antarctic circumpolar waves an indication of ocean atmosphere coupling in the extratropics recent observational studies have detected coherent oceanic and atmospheric antarctic circumpolar waves acws which propagate eastward at speeds of 6 8 cm s 1 with a circumpolar wavenumber of 2 analysis of global wind data suggests that the acws are not remotely forced by tropical el nino activity through atmospheric teleconnection rather a coupled instability of the antarctic circumpolar current and its overlying atmospheric motion is proposed to be responsible for the generation of the acws the phase relationship among the observed oceanic and atmospheric variables supports the coupled instability theory this study provides one clear example that extratropical ocean atmosphere dynamical coupling is essential in generating climate variations on time scales of several years and longer

quasi periodicity and global symmetries in interdecadal upper ocean temperature variability recent studies find interannual i e 3 to 7 year decadal i e 9 to 13 year and interdecadal i e 18 to 23 year periodicities and a trend dominating global sea surface temperature sst and sea level pressure slp variability over the past hundred years with the interdecadal signal dominating sub el nino southern oscillation enso frequencies we isolate interdecadal frequencies in sst and slp records by band passing with a window admitting 15 to 30 year periods from 1900 to 1989 the rms of interdecadal filtered sst and slp anomalies is largest in the extratropics and eastern boundaries first mode empirical orthogonal functions eofs explain about half the interdecadal variance in both variables with the tropical warm phase peaking near 1900 1920 1940 1960 and 1980 from 1955 to 1994 eof spatial patterns of interdecadal sst slp and 400m temperature t400 anomalies reveals global reflection symmetries about the equator and global translation symmetries between ocean basins with tropical and eastern ocean ssts warmer cooler than normal covarying with stronger weaker extratropical westerly winds cooler warmer ssts in western central subarctic and subantarctic frontal zones safzs stronger weaker subtropic and subarctic gyre circulations in north pacific and north atlantic oceans and warmer cooler basin and global average ssts of 0 1 c or so evolution of interdecadal variability from the tropical warm phase to the tropical cool phase is propagative also characterized by reflection and translation symmetries during the tropical warm phase cool sst anomalies along western central safzs are advected slowly eastward to the eastern boundaries and subsequently advected poleward and equatorward by the mean gyre circulation the latter conducting extratropical sst anomalies into the tropics a delayed action oscillation model is constructed that yields the quasiperiodicity of interdecadal variability in a manner consistent with these global symmetries in both pattern and evolution

radium isotopes to investigate the water mass pathways on the kerguelen plateau southern ocean abstract natural iron fertilization promotes the phytoplankton bloom that takes place on the kerguelen plateau in the indian sector of the southern ocean we measured 228 ra t 1 2 5 75 yr and 226 ra t 1 2 1602 yr in waters above the kerguelen plateau in order to provide information on the water mass pathways which in turn could help elucidate the mechanisms controlling iron fertilization in that area 228 ra activities are extremely low in this region being in most cases 18 g kg station a3 520 m depth located on the plateau in the middle of the bloom area also displays such low values but with higher 228 ra activities and higher 228 ra 226 ra ratios in the upper 150 m such a pattern suggests the presence of a water mass that recently interacted with sediments and therefore has been advected onto the kerguelen plateau elevated 228 ra activities were found in shallow waters in the vicinity of heard island south of the kerguelen plateau contact of the water masses with the shallow lithogenic sediments likely explains these high 228 ra activities when combined with physical observations these results suggest that the water mass advected onto the plateau originates from the south of the kerguelen plateau this northward advection might represent a supply of dissolved and or particulate fe for the observed phytoplankton bloom using the 228 ra profile obtained at station a3 we could estimate the vertical eddy diffusivity k z on the kerguelen plateau our k z estimate 1 5 10 4 1 3 10 4 m 2 s compares well with that reported by park et al 2008a internal tides and vertical mixing over the kerguelen plateau deep sea research ii doi 10 1016 j dsr2 2007 12 027 based on ctd ladcp data by combining this k z estimate with the gradient of dissolved fe observed at a3 blain s sarthou g laan p 2008 distribution of dissolved iron during the natural iron fertilization experiment keops kerguelen plateau southern ocean deep sea research ii doi 10 1016 j dsr2 2007 12 028 we calculate a vertical fe flux of 1 0 14 3 nmol m 2 d

