how do ocean warm anomalies favor the aggregation of deep convective clouds abstractwe investigate the role of a warm sea surface temperature sst anomaly hot spot of typically 3 k to 5 k on the aggregation of convection using cloud resolving simulations in a non rotati

petrology geochemistry and na metasomatism of triassic jurassic non marine clastic sediments in the newark hartford and deerfield rift basins northeastern usa many sandstones and associated siltstones and shales of the triassic jurassic newark supergroup in the newark hartford and deerfield rift basins are immature feldspathic alluvial and lacustrine closed basin deposits they were derived from felsic igneous and metamorphic continental blocks on the flanks of their depositional basins the provenance was dominantly calc alkaline basement rocks similar to the sierra nevada of california the physical and chemical environments of erosion and deposition were probably similar to those in moist pleistocene holocene alluvial basins and playas in the great basin of california and nevada new petrographic and geochemical data for 113 samples indicate that albite rich sandstones and shales of the stockton lockatong and passaic formations in the newark basin and in the portland and east berlin formations of the hartford basin and analcime rich shales up to 52 normative analcime of the lockatong formation have unusually high na2o contents 4 7 textural evidence indicates both sodium replacement in feldspars and formation of authigenic albite and analcime in these rocks by comparison with modem sediments derived from similar provenance using mixing models it is estimated that up to 4 na2o was diagenetically added to the detrital clastics trace metals co cr cu ni zn abundances were apparently enhanced by deposition from brines in the lockatong formation analcime deposition occurred in shales with al2o3 na2o sio2 0 46 this ratio is found only in sediments to which na has been added from salts brines source rocks and the weathering products derived from them may be considered as a closed system in which sodium was retained partly in solids as feldspar and part went into solution during weathering the dilute solution migrated into the depositional basin where evaporation yielded concentrated brine during semi arid to arid climate in the drier parts of 21 000 yr milankovitch cycles reaction of brine during diagenesis at near surface and or shallow depths 2 km with ca plagioclase k feldspar and layer silicates at estimated temperatures 50 c to 100 c and ph 7 9 yielded thermodynamically stable authigenic albite and analcime in the sodium metasomatised clastic sediments low activity of k precluded development of authigenic k feldspar however k from solution incorporated into muds and silts as smectites were transformed to illite some lockatong beds contain anomalously high p2o5 ce la y th and u in authigenic apatite or monazite suggestive of mobilization of these elements in diagenesis

radiative dynamical consequences of dry tongues in the tropical troposphere abstract dry layers are frequently observed in atmospheric soundings from the climatologically humid western pacific warm pool region some 2400 soundings from the toga coare field program were objectively examined for humidity drops layers in which relative humidity decreases rapidly with height indicative of the bases of dry layers these occur throughout the lower and middle troposphere with frequency peaks near 550 the 0 c level 800 and 950 mb a composite constructed from these sounding data indicates the following almost all dry layers are too dry and not warm enough to be interpreted as conservative vertical displacements rather they apparently consist of filaments or tongues of low moist static energy air advected into the column often from the subtropics dry tongues are anomalously virtually warm near their bases with a slight cool layer below that is they sit atop sharp stable layers or inversions the authors hypothesize that radiation is responsible for the thermal structure o

