sedimentary record of a fluctuating ice margin from the pennsylvanian of western gondwana parana basin southern brazil abstract the parana basin is a key locality in the context of the late paleozoic ice age lpia because of its location east of the andean proto margin of gondwana and west of contiguous interior basins today found in western africa in this paper we document the sedimentary record associated with an ice margin that reached the eastern border of the parana basin during the pennsylvanian with the aim of interpreting the depositional environments and discussing paleogeographic implications the examined stratigraphic succession is divided in four stacked facies associations that record an upward transition from subglacial to glaciomarine environments deposition took place during deglaciation but was punctuated by minor readvances of the ice margin that deformed the sediment pile tillites well preserved landforms of subglacial erosion and glaciotectonic deformational structures indicate that the ice flowed to the north and northwest and that the ice margin did not advance far throughout the basin during the glacial maximum consequently time equivalent glacial deposits that crop out in other localities of eastern parana basin are better explained by assuming multiple smaller ice lobes instead of one single large glacier these ice lobes flowed from an ice cap covering uplifted lands now located in western namibia where glacial deposits are younger and occur confined within paleovalleys cut onto the precambrian basement this conclusion corroborates the idea of a topographically controlled ice spreading center in southwestern africa and does not support the view of a large polar ice sheet controlling deposition in the parana basin during the lpia

on the origin of the itarare group basal nonconformity and its implications for the late paleozoic glaciation in the parana basin brazil abstract outcrop studies of the itarare group in the alfredo wagner area along the eastern margin of the parana basin in brazil reveal a partially exhumed nnw sse oriented glacial paleovalley the carboniferous rio do sul formation represents the basal interval of the glacially influenced itarare group and rests directly on precambrian basement rocks this nonconformity is thought to represent an areal scouring surface as indicated by the series of glacially carved linear depressions that were incised into the glaciated bedrock during glacial advances these large scale erosional landforms differ in their extent by orders of magnitude and include wide deep troughs as well as narrower shallower gouges glacial troughs and gouges usually display smaller scale subglacial erosion landforms such as polished and grooved striations on their walls and floors these indicate the nnw motion of a warm based grounded glacier in addition large scale erosional features represent local topographic lows within the major glacial paleovalley these local lows are large enough to contain part of the succeeding deglacial deposits which thin toward and onlap the wall of these depressions we grouped these deglacial deposits into six genetic facies associations fa 1 to 6 within three fining upward glacial cycles fa 1 is composed of black shale and represents an initial marine flooding event it can be correlated with the regionally widespread lontras shale fa 2 is composed of sandstones and mudstones associated with flood derived hyperpycnal flows and occasionally with surge type turbidites fa 3 is represented by plastered or injected matrix supported conglomerates emplaced as lodgment tills fa 4 comprises matrix and clast supported conglomerates sandstones and mudstones attributed to ice rafting and concentrated flows in grounding line fan facies this unit also contains ice keel dragging features carved into soft substrate fa 5 is composed of dropstone bearing black shale related to a second major marine flooding event within the paleovalley fa 6 comprises sandstones associated with channelized surge type turbidites forming the second turbidite system in the succession as these deposits are confined to a paleovalley we infer that sedimentation was influenced by topographically controlled ice streams instead of non confined widespread ice lobes as previously suggested reconstructing south america and southern africa in their positions during the lpia suggests that the glacial valleys then present in the namibia area may have extended further into the eastern margin of the parana basin in this scenario confined outlet glaciers would have flowed out from the namibian windhoek ice cap and terminated along the eastern margin of the parana basin

stratigraphy and reservoir potential of glacial deposits of the itarare group carboniferous permian parana basin brazil drilling in the parana basin of brazil in the mid 1980s discovered gas and condensate in the itarare group and showed that glacial deposits in brazil can contain hydrocarbons the reservoir potential of the carboniferous permian itarare group of the basin is analyzed using new subsurface data from 20 deep wells drilled in the early to middle 1980s central to the analysis was the construction of over 3000 km of cross sections based on more than 100 wells the description of more than 400 m of core and study of 95 thin sections subsurface exploration and mapping of the itarare are greatly aided by the recognition of three recently defined and described formations and four members which are traceable for hundreds of kilometers these units belong to three major glacial cycles in which the pebbly mudstones and shales are seals and glacially related sandstones are reservoirs the best sandstone reservoirs in the deep subsurface belong to the rio segredo member the uppermost sandy unit of the itarare the rio segredo member is the best petroleum target because it is overlain by thick seals and massive pebbly mudstones and shales and because it is shallower and less compacted than underlying more deeply buried sandstones this member has little detrital matrix and much of its porosity is secondary developed by carboxylic acid and co 2 generated when jurassic cretaceous basalts sills and dikes were intruded into the parana basin as gondwana broke up

paludal environments of the mary lee coal zone pottsville formation alabama stacked clastic swamps and peat mires abstract the blue creek and mary lee coals in the lower part of the mary lee coal zone upper pottsville formation northwestern alabama record deposition in peat accumulating environments or mires intervening strata contain a series of stacked clastic swamps forested wetlands which grew on a classtic sediment substrate rather than a peat soil these clastic swamp horizons are identified on the basis of 1 autochthonous erect lycophyte and calamites trunks 2 mud cast prostrate hypoautochthonous lycophyte and calamites trunks 3 compression impression assemblages of autochthonous to hypoautochthonous pteridosperm and lycophyte foliage branches and reproductive structures 4 autochthonous axes and appendages of stigmaria and pinnularia and 5 siderite nodules associated with rooting structures and other plant material sedimentological and biostratinomic features of the mary lee coal to blue creek coal interval are used as the basis for the interpretation that sediment loading and compaction of buried peat controlled the alternation between peat mires and clastic swamps and the stacking of the clastic swamps

eddies and the annular modes of climate variability the dominant modes of month to month varia tion in the troposphere are realistically simulated in a gen eral circulation model whose lower boundary is prescribed with realistic topography and seasonally varying climato logical sea surface temperatures in both hemispheres these internal modes describe a nearly zonally symmetric north south shifting of the zonal jets as anomalous westerlies vac illate between high 50 60 a nd low 30 40 latitudes the eddy structures evolve with the jets and the corre sponding eddy momentum forcings support the shifts in jet position stationary synoptic wave variations mainly ac count for the total eddy forcings in the northern south ern hemisphere pronounced eddy variations occur over the north atlantic sector

