heating and moistening of the mjo during dynamo in ecmwf reforecasts abstractreforecasts produced by the ecmwf integrated forecast system ifs were used to study heating and moistening processes associated with three mjo events over the equatorial indian ocean during the dynamics of the madden julian oscillation dynamo field campaign variables produced by and derived from the ifs reforecast ifs rf agree reasonably well with observations over the dynamo sounding arrays and they vary smoothly from the western to eastern equatorial indian ocean this lends confidence toward using ifs rf as a surrogate of observations over the equatorial indian ocean outside the dynamo arrays the apparent heat source q1 and apparent moisture sink q2 produced by ifs are primarily generated by parameterized cumulus convection followed by microphysics and radiation the vertical growth of positive q1 and q2 associated with the progression of mjo convection can be gradual stepwise or rapid depending on the event and its location over the broader equatorial indian ocean the time for con

intraseasonal variability over tropical africa during northern summer abstract the intraseasonal variability over africa during northern summer was analyzed using 25 years of ncep ncar reanalysis and satellite data the dominant pattern of variability was one of enhanced deep convection over the whole african monsoon region it appeared to arise at least partly as a remote response to the intraseasonal madden julian oscillation over the warm pool sector twenty days prior to the maximum in convection over africa there was no signal over africa but convection was reduced over the equatorial warm pool an equatorial kelvin wave response to this change in warm pool convection propagated eastward and an equatorial rossby wave response propagated westward and between them they completed a circuit of the equator and met up 20 days later over africa where the negative midtropospheric temperature anomalies in the kelvin and rossby waves favored deep convection over west africa the kelvin wave component contained lower tropospheric westerly anomalies that acted to increase t

intraseasonal modulation of south american summer precipitation intraseasonal variation of convection over south america is examined using singular spectrum analysis ssa the dipole convection pattern with centers of action over the sacz and the subtropical plains is modulated by modes of different timescales both oscillatory modes with periods of 36 40 days mode 40 and 22 28 days mode 22 influence convection over the sacz with the faster mode mode 22 leading the variability over the subtropical plains mode 40 is related to the madden julian oscillation outgoing longwave radiation anomalies olra propagate eastward from the western pacific to the central pacific with a period of 40 48 days the 200 hpa streamfunction composites show a wavenumber 1 structure in the tropics and a wave train propagating downstream from the convective area in the tropical pacific the development of the dipole pattern is also contributed by mode 22 which features the meridional propagation of olra over south america from midlatitudes to the tropics the streamfunction composites for mode 22 show a wave train extending from the central pacific eastward to about 608s and curving toward the northeast over south america when the sacz is enhanced these two modes become meridionally aligned locally such episodes are characterized by a wave train propagating northeastward from southern south america toward the tropics composites based on the ssa decomposition indicate that the dominant periods of variability 22 and 40 days cancel out over the pacific region and reinforce each other over the sacz for times close to onset of the enhanced sacz episodes

propagation and the vertical structure of the madden julian oscillation abstract the madden julian oscillation mjo dominates tropical variability on time scales of 30 70 days during the boreal winter spring it is manifested as an eastward propagating disturbance with a strong convective signature over the eastern hemisphere the space time structure of the mjo is described using the national centers for environmental prediction national center for atmospheric research reanalysis advanced very high resolution radiometer outgoing longwave radiation observed sea surface temperature and the climate prediction center merged analysis of precipitation empirical orthogonal function analysis is used to identify the convective signature of the mjo and regression is used to identify key relationships with the convection compared to analyzing successive years of data the selection of years of strong mjo activity results in a more robust lead lag structure and an increase in explained variance the mjo exhibits a rich vertical structure with low level moisture convergence bein

interaction of deep and shallow convection is key to madden julian oscillation simulation 1 this study investigates the role of the interaction between deep and shallow convection in mjo simulation using the ncar cam3 two simulations were performed one using a revised zhang mcfarlane convection scheme for deep convection and the hack scheme for shallow convection and the other disallowing shallow convection below 700 mb in the tropical belt the two simulations produce dramatically different mjo characteristics while the control simulation produces realistic mjos the simulation without shallow convection has very weak mjo signals in the indian ocean and western pacific composite analysis finds that shallow convection serves to precondition the lower troposphere by moistening it ahead of deep convection it also produces enhanced low level mass convergence below 850 mb ahead of deep convection this work together with previous studies suggests that a correct simulation of the interaction between deep and shallow convection is key to mjo simulation in global climate models

asian summer monsoon changes the pollen flow on the tibetan plateau abstract abundant evidence has revealed that the tibetan plateau s uplift influenced the evolution of the asian summer monsoon system pollen as fine powdery substance which can be easily transmitted by wind currents has great potential to be used as an indicator of the monsoon s intensity and flow direction and used for the detection and evaluation of the ancient monsoon on the tibetan plateau hence it is extremely important and necessary to achieve a better understanding of the modern pollen deposition model on the plateau however most of the previous studies mainly focused on the coupling of surface pollen deposition and regional vegetation and the establishment of the transfer function between pollen vegetation climate on the tibetan plateau but largely neglected the direct correlation of the modern surface pollen deposition and the monsoon s intensity and its current direction we have comprehensively analysed a dataset of the surface pollen on the tibetan plateau and discovered that 1 the surface pollen assemblage can reflect the alpine meadows steppe and desert vegetation which means that surface pollen data can be used to assess the deep time vegetation 2 most of the exotic pollen are from trees the spatial distribution trend of these tree pollen s relative abundance is highly coupled with the path of the asian summer monsoon and the extent to which it encroached on the tibetan plateau these results unambiguously demonstrate that tree pollen deposition on the tibetan plateau is dominated by the asian summer monsoon i e the upslope movement of the modern asian summer monsoon drives the spread of pollen rain from low altitude vegetation to high altitude areas if a similar scenario happened at different stages of the asian summer monsoon evolution and the tibetan plateau uplift the pollen buried in the sediments have the potential to reflect the current direction and intensity of the asian summer monsoon at that time moreover it would provide a simple and potentially practical proxy for the study of the evolutionary history of the asian summer monsoon e g wind direction and intensity under the influence of the plateau s uplift