impact of explicit atmosphere ocean coupling on mjo like coherent structures in idealized aquaplanet simulations this paper discusses the impact of the atmosphere ocean coupling on the large scale organization of tropical convection simulated by an idealized global model applying the cloud resolving convection parameterization crcp superparameterization because the organization resembles the madden julian oscillation mjo the results contribute to the debate concerning the role of atmosphere ocean coupling in tropical intraseasonal oscillations the modeling setup is an aquaplanet with globally uniform mean sea surface temperature sst of 30 c tropics everywhere in radiative convective quasi equilibrium the simulations apply an interactive radiation transfer model and a slab ocean model with a fixed oceanic mixed layer depth results from several 80and 100 day long simulations are discussed where the only difference between the simulations is the prescribed oceanic mixed layer depth which varied from 5 to 45 m a simulation with a very deep oceanic mixed layer is also performed to represent constant sst conditions the simulations demonstrate that the interactive sst impedes the development of large scale organization and has insignificant impact on the dynamics of mature mjo like systems the impediment is the result of a negative feedback between the large scale organization of convection and sst the convection sst feedback in this feedback sst increases in regions of already suppressed convection and decreases in regions with enhanced convection thus hindering the large scale organization once developed however the mjo like systems are equally strong in interactive and constant sst simulations and compare favorably with the observed mjo the above impacts of the atmosphere ocean coupling contradict the majority of previous studies using traditional general circulation models where typically an enhancement of the intraseasonal signal occurs compared to prescribed sst simulations an explanation of this discrepancy is suggested

a theory for strong long lived squall lines abstract we study herein the mechanics of long lived line oriented precipitating cumulus convection squall lines using two and three dimensional numerical models of moist convection these models used in juxtaposition enable us to address the important theoretical issue of whether a squall line is a system of special long lived cells or whether it is a long lived system of ordinary short lived cells our review of the observational literature indicates that the latter is the most consistent paradigm for the vast majority of cases but on occasion a squall line may be composed of essentially steady supercell thunderstorms the numerical experiments presented herein show that either type of squall line may develop from an initial line like disturbance depending on the magnitude and orientation of the environmental shear with respect to the line with shallow shear oriented perpendicular to the line a long lived line evolves containing individually short lived cells our analysis of this type o

multiscale organization of convection simulated with explicit cloud processes on an aquaplanet abstract this study investigated the multiscale organization of tropical convection on an aquaplanet in a model experiment with a horizontal mesh size of 3 5 km for a 10 day simulation and 7 km for a 40 day simulation the numerical experiment used the nonhydrostatic icosahedral atmospheric model nicam with explicit cloud physics the simulation realistically reproduced multiscale cloud systems eastward propagating super cloud clusters sccs contained westward propagating cloud clusters ccs sccs ccs had zonal sizes of several thousand hundred kilometers typical propagation speed was 17 10 m s 1 smaller convective structures such as mesoscale cloud systems mcs of o 10 km and cloud scale elements 16 km of o 100 km area was also reproduced planetary scale equatorial waves with wavelengths of 10 000 and 40 000 km had a major influence on the eastward propagation of the simulated scc destabilization east of the

the origin and migration of mud volcano fluids in taiwan evidence from hydrogen oxygen and strontium isotopic compositions abstract mud volcanoes are important gateways for deep fluids to migrate upward and provide windows for studying fluid sediment interaction at depth fluids emitted from 40 terrestrial mud volcanoes were collected in southern and eastern taiwan to study their chemical compositions including h o and sr isotopes 87sr 86sr and 88 86sr relative to seawater the mud volcano fluids are depleted in cl mg so42 and d and are elevated in b ba li and 18o possibly due to water rock interaction and clay dehydration mainly smectite to illite transformation in the source region the distribution of sr in mud volcano fluids shows patterns associated with their localities and geological settings most fluids have higher 87sr 86s than seawater indicating water rock interaction at depth the low na 87sr 86s and high ca fluids emitted from eastern taiwan imply intense interaction with igneous basement most fluids have higher sr cl and lower 88sr than seawater except mud volcanoes in the northern chu kou fault which emit low sr cl and extremely high 88sr up to 0 82 fluids we performed laboratory carbonate precipitation experiments that indicate that these high sr isotope ratios are caused by co precipitation of carbonates from high alkalinity fluids mud volcano fluids in taiwan originate at depth and their chemical compositions are controlled by the host rock degrees of water rock interaction and clay dehydration but also are masked by retrograde progresses such as carbonate precipitation during migration our results show that an approach combining water isotopes d and 18o and strontium isotopes 87sr 86sr and 88 86sr provides a robust tool for tracing fluid sources and migration pathways in accretionary prisms

