2 and 12 4 sv 1 sv 106 m3 s 1 and standard deviations of 10 2 7 1 and 11 3 sv they have dominant seasonal variations with the maximum in winter and spring and the minimum in summer the interannual variation of the transport anomaly which co varies with the rcs core results from westward propagating mesoscale eddies arriving from the pacific interior

summary of fossil vertebrate taxa named by richard c fox with an annotated list of taxa named between 1962 and 2012 and new photographs for non mammalian therapsid and mammalian holotypes erected between 1968 and 1994 beginning in 1962 and extending to the present richard c fox and colleagues have named 87 species of fossil vertebrates 1 fish 4 amphibians 2 choristoderes 12 lizards 1 crocodile 1 dinosaur 2 pelycosaurs 2 non mammalian therapsids and 62 mammals and numerous new supraspecific taxa virtually all of these species continue to be accepted although the higher level assignments of several have been altered the vast majority of the named species were founded on specimens collected during the mid 1960s to early 2000s by field parties under fox s direction from the late cretaceous late santonian to late maastrichtian and paleocene of alberta and saskatchewan canada and that are housed at the university of alberta laboratory for vertebrate paleontology here we present i an annotated list of all fossil vertebrate species named by richard fox between 1962 and 2012 ii updated information on the stratigraphic nomenclature and age estimates for the eight localities in alberta that yielded ho

near field hydro isostasy the implementation of a revised sea level equation summary we describe how the existing sea level equation incorrectly predicts the change in sea level and thus the ocean load in ice covered subgeoidal geographic regions during periods of deglaciation we go on to present a new sea level equation that overcomes this problem and we describe how this equation can be solved in a gravitationally self consistent manner by employing a well known spectral technique application of the new theory to predict relative sea level rsl histories and present day 3 d solid surface deformation rates in northeastern canada based on a single earth model characterized by a lithospheric thickness of 100 km and upper and lower mantle viscosities of 5 1020 and 5 1021 pa s respectively demonstrates that a significant error is introduced when the original theory is employed to predict the oceanic component of the surface load predictions of rsl curves show a discrepancy of 40 per cent at sites where data have been obtained and employed to constrain models of earth viscosity structure and ice sheet histories this error will significantly bias estimates of mantle viscosity structure and ice thicknesses that are based on the original theory in addition predictions of 3 d deformation rates differ by up to 25 per cent in some regions and so future applications that employ these data to constrain models of the glacial isostatic adjustment process should adopt the improved sea level theory in contrast estimates of inverse decay times from the predicted rsl curves are insensitive to within the observational error to the improvement in the surface load introduced by the new theory thus viscosity structure inferences based on this parametrization and the original sea level equation are unaffected by the error in the ocean load finally the new theory predicts a eustatic i e globally uniform rise in sea level over the postglacial period that is 11 m lower than that determined via the original theory therefore estimates of the global ice budget at the last glacial maximum based on far field rsl data and the original sea level theory will be too small by 10 per cent

deglacial history of the pensacola mountains antarctica from glacial geomorphology and cosmogenic nuclide surface exposure dating the retreat history of the antarctic ice sheet is important for understanding rapid deglaciation as well as to constrain numerical ice sheet models and ice loading models required for glacial isostatic adjustment modelling there is particular debate about the extent of grounded ice in the weddell sea embayment at the last glacial maximum and its subsequent deglacial history here we provide a new dataset of geomorphological observations and cosmogenic nuclide surface exposure ages of erratic samples that constrain the deglacial history of the pensacola mountains adjacent to the present day foundation ice stream and academy glacier in the southern weddell sea embayment we show there is evidence of at least two glaciations the first of which was relatively old and warm based and a more recent cold based glaciation during the most recent glaciation ice thickened by at least 450 m in the williams hills and at least 380 m on mt bragg progressive thinning from these sites was well underway by 10 ka bp and ice reached present levels by 2 5 ka bp and is broadly similar to the relatively modest thinning histories in the southern ellsworth mountains the thinning history is consistent with but does not mandate a late holocene retreat of the grounding line to a smaller than present configuration as has been recently hypothesized based on ice sheet and glacial isostatic modelling the data also show that clasts with complex exposure histories are pervasive and that clast recycling is highly site dependent these new data provide constraints on a reconstruction of the retreat history of the formerly expanded foundation ice stream derived using a numerical flowband model