zonal and vertical structure of the madden julian oscillation abstract a statistical study of the three dimensional structure of the madden julian oscillation mjo is carried out by projecting dynamical fields from reanalysis and radiosonde data onto space time filtered outgoing longwave radiation olr data mjo convection is generally preceded by low level convergence and upward motion in the lower troposphere while subsidence cooling and drying prevail aloft this leads to moistening of the boundary layer and the development of shallow convection followed by a gradual and then more rapid lofting of moisture into the middle troposphere at the onset of deep convection after the passage of the heaviest rainfall a westerly wind burst region is accompanied by stratiform precipitation where lower tropospheric subsidence and drying coincide with continuing upper tropospheric upward motion the evolution of the heating field leads to a temperature structure that favors the growth of the mjo the analysis also reveals distinct differences in the vertical structure

mjo signals in latent heating results from trmm retrievals abstract four tropical rainfall measuring mission trmm datasets of latent heating were diagnosed for signals in the madden julian oscillation mjo in all four datasets vertical structures of latent heating are dominated by two components one deep with its peak above the melting level and one shallow with its peak below profiles of the two components are nearly ubiquitous in longitude allowing a separation of the vertical and zonal temporal variations when the latitudinal dependence is not considered all four datasets exhibit robust mjo spectral signals in the deep component as eastward propagating spectral peaks centered at a period of 50 days and zonal wavenumber 1 well distinguished from lower and higher frequency power and much stronger than the corresponding westward power the shallow component shows similar but slightly less robust mjo spectral peaks mjo signals were further extracted from a combination of bandpass 30 90 day filtered deep and shallow components largest amplitudes of bo

late pleistocene rise of the sedom diapir on the backdrop of water level fluctuations of lake lisan dead sea basin abstract during the last glacial between 70 and 15 kyr b p large parts of the dead sea rift were inundated by lake lisan we use the established history of lake lisan water level fluctuations as a tool for determining the rates and styles of the salt tectonic uplift of the sedom salt diapir our reconstruction is based on new accurate mc icpms u th ages of lake lisan deposits overlying the top of mount sedom the surface expression of the sedom diapir these sediments range in age between 46 4 and 15 5 kyr b p comparison of the present elevations of the studied lisan sediments to the lake lisan level curve indicates that these sediments were uplifted to their present elevations due to the diapiric rise of mount sedom during the late pleistocene lisan sediments older than 46 4 kyr b p were not found yet on mount sedom suggesting that it was exposed prior to that time we correlate the exposure phase of mount sedom with the lowest stand of lake lisan between 48 and 43 kyr b p during which previously deposited sediments were eroded the age of the top of the lisan formation on mount sedom is 15 5 kyr b p and it has been uplifted by 75 m since then

vertical diabatic heating structure of the mjo intercomparison between recent reanalyses and trmm estimates abstractcapitalizing on recently released reanalysis datasets and diabatic heating estimates based on tropical rainfall measuring mission trmm the authors have conducted a composite analysis of vertical anomalous heating structures associated with the madden julian oscillation mjo because diabatic heating lies at the heart of prevailing mjo theories the intention of this effort is to provide new insights into the fundamental physics of the mjo however some discrepancies in the composite vertical mjo heating profiles are noted among the datasets particularly between three reanalyses and three trmm estimates a westward tilting with altitude in the vertical heating structure of the mjo is clearly evident during its eastward propagation based on three reanalysis datasets which is particularly pronounced when the mjo migrates from the equatorial eastern indian ocean eeio to the western pacific wp in contrast this vertical tilt in heating structure is not readily seen in the three trmm product

salt tectonics in pull apart basins with application to the dead sea basin the dead sea basin displays a broad range of salt related structures that developed in a sinistral strike slip tectonic environment en echelon salt ridges large salt diapirs transverse oblique normal faults salt walls and rollovers laboratory experiments are used to investigate the mechanics of salt tectonics in pull apart systems the results show that in an elongated pull apart basin the basin fill although decoupled from the underlying basement by a salt layer remains frictionally coupled to the boundary the basin fill therefore undergoes a strike slip shear couple that simultaneously generates en echelon fold trains and oblique normal faults trending mutually perpendicular according to the orientation of basin boundaries sedimentary cover deformation can be dominantly contractional or extensional at the extremities of pull apart basins forming either folds and thrusts or normal faults respectively these guidelines applied to the analysis of the dead sea basin show that the various salt related structures form a coherent set in the frame of a sinistral strike slip shearing deformation of the sedimentary basin fill

space time structure of diabatic heating in monsoon intraseasonal oscillation abstractthe space time structure of the leading monsoon intraseasonal oscillation miso in three dimensional diabatic heating is studied using the era interim data of the european centre for medium range weather forecasts the diabatic heating data were constructed by the residual method of the thermodynamic equation the miso was extracted by applying multichannel singular spectrum analysis on the daily anomalies of three dimensional diabatic heating over the south asian monsoon region for the period 1979 2011 the diabatic heating miso has a period of 45 days and exhibits eastward propagation in the equatorial indian and pacific oceans and northward propagation over the entire monsoon region the horizontal structure shows a long tilted band of heating anomalies propagating northeastward the period horizontal pattern and propagation properties of the diabatic heating miso are similar to those found in precipitation outgoing longwave radiation and circulation in earlier studies the vertical struc