an improved real time global sea surface temperature analysis abstract the monthly global sea surface temperature sst analysis of reynolds using real time in situ and satellite sst data has now been improved by using sea ice data to simulate ssts in ice covered regions the simulated ssts now become the external boundary condition for the analysis solution this technique eliminates any high latitude satellite biases and extends the analysis to the ice edge the analysis with the ice data has been computed for the period january 1982 to present

evolution of the enso signal over the indo pacific domain abstract the evolution of the el nino southern oscillation enso in the indian and western pacific oceans is investigated observations of sea surface temperature sst heat storage in the upper 400 m hs zonal surface wind stress zsws and meridional surface wind stress msws are mapped monthly onto a 2 latitude longitude grid over as much of the indian and western pacific oceans i e 40 s 50 n 40 e 180 as possible for a 13 year period 1979 91 this grid resolution allows upper ocean temperature variability to be resolved in the eastern indian ocean i e timor sea and the western pacific ocean i e philippine sea time sequences of these variables at each grid node are band passed filtered to yield the enso period scales of 3 to 6 years extended empirical orthogonal functions analysis is applied to the filtered time sequences yielding an animation of the enso development in indian and western pacific oceans for the first modes of the four variables sst hs zsws and msws peak a

interaction of the monsoon and pacific trade wind system at interannual time scales part iii a partial anatomy of the southern oscillation abstract studies of surface wind fields sea surface temperature sst precipitation and sea level pressure in the tropical band extending 30 of the equator from africa to south america led to the following conclusions the southern oscillation el niflo and climatic variations in the monsoon system are all part of one global scale phenomenon the new information is that this phenomenon appears in the sea level pressure field to have a strong propagating component that appears first in the northern indian ocean and moves eastwardinto the eastern pacific similar propagation of information was found in the surface wind field and equatorial precipitation regimes these same conditions were amply demonstrated during the 1982 83 event and so it may be concluded that the evolution of that event bears many similarities to those in the historical record studies referred to in this paper in the surface wind field of the equatorial wave guide the large scale signal appears to take the form of a forced kelvin

platform collapse and pelagic seamount facies jurassic development of central tunisia abstract in central tunisia the lower liassic facies consists of peritidal carbonates deposited on a wide platform which has been broken into irregular tilted blocks in the early pliensbachian black shale was deposited in some of the down faulted blocks during the early toarcian oceanic anoxic event the bajocian bathonian deposits are represented by ironstones and hemipelagic ammonite and zoophycos rich marl limestones the upper jurassic is composed by pelagic limestones and debris flow deposits the middle jurassic deep marine sedimentation was frequently associated with condensed sections submarine erosion leading to stratigraphic hiatuses the latter results from the interaction between global sea level fluctuations and regional tectonic activity generating an uplifted block in central tunisia in relation with early mesozoic rifting and associated distensional drifting of the north african tethyan margin this horst block has acted as a starved pelagic shoal on which sedimentation has been recorded especially during retrogradational and the aggradational phases