dynamics of the shallow meridional circulation around intertropical convergence zones the generally accepted view of the meridional circulation in the tropical east pacific is that of a single deep overturning cell driven by deep convective heating in the intertropical convergence zone itcz similar to the zonal mean hadley circulation however recent observations of the atmosphere from the tropical eastern pacific have called this view into question in several independent datasets significant meridional return flows out of the itcz region were observed not only at high altitudes but also at low altitudes just above the atmospheric boundary layer this paper presents a theory and idealized simulations to understand the causes and dynamics of this shallow meridional circulation smc fundamentally the smc can be seen as a large scale sea breeze circulation driven by sea surface temperature gradients when deep convection is absent in the itcz region a simple model of this circulation is presented using observed values the sea breeze model shows that the pressure gradient above the boundary can indeed reverse leading to the pressure force that drives the shallow return flow out of the itcz the weather research and forecast model wrf is used to simulate an idealized hadley circulation driven by moist convection in a tropical channel the smc is reproduced with reasonable similarity to the circulation observed in the east pacific the simulations confirm that the smc is driven by a reversal of the pressure gradient above the boundary layer and that the return flow is strongest when deep convection is absent in the itcz and weakest when deep convection is active the model also shows that moisture transport out of the itcz region is far greater in the low level shallow return flow than in the high altitude return flow associated with the deep overturning and that a budget for water transport in and out of the itcz region is grossly incomplete without it much of the moisture carried in the shallow return flow is recycled into the boundary layer but does not appear to contribute to enhanced cloudiness in the subtropical stratocumulus poleward of the itcz

stratigraphic record of the early mesozoic breakup of pangea in the laurasia gondwana rift system rift basins of the central atlantic margins cam of north america and morocco preserve largely continental sequences of sedimentary strata and less important minor basalt flows spanning much of the early mesozoic the best known is the newark basin of new jersey new york and pennsylvania where an astronomically calibrated magnetic polarity time scale is developed lacustrine cycles of milankovitch origin are commonly present in cam basins with the period changing from 10 ky paleoequator with coals to 20 ky 4 10n to perhaps 40 ky northward with evaporites cycles of100 ky 413 ky and2 my are also important four mostly unconformity bounded tectonostratigraphic sequences are present the anisian ts i is fluvial and eolian ts ii ts iv late triassic to early jurassic consist of tripartite lacustrine sequences caused by extension pulses the newark basin accumulation rate history allows comparison with quantitative rift basin models the north american plate s slow northward drift resulted in a relative shift of climate although the rapid humidification during the latest triassic and early jurassic is associated with a sea level rise the triassic jurassic mass extinction is of independent origin plausibly impact related

trace elements in shale as indicators of crustal provenance and terrane accretion in the southern canadian cordillera in this study the trace element geochemistry of shale is used to infer the nature of adjacent crustal blocks during terrane amalgamation and accretion in southern british columbia the geochemistry of about fifty shale samples from one of the best dated stratigraphic sections in the north america cordillera is used to 1 infer proximity to source regions characterized by juvenile ocean arcs continental arcs and ophiolites and 2 address a controversy concerning the timing of terrane amalgamation and accretion this study includes analyses of shale from the entire mesozoic stratigraphic section of the cadwallader terrane and overlying tyaughton basin as well as argillites from the structurally adjacent bridge river complex the mid cretaceous albian strata of the upper taylor creek group show light rare earth lree enrichment la n sm n of 3 0 and anomalously high cr and ni older units upper triassic lower cretaceous that stratigraphically underlie the upper taylor creek group have less lree enrichment high ba n la n ratios and no cr or ni anomaly the mid cretaceous strata were probably derived from a continental arc during a period of uplift and erosion of ultramafic rocks probably ophiolites and the co extensive nature of these sediments suggests accretion of many basement terranes to the edge of a continent the trace element geochemistry of the older strata is similar to that of sediment derived from an oceanic arc however lower cretaceous strata of the relay mountain group may record the incipient collision and progressive closure of this ocean basin the bridge river complex which is dominated by oceanic rocks and is interpreted to be an accretionary complex contains two suites of argillites one of which shows significant lree enrichment and isotopic data suggest a jurassic cretaceous age for these argillites that compose the matrix in this complex leitch et al 1991 we suggest that the bridge river complex was a jurassic cretaceous accretionary complex that formed outboard of the methow section of rocks and was not juxtaposed with the cadwallader terrane and tyaughton basin until the albian when these terranes were accreted to north america paleomagnetic data from these rocks maxson et al 1993 indicate that accretion took place at the latitude of central mexico and that subsequent strike slip faulting brought these terranes to their present position by eocene time