deposition extension and the shape of downbuilding salt diapirs the authors present a new hypothesis for diapir growth in which deposition and extension interact with coeval salt flow the hypothesis is based on scaled tectonic experiments in which viscous polymers simulated ductile salt and frictional plastic dry sand simulated brittle overburden the model diapirs all grew by downbuilding beneath accumulating overburdens without regional extension sedimentary differential loading causes salt to rise where the overburden is thinnest the diapir shape depends on the overburden aggradation rate relative to the flow rate of salt up the diapir conduit with rapid deposition strata onlap the diapir which narrows upward and eventually becomes buried and inactive with moderate deposition strata uplap against vertical diapir flanks with slow deposition salt spreads by extrusion or shallow intrusion and steeply overrides toplapped strata the diapir widens upward until salt supply is depleted with very slow deposition subhorizontal tongues of salt override toplapped strata thin skinned regional extension initially promotes piercement by tectonic differential loading but it also impedes upward salt flow by horizontally stretching the diapir with rapid extension the diapir sags and is indented by growth faults and overlain by depotroughs with moderate extension rates the diapir widens with time and thus narrows upward only where extensionmore is very slow can upward widening or near vertical diapir walls form changes in rates of aggradation flow or extension during diapirism can explain complex geometries such as inverted teardrop shapes without invoking shrinking stems model results are applied to examples from the gulf of mexico and other salt regions less

internal structure of the dead sea leaky transform rift in relation to plate kinematics abstract the structures along the dead sea transform rift are related to the motions of the sinai and arabia plates which border it and to the irregularities of their boundaries the total slip was 105 km left lateral but the present structures were formed mainly during the last 40 km of slip which probably occurred in the plio pleistocene along the southern half of the transform the strike slip motion takes place on en echelon faults this produces rhomb shaped grabens or pull aparts which are sometimes composite and in which there is local crustal separation thus much of the transform is leaky these structures occur in a morpho tectonic rift valley delimited by normal faults which express a small component of transverse extension along a few segments the shape of the transform is such that lateral motion produces local transverse compression the geometric relations of the structures along the transform define an eulerian pole of relative plate motions at 32 8 n 22 6 e 0 5 the older motion was somewhat different and is described by a pole located about 5 west of the above then the component of transverse extension and crustal separation was much smaller than now while local transverse compression was more important the northern half of the dead sea transform has an irregular shape and the bordering plates did not remain rigid as lateral motion continued here transverse compression is often important

regional differences in the kinematic and thermodynamic structure of african easterly waves this study examines regional differences in the structure of african easterly waves aews at four locations between east africa and the east atlantic in a 12 yr 1998 2009 climatology we focus on the cold core convectively active portions of the aews which are typically found between 5 and 15 n african easterly wave composites are produced from three reanalyses using the tracks of synoptic scale middle tropospheric vorticity maxima the vertical structure of temperature and vorticity in the composite aews are related to regional differences in the climatological and vortex centred diabatic heating and diabatic potential vorticity pv generation profiles from the reanalyses in addition differences in aew structure and activity between the three reanalyses are related to differences in rainfall and diabatic heating between the reanalyses the climatological diabatic heating over east africa which is associated mostly with latent heating peaks at 450 hpa with diabatic cooling below 750 hpa in contrast the convectively active west african coast and the east atlantic have increased diabatic heating in the lower troposphere due to these regional differences in diabatic heating diabatic pv generation peaks near 700 hpa over the continent and below 800 hpa over the east atlantic moving westwards from east africa to the east atlantic aew composites have weaker lower tropospheric cold cores and significantly increased lower tropospheric vorticity within the convectively active troughs the shape of the diabatic heating and pv generation profiles within the trough of the regional aew composites are similar to the climatological profiles in each respective region this suggests that regional differences in moist convection particularly the land ocean contrast provide a strong constraint on the diabatic process within the aew trough and therefore the vertical structure of the aews

stratigraphy depositional environments and level reconstruction of the last interglacial lake samra in the dead sea basin in this paper we describe the stratigraphy and sediments deposited in lake samra that occupied the dead sea basin between 135 and 75 ka this information is combined with u th dating of primary aragonites in order to estimate a relative lake level curve that serves as a regional paleohydrological monitor the lake stood at an elevation of 340 m below mean sea level msl during most of the last interglacial this level is relatively higher than the average holocene dead sea 400 30 m below msl at 120 and 85 ka lake samra rose to 320 m below msl while it dropped to levels lower than 380 m below msl at 135 and 75 ka reflecting arid conditions in the drainage area lowstands are correlated with warm intervals in the northern hemisphere while minor lake rises are probably related to cold episodes during mis 5b and mis 5d similar climate relationships are documented for the last glacial highstand lake lisan and the lowstand holocene dead sea yet the dominance of detrital calcites and precipitation of travertines in the dead sea basin during the last interglacial interval suggest intense pluvial conditions and possible contribution of southern sources of wetness to the region

numerical modeling on progressive internal deformation in down built diapirs a two dimensional finite difference code fdcon is used to estimate the finite deformationwithin a down builtdiapir the geometry of the down built diapir is fixed by using two rigid rectangular o

formation and dating of a salt pillar in mount sedom diapir israel the formation of a 20 m high salt pillar in mount sedom dead sea area was analyzed and dated and these results were complemented by measurement of present uplift rate because the pillar is a part of the actively rising sedom diapir contrary to earlier assumptions which stated that the salt pillar was formed by direct rainfall the observed solutional notches and morphology of the neighboring chasm indicate that the salt pillar is due to a karstic cave that collapsed the uppermost part of the cave still carried an underground ephemeral stream 4000 yr ago as indicated by six 14c dates of wood washed into the highest cave level the sudden collapse that left the isolated salt pillar was probably triggered by a catastrophic earthquake the measured uplift rate 9 3 3 5 mm yr shows that when the pillar formed it was much closer to the base of mount sedom