the antarctic circumpolar wave a beta effect in ocean atmosphere coupling over the southern ocean the antarctic circumpolar wave acw is a nominal 4 yr climate signal in the ocean atmosphere system in the southern ocean propagating eastward at an average speed of 6 8 cm s21 composed of two waves taking approximately 8 years to circle the globe the acw is characterized by a persistent phase relationship between warm cool sea surface temperature sst anomalies and poleward equatorward meridional surface wind msw anomalies recently white and chen demonstrated that sst anomalies in the southern ocean operate to induce anomalous vortex stretching in the lower troposphere that is balanced by the anomalous meridional advection of planetary vorticity yielding msw anomalies as observed in the present study the authors seek to understand how this atmospheric response to sst anomalies produces a positive feedback to the ocean i e an anomalous sst tendency displaced eastward of sst anomalies that both maintains the acw against dissipation and accounts for its eastward propagation to achieve this we couple a global equilibrium climate model for the lower troposphere to a global heat budget model for the upper ocean in the absence of coupling the model antarctic circumpolar current acc advects sst anomalies from initial conditions to the east at speeds slower than observed taking 12 14 years to circle the globe with amplitudes that become insignificant after 6 8 years in the presence of coupling eastward speeds of the model acc are matched by those due to coupling together yielding a model acw of a nominal 4 yr period composed of two waves that circle the globe in approximately 8 years as observed feedback from atmosphere to ocean works through the anomalous zonal surface wind response to sst anomalies yielding poleward ekman flow anomalies in phase with warm sst anomalies as such maintenance of the model acw is achieved through a balance between anomalous meridional ekman heat advection and anomalous sensible plus latent heat loss to the atmosphere this balance requires the alignment of covarying sst and msw anomalies to be tilted into the southwest northeast direction which accounts for the spiral structure observed in global sst and sea level pressure anomaly patterns around the southern ocean eastward coupling speeds of the model acw derive from a beta effect in coupling that displaces a portion of the anomalous meridional ekman heat advection and its corresponding anomalous sst tendency to the east of sst anomalies therefore the acw is an example of self organization within the global ocean atmosphere system depending upon the spherical shape of the rotating earth for its propagation and the mean meridional sst gradient for its maintenance and producing a net poleward eddy heat flux in the upper ocean that tends to reduce this mean gradient

variations in near global sea level pressure abstract analysis of a near global sea level pressure slp data set for the period 1951 80 was carried out in terms of complex empirical orthogonal function a large scale propagating slp signal was discovered that seems to include variability previously associated with the southern oscillation monsoons and tropical midlatitude teleconnection patterns in this sense the new feature offers an empirical framework for many of the well known features of the global climate system extensive comparisons show the feature to be observable in the raw data field and thus not a figment of the analysis technique the large slp signal may have its origins in a slp snow feedback loop that acts over the region from siberia to india it is suggested that the maintenance of the slp signal involves slp precipation feedbacks and more importantly the excitation of a major natural mode of climate variation the slp signal is only excited at time scales larger than about 18 mouths i e time scales characteristic of ocea

an antarctic circumpolar wave in surface pressure wind temperature and sea ice extent the southern ocean is the only oceanic domain encircling the globe it contains the strong eastward flow of the antarctic circumpolar current and is the unifying link for exchanges of water masses at all depths between the world s major ocean basins1 as these exchanges are an important control on mean global climate the southern ocean is expected to play an important role in transmitting climate anomalies around the globe interannual variability has been often observed at high southern latitudes and observations of sea ice extent suggest that such features propagate eastwards around the southern ocean2 3 here we use data from a variety of observational techniques to identify significant interannual variations in the atmospheric pressure at sea level wind stress sea surface temperature and sea ice extent over the southern ocean these anomalies propagate eastward with the circumpolar flow with a period of 4 5 years and taking 8 10 years to encircle the pole this system of coupled anomalies which we call the antarctic circumpolar wave is likely to play an important role in climate regulation and dynamics both within and beyond the southern ocean

slow instabilities in tropical ocean basin global atmosphere models abstract the effect of ocean boundaries on instability in coupled ocean natmosphere models is determined eigenvalues and eigenvectors are calculated for coupled systems featuring an ocean basin bounded zonally by a flat continent the atmosphere is periodic zonally about the globe the oceanic and atmospheric dynamics are both represented by linear shallow water equations on the equatorial plane the calculation involves latitudinal series expansion and longitudinal finite differencing certain of the modes i e eigenvectors have amplitudes that grow with time the growth being a direct result of the ocean atmosphere coupling comparison is made to modes previously determined for the theoretically simpler case where the ocean is zonally unbounded growing modes in the bounded ocean case correspond in aspects of behavior and structure to particular modes of appropriate wavelength in the unbounded ocean basin the basic mechanism of instability is the same in both cases growing modes in the bounded o