a simple multicloud parameterization for convectively coupled tropical waves part ii nonlinear simulations observations in the tropics point to the important role of three cloud types congestus stratiform and deep convective clouds besides ubiquitous shallow boundary layer clouds for both the climatology and large scale organized anomalies such as convectively coupled kelvin waves two day waves and the madden julian oscillation recently the authors have developed a systematic model convective parameterization highlighting the dynamic role of the three cloud types through two baroclinic modes of vertical structure a deep convective heating mode and a second mode with lower troposphere heating and cooling corresponding respectively to congestus and stratiform clouds the model includes both a systematic moisture equation where the lower troposphere moisture increases through detrainment of shallow cumulus clouds evaporation of stratiform rain and moisture convergence and decreases through deep convective precipitation and also a nonlinear switch that favors either deep or congestus convection depending on whether the lower middle troposphere is moist or dry here these model convective parameterizations are applied to a 40 000 km periodic equatorial ring without rotation with a background sea surface temperature sst gradient and realistic radiative cooling mimicking a tropical warm pool both the emerging walker cell climatology and the convectively coupled wave fluctuations are analyzed here while various parameters in the model are varied the model exhibits weak congestus moisture coupled waves outside the warm pool in a turbulent bath that intermittently amplify in the warm pool generating convectively coupled moist gravity wave trains propagating at speeds ranging from 15 to 20 m s 1 over the warm pool while retaining a classical walker cell in the mean climatology the envelope of the deep convective events in these convectively coupled wave trains often exhibits large scale organization with a slower propagation speed of 3 5 m s 1 over the warm pool and adjacent region occasional much rarer intermittent deep convection also occurs outside the warm pool the realistic parameter regimes in the multicloud model are identified as those with linearized growth rates for large scale instabilities roughly in the range of 0 5 k day 1

trace and rare earth element ree characteristics of mudstones from eocene pinghu formation and oligocene huagang formation in xihu sag east china sea basin implications for provenance depositional conditions and paleoclimate abstract the interpretation of depositional conditions provenance and paleoclimate provide important information to understand hydrocarbon source rock formation and distribution the concentrations of trace elements and rare earth elements rees of fifty mudstone samples from eocene pinghu formation and oligocene huagang formation in xihu sag east china sea basin were determined by inductively coupled plasma mass spectrometry icp ms to test the depositional conditions provenance and paleoclimate evidences from the visual comparisons of the simple bivariate plots diagrams and statistical comparisons of the mann whitney rank sum test suggest that there may be a common source for the pinghu formation and huagang formation mudstones sedimentary provenance from bivariate plots diagrams of hf versus la th and la sc versus co th shows that pinghu formation mudstones are mainly composed of mixed felsic basic source and acidic source whereas huagang formation is mainly acidic source additionally the ree vs la yb discrimination diagram shows that the property of the provenance for the pinghu formation mudstones consists sedimentary rock alkaline basalt and a small amount of continent tholeiitic basalts whereas that of the huagang formation is mainly alkaline basalt and sedimentary rock discriminant diagrams consisting of la th sc and th co zr 10 suggest that the mudstones of two formations were deposited in continental island arc and active continental margin tectonic setting redox proxies v ni v v ni and ce indicate that most of the mudstones of two formations were deposited in a relatively dysoxic anoxic condition the cool and humid climate represented by sr cu and rb sr ratios were prevailing in xihu sag during the eocene and oligocene period and the oligocene was cooler than eocene moreover five long term base level cycles siii1 siii5 and four sequence boundaries sb2 sb5 were recognized in the pinghu formation and huagang formation based on the previous research we find that the abnormal surfaces of geochemical parameters such as v ni sr ba u ti v ti ti and ree to some extent agree with sequence boundaries sb2 sb3 sb4 and sb5 in mudstones additionally the increment of ti and ree concentrations and the decrease of sr ba v ni u ti and v ti ratios above the sb4 indicates that terrigenous clast grew significantly and the sea level dropped after late eocene which is related with the late eocene tectonic movement