structural evolution in heating profiles of the mjo in global reanalyses and trmm retrievals abstract diabatic and latent heating profiles from four global reanalyses and three tropical rainfall measuring mission trmm algorithms were compared first generally for the tropics and then in the context of the madden julian oscillation mjo most of them exhibit three heating maxima corresponding to known convection centers over south america africa and the indian western pacific warm pool but they still differ substantially in many ways most noticeably a double peak vertical structure with one peak in the upper and the other in the lower troposphere and relative weak heating over the maritime continent in comparison to heating over the indian and western pacific oceans are clearly seen in some heating data but absent in others heating profiles associated with the mjo were diagnosed through composites and case studies the composites were constructed as functions of mjo phases at three longitudes representing the indian ocean maritime continent and western pacific respectively four mjo ev

subseasonal variations of rainfall in south america in the vicinity of the low level jet east of the andes and comparison to those in the south atlantic convergence zone abstract regional and large scale circulation anomalies associated with variations in rainfall downstream of the south american low level jet are identified and compared to those in the south atlantic convergence zone sacz composites of precipitation associated with strong jets reveal an approximate doubling of the quantities one would expect from climatology with an evolution of the rainfall pattern from south to north the occurrence of extreme precipitation events follows a similar pattern meridional cross sections of composite wind reveal a distinct low level jet near 20 s and a baroclinic development farther south that appears to force the jet geopotential height temperature and large scale wind composites suggest that this developing disturbance is tied to a wave train that originates in the midlatitude pacific and turns equatorward as it crosses the andes mountains similar composites based on sacz rainfall reveal similar features but of opposite sign suggesting that the phase of the wave

trmm observed shallow versus deep convection in the eastern pacific related to large scale circulations in reanalysis datasets abstractover the eastern pacific recent studies have shown that a shallow large scale meridional circulation with its return flow just above the boundary layer coexists with a deep hadley circulation this study examines how the vertical structure of large scale circulations is related to satellite observed individual precipitation properties over the eastern pacific in boreal autumn three reanalysis datasets are used to describe differences in their behavior the results are compared among reanalyses and three distinctly different convection periods which are defined according to their radar echo depths shallow and deep circulations are shown to often coexist for each of the three periods resulting in the multicell circulation structure deep shallow circulations preferentially appear in the mostly deep shallow convection period of radar echo depths thus depth of convection basically corresponds to which circulation branch is dominant this anticipated relationship between the circulation stru

insar mapping and modelling of an active iranian salt extrusion abstract interferometric synthetic aperture radar insar imaging is a powerful technique that is increasingly used to extract detailed 3d information on earth surface structures including exposed diapiric surfaces we have used insar to map for the first time the cumulative surface deformation in a 6 km 6 km region surrounding an active salt diapir syahoo and its associated surface salt flow or namakier exposed in the zagros mountains of southern iran images provided by the european space agency were acquired in 12 increments ranging in length between 35 and 1248 days over a 14 year interval between july 1992 and may 2006 the deformation of the salt surface is non steady with extrapolated rates of displacement varying between surficial uplifts of 1 4 mm day 1 511 mm a 1 and subsidence of 2 2 mm day 1 803 mm a 1 growth of a central topographic dome occurs following short wet intervals to create a salt fountain morphology which then slowly decays during the intervening long dry periods salt associated with dynamic bulging9 of the central dome during wet intervals may flow laterally via gravity spreading into the surrounding salt sheet resulting in deflation and subsidence of the dome which is counteracted by growth and inflation of the adjacent namakiers salt bulges9 that migrate down the namakier resulting in local inflationary and deflationary cycles of the surface may be regarded as episodic pulses of gravity spreading areas of inflation and deflation are also observed to commonly reverse during dry to wet periods as the overall salt system effectively self regulates as it continually strives for dynamic equilibrium as long as the source of salt remains undepleted gravity spreading of the dome ultimately results in more buoyancy driven salt flowing up the diapiric neck to replenish and feed the extrusion and maintain the gross fountain morphology

exploring the relative contribution of mineralogy and cpo to the seismic velocity anisotropy of evaporites we present the influence of mineralogy and microstructure on the seismic velocity anisotropy of evaporites bulk elastic properties and seismic velocities are calculated for a suite of 20 natural evaporite samples which consist mainly of halite anhydrite and gypsum they exhibit strong fabrics as a result of tectonic and diagenetic processes sample mineralogy and crystallographic preferred orientation cpo were obtained with the electron backscatter diffraction ebsd technique and the data used for seismic velocity calculations bulk seismic properties for polymineralic evaporites were evaluated with a rock recipe approach ultrasonic velocity measurements were also taken on cube shaped samples to assess the contribution of grain scale shape preferred orientation spo to the total seismic anisotropy the sample results suggest that cpo is responsible for a significant fraction of the bulk seismic properties in agreement with observations from previous studies results from the rock recipe indicate that increasing modal proportion of anhydrite grains can lead to a greater seismic anisotropy of a halite dominated rock conversely it can lead to a smaller seismic anisotropy degree of a gypsum dominated rock until an estimated threshold proportion after which anisotropy increases again the difference between the predicted anisotropy due to cpo and the anisotropy measured with ultrasonic velocities is attributed to the spo and grain boundary effects in these evaporites