slow oceanic teleconnections linking the antarctic circumpolar wave with the tropical el nino southern oscillation a case study for the period 1982 1994 shows that a major source for the antarctic circumpolar wave is in the western subtropical south pacific where interannual anomalies in sea surface temperature sst and precipitable water prwat form once established these interannual anomalies in tandem with anomalies in sea level pressure slp move south toward the southern ocean the system then migrates east around the globe through a combination of oceanic advection with the antarctic circumpolar current and ocean atmosphere coupling the coincidence of interannual anomalies in sst slp and prwat indicates the extratropical ocean and atmosphere are tightly linked on these timescales large portions of the interannual sst anomalies branch advectively northward into the south atlantic and indian oceans ultimately reaching the tropics in each basin some 6 8 years after appearing in the low latitude pacific this constitutes a slow oceanic teleconnection that is unique in climate dynamics made possible by the continuity of earth s oceans via the southern ocean in the tropical indian ocean these interannual anomalies move east and arrive at the indo pacific transition in advance of the trans pacific propagation of the respective el nino southern oscillation enso phases the interannual sst and prwat anomalies that appear in the subtropical south pacific are directly linked with the enso cycle on the equator through anomalous vertical convection and a regional overturning cell in the troposphere the same cell that initiates fast planetary waves in the atmosphere that carry enso signals around the southern hemisphere on much shorter timescales

a global el nino southern oscillation wave in surface temperature and pressure and its interdecadal modulation from 1900 to 1997 zonal wavenumber frequency spectra of sea surface temperature sst anomalies along the equator in the indo pacific basin for the 98 years from 1900 to 1997 and of surface temperature st and sea level pressure slp anomalies extending around the globe along 10 n for the 48 years from 1950 to 1997 display significant peak spectral energy density for standing and eastward propagating waves of 3 7 year periods and 120 360 zonal wavelengths the global standing wave is the familiar southern oscillation but the global propagating wave represents a new paradigm for the el nino southern oscillation enso global distributions of the phase velocities for this global enso wave finds covarying slp and st anomalies propagating eastward along the mean path of the intertropical convergence zone itcz with the global zonal wavenumber 1 2 component taking 4 6 years to cross the tropical indian pacific and atlantic oceans at a zonal average speed of 90 60 longitude per year along this path the interannual sst and slp anomalies are directly out of phase since thermocline depth anomalies underneath the itcz in the pacific ocean propagate westward white et al 1985 we view the global enso wave as a slow coupled sst wave trapped onto the itcz separating the global enso wave from the southern oscillation using complex empirical orthogonal function analysis finds the amplitude of the propagating wave to be half that of the standing wave with the former latter accounting for one third two thirds of the interannual variability in nino 3 sst and slp indices during the 1980s the global enso wave is shown to be responsible for the eastward propagation of covarying zonal surface wind and thermocline depth anomalies across the equatorial pacific ocean and through this mechanism is able to influence both the phasing and intensity of el nino examining the persistence of the global enso wave from 1900 to 1997 finds it and the intensity of el nino in the eastern equatorial pacific ocean modulated by interdecadal change both were strong weak or absent during decades of global tropical cooling warming

interdecadal changes of surface temperature since the late nineteenth century we present global fields of decadal annual surface temperature anomalies referred to the period 1951 1980 for each decade from 1881 1890 to 1981 1990 and for 1984 1993 in addition we show decadal calendar seasonal anomaly fields for the warm decades 1936 1945 and 1981 1990 the fields are based on sea surface temperature sst and land surface air temperature data the ssts are corrected for the pre world war ii use of uninsulated sea temperature buckets and incorporate adjusted satellite based ssts from 1982 onward our results extend those published in the 1990 intergovernmental panel on climate change scientific assessment and its 1992 supplement we assess the impact of various sources of error in the fields despite poor data coverage initially and around the two world wars the generally cold end of the nineteenth century and start to the twentieth century are confirmed together with the substantial warming between about 1920 and 1940 slight cooling of the northern hemisphere took place between the 1950s and the mid 1970s although slight warming continued south of the equator recent warmth has been most marked over the northern continents in winter and spring but the 1980s were warm almost everywhere apart from greenland the northwestern atlantic and the midlatitude north pacific parts of the middle to high latitude southern ocean may also have been cool in the 1980s but in this area the 1951 1980 climatology is unreliable the impact of the satellite data is reduced because the record of blended satellite and in situ sst is still too short to yield a climatology from which to calculate representative anomalies reflecting climatic change in the southern ocean however we propose a method of using existing satellite data in a step toward this target the maps are condensed into global and hemispheric decadal surface temperature anomalies we show the sensitivity of these estimated anomalies to alternative methods of compositing the spatially incomplete fields running decadal zonal means and annual global and hemispheric time series are also shown finally we discuss some salient features in terms of observed atmospheric circulation changes and of the results of climate model integrations with increasing atmospheric greenhouse gases