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

the kerogen type depositional environment and maturity of the irati shale upper permian of parana basin southern brazil abstract two samples from the upper and lower horizons of the irati oil shale of the parana basin brazil were sampled in a single borehole and analysed using organic petrography and geochemistry the results are interpreted in terms of the kerogen type maturity and depositional environment of the two horizons organic petrography shows the oil shales to be composed of a mineral groundmass mainly clay minerals carbonate and pyrite associated and sometimes impregnated with fluorescing organic material and disseminated phytoclasts humic material is fairly rare and mostly present as very small particles the liptinitic particles are mostly alginite a and b sporinite and more rarely resinite reflectance measurements upper seam 0 34 r0 lower seam 0 40 r0 indicate an equivalent rank of lignite sub bituminous coal astm i e immature with respect to oil and gas generation different organic geochemical methods rock eval pyrolysis solvent extraction gc and gc ms demonstrate both samples to be immature rich oil shales 100 114 kg ton containing type i kerogen of a dominantly bacterially degraded algal origin deposited in a lacustrine environment the presence of botryococcus suggests deposition under fresh brackish water conditions a tentative interpretation of the extract and vitrinite reflectance data suggests a maximum paleo burial of between 1 3 and 2 8 km for the analysed section of the irati formation

origin of late paleozoic multiple glacially striated surfaces in northern parana basin brazil some implications for the dynamics of the parana glacial lobe abstract four stratigraphically repeated closely spaced striated surfaces on late paleozoic sandstone at the base of the itarare subgroup in northern parana basin were generated by subglacial erosion during advances of the grounding zone of the tidewater terminus of the parana glacial lobe on unconsolidated sand the sandstone corresponds to a channelized sheet like proglacial outwash fan accumulated sub aquatically in front of the tidewater terminus of a temperate warm based glacier at the margin of the marine flooded parana basin sandy siltstone beds intercalated with the sandstone and resting on top of the striated surfaces represent aggradational mud deposited from settling of fine debris plumes overflows erosion was mostly by abrasion wear of the sand bed under a glacier sliding over an unfrozen substratum evidence of ploughing is minimal the glacier bed is thought to have behaved rheologically as a rigid essentially undeformable substratum discontinuities in the distribution of striations on the surfaces indicate that ice may have at places decoupled from its bed the section studied documents an upward fining and deepening deglacial sequence comprising four stratigraphic cycles of accumulation of sand formation of a striated surface followed by deposition of mud cycles are correlated with short lived probably fast seasonal advances of the tidewater terminus during general retreat of the parana lobe ice advances were not associated with deposition of subglacial diamicton or lodgement of clasts but to erosion of sand probably by ice protuberances under the sliding glacier

ice keel scour marks in the geological record evidence from carboniferous soft sediment striated surfaces in the parana basin southern brazil abstract soft sediment glacially striated surfaces are common structures in ancient glacial successions such as the gondwanic paleozoic record and document ice erosion on non lithified beds in most cases they have been interpreted as the product of subglacial erosion beneath advancing marine or terrestrial glaciers although direct evidence for glacial sedimentation in associated strata is infrequent in this paper we document soft sediment striated surfaces of carboniferous age occurring in cross laminated sandstones of the lower itarare group southern parana basin brazil and interpret them as scour marks generated by keels of floating ice striated surfaces occur in closely spaced multiple stratigraphic horizons in the lower half of a deglacial sequence whose facies characteristics indicate sedimentation in subaqueous outwash and deltaic settings surfaces are laterally discontinuous commonly bordered by marginal berms and in some cases capped by mudstones with dropstones they have orientations that deviate from the regional paleo ice flow indicated by glacial grooves carved on the pre glacial basement the characteristics observed are consistent with modern and pleistocene ice keel scour marks in addition soft sediment striated surfaces from other gondwanic localities have similar attributes suggesting that ice keel scour marks may be more common in the geological record than previously considered and that vertically repeated striated surfaces do not necessarily indicate multiple ice sheet advances therefore paleo ice flow reconstructions based on soft sediment striated surfaces need to be revaluated considering that the movement of free floating ice masses is controlled by phenomena other than glacier advance

postglacial transgressions in late paleozoic basins of western argentina a record of glacioeustatic sea level rise the areas marginal to main glaciated centers are appropriate sites to distinguish the record of glacioeustatic sea level fluctuations the late paleozoic basins of western argentina show a marginal position with respect to the glaciated areas of eastern south america brazil in three of these basins tarija calingasta uspallata and central patagonian widespread glacial marine diamictites and their gravity reworked counterparts pass upward to open marine fine clastics mudstones shales and scarce fine sandstones with fossils of the levipustula zone of middle carboniferous late namurian westphalian age the presence of fine grained marine sequences capping the diamictitic deposits is interpreted as the sedimentary response to a glacioeustatic sea level rise expressed as a transgression in stratigraphic terms the glacioeustatic nature of this sea level rise is confirmed by the interbasinal facies based correlation of the transgressive episode and the paleolatitudinal positioning of this portion of gondwanaland during carboniferous times

bimodal character of the late paleozoic glaciations in argentina and bipolarity of climatic changes abstract the upper paleozoic sedimentary rock sequences of argentina show an outstanding record of climatic fluctuations during this interval and the complexity and rapidity of the climatic changes there were two distinct events of cooling or glacial periods the older in the middle carboniferous late visean bashkirian and the younger in the early permian asselian tastubian and these were separated by a long lasting interval of warming during the late pennsylvanian it is postulated that climatic fluctuations in the northern paleotemperate realm may have had the same causes as in argentina and that these periods of cooling and warming probably occurred at the same time in both hemispheres in western argentina and central patagonia the occurrence of the early permian glacial phase and the absence of the younger phases like those present in eastern argentina and south africa suggest that during the final deglaciation in gondwana thawing gradually progressed to the east then located closer to the paleopolar region

the applicability of the chemical index of alteration as a paleoclimatic indicator an example from the permian of the parana basin brazil abstract the chemical index of alteration cia was expressed as cia molar to become a more sensitive measure of the degree of chemical weathering the cia molar has the value of 1 for fresh feldspars and for unweathered non peraluminous igneous rocks but increases towards infinity as chemical weathering progresses the utility of this index as a humidity indicator for both modern and ancient muds was tested a database comprising 281 entries with chemical data for modern and ancient sediments deposited under arid semi arid semi humid and humid climate was assembled from the literature and used to calibrate the relationship between humidity and cia molar values for both modern and ancient sediments the histograms display a shift towards higher values with increasing geological indicators of humidity whereas sediments deposited under conditions inferred to be arid from other geological indicators show values tightly clustered around 1 the permian of the parana basin was then used as an example of the applicability of the cia molar for paleoclimatic studies major element analyses al2o3 k2o na2o cao were performed on 55 claystones and shales from three drill cores in a stratigraphic succession spanning the early to late permian the cia molar for these rocks accorded with expectations based on sedimentologic and paleontologic evidence discriminating well between arid and humid conditions in the basin independently determined from sedimentological and paleontological indicators the use of the cia molar as a paleo humidity indicator however can be limited by the presence of carbonate rich sediments the occurrence of post depositional k addition metasomatism metamorphism diagenetic illitization as well as by inheritance of clays from sedimentary rocks in the source area nevertheless with appropriate caution the cia molar is a useful tool for the assessment of the humidity conditions in the rock record

sedimentation in glacial environments and the identification of tills and tillites in ancient sedimentary sequences abstract tills and tillites are defined and subdivided into primary tills comprising lodgement tills melt out tills and sublimation tills and secondary tills comprising flow tills and deformation tills they are defined on the basis of their mode of deposition which endows them with their distinctive properties another category of till that of supra till is defined on the basis of its debris source derived supraglacially from valley sides and nunataks which gives these tills a coarse grained character the processes of till deposition and of outwash sedimentation are associated in several recurrent combinations which allow the definition of three principal glacial sediment associations and land systems which define the character of the sequences within which tills tend to occur the criteria which allow tills of different genesis to be identified and to be distinguished from non till diamictons are reviewed there are several features which are uniquely characteristic of till but unfortunately these are few it has been found generally necessary to employ an array of characteristics which though not individually unique to till when taken together can be strong evidence for particular till types the recognition of several typical and repetitive facies sequences which form in the major glacial sedimentary environments can also be important indicators of till genesis

classification seasonality and persistence of low frequency atmospheric circulation patterns abstract orthogonally rotated principle component analysis rpca of northern hemisphere 1 month mean 700 mb heights is used to identify and describe the seasonality and persistence of the major modes of interannual variability the analysis is detailed and comprehensive in that 1 a high resolution approximately equal area 358 point grid is used for the virtually maximum possible 35 year period of record 2 a positive bias in the nmc data base in the early 1950s in the subtropics is largely eliminated for the first time and 3 homogeneous separate analyses of each month of the year are carried out detailing the mouth to month changes in the dominant circulation patterns winter results are similar to those of other recent rpca and teleconnection studies except that some less obvious patterns are identified and further detail of the better known patterns is provided two north south dipole patterns are found over the pacific ocean west pacific oscillation and east pacific pattern and over the atla