estimating vertical motion profile shape within tropical weather states over the oceans abstractthe vertical structure of tropical deep convection strongly influences interactions with larger scale circulations and climate this paper focuses on investigating this vertical structure and its relationship with mesoscale tropical weather states the authors test the hypothesis that latent heating plus turbulent flux convergence varies in space and time in association with weather state type the authors estimate mean state vertical motion profile shape and latent heating plus turbulent flux convergence for six weather states defined using cloud top pressure and optical depth properties from the international satellite cloud climatology project isccp dataset assuming two modes of vertical motion profile variability these modes are statistically extracted from reanalysis data using a principal component analysis using these modes and the relationship between vertical motion the dry static energy budget and mass continuity the authors estimate vertical motion profile shape in these estim

modeling tropical convergence based on the moist static energy budget abstract the vertically integrated moist static energy equation provides a convenient starting point for the construction of simple models of the time mean low level convergence in the tropics a vertically integrated measure of the moist static stability the gross moist stability proves to be of central importance minima in this quantity mark the positions of the tropical convergence zones we argue that the positions of these minima are determined by the time mean moisture field which is in turn closely tied to the time mean surface temperature

mechanics of active salt diapirism abstract an active diapir forcefully intrudes its overburden driven by diapir pressure that overcomes the resistance of the overburden strength possible causes for the driving pressure are differential loading of the source layer and a density contrast with the overburden possible resisting forces derive from the mass of the roof block and resistance to the faulting and folding that accommodate the intrusion for a typical density contrast between salt and a sedimentary overburden a simple force balance demonstrates that the diapir height must be more than two thirds to three quarters the thickness of the surrounding overburden to initiate substantial active diapirism narrow diapirs must be even taller physical and numerical modeling show that typical structures of active diapirism are a central crestal graben flanked by relatively unstrained flaps that rotate upward and outward curved reverse faults can separate the flaps from the regional overburden normal faults in the crestal graben propagate downward with new faults created farther outward as the roof arches over the rising diapir thin wide roofs develop multiple grabens separating a relatively flat roof from the rotating flaps in cases leading to emergence the piercing diapir evolves from a pointed crest to a progressively rounded and widening crest as the flaps rotate outward the numerical models show that overburden flexure contributes to early formation of active diapir structures but piercement does not continue to emergence unless the diapir is very wide or tall relative to the overburden thickness active diapirism becomes progressively more difficult for diapir crests ranging from a rectangle a round cornered rectangle a semicircle to a triangle with a pointed crest

salt diapirs in the dead sea basin and their relationship to quaternary extensional tectonics abstract regional extension of a brittle overburden and underlying salt causes differential loading that is thought to initiate the rise of reactive diapirs below and through regions of thin overburden we present a modern example of a large salt diapir in the dead sea pull apart basin the lisan diapir which we believe was formed during the quaternary due to basin transtension and subsidence using newly released seismic data that are correlated to several deep wells we determine the size of the diapir to be 13 10 km its maximum depth 7 2 km and its roof 125 m below the surface from seismic stratigraphy we infer that the diapir started rising during the early to middle pleistocene as this section of the basin underwent rapid subsidence and significant extension of the overburden during the middle to late pleistocene the diapir pierced through the extensionally thinned overburden as indicated by rim synclines which attest to rapid salt withdrawal from the surrounding regions slight positive topography above the diapir and shallow folded horizons indicate that it is still rising intermittently the smaller sedom diapir exposed along the western bounding fault of the basin is presently rising and forms a 200 m high ridge its initiation is explained by localized e w extension due monoclinal draping over the edge of a rapidly subsiding basin during the early to middle pleistocene and its continued rise by lateral squeezing due to continued rotation of the amazyahu diagonal fault

cycles of passive versus active diapirism recorded along an exposed salt wall abstract although it has long been recognised that passive salt diapirism may encompass sub ordinate cycles of active diapirism where sedimentary overburden is periodically shed off the roof of the rising salt there has been very little study of this process around exposed salt halite diapirs however the late miocene pliocene sedom salt wall on the western side of the dead sea basin presents an opportunity for detailed outcrop analysis of diapiric salt and the associated depositional and deformational record of its movement during both passive and active phases of diapirism the sub seismic scale record of diapirism includes sedimentary breccia horizons interpreted to reflect sediments being shed off the crest of the growing salt wall together with exceptional preservation of rotated unconformities and growth faults areas of more pronounced dips directed towards the salt wall are capped by unconformities and interpreted to represent withdrawal basins within the overburden that extend for at least 1500 m from the salt margin elsewhere broad areas of upturn directed away from the salt extend for up to 1250 m and are marked by a sequence of rotated unconformities which are interpreted to bound halokinetic sequences the margins of the salt wall are defined by steep extensional boundary faults that cut upturned strata and have enabled rapid and active uplift of the salt since the holocene the sedom salt wall therefore charts the transition from passive growth marked by withdrawal basins growth faults and unconformities to more active intrusion associated with major boundary faults that enable the rapid uplift of overburden deposited on top of the salt to 100 m above regional elevations in the past 43 ka individual cycles of passive and active diapirism occur over timescales of

overburden deformation patterns and mechanisms of salt diapir penetration in the central graben north sea abstract active and passive diapirism control the deformation and geometry of hydrocarbon traps in the overburden and a more detailed understanding of this process will help reservoir prediction and hydrocarbon recovery cores studies of seven central graben diapirs indicate zechstein salt penetrated late cretaceous chalk by extreme tectonic thinning with high angle 70 to bedding normal faulting tensile fracturing and pressure solution attenuation of the chalk significantly weakens the overburden allowing buoyancy forces to dome up the overburden doming created enough topography for downslope sliding of chalk slabs on slip planes parallel to bedding or in the case of the kyle diapir for chaotic debris flows of lithified chalk significant extensional bedding parallel faults and slump folds are developed within palaeocene shale on the diapiric flanks inter granular slip in unconsolidated clastic material was probably the dominant deformation mechanism diapirs have penetrated the palaeocene clastic sediments by maintaining topographic relief so that unlithified sediment continually slid off the crest producing translated intact rafts up to several tens of metres in thickness