subsurface mesozoic basins in the central atlas of tunisia tectonics sequence deposit distribution and hydrocarbon potential the mesozoic and cenozoic outcrops of the central and meridional atlas of tunisia have been studied by structural biostratigraphic and sedimentologic approaches we extend these studies to the subsurface employing seismic and well data addressing structures sequence stratigraphy and hydrocarbon potential the basin structures are related to strike slip fault systems associated with triassic evaporites mesozoic sedimentary sections in the areas of the gafsa sidi ali ben oun sidi aich and majoura blocks were studied by an integrated seismic sequence stratigraphic and tectonic approach calibrated to wells and surface geologic controls we identified tectonic corridors where upper triassic evaporites intruded younger mesozoic rocks beginning in the jurassic the organization of the tectonic blocks is characterized by the distribution of subsiding basin zones of graben and rim synclines and resistant areas of platforms triassic intrusions induced by the strike slip movements formed salt pillows and domes that accentuate the border elevations between the rim syncline depocenters and the platforms mesozoic sequence deposits are distributed along the flanks of the basin platform borders according to lowstand prograding downlap systems tracts overlapped by aggrading and retrograding onlap and toplap deposits the time space distribution of the systems tract deposits indicates the possibility of formation of triassic jurassic and cretaceous carbonate and sandstone prograding turbidites reefs structural and stratigraphic pinch outs and unconformities in the flanks of salt domes and basins the geometry and distribution of reservoir and seal systems tracts permit the consideration of new triassic jurassic and cretaceous combined stratigraphic and structural hydrocarbon traps around the basins and the platforms this begin page 886 is a new tectonic model of the central atlas of tunisia that shows new potential objectives and traps

off equatorial westward propagating rossby waves in the tropical pacific during the 1982 83 and 1986 87 enso events abstract analysis of anomalous vertically averaged temperatures tav in the tropical pacific ocean for the eight year period 1979 86 finds the development during the onset phase one to two years before the mature phase of the two enso events of the period having dynamically significant similarities both north and south of the equator during the onset phase of both enso events each beginning in the off equatorial western tropical pacific about 10 latitude positive anomalies of tav occurred during northern autumn winter one year prior to the mature phase of each enso event in both northern and southern hemispheres this corroborates model results of pazan et al and supports the hindcasting forecasting capability of enso events obtained by white et al though the latter considered only the northern hemisphere it is also demonstrated that the development of positive tav anomalies in northern autumn winter along the tropical maritime western boundary of both hemispheres was associated with wind

identification characterization and statistical analysis of mudstone aggregate clasts cretaceous carlile formation central alberta canada abstract while clastic mudstones and shale were traditionally interpreted to have been deposited in quiet water settings recent flume experiments and studies have shown that mud can be transported in and deposited by traction currents as migrating ripples of mud aggregates despite these recent advances mud aggregates have rarely been adequately described in the rock record these mud aggregates and the sedimentary structures they form in mudstone successions are difficult to observe in the rock record due to compaction which often obliterates the aggregates and flattens bedforms this paper documents unambiguously identifiable sand sized mudstone aggregates in thin sections and sem transported in traction and deposited in a series of prograding clinothems these aggregates were sufficiently indurated to locally preserve shelter porosity significantly improving the hydrocarbon reservoir properties grain size analysis of the aggregates was performed on thin sections as well as disaggregated samples measured by a laser diffraction grain size analyzer for comparison these analyses showed that sand sized aggregates often comprise more than half of the sediment volume while the clay rich composition of the carlile formation would suggest that it is a mudstone statistical analysis of these grain size measurements show that it could alternatively be described as a silty sandstone these findings potentially change how we think about mudstone classification fine grained sedimentation and mudstone dominated petroleum reservoirs