eastward propagating intraseasonal oscillation represented by chikira sugiyama cumulus parameterization part ii understanding moisture variation under weak temperature gradient balance abstractthe eastward propagating intraseasonal oscillation represented by the chikira sugiyama cumulus scheme in a general circulation model was investigated focusing on the variation of the free tropospheric humidity the net effect of the vertical advection and cloud process amplifies the positive moisture anomaly in the mature phase supporting the moisture mode theory the horizontal advection causes the eastward propagation of the field the variation of the moisture profile is accurately understood by using environmental vertical velocity outside cumuli the velocity is regulated by a thermodynamic balance under a weak temperature gradient a nondimensional parameter plays an important role in the moisture variation which characterizes the efficiency of moistening drying induced by external heating cooling in the middle and lower troposphere the major moistening factor is the radiative warming anomaly which induces the upward environmental vertical velocity anomaly the reevaporation of th

new biostratigraphic information from the western part of the hamburg klippe pennsylvania and its significance for interpreting the depositional and tectonic history of the klippe biostratigraphic investigation of the graptolite and conodont faunas of the western part of the hamburg klippe of eastern pennsylvania permits a revised stratigraphic framework and new conclusions regarding its likely tectonic setting graptolite and conodont data reveal an almost complete lower to lower upper ordovician zonal section no cambrian strata appear to be present with the possible exception of the uppermost part during early to early middle ordovician time medium to fine grained siliciclastics and minor carbonate sediments were deposited in a lower slope and rise setting these sediments were consolidated and incorporated as olistoliths in an olistostrome possibly as a trench fill complex during the middle ordovician darriwilian 3 4 this olistostrome which contains large lower and lower middle ordovician fragments within a matrix of shales siltstones and sandstones of da 3 4 age is herein named the shellsville member of the dauphin formation turbidites here assigned to the nyes road member of the dauphin formation were also deposited during da 3 4 time these rocks interfinger with red beds of the here named manada hill member of the dauphin formation the red shales cherts and associated rocks of the manada hill member are pelagic deposits that range in age from at least early arenig through middle llanvirn time these allochthonous rocks were emplaced as a gravity generated klippe into the martinsburg foreland basin during late climacograptus bicornis or early dicranograptus clingani time these three members compose the dauphin formation new in the western part of the klippe area prior to emplacement of the allochthon syntectonic flysch and scattered wildflysch of the martinsburg formation were deposited some graptolite faunas from the martinsburg formation where contiguous with the klippe may be slightly older than those known from areas farther from the klippe this could indicate an earlier start of deposition in the martinsburg foreland basin in advance of the allochthon the klippe occupied a large space in the martinsburg foreland basin and it diverted deposition in this area until it was finally covered by late martinsburg age sediment the dauphin formation is now structurally interleaved and folded with the martinsburg formation as a result of late taconian and later alleghenian tectonism