characteristics of precipitation cloud and latent heating associated with the madden julian oscillation abstract this study investigates the evolution of cloud and rainfall structures associated with madden julian oscillation mjo using tropical rainfall measuring mission trmm data two complementary indices are used to define mjo phases joint probability distribution functions pdfs of cloud top temperature and radar echo top height are constructed for each of the eight mjo phases the genesis stage of mjo convection over the western pacific phases 1 and 2 features a bottom heavy pdf characterized by abundant warm rain low clouds suppressed deep convection and higher sea surface temperature sst as mjo convection develops phases 3 and 4 a transition from the bottom heavy to top heavy pdf occurs the latter is associated with the development of mixed phase rain and middle to high clouds coupled with rapid sst cooling at the mjo convection peak phase 5 a top heavy pdf contributed by deep convection with mixed phase and ice phase rain and high echo top heights 5 km dominates the decay

latent heating characteristics of the mjo computed from trmm observations the tropical rainfall measurement mission s trmm spectral latent heating algorithm shows the contributions of different forms of convection to the latent heating profiles of the madden julian oscillation over the central indian and west pacific oceans in both oceanic regions storms containing broad stratiform regions produce increased upper level heating during active madden julian oscillation mjo phases the largest differences between the central indian and west pacific ocean heating are associated with heating produced by convective elements examination of the most extreme forms of convection shows that mesoscale organized convection often produces at least as much latent heat as young vigorous deep convection heating from nonextreme often midlevel topped convection is an important component of the mjo heating in both regions in all stages of the mjo over the central indian ocean the heating profile changes from having a maximum at 2 km due to nonextreme convection to a profile during the active stage that has two maxima one at 3 km due to nonextreme convection and 6 km owing to numerous mature mesoscale storms with broad stratiform precipitation components over the west pacific the maxima at 3 and 6 km are present in all mjo stages but the magnitude of the 6 km maximum sharply increases in the active mjo stage due to an increase in the number of storms with broad stratiform precipitation areas

primary carbonates and ca chloride brines as monitors of a paleo hydrological regime in the dead sea basin abstract lakes samra lisan and the dead sea occupied the dead sea basin during the last interglacial 140 75 ka bp last glacial 70 14 ka bp and holocene periods respectively the age of lake lisan and samra was determined by u th dating of primary aragonites comprising parts of the lacustrine sedimentary sequences the lakes have periodically deposited sequences of layered calcitic marls lake samra or laminated primary aragonite lake lisan the deposition of aragonite as the primary carbonate phase reflects the contribution of the incoming freshwater loaded with bi carbonate and high mg ca chloride brine that originated from the subsurface vicinity of the dead sea basin deposition of calcitic marls suggests a minor effect of the brines the ca chloride subsurface brine has been migrating in and out of the wall rocks of the dead sea basin reflecting the regional hydrological conditions during most of the last glacial period and during the late holocene sufficient precipitation above the judea mountains pushed the subsurface ca chloride brines into the lakes causing the deposition of aragonite during the last interglacial period the rain that precipitated above the judea mountains was insufficient to induce brine flow toward lake samra it appears that sporadic floods provided calcium bicarbonate and detritus to produce the samra calcitic marls travertines deposited at the samra lisan boundary indicate the early stage in the resumption of groundwater springs activity that led to the resurgence of ca chloride brine and rise of lake lisan similar variations in the regional rain precipitation and hydrological activity probably characterized the long term geochemical evolution of pleistocene lacustrine water bodies in the dead sea basin enabling the use of the carbonates as paleo hydrological monitors

simulation of the madden julian oscillation in the ncar ccm3 using a revised zhang mcfarlane convection parameterization scheme abstract this study presents the simulation of the madden julian oscillation mjo in the ncar ccm3 using a modified zhang mcfarlane convection parameterization scheme it is shown that with the modified scheme the intraseasonal 20 80 day variability in precipitation zonal wind and outgoing longwave radiation olr is enhanced substantially compared to the standard ccm3 simulation using a composite technique based on the empirical orthogonal function eof analysis the paper demonstrates that the simulated mjos are in better agreement with the observations than the standard model in many important aspects the amplitudes of the mjos in 850 mb zonal wind precipitation and olr are comparable to those of the observations and the mjos show clearly eastward propagation from the indian ocean to the pacific in contrast the simulated mjos in the standard ccm3 simulation are weak and have a tendency to propagate westward in the indian ocean nevertheless there remain several deficiencies that are yet

dilation of anisotropic rock salt evidence from mount sedom diapir the mechanical behavior of bedded rock salt is studied using constant strain rate biaxial tests performed on 24 bedded rock salt samples from mount sedom diapir careful measurements of elastic parameters in unload reload loops indicate that they are influenced by confining pressure but are not sensitive to anisotropy the yield stress is also influenced by confining pressure but not by anisotropy the stress strain curve therefore indicates isotropy up to the yield stress initiation of dilation marks the onset of dependence of volumetric strain on anisotropy major principal compressive stress at dilation 1 d is at maximum when compression is normal to bedding planes 0 the stress decreases with increasing values of and minimum values are measured when compression is parallel to bedding planes 90 beyond onset of dilation point the relative dilation with respect to stress difference v e 1 3 1 1 d mpa 1 increases with decreasing confining pressure and with increasing namely dilation is intensified with decreasing confining pressure and as the major principal compressive stress direction becomes parallel with bedding plane orientation current models for compression dilation boundary ignore anisotropy and therefore provide site specific solutions but fail to describe general rock salt behaviour a new empirical model for compression dilation boundary in anisotropic rock salt developed for a data set from mount sedom predicts that stress at onset of dilation decreases with decreasing confining pressure and with increasing value of the rate of change of 1 d with respect to decreases with decreasing confining pressure and the rate of change of 1 d decreases with increasing confining pressure for all values of