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

depositional models for the glaciomarine sequences of andean late paleozoic basins of argentina abstract diamictite bearing late paleozoic sequences of probably glacial origin crop out in three basins of western argentina 1 the tarija basin 2 the calingasta uspallata basin and 3 the central patagonian basin the tarija section shows clear evidence of soft sediment deformation in a shallow marine environment slump overfolds and hook like and pull apart structures are common in lenses of well sorted sandstones within a sequence mostly composed of massive matrix supported pebbly mudstones the overall shallowing upward trend of the section suggests alluvial progradation underlying fine grained rocks represent quiet water prodelta deposits the diamictites suggest a delta slope position and the overlying red mudstones with cross bedded sandstones and conglomerates correspond to delta plain deposits in the calingasta uspallata basin the hoyada verde formation represents the best example of an ice contact glaciomarine depositional system with minor gravity flow deposits massive matrix supported sandy diamictites associated with a boulder pavement together with sandstone and conglomerate channels represent grounded ice deposits grading to subglacial flow tills thin bedded matrix supported muddy diamictites with dropstones are the product of a process of gravity resedimentation debris flows and ice rafting pebbly shales represent shelf sedimentation with local deposition from floating ice the ansilta formation shows characteristic features of low and high turbidity current dominated environments basal diamictites resemble debris flow deposits and are associated with thickening upward sequences of bouma tb c turbidites and massive sandstones with fluid scape structures these two sections described above represent the end members of a continuum from glaciomarine rocks to gravity induced deposits formed by subaqueous reworking of glacial debris fine grained rocks associated with diamictites contain marine fossils belonging to the livipustula zone of westphalian age middle carboniferous the central patagonian diamictites appear to be clearly associated with classical turbidites with bouma sequences resedimented conglomerates and high density turbidity current sandstones the conglomerates and sandstones form composite channels with common amalgamation and internal scour surfaces the depositional models proposed for the diamictite bearing sequences of the three basins can be placed in a broader model which embraces several types of complex interactions among glaciomarine nearshore and gravity flow dominated environments

facies petrophysical and geochemical properties of gravity flow deposits in reservoir analogs from the itarare group late carboniferous parana basin brazil abstract since many reservoirs do not allow direct observation due to their depth and or difficulty of sampling studies of analogs have been commonly used as a tool to understand the spatial distribution of reservoir properties the parana basin is 1 6 million km2 large and has two known petroleum systems however there are only 124 irregularly distributed wells drilled in the basin among which 22 contain gas or oil shows and 10 have sub commercial accumulations the permo carboniferous itarare group due to the exploration history is the best exploratory target in the basin because it has thick intervals of sandstones with moderate to good reservoir quality and also because it often lies directly on gas prone source rocks of the devonian ponta grossa formation in order to increase knowledge about itarare group reservoirs as well as to better understand its heterogeneities this study aims to integrate petrophysical data with facies and facies associations using both outcrop and cores from shallow wells in southeastern parana basin by doing this it is expected to fill a gap of quantitative data in previous studies on reservoir analogs in the itarare group cores and outcrops were analyzed in sandstones in order to integrate surface and subsurface data and to understand the lateral continuity according to stratigraphic correlations equipment such as gamma ray spectrometer portable x ray fluorescence and a minipermeameter were used for the acquisition of quantitative data sedimentological description of cores and outcrops as well as thin section description were also carried out the facies with the greatest reservoir potential are medium to fine grained massive sm and normally graded sg sandstones in one outcrop locality rio dos cedros the sg facies presents the best reservoir properties such as secondary porosity of 32 and average permeability of 1439 md the geochemical data allowed evaluating the gamma ray variation in relation to chemical elements such as iron oxide in outcrop api radiation is higher in relation to the cores as well as al2o3 and fe2o3 these values are related to the large amount of intraclasts and cementation by iron oxides hydroxides despite in the great amount of iron presents in the rio dos cedros samples the porosity is mainly secondary generated by the feldspars dissolution the correlation between the cores and outcrops allowed the evaluation of the influences of mass transport deposits in the petrophysical properties of sandstones in cores sandstones interbedded with these deposits have high permeability but it is not possible to evaluate its lateral continuity in outcrops it was possible to observe that these deposits affect lateral continuity permeability and porosity we conclude that the best reservoir facies in the itarare group will be associated with sites within the basin that are away from the slope region and the influence of mass transport processes

the statistical connection between tropospheric and stratospheric circulation of the northern hemisphere in winter abstract the associated anomaly patterns of the stratospheric geopotential height field and the tropospheric geopetential and temperature height fields of the northern hemisphere are determined applying the canonical correlation analysis with this linear multivariate technique the coupled modes of variability of lime series of two fields are isolated in the space of empirical orthogonal functions the one dataset is the 50 hpa geopotential height field the other set consists of different height fields of the tropospheric pressure levels 200 500 700 and 850 hpa and the temperature of the 850 hpa pressure level for the winter months december january february two natural coupled modes a barotropic and a baroclinic one of linear relationship between stratospheric and tropospheric circulation are found the baroclinic mode describes a connection between the strength of the stratospheric cyclonic winter vortex and the tropospheric circulation over the north atlantic the corresponding temperature