organization of tropical convection in low vertical wind shears the role of water vapor abstract a modeling study is conducted to gain insight into the factors that control the intensity and organization of tropical convection and in particular to examine if organization occurs in the absence of factors such as vertical wind shear or underlying sea surface temperature sst gradient the control experiment integrates a cloud resolving model for 15 days using a 3d domain exceeding 1000 km in length with no imposed winds and horizontally uniform sst and forcing for convection after 2 days of random activity the convection organizes into clusters with dimensions of approximately 200 km convective systems propagate through the clusters at speeds of 2 3 m s 1 while the clusters themselves propagate at minimal speeds of around 0 5 m s 1 examining the thermodynamic structure of the model domain it is found that the convective free bands separating the clusters are very dry throughout the troposphere and due to virtual temperature effects are correspondingly warmer in the lower tropospher

an integrated view of the 1987 australian monsoon and its mesoscale convective systems i horizontal structure this observational study is organized around three issues the forcing of the monsoon flow by embedded deep convection the thermodynamic conditions that support the convection and the structures of the mesoscale convective systems mcss that constitute much of the deep convection the monsoon convective cloudiness occurred predominantly offshore over the earth s warmest waters week long periods of widespread deep convection caused cycles of monsoon spin up culminating in tropical cyclone formation momentum transports by the convection also created smaller scale vortex pairs in the upper troposphere sounding data suggest that the convection was modulated by low level processes not by large scale deep forced ascent triggering by mesoscale boundary layer cold pool boundaries and coastlines determined specifically where convection occurred while several positive feedbacks acted to keep regional thermodynamic conditions favourable hence monsoon convection once initiated persisted as self exciting superclusters composed at any instant of many distinct mcss the observed mcss all contained areas of deep convection and stratiform precipitation areas stratiform precipitation usually evolved in place from convective cells although precipitation also occasionally fell from overhanging anvils created by upper level shear the mcss within similar synoptic wind environments tended to have similar mesoscale structures this fact reflects the effects illustrated herein of environmental winds upon the relative motions of cold pools which trigger new convective cells and stratiform precipitation areas which evolve from old convective cells

convective self aggregation and tropical cyclogenesis under the hypohydrostatic rescaling abstractthe behavior of rotating and nonrotating aggregated convection is examined at various horizontal resolutions using the hypohydrostatic or reduced acceleration in the vertical rave rescaling this modification of the equations of motion reduces the scale separation between convective and larger scale motions enabling the simultaneous and explicit representation of both types of flow in a single model without convective parameterization without the rave rescaling a dry bias develops when simulations of nonrotating radiative convective equilibrium are integrated at coarse resolution in domains large enough to permit convective self aggregation the rescaling reduces this dry bias and here it is suggested that the rescaling moistens the troposphere by weakening the amplitude and slowing the group velocity of gravity waves thus reducing the subsidence drying around aggregated convection separate simulations of rotating radiative convective equilibrium exhibit tropical cyclogenesis as horizo

impact of convective organization on the response of tropical precipitation extremes to warming abstractin this study the response of tropical precipitation extremes to warming in organized convection is examined using a cloud resolving model vertical shear is imposed to organize the convection into squall lines earlier studies show that in disorganized convection the fractional increase of precipitation extremes is similar to that of surface water vapor which is substantially smaller than the increase in column water vapor it has been suggested that organized convection could lead to stronger amplifications regardless of the strength of the shear amplifications of precipitation extremes in the cloud resolving simulations are comparable to those of surface water vapor and are substantially less than increases in column water vapor the results without shear and with critical shear for which the squall lines are perpendicular to the shear are surprisingly similar with a fractional rate of increase of precipitation extremes slightly smaller than that of surface water vapor interestingly the