large scale distinctions between mjo and non mjo convective initiation over the tropical indian ocean abstractin this study the authors seek large scale signals that may distinguish mjo from non mjo convective events before they start over the indian ocean three such signals were found low level easterly anomalies extend from the surface to the midtroposphere and move from the western to eastern indian ocean surface pressure anomalies exhibit a zonal structure of wavenumber 1 with an equatorial low pressure surge penetrating eastward from africa through the indian ocean and reaching the maritime continent negative temperature anomalies in the middle to upper troposphere start over the indian ocean and move eastward all of them emerge 20 days before convective initiation of the mjo and move eastward at speeds close to that of the mjo without any direct connection to mjo convection they are not obviously related to the extratropics in any discernible way or any preceding mjo events they are absent in non mjo convective events these signals provide useful information for forecasting mjo initiation o

the development of upper tropospheric geopotential height anomaly in the western hemisphere during mjo convective initiations this study uses geopotential height budget and composite analysis of reanalysis data to examine the driving dynamics and structural evolution of intraseasonal upper tropospheric circulation over the western hemisphere wh prior to and during the convective initiation of the madden julian oscillation mjo over the indian basin previous studies by the authors showed that during most of mjo convective initiation events over the indian basin upper tropospheric equatorial easterly wind anomaly initially develops in association with subtropical and midlatitude rossby ridges over the east pacific basin as the easterly wind continues to amplify and propagate farther eastward a negative upper tropospheric geopotential height anomaly develops over tropical south america and couples with the easterly wind anomaly forming a structure consistent with theoretical kelvin waves this study shows that the development of the negative geopotential height anomaly over south america is driven by net tropospheric adiabatic cooling induced by updrafts the convection associated with the updrafts is triggered by the intrusion of a midlatitude wave train from the southern hemisphere suggesting that the interaction with midlatitude circulation is a part of the dynamics driving the formation of upper tropospheric kelvin wave structure over the wh during some mjo convective initiation events the upper tropospheric zonal wind anomaly is positive over the east pacific basin and the formation of kelvin wave structure is weak or absent over south america those events subsequently develop weaker mjo convective envelopes over the indian basin apparently due to the absence of upper tropospheric divergence induced by the incoming kelvin wave circulation that enhances convective updrafts over the region of initiating convection the results suggest that the formation of the upper tropospheric kelvin wave over the wh partly determines the subsequent development of mjo convection over the indian basin

the role of tilted heating in the evolution of the mjo there has been much discussion about the role of tilted heating in the evolution of the mjo it is believed that the inability of many general circulation models to produce a robust mjo is directly related to deficiencies in the model produced tropical heating distributions given the mjo s importance in tropical climate we need to better understand what heating distributions are required in climate models to produce strong mjos this study addresses the role of tilted heating in the community atmospheric model version 4 cam4 idealized and observed heating distributions are added to the tropical atmosphere in cam4 these include heating that tilts westward with height in the lower and upper atmosphere as well as various tilted and untilted heating in the form of either idealized blobs or observations derived from the tropical rainfall measuring mission precipitation radar and the international satellite cloud climatology project we find that low level heating ahead of the mjo convective center is critical for the initial strengthening and later maintenance of the mjo however tilted heating is not necessary to simulate a realistic mjo in addition excess upper level heating whether tilted or not appears to degrade the mjo signal although rossby wave modes are evident only in runs with additional upper level heating kelvin waves are evident during strong mjos for all simulations but are only visible over the central pacific results suggest that accurate shallow convective parameterizations may be more important than deep convective ones in the evolution of the mjo

microphysical characteristics of mjo convection over the indian ocean during dynamo the microphysical characteristics of precipitating convection occurring in various stages of the madden julian oscillation mjo over the indian ocean are determined from data obtained from the national center for atmospheric research dual polarimetric doppler s band radar s polka deployed as part of the dynamics of the mjo dynamo field experiment active mjo events with increased rainfall occurred in october november and december 2011 during each of these active mjo phases in addition to enhanced rainfall convection became deeper and ice phase microphysics played a greater role s polka consistently showed nonoriented small ice particles dominating the radar echoes at altitudes of 9 10 km dry aggregates concentrated between 7 and 9 km and wet aggregates and graupel near the melting level 5 km graupel occurred mainly in actively convective towers while the wet aggregates occurred almost exclusively in the stratiform regions of mesoscale convective systems mcss during each of the three multiweek mjo active phases the maximum rainfall occurred in short bursts lasting a few days each multiday rainy period began with deepening convective elements and a concurrent increase in occurrence of dry aggregates which maximized just prior to organization into mcss the peak rainfall occurrence coincided with the maximum coverage of the radar domain by mcss reflecting large stratiform regions that exhibited the most frequent occurrence of wet aggregates during the december active mjo phase however the mcss were shallower and had a slightly lower tendency for wet aggregates in the stratiform regions and therefore generally weaker brightbands