patterns of late palaeozoic deglaciation in the parana basin brazil abstract the itarare subgroup middle carboniferous early permian of the parana basin of southeastern brazil contains the thickest most extensive and one of the longest records of late palaeozoic glaciation in all of the gondwana supercontinent glacially controlled deposition started as early as the middle carboniferous when lobate termini of ice streams from the windhoek ice sheet wis and rio grande do sul and asuncion ice caps moved into the parana basin lobes reached sea level and advanced grounded at least as far as 200 km into the basin stabilizing as tidal intertidal margins glaciation and glacial sedimentation occurred penecontemporaneously with the transgressive phase of the late palaeozoic tectonic cycle of the parana basin while gondwana was gradually moving away from the south pole evolution involved complex interaction of tectonic palaeogeographic and palaeoclimatic factors initial flooding of the basin by an epicontinental sea in the middle carboniferous may have provided moisture necessary for the growth of glaciers conversely episodes of sea level rise probably affected the stability of marine glaciers the palaeoclimatic setting for the wis and other ice masses at the margins of the parana basin was mostly temperate multiple ice advances are evidenced by subglacial tillites resting on striated and or glaciotectonized basement and deformed glacigenic sediments identified at different stratigraphic levels in the itarare subgroup glaciation reached its maximum expansion sometime between the late carboniferous and early permian gradually diminishing and vanishing in the late early permian the reconstructed palaeogeographic evolution favors a model of irregular melt back of ice masses particularly along the eastern margin of the parana basin in analogy with the deglacial pattern of the pleistocene laurentide ice sheet in north america retreat of marine glaciers was mostly associated with relatively simple accumulations or complex build ups of ice contact proglacial facies associations in glacial estuarine embayments fast retreat was mainly controlled by decoupling associated with sea level rise and intense calving in the terrestrial environment more fragmentary evidence shows that retreat may have involved several mechanisms including downwasting of stagnant inactive ice margins and destabilization by surging of glaciers moving over deformable sediments highstand sea level following ice wastage is often marked by widespread deposition of relatively thin marine beds at least four stratigraphically different basinwide marine horizons are recognized isostatic rebound of deglaciated margins of the parana basin is recorded by transition from deep marine beds to shallowing coarsening upward prograding sequences of littoral fluvio deltaic facies basinwards sourced from raised basin margins eventually upon emersion these constituted platforms for interglacial and postglacial peat development although glaciation lasted for a long time glacial sedimentation alternated with relatively long periods of intense and widespread subaerial and subaquatic submarine reworking of previously deposited glacigenic sediments and deposition of normal non glacial sediments that comprise the bulk of the itarare subgroup sequence thin coal beds which locally rest on fossil soils denote climatic amelioration during these interglacial phases

variability of the observed midlatitude storm tracks in relation to low frequency changes in the circulation pattern abstract the principal modes of month to month variability of the wintertime storm tracks over the north pacific and north atlantic are identified by empirical orthogonal function analysis of the root mean square statistics of bandpass 2 5 6 day filtered geopotential height data for 19 yr one of the two leading modes depicts fluctuations in the level of synoptic scale activity without any noticeable spatial displacement of the storm track axes whereas the other mode is associated with meridional shifts of the storm tracks from their time averaged positions higher order modes are indicative of diversion or truncation of cyclone tracks in particular geographical regions it is demonstrated that the leading storm track modes are linked to some of the best known monthly averaged teleconnection patterns the dipolar western pacific and western atlantic patterns for the monthly mean flow are seen to be accompanied by marked changes in the intensity of the storm tracks over the western oceans whereas the m

polar vortex controls coupling of north atlantic ocean and atmosphere 1 the structure of the north atlantic leading atmospheric winter variability mode strongly depends on the state of the polar stratospheric vortex if the polar vortex is strong one teleconnection pattern emerges in the upper troposphere while two mostly independent ones appear when the vortex is weak the anomaly patterns associated with the different polarities of these modes show strong differences in the wind fields and in the correlation of atmospheric variability with the sea surface temperature of the north atlantic only when the polar vortex is strong does a basin wide tripole correlation pattern exist between tropospheric variability and sea surface temperature under weak vortex conditions one of the variability modes correlates with the subtropical the other with the subpolar gyre these results suggest that a nao index based on near surface pressure that fails to account for the state of the polar vortex is a suboptimal representation of the tropospheric circulation variability

ichnological signatures of shallow freshwater lakes in the glacial itarare group mafra formation upper carboniferous lower permian of parana basin s brazil abstract the upper carboniferous lower permian glacigenic deposits of the itarare group parana basin are widely known and cover an extensive area in the southern brazil these deposits consist of different arrangements of massive shales diamictites rhythmites and fine to medium grained sandstones with trough cross stratification five genetically distinct thickening locally coarsening upward successions of regular rhythmites can be distinguished in the mafra rio negro region santa catarina and parana states southern brazil representing the landward portion of an incised valley filled during deglaciation a low diversity invertebrate ichnofauna composed of a freshwater shallow burrow dominated suite and trackway dominated suite occurs in these rhythmites the freshwater shallow burrow dominated suite is composed of cochlichnus anguineus cruziana cf problematica gordia arcuata gordia marina hormosiroidea meandrica rusophycus cf carbonarius and treptichnus pollardi as well as undichnia consulca and intermittent rusophiciform traces it represents a mermia ichnocoenosis and occurs in the rhythmites of the upper sets commonly overlapped by d gouldi and d biformis in palimpsest preservation d gouldi and d biformis compose the trackway dominated suite which occur in all ichnofossiliferous paired mudstone siltstone of the basal sets of the rhythmite succession and in almost all of the upper sets it represents an atypical scoyenia ichnocoenosis and is generally preserved over microbially induced wrinkle structures the rhythmic deposition suggests distal underwater gravity flow deposits filling shallow lakes or ponds in depressed areas the siltstones deposited by melting currents and the mudstones by sediment fall out after the flux ceased the abundant wrinkle structures suggest quiet waters the overlying deposits bearing a brackish water ichnofauna and marine fossils suggest a coastal setting connected with the sea although atypical the occurrence of a scoyenia ichnocoenosis in almost all ichnofossiliferous rhythmite couplets preserved over wrinkle structures or overlapping mermia ichnocoenosis suggests that these shallow lakes were episodically dried up at least partially the present data allow interpreting the regular ichnofossiliferous rhythmites of the mafra formation as deposited in shallow lakes or ponds developed in outwash plains at the landward side of a fjord embayment during deglaciation

two key parameters for the el nino continuum zonal wind anomalies and western pacific subsurface potential temperature this is the author accepted manuscript the final version is available via springer at http link springer com article 10 1007 2fs00382 015 2550 0

development of the late paleozoic glaciations of the south american gondwana in western argentina abstract the late paleozoic ice age in the south american segment of gondwana consisted of several glaciations which can be grouped into two main glacial periods the oldest of them occurred in late early to early late carboniferous time and the younger in early permian time paleontological evidence in the western argentine precordillera supports a late visean age for the beginning and a probable early westphalian age for the end of the carboniferous glacial period in this span of time subsidence and deposition of glacial debris took place in the western mobile belt and in patagonia but no sediments of that age were deposited in the eastern portion of the south american gondwana where subsidence started later a carboniferous glacial sequence is remarkably well preserved in the san eduardo group on the western flank of the precordillera where at least three distinct glaciations are recognized this sequence can be taken as a reference section for the carboniferous glacial deposits shorter than the former and probably restricted to the asselian epoch the permian glacial period is better known the evidence for it is well developed in eastern south american gondwana although a relic is also present in the precordillera the recognition of two glacial periods within the late paleozoic ice age is supported by the existence of a long lasting interglacial which seemingly began in the late westphalian and lasted until the end of the carboniferous period this major interglacial period is inferred from the total absence of glacial features in the upper carboniferous sequences in spite of the existence of a mountainous belt parallel to the pacific during the carboniferous period the presence of marine beds and glacial drift well to the east of these ranges suggests that it was not altitude that was the main factor in determining the formation of glaciers but latitude plus a global change in temperature it is argued that the ice sheets extended greatly during the carboniferous glaciations and reached neighboring areas of the paganzo basin in central argentina