hindcast forecast of enso events based upon the redistribution of observed and model heat content in the western tropical pacific 1964 86 anomalous sea level anomalous observed dynamic height 0 400 db and anomalous model dynamic height are examined at the locations of 13 island sea level stations in the tropical pacific for each bimonth of the four year period 1979 to 1982 starting in 1981 the anomalous dynamic height data show off equatorial rossby waves propagated toward the w boundary of the pacific basin at the w boundary the model rossby wave activity was found to have excited coastally trapped kelvin munk waves which transmitted the anomalous dynamic height equatorward at the equator coastally trapped wave activity excited eastward propagating equatorial kelvin waves yielding a pair of anomalous peaks in dynamic height variability in the e equatorial pacific associated with the 1982 1983 enso event the evolution of the peaks in dynamic height associated with the rossby and kelvin wave activity reflects the redistribution of observed upper ocean heat content in the w tropical pacific providing a qualitative hindcast for the 1982 1983 enso event

evolution of interdecadal variability in sea level pressure sea surface temperature and upper ocean temperature over the pacific ocean abstract interdecadal variability in sea level pressure slp and sea surface temperature sst anomalies in the pacific ocean was quasiperiodic from 1900 91 the coherent variability of this phenomenon is investigated using gridded observational data from the turn of the century sst and slp and of upper ocean heat content hs from the recent two and a half decades the nominal cycle in atmosphere ocean variables is roughly two decades long but growth and decay can happen on a shorter timescale e g half a cycle or so the authors divide the full cycle into four phases an onset phase during which a weak slp anomaly pattern off japan takes approximately 2 4 yr to expand eastward leads to large slp anomalies in the region of the aleutian low a quasi stationary growth phase with the midlatitude slp anomaly pattern in the eastern ocean intensifies over a 2 4 yr period the persistent slp anomalies evolve in concert with large sst and hs anomalies of the same polarity located to the south sout

a transition from carbonate shelf to pelagic basin environments of deposition rifting and depositional systems in the jurassic of northeastern tunisia jurassic deposition in the maghrebian tethys was governed by eustasy and rifting two periods were delineated 1 a carbonate shelf rhaetian early pliensbachian and 2 a platform basin complex early pliensbachian callovian the carbonate shelf evolved in four stages generating three sedimentary sequences j1 to j3 separated by boundary sea level falls drawdown exposure and local erosion sediment facies bear evidence of sea level rises and falls lateral changes in lithofacies indicate shoaling and deepening upward during the sinemurian a major pulse of rifting with an abrupt transition from carbonate shelf to pelagic basin environments of deposition marks the upper boundary of the lower pliensbachian carbonate shelf deposits this rifting episode with brittle fractures broke up the rhaetian early pliensbachian carbonate shelf and has created a network of grabens half grabens horsts and stacked ramps following this episode a relative sea level rise led to pelagic sedimentation in the rift basins with local anoxic environments that also received debris shed from uplifted ramp crests another major episode spanning the whole early pliensbachian bajocian is suggested by early brecciation mass flows slumps olistolites erosion pinch outs and sedimentary prisms a later increase in the rates of drifting marked a progress toward rift cessation during the late jurassic these jurassic carbonates with detrital deposits and black shales as the source rocks in northeastern tunisia may define interesting petroleum plays pinch out flanking ramps onlaps and structurally upraised blocks sealed inside grabens source rock maturation and hydrocarbon migration began early in the cretaceous and reached a maximum during the late tortonian pliocene atlassic orogeny