u th dating of lake lisan late pleistocene dead sea aragonite and implications for glacial east mediterranean climate change u series dating can be an effective means to obtain accurate and precise ages on quaternary carbonates however most samples require a correction for u and th in admixed detritus this complication is often addressed through generation of u th isochrons requiring analyses of several coeval samples in addition presence of water derived hydrogenous th in the carbonate can cause inaccuracies in isochron ages this study reports a high resolution u series chronology of sediments deposited by lake lisan the last glacial precursor of the dead sea the strategy employed combines multiple measurements from a few stratigraphic heights and fewer analyses from many heights in a single described and measured section the resulting chronology is based on ages at 22 heights in a 40 m thick section covering the interval of 70 14 calendar ka bp the effects of admixed detritus are evaluated using trace elements nearly pure aragonite samples indicated by very low abundances of insoluble elements such as nb and zr were found to contain hydrogenous th which causes the uncorrected u 230th age of a modern sample to be 2 5 ka nevertheless accurate ages have been obtained by correcting for the detrital and aqueous interferences the resulting ages are in stratigraphic order and their accuracy is evidenced by consistency of lisan formation u series and 14c ages with the coral based calendar radiocarbon age calibration the u th ages provide a context to unravel the limnological history of lake lisan boundaries between the lower middle and upper stratigraphic units correspond to the mis 4 3 and 3 2 transitions respectively during mis 2 and 4 the lake generally showed a stable two layer configuration and a positive fresh water balance reflected by deposition of laminated aragonite detritus dry intervals during mis 2 and 4 are indicated by thick gypsum layers and an inferred depositional hiatus which are temporally associated with heinrich events h1 at 17 ka and h6 at 65 ka respectively during mis 3 the lake level was unstable with intermittent dry periods indicated by abundant clastic layers and a significant hiatus between 43 49 ka clastic layers are associated with dansgaard oeschger events during mis 3 and indicate lake level declines during abrupt northern hemisphere warmings overall the climate of the eastern mediterranean region shows a strong linkage to the northern hemisphere climate with increasing lake size and stability during cold periods and fluctuations and dessication during warmings and heinrich events

deformation within an exposed salt wall recumbent folding and extrusion of evaporites in the dead sea basin abstract despite the enormous global interest in salt tectonics which is largely driven by its importance to hydrocarbon exploration direct field based studies of salt exposed at the earth s surface are rare however mount sedom located at the western side of the dead sea basin presents one such opportunity for detailed analysis of salt and the associated sedimentary and structural record of its movement the sedom salt wall is a 10 km 1 5 km n s trending ridge comprising a range of late miocene pliocene evaporites and clastics which have penetrated the overlying pleistocene clastic sequence the salt wall displays a moderate steep west dipping western margin and an overturned west dipping eastern flank the sedimentary record of passive wall growth includes sedimentary breccia horizons that locally truncate underlying beds and are interpreted to reflect sediments having been shed off the crest of the growing salt wall structurally the overturned eastern flank is marked by upturn within the overburden extending for 300 m from the salt wall deformation within the evaporites is characterised by ductile folding and boudinage while a 200 m thick clastic unit within the salt wall forms a tight recumbent fold traceable for 5 km along strike and associated with a 500 m wide inverted limb this overturned gently dipping limb is marked by ne directed folding and thrusting sedimentary injections and a remarkable attenuation of the underlying salt from 380 m to

unraveling rift margin evolution and escarpment development ages along the dead sea fault using cosmogenic burial ages abstract the dead sea fault dsf is one of the most active plate boundaries in the world understanding the quaternary history and sediments of the dsf requires investigation into the neogene development of this plate boundary dsf lateral motion preceded significant extension and rift morphology by 10 ma sediments of the sedom formation dated here between 5 0 0 5 ma and 6 2 2 1 inf ma yielded extremely low 10be concentrations and 26al is absent these reflect the antiquity of the sediments deposited in the sedom lagoon which evolved in a subdued landscape and was connected to the mediterranean sea the base of the overlying amora formation deposited in the terminal amora lake which developed under increasing relief that promoted escarpment incision was dated at 3 3 0 8 0 9 ma burial ages of fluvial sediments within caves 3 4 0 2 ma and 3 6 0 4 ma represent the timing of initial incision initial dsf topography coincides with the earliest red sea morb s and the east anatolian fault initiation these suggest a change in the relative arabian african plate motion this change introduced the rifting component to the dsf followed by a significant subsidence margin uplift and a reorganization of relief and drainage pattern in the region resulting in the topographic framework observed today

enigmatic structures within salt walls of the santos basin part 2 mechanical explanation from physical modelling abstract jackson et al this volume used 3d seismic reflection data to describe intrasalt deformation in salt walls in the santos basin they focused on the origin of enigmatic allochthonous salt sheets of older evaporites a1 unit emplaced above overlying stratified evaporites a2 a4 units their kinematic model incorporates i initial inward flow and thickening of a1 salt within the rising wall and arching of a2 a4 overburden ii breaching of the arched overburden ascent of mobile a1 evaporites along single or multiple feeders and emplacement of upper wall sheets or canopies and iii a component of regional shortening within the salt this companion paper uses physical modelling to explain how and why these structures occur and proposes a mechanical basis for the kinematic model our first two models simulated salt having uniform internal density with walls growing by i initially symmetric differential loading and ii initially symmetric differential loading plus shortening these models reproduced anticlines and injection folds seen in the simpler deformed walls in the santos basin however neither model reproduced the most complex structures within the santos evaporites which are i allochthonous intrusions ii steep feeders and iii recumbent synclines thus differential loading and shortening alone are insufficient to generate these complex structures in our third model a less dense lower evaporite a1 was overlain by denser upper evaporites a2 a4 similar to the density structure found by santos basin wellbores the wall rose solely by differential loading in this model a1 breached the overlying evaporites to form vertical diapirs feeding salt sheets and salt wings in the upper part of the salt wall breakthrough of a1 folded a2 a4 evaporites into recumbent synclines model sections closely resemble santos seismic examples suggesting that the key to forming these complex intrasalt structures is a density inversion within the evaporite sequence that creates a rayleigh taylor instability