late paleozoic paleoclimatology of central west argentina abstract based on sedimentologic and paleontological characteristics present in the sedimentary record of the calingasta uspallata and paganzo basins a model of paleoclimatic evolution for the late paleozoic of central west argentina is proposed additional evidence is also provided by data from other basins of southern san rafael and tepuel basins and northern tarija basin west argentina five paleoclimatic stages have been defined paleoclimatic stage i tournalism visean early carboniferous is characterized by temperature and humid preglacial conditions as evidencedin the el raton and maliman formations calingasta uspallata basin plant remains of archeosigillaria and lepidodendropsis zone are present in both units the paleoclimatic stage ii namurian early westphalian middle carboniferous comprises widespread glacial deposits including glaciomarine sequence in the westernmost basins calingasta uspallata western paganzo san rafael and tepuel and terrestrial tillites and glaciolacustrine fine clastics in some areas of the paganzo basin fossils of the levipustula fauna are distinctive in the glaciomarine deposits of this stage and in the overlying postglacial fine clastics of the basal portion of stage iii substage iiia the paleoclimatic stage iii of middle carboniferous late westphalian age corresponds to postglacial transgressions that flooded the previously glaciated shelves in the calingasta uspallata and tepuel basins terminal glaciolacustrine deposits substage iiia indicate of the demise of glacial conditions and coal measures of fluvial affinity in the paganzo basin substage iiib probably this postglacial stage was characterized by high humidity and moderate temperatures this stage is paleobiologi defined by a floral assemblage known as nbg nothorhacopteris botrychiopsis and ginkgophyllum the paleoclimatic stage iv late carboniferous stephanian early permian corresponds to a time interval characterized by seasonally dry climates and a progressive amelioration in humidity clear evidence of these climatic conditions is present in several localities in the paganzo basin the first astherothecae and glossopteris leaves are found finally paleoclimatic stage v middle late permian is dominated by red beds thick eolian sequences and saline lake facies deposited under arid to semi arid conditions coeval volcanism derived from the west is expressed by interbedded tuffs and agglomerates calingasta uspallata paganzo and san rafael basins

an assessment of the impact of transient eddies on the zonal flow during a blocking episode using localized eliassen palm flux diagnostics abstract the eliassen palm e p flux applied to zonal men flows is an indicator of both the flux of eddy activity and the eddy forcing of the zonal mean flow for time mean flows a localized e p flux is derived and used diagnostically to assess the impact of transient eddies on a major blocking episode that occurred over the south pacific during the southern hemisphere winter of 1979 in contrast to previous studies that have focused on the mean quasi geostrophic potential vorticity equation the focus here is on the mean momentum equations eddy transports and the associated induced meridional circulation and other internal adjustments necessary to maintain the thermal wind balance are gathered together allowing the residual circulation and the effects of the eddies to be determined the time mean equations of motion are thus transformed to consist of mean terms the residual circulation and the divergence of a localized e p flux vector the latter is a measure of the eddy forcing of the mean flow

anomalous tropical ocean circulation associated with la nina modoki 1 el nino modoki is a variant of el nino characterized by warming around the dateline flanked by anomalous cooling in the east and west however the opposite phase la nina modoki has received little attention because the prominent cooling of sea surface temperature sst during major la nina events is observed in the central pacific and thus it is difficult to define the two different types of cold events from the sst anomaly pattern here we demonstrate that cold events in 2000 and 2008 can be clearly distinguished from traditional la nina events using surface currents derived from satellite observations during 2000 and 2008 anomalous zonal currents in the equatorial pacific demonstrate divergence with westward currents west of the dateline and eastward currents east of it these currents are opposite to the circulation pattern during the 2004 el nino modoki event an empirical orthogonal function eof analysis of surface currents for the period 1993 2009 shows a circulation anomaly pattern similar to that in 2000 2004 and 2008 in the second eof the first eof is consistent with traditional el nino la nina events and does not exhibit a current reversal along the equator our results also indicate that strong cyclonic anticyclonic circulation anomalies occur in the tropical western pacific around 5 n 15 n during the 2004 2000 and 2008 el nino la nina modoki events and during the strong traditional el nino la nina events of 1997 1998 these circulation anomalies are related to an sst gradient in the western and central pacific

roles of enso and pdo in the link of the east asian winter monsoon to the following summer monsoon abstractthe present study investigates the roles of el nino southern oscillation enso and the pacific decadal oscillation pdo in the relationship between the east asian winter monsoon eawm and the following east asian summer monsoon easm the variability of the eawm is divided into an enso related part named eawmen and an enso unrelated part named eawmres corresponding to a weak eawmen an anomalous low level anticyclone forms over the western north pacific wnp and persists from winter to the following summer this anticyclone enhances southerlies over the coast of east asia in summer hence a weak eawmen tends to be followed by a strong easm and vice versa as such a link is established between the eawmen and the easm the persistence of this wnp anticyclone may be mainly attributed to the sea surface temperature anomalies associated with the enso related eawm part in the tropical indian ocean and the extratropical north pacific in contrast corresponding to a weak eawmres the anomalous wn

contributions of downstream eddy development to the teleconnection between enso and the atmospheric circulation over the north atlantic abstractthe spatiotemporal evolution of various meteorological phenomena associated with el nino southern oscillation enso in the north pacific north american north atlantic sector is examined using both ncep ncar reanalyses and output from a 2000 yr integration of a global coupled climate model particular attention is devoted to the implications of downstream eddy developments on the relationship between enso and the atmospheric circulation over the north atlantic the el nino related persistent events are characterized by a strengthened pacific subtropical jet stream and an equatorward shifted storm track over the north pacific the wave packets that populate the storm tracks travel eastward through downstream development the barotropic forcing of the embedded synoptic scale eddies is conducive to the formation of a flow that resembles the negative phase of the north atlantic oscillation nao the more frequent and higher persistence of those episodes during el nino winters contribute to the prevale

intertidal boulder pavements in the northeastern gulf of alaska and their geological significance abstract striated boulder pavements consisting of planar concentrations of clasts having striated upper surfaces are a common feature of glacigenic deposits but their origin is not well understood laterally extensive pavements are currently forming in the intertidal zone west of icy bay in the gulf of alaska pavements comprise armoured layers of interlocking boulders one clast thick that have been eroded from underlying outcrops of late cenozoic glaciomarine diamictites they originate essentially as lag surfaces along a high energy storm dominated mesotidal shoreline boulder pavements are either flat or show a nucleated plan form where successively smaller boulders have been accreted around a large core boulder nucleation imparts a hummocky surface topography to the pavements and suggests that some form of size sorting of clasts has occurred packing is promoted by repeated tamping of the clast lag by floating masses of glacier ice which become grounded across the intertidal zone at low tide repeated abrasion of the pavement surface by debris contained within ice blocks produces smooth flattened clast upper surfaces and short randomly oriented striations data from icy bay can be used to constrain the origin of laterally extensive boulder pavements exposed in late cenozoic glaciomarine sediments on middleton island the significance of such pavements in the geologic record is that they form along erosional unconformities and may identify sequence boundaries