rapid thinning of pine island glacier in the early holocene pine island glacier a major outlet of the west antarctic ice sheet has been undergoing rapid thinning and retreat for the past two decades here we demonstrate using glacial geological and geochronological data that pine island glacier also experienced rapid thinning during the early holocene around 8 000 years ago cosmogenic 10be concentrations in glacially transported rocks show that this thinning was sustained for decades to centuries at an average rate of more than 100 cm yr 1 comparable to contemporary thinning rates the most likely mechanism was a reduction in ice shelf buttressing our findings reveal that pine island glacier has experienced rapid thinning at least once in the past and that once set in motion rapid ice sheet changes in this region can persist for centuries

effects of mesoscale eddies on the volume transport and branch pattern of the kuroshio east of taiwan using satellite altimeter data and a long term altimetric transport index for the kuroshio inflow northeast of taiwan the effects of mesoscale eddies on the kuroshio volume transport kvt at the east taiwan channel and the branching pattern of the kuroshio east of taiwan are investigated at scales from those of individual events to interannual timescales both anticyclonic and cyclonic eddies are found to be able either to strengthen or weaken the kvt depending on the relative strength of mass convergence and divergence produced upstream and downstream of the eddies the major factor influencing the intensity of the kuroshio inflow is the meridional location of the eddies for single eddy events the kvt is significantly correlated with the latitude of the eddy s center the correlations being 0 44 and 0 48 for anticyclonic and cyclonic eddies respectively for dipole eddy events when the direction angle falls in the interval 40 150 240 300 the kvt anomaly tends to be positive negative furthermore low kvt events generally correspond to the formation of the ryukyu current branch which is also generated from strong mass divergence produced by the eddies in addition on interannual time scales the variation of kvt is closely related to the relative number of anticyclonic to cyclonic eddies west of 125 e with a correlation of 0 5 this article is protected by copyright all rights reserved

exposure age record of holocene ice sheet and ice shelf change in the northeast antarctic peninsula abstract this paper describes glacial geologic observations and cosmogenic nuclide exposure ages from ice free areas adjacent to the sjogren boydell and drygalski glaciers of the northeast antarctic peninsula these provide a record of holocene glacier and ice shelf change in this region early holocene ice surface elevation near the present coastline was locally at least 500 m above present sea level but our observations do not constrain the maximum thickness of last glacial maximum lgm ice or the time at which it was attained the boundary between frozen based and wet based ice reached a maximum elevation of 100 150 m above present sea level the ice surface elevation decreased from 300 500 m elevation to near present sea level between 9 ka and ca 4 ka below 160 m elevation we observed a bimodal distribution of apparent exposure ages in which a population of glacially transported clasts with mid holocene exposure ages coexists with another that has exposure ages of 100 600 years we consider the most likely explanation for this to be i complete deglaciation of currently ice free areas which presumably required the absence of ice shelves at 3 5 4 5 ka followed by ii subsequent ice shelf formation and grounding line advance after ca 1 4 ka and iii complete re exposure of the sites after ice shelf breakup and glacier surface lowering in recent decades this explanation is consistent with marine sedimentary records indicating that ice shelves in the prince gustav channel and larsen a embayment were absent in the middle to late holocene and were re established within the last 2000 years

the instabilities and multiscale energetics underlying the mean interannual eddy interactions in the kuroshio extension region abstractusing a recently developed energetics diagnostic methodology namely the localized multiscale energy and vorticity analysis ms eva this study investigates the intricate nonlinear mutual interactions among the decadally modulating mean flow the interannual fluctuations and the transient eddies in the kuroshio extension region it is found that the mean kinetic energy maximizes immediately east of the izu ogasawara ridge while the transient eddy kinetic energy does not peak until 400 km away downstream the interannual variabilities which are dominated by a jet trapped rossby wave mode provide an energy reservoir comparable to the other counterparts in the upstream strong localized barotropic and baroclinic transfers from the mean flow to the eddies are observed whereas those from the interannual variabilities are not significant besides fueling the eddies the unstable mean jet also releases energy to the interannual scale processes between 144 and 154 e both transfers from the mean