seasonal modulations of different impacts of two types of enso events on tropical cyclone activity in the western north pacific the paper examines different impacts of eastern pacific warm cold epw epc and central pacific warm cold cpw cpc events on tropical cyclones tcs in the western north pacific wnp by considering the early season of april june amj the peak season of july september jas and the late season of october december ond during amj epw epc is associated with a significant increase of the tc genesis number in the southeastern southwestern sub region of the wnp but no class of el nino southern oscillation enso events shows a significant change in the tc lifetime and intensity during jas epw corresponds to an increase decrease of the tc genesis number in the southeastern northwestern sub region but cpw shows no significant change epc increases the tc genesis in the northwestern and northeastern sub regions and decreases the genesis in the southwestern sub region whereas cpc suppresses the genesis in the southeastern sub region both the lifetime and intensity of tcs are increased in epw but only a shortened lifetime is seen for cpc during ond epw reduces the tc genesis in the southwestern and northwestern sub regions whereas cpw enhances the genesis in the southeastern sub region over the south china sea cpw and cpc show a significant decrease and increase of the tc genesis respectively the tc lifetime is significantly longer in both epw and cpw and shorter in epc and tcs tend to be more less intense in epw cpc all of these variations are consistent with the development of enso related sst anomalies during different seasons and are supported by distributions of the genesis potential index a combination of large scale oceanic and atmospheric factors that affect tc activity tcs in the wnp mainly take the straight westward northwestward and recurving tracks during amj of epw years the tc steering flow patterns favor the recurving track and suppress the straight westward and northwestward tracks during jas epw is associated with the steering flows that are unfavorable for tcs to move northwestward or westward whereas cpw favors the northwestward track and suppresses the straight westward track the steering flow patterns during ond are similar to those during jas except that epc may increase the possibility of the northwestward track

nature and classification of waterlain glaciogenic sediments exemplified by pleistocene late paleozoic and late precambrian deposits this study of waterlain glaciogenic sediments is designed to present both a review and new information on glaciogenic subaquatic deposits of differing age in a number of localities in north and south america and south africa the late paleozoic glaciogenic deposits of the parana basin in brazil and the karoo basin of south africa are singled out for special attention as they show a reasonably complete lateral sequence of terrestrial to off shore glaciogenic sedimentation although the environment of subaquatic glaciogenic sedimentation varies from one area to the next certain common elements are found which can be used to develop a generalized model for both glaciomarine and glaciolacustrine sedimentation for descriptive purposes the model is divided into two broad categories a shelf facies and a basinal facies the shelf facies is marked by massive diamicton ite which may be 200 m or more in thickness and which is frequently overlain by a complex of clastic sediments consisting primarily of gravity and fluid flows the basinal facies is marked by products of subaquatic slumps and more distal turbidites and glaciomarine sediments new terminology is introduced the massive diamicton ite which is diagnostic of the shelf facies probably represents deposition from the base of active ice in a subaquatic environment and is termed undermelt diamicton ite the gravity and fluid flows which are usually found overlying undermelt diamicton ite and in the basinal facies are subdivided into six categories glaciogenic subaquatic outwash glaciogenic suspension flow glaciogenic chaotic debris flow glaciogenic subaquatic debris flow glaciogenic slurry flow and glaciogenic turbidity flow the relative abundance of undermelt diamicton ite and the various types of gravity and fluid flows can be used to define inner shelf outer shelf inner basin and outer basin facies of glaciomarine sedimentation

floral diversity data in the assessment of paleoclimate in the parana basin southern brazil abstract the comparative analysis of floral diversity data on permian rocks from the parana basin brazil and nine australian basins revealed that the south american and the australian basins bear completely different floral diversity signatures the parana basin displays a peak in microfloral diversity during deposition of the coal bearing rio bonito formation followed by a steady decrease during the middle and late permian whereas diversity in australia remained high throughout the permian these data suggest that while the flora in the parana basin was submitted to more stressful conditions as the continent moved from humid temperate zones into subtropical desertic ones the flora in australia thrived under persistently humid conditions therefore the increased aridity recorded by the permian rocks in the parana basin is more likely to be due to the northward migration of western gondwana across climate zones rather than a global trend throughout the permian

impact of enso on the atmospheric variability over the north atlantic in late winter role of transient eddies abstractthe dynamical mechanism for the late winter teleconnection between el nino southern oscillation enso and the north atlantic oscillation nao is examined using the output from a 2000 yr integration of a coupled general circulation model gcm the coupled model captures many salient features of the observed behavior of both enso and nao as well as their impact on the surface climate in late winter both the observational and model data indicate more occurrences of negative phase of nao in late winter during el nino events and positive nao in la nina episodes the potential role of high frequency transient eddies in the above teleconnection is diagnosed during el nino winters the intensified transient disturbances along the equatorward shifted north pacific storm track extend their influences farther downstream the eddy induced negative height tendencies are found to be more coherent and stronger over north atlantic than that over north pacific these negative height tendencies over the north

an extension of the airy theory for linear waves into shallow water as a fully developed airy wave propagates from deep into shallow water its crest becomes more peaked while the trough flattens out the median crest diameter mcd defined as the distance between the wave flanks under the crest at a level halfway between the crest and trough therefore decreases relative to the similarly defined median trough diameter mtd which remains constant up to the breaking point the mcd is directly related to other wave characteristics which enables water particle velocities to be calculated for any water depth without having to recur to more complex higher order stokes cnoidal or fenton theories over a nearly horizontal bottom most fully developed wave characteristics can be expressed as functions of the wave period tw it is shown that the horizontal particle velocity at the bottom under the breaker crest is at least 9 times faster than under the breaker trough which explains why sediment is transported landward under fair weather conditions the proposed equations also shed new light on the formation of spilling plunging and surging collapsing breakers

models of glaciomarine sedimentation and their application to the interpretation of ancient glacial sequences abstract this paper argues that glaciomarine environments can be regarded as special glacially influenced types of continental margin environments e g continental shelf slope rise and basin plain knowledge of the stratigraphic architecture and typical sedimentary sequences of non glacial margins is becoming well known but remains limited for those that have been glacially modified the principal influences on sedimentation in these environments relate to the glacial sediment input controlled by relief of basin margin glacier thermal regime and ice flow dynamics and depositional environments influence of traction currents substrate relief and proximity to nearby ice margins typical ranges of sedimentation rates can be established for glacially influenced continental margin environments and these may provide a framework for ancient sequences starvation of sediment supply to glacially influenced continental margins is common the nature of sub ice shelf sedimentation a model that has been applied to many ancient glacial sequences is critically reviewed the significance of such sedimentation in the rock record has probably been exaggerated because of oversimplistic interpretations of diamictite sequences existing process models of glaciomarine sedimentation derived from study of modern environments are sometimes difficult to employ in investigation of ancient sedimentary sequences because simple lithofacies criteria and typical vertical profiles are not available to aid in interpretation in addition compositional data emphasized by many workers for distinguishing glaciomarine from continental glacial diamict ite s frequently fingerprint sediment source and not mode of deposition the importance of facies analysis methods for isolating depositional environments is illustrated by three examples of ancient glaciomarine sequences these are the early proterozoic gowganda formation 2 3 ga of northern ontario canada the late proterozoic port askaig formation 670 ma of scotland and ireland and the late cenozoic yakataga formation 20 ma to recent of the gulf of alaska these examples illustrate the significance of detailed genetic studies of ancient glacial rocks in the interpretation of palaeogeographic and tectonic settings diamictite units in ancient glaciomarine sequences cannot be easily interpreted in terms of climatic or ice advance retreat cycles because of the varied controls on diamict accumulation and diamictite preservation in marine basins

observational constraints on the tropospheric and near surface winter signature of the northern hemisphere stratospheric polar vortex a composite analysis of northern hemisphere s mid winter tropospheric anomalies under the conditions of strong and weak stratospheric polar vortex was performed on ncep ncar reanalysis data from 1948 to 2013 considering as additional grouping criteria the coincidental states of major seasonally relevant climate phenomena such as el nino southern oscillation enso quasi biennial oscillation and strong volcanic eruptions the analysis reveals that samples of strong polar vortex nearly exclusively occur during cold enso states while a weak polar vortex is observed for both cold and warm enso the strongest tropospheric and near surface anomalies are found for warm enso and weak polar vortex conditions suggesting that internal tropospheric circulation anomalies related to warm enso constructively superpose on dynamical effects from the stratosphere additionally substantial differences are found between the continental winter warming patterns under strong polar vortex conditions in volcanically disturbed and volcanically undisturbed winters however the small size samples obtained from the multi compositing prevent conclusive statements about typical patterns dominating effects and mechanisms of stratosphere troposphere interaction on the seasonal time scale based on observational reanalysis data alone hence our analysis demonstrates that patterns derived from observational reanalysis time series need to be taken with caution as they not always provide sufficiently robust constraints to the inferred mechanisms implicated with stratospheric polar vortex variability and its tropospheric and near surface signature notwithstanding this argument we propose a limited set of mechanisms that together may explain a relevant part of observed climate variability these may serve to define future numerical model experiments minimizing the sample biases and thus improving process understanding

lacustrine turbidites in the green river formation northwestern colorado a preliminary study of drill cores of blebby and streaked oil shale from the green river formation eocene in the deep northern part of the piceance creek basin colorado shows sedimentary structures that suggest deposition by turbidity currents this type of oil shale composes about one half of the oil shale deposits at the saline depocenter of eocene lake uinta where it is interbedded with the well known laminated type of oil shale described previously in the literature episodic and rapid deposition by lake bottom currents of large amounts of carbonate silicate sediments that formed high grade oil shale is a new concept for the origin of a major part of the green river oil shale deposits in contrast the laminated oil shale as previously described accumulated very slowly as thin varves in a chemically stratified lake under stagnant conditions

on the three dimensional propagation of stationary waves abstract a locally applicable nonzonally averaged conservation relation is derived for quasi geostrophic stationary waves on a zonal flow a generalization of the eliassen palm relation the flux which appears in this relation constitutes it is argued a useful diagnostic of the three dimensional propagation of stationary wave activity this is illustrated by application to a simple theoretical model of a forced rossby wave train and to a northern hemisphere winter climatology results of the latter procedure suggest that the major forcing of the stationary wave field derives from the orographic effects of the tibetan plateau and from nonorographic effects diabatic heating and or interaction with transient eddies in the western north atlantic and north pacific oceans and siberia no evidence is found in the data for wave trains of tropical origin forcing by the orographic effects of the rocky mountains seems to be of secondary importance

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

steady linear response to tropical heating in barotropic and baroclinic models abstract the atmospheric response to tropical heating is examined using both the linear multilevel baroclinic model with an imposed tropical heat source and the one level barotropic model with a tropical divergence forcing the divergent component of the response in the baroclinic model is characterized by a tropical divergence confined to the heated region plus convergence and divergence centers away from the tropical heated region at the outflow level the rotational component of the response is depicted by a local baroclinic response in the tropics and a remote equivalent barotropic wave train in the extratropics the barotropic model responses to a fixed tropical divergence are highly sensitive to the strength of the zonal mena zonal flow at different vertical levels in the upper troposphere the sensitivity is induced by the dependence of the propagation speed of the stationary rossby wave rays on the strength of the zonal mean zonal flow the barotropic response to a tropical divergence when line

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

a simple method to determine breaker height and depth for different deepwater wave height length ratios and sea floor slopes existing easily applicable methods to calculate the depth and height of breaking waves are hampered by two obstacles first the breaker depth is usually required to compute its height and vice versa second the equations take into account either the deepwater height to wavelength ratio or the sea floor slope but not both a simple iterative procedure is therefore proposed which incorporates both elements for fully developed waves breaking over a nearly horizontal bottom the breaker height and depth are also direct functions of the deepwater wavelength

a simple method to determine breaker height and depth for different wave height length ratios and sea floor slopes reply to discussion by m c haller and p c catalan

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

influence of el nino modoki on spring rainfall over south china 1 using observed data sets from 1979 to 2006 the relationship between el nino modoki and spring rainfall over south china sc is investigated of particular interest is the difference in the influence on spring rainfall of typical el nino events and the recently recognized el nino modoki events which are characterized by distinct warm sea surface temperature anomalies ssta in the central pacific and weaker cold anomalies in the western and eastern parts of the basin associated with the ssta anomalous ascent occurs over the central pacific and downward flow is observed over the eastern and western pacific the anomalous flow is associated with anomalous convergence in the upper troposphere over the western pacific sc is influenced by an anomalous anticyclonic circulation with prevailing northeasterly anomalies the convective activity in sc becomes weaker resulting in reduced rainfall however the situation is different in the case of el nino in terms of the influence on rainfall over sc while el nino modoki events are accompanied by a significant reduction in rainfall over sc there is enhanced rainfall associated with el nino events moreover there exists a strong asymmetry in the relationship between sc spring rainfall typical el nino southern oscillation enso and enso modoki events it appears that these relationships are only statistically significant for positive events the asymmetric influence of positive and negative in two enso phenomena may explain the difference in their respective relationships with spring rainfall over sc

the shape propagation and mean flow interaction of large scale weather systems abstract for a zonal average operator the eliassen palm flux provides a diagnostic of both eddy behavior and the feedback of the eddies onto the mean flow this paper addresses the diagnosis problem for other averaging operators and in particular for time averaging which has proved in recent years such a powerful means of viewing the three dimensional tropospheric flow the horizontal velocity correlation tensor gives a measure of the characteristic horizontal eddy shape at a point it also implies the direction of the group velocity relative to the mean flow in cases where such a concept is valid however the major emphasis here is on the mean flow feedback of eddies in this respect the eddy vorticity flux is determined by derivatives of the components of the anisotropic part of the tensor making a reasonable approximation allows the eddy vorticity flux convergence to be written in terms of e v 2 u 2 u v a simple interpretation of the mean flow feedback of eddies is then possible a sligh

anomalous winter climate conditions in the pacific rim during recent el nino modoki and el nino events present work compares impacts of el nino modoki and el nino on anomalous climate in the pacific rim during boreal winters of 1979 2005 el nino modoki el nino is associated with tripole dipole patterns in anomalies of sea surface temperature precipitation and upper level divergent wind in the tropical pacific which are related to multiple boomerangs of ocean atmosphere conditions in the pacific zonal and meridional extents of those boomerangs reflect their independent influences which are seen from lower latitudes in the west to higher latitudes in the east in the central pacific more moisture is transported from the tropics to higher latitudes during el nino modoki owing to displacement of the wet boomerang arms more poleward toward east discontinuities at outer boomerang arms manifest intense interactions between tropical and subtropical extratropical systems the pacific north american pattern and related climate anomalies in north america found in earlier studies are modified in very different ways by the two phenomena the seesaw with the dry north and the wet south in the western usa is more likely to occur during el nino modoki while much of the western usa is wet during el nino the moisture to the southwestern usa is transported from the northward shifted itcz during el nino modoki while it is carried by the storms traveling along the southerly shifted polar front jet during el nino the east asian winter monsoon related anticyclone is over the south china sea during el nino modoki as compared to its position over the philippine sea during el nino causing opposite precipitation anomalies in the southern east asia between the two phenomena

late paleozoic glaciotectonic structures in northern parana basin brazil abstract fluviatile deltaic sediments containing thin coal layers and glaciofluvial sediments of the itarare subgroup late paleozoic cropping out near cerquilho northern parana basin exhibit post depositional deformation such as recumbent and drag folds shear fractures faults and shear lamination the deformation occurs in an interval of 3 4 m thick and is confined between horizontal strata the deformed strata are directly overlain along a horizontal erosional tectonic contact surface by a silty sandy massive 1 m thick clast poor tillite deformation shows a consistent geometry indicating a predominant vergence toward the ssw having been developed under a horizontal stress oriented from nne to ssw the deformation is interpreted to be of glaciotectonic origin associated with an ice readvance in the area the glacier moved toward the ssw on relatively soft deformable sediments depositing the subglacial till on top of them the tillite shows parallel upglacier dipping shear fractures at its base and wedge like intrusions into the underlying sandstone probably formed during its subglacial deposition the tillite is overlain by cyclic braided stream fluviatile sandstone beds the top of these shows deformations small recumbent folds and reverse faults below another clast poor silty sandy tillite this could represent another glacial readvance with subglacial deposition of till occurrence of glaciotectonic deformation overlain by subglacially deposited tillites in the cerquilho area indicates glacier readvances and permanence of the glacial influence in the upper part of the itarare subgroup absence of incorporated material from the underlying deformed sediments in the tillite and the style of the deformations suggest an unfrozen water saturated mostly unconsolidated substratum these conditions may have generated instability and fast ice flow of the glacier they also suggest that the sediment may have most likely failed in this manner under rapidly applied stresses associated with a surging behavior of the retreating glacier

patterns of late paleozoic glacial sedimentation on the southeast side of the parana basin brazil abstract during the late paleozoic glaciation glaciers moved from southern africa over a platform composed of crystalline and sedimentary rocks into the subsiding parana basin of southeastern brazil in each successive glacial advance the platform was eroded and is marked by crescentic gouges striae roches moutonnees grooves and glacially modified valleys the glacial sediments which are found on the platform in southeastern brazil and margins of the parana basin were deposited from grounded ice and are termed terrestrial these sediments which are best exposed in the northern part of the study area are composed of supraglacial deposits such as layers of diamictite flow tillite interbedded with sandstones and minor amounts of lodgement tillite the supraglacial deposits are frequently faulted and the sandstones show pull apart structures and abnormal dips these features and others suggest that ice retreat in the terrestrial environment was primarily by down wasting the glaciogenic sediments found within the subsiding parana basin are termed basinal even though it is not certain that they were all deposited in a subaquatic environment they are composed primarily of sandstones siltstones shales and mudstones interbedded with massive and laminated diamictites it is suggested that the massive diamictite was deposited from the base of the advancing glaciers by basal melting during ice retreat from water filled parts of the basin unstable masses of glaciogenic debris flowed down slope resulting in layered debris flows and in some instances chaotic debris flows which may have been triggered by subaquatic slupms and slides as the ice continued to retreat to the margin of the basin a complex of subaquatic outwash including deltaic sands was deposited minor varvites were deposited in shallow restricted embayments in the shoreline which were flooded with fresh glacial meltwaters deposits of retreat including the varvites interfinger with marine fossiliferous sediments which suggests that the water level in the basin was rising during deglaciation it is not known how may times glaciers advanced into the parana basin but recent studies show that there were at least nine glaciations in the northern part of this study area covering a time span of from 10 to 35 million years

palaeolimnology of palaeozoic lakes focussing on a single lake cycle in the middle devonian of the orcadian basin scotland there are few palaeolimnological studies of palaeozoic lake deposits using methodologies developed for the study of quaternary lakes new research described here indicates the benefits of applying multidisciplinary high resolution sampling and analysis on the middle devonian lake deposits of the orcadian basin in order to understand lake palaeoecology and response to water chemistry change and possible climate change in a continuously sampled 4 m thick lake cycle in two correlated boreholes in caithness there are two distinct features there is a broad trend in 13c of sedimentary organic matter from high values in the shallow water deposits to lower values in the deeper water deposits attributed to changing contributions from terrestrial plant material 13corg c 28 and algal material 13corg c 33 this variation is consistent with palynological data and is best explained by proximal distal variation as the lake filled a smaller but well correlated up section decreasing 13corg trend occurs over approximately 1 m starting at the cycle centre where the lake was at its deepest since the same feature is seen in two boreholes we suggest that local effects of migrated bitumen diagenesis or facies changes are unlikely to be the cause and that changes in the carbon cycle of the lake are responsible explanations for this trend may relate to the source of carbon that algae utilised as the lake changed from a fresher to a more saline environment and to changes in the carbon isotope composition of the lake water during periods of enhanced productivity

late ordovician glaciomarine deposits orea shale in the sierra de albarracin spain abstract a description and interpretation is given of marine fragment bearing arenaceous shales occuring near the ordovician silurian boundary in northeast spain these deposits known as the orea shales have been reported before as non glacial or questionably glaciomarine sedimentary features and scanning electron microscopical examination of quartz grains however reveal that much of the debris has been supplied by ice rafting paratillite close similarity between these spanish deposits and coeval normandian paratillites supports the theory that the iberian peninsula and northwest france belonged to one depositional realm probably forming a microcontinent armorica separated from the glaciated gondwanaland

analysis of the nonlinearity of el nino southern oscillation teleconnections abstractel nino southern oscillation enso has significant variations and nonlinearities in its pattern and strength enso events vary in their position along the equator with some located in the central pacific cp and others in the east pacific ep to study how these variations are reflected in global enso teleconnections both observations and idealized atmospheric general circulation model agcm simulations are analyzed clear nonlinearities exist in observed teleconnections of sea level pressure slp and precipitation however it is difficult to distinguish if these are caused by the different signs strengths or spatial patterns of events strong el nino events mostly being ep events and strong la nina events mostly being cp events or by combinations of these therefore sensitivity experiments are performed with an agcm forced with idealized ep and cp enso sea surface temperature sst patterns with varying signs and strengths the response is generally stronger for warm events than for c

the relationship between the north atlantic oscillation and el nino southern oscillation we have applied a multiresolution cross spectral analysis technique to resolve the temporal relationship between the nao and enso the study shows significant coherence between nao and nino3 sst in about 70 of the warm enso events from 1900 to 1995 of which 33 and 37 are associated with a 5 to 6 year period e1 and a 2 to 4 year period e2 oscillation terms in the spectral decomposition respectively the dominant teleconnection pattern associated with changes in the mean atmospheric circulation during the initial winter of a typical e1 and e2 events is the positive phase of the pacific north american pna pattern non coherence between the nao and enso occurs during relatively weak nino3 sst anomaly with a teleconnection pattern which shows a strong negative phase of the nao and a pattern which resembles a weak eastward shifted negative phase of the pna pattern