the role of environmental shear and thermodynamic conditions in determining the structure and evolution of mesoscale convective systems during toga coare abstract a collection of case studies is used to elucidate the influence of environmental soundings on the structure and evolution of the convection in the mesoscale convective systems sampled by the turboprop aircraft in the tropical ocean global atmosphere toga coupled ocean atmosphere response experiment coare the soundings were constructed primarily from aircraft data below 5 6 km and primarily from radiosonde data at higher altitudes the well documented role of the vertical shear of the horizontal wind in determining the mesoscale structure of tropical convection is confirmed and extended as noted by earlier investigators nearly all convective bands occurring in environments with appreciable shear below a low level wind maximum are oriented nearly normal to the shear beneath the wind maximum and propagate in the direction of the low level shear at a speed close to the wind maximum when there is appreciable shear at middle levels 800 400 mb convective bands form parallel to the shear with

cape and convective events in the southwest during the north american monsoon abstract the relationship between atmospheric stability measured as cape and deep precipitating convection has been widely studied but is not definitive in the maritime tropics cape and precipitation are usually inversely correlated in continental convection i e midlatitude and tropical no consistent relationship has been found in this study of the semiarid southwest a moderate positive correlation exists approaching 0 6 correlations based on radiosonde data are found to be sensitive to the parcel level of origin the strongest correlations are found by modifying the preconvective morning sounding with the maximum reported surface temperature assuming well mixed adiabatic layers to the level of free convection with pseudoadiabatic ascent these results show that the upper bounds on parcel instability correlate best with precipitation furthermore the cape precipitation relationship is argued to depend on the convective regime being considered the north american monsoon convective regime r

geochemical controls on arsenic and rare earth elements approximately along a groundwater flow path in the shallow aquifer of the hetao basin inner mongolia article i nfo groundwaters and sediments were sampled approximately along a groundwater flow path in the shallow aquifer of the hetao basin inner mongolia along a flow path with a length of about 9 km groundwater evolves from ca hco3 so4 through mg ca hco3 cl to na cl hco3 from the recharge zone to the discharge

sensitivity of tropical pacific convection to dry layers at mid to upper levels simulation and parameterization tests abstract numerical forecast experiments are carried out to investigate the implications of observed moisture variability in the tropical pacific for deep convection the study uses a series of quasi cloud resolving model forecasts with a triple nested version of the naval research laboratory s coupled ocean atmosphere mesoscale prediction system coamps the forecasts are carried out for a dry tongue episode in the tropical western pacific in november 1998 during a 24 h forecast a number of convective cells develop in an area of deep convection near the edge of the simulated dry tongue in the coamps 3 km mesh inner grid which is located in the southern portion of the domain of the tropical ocean global atmosphere coupled ocean atmosphere response experiment toga coare field program the forecast is repeated multiple times using a moisture profile from a toga coare dry tongue episode to modify the lateral boundary conditions for the 3 km mesh grid over layers of varying depth and altitude the entrai

tropical south america atlantic sector convective margins and their relationship to low level inflow abstract the edges or margins of tropical convective zones are hypothesized to be sensitive to low level inflow conditions the present study evaluates where and to what extent convective margin variability is sensitive to low level inflow variability using observed precipitation and reanalysis wind and total precipitable water data over the tropical south america atlantic sector in austral summer composite analysis based on an inflow measure defined by projecting low level monthly mean atmospheric boundary layer abl or lower free troposphere lft winds onto either mean horizontal precipitation or precipitable water gradients shows widespread contraction of the edges of convection zones in the direction of stronger convection for anomalously strong low level inflow such behavior is consistent with enhanced import of relatively dry air along the edges of convection zones however the distinction between abl and lft winds may be significant regionally for example along the atlantic itcz s northern m

multiscale convective wave disturbances in the tropics insights from a two dimensional cloud resolving model abstract multiscale convective wave disturbances with structures broadly resembling observed tropical waves are found to emerge spontaneously in a nonrotating two dimensional cloud model forced by uniform cooling to articulate the dynamics of these waves model outputs are objectively analyzed in a discrete truncated space consisting of three cloud types shallow convective deep convective and stratiform and three dynamical vertical wavelength bands model experiments confirm that diabatic processes in deep convective and stratiform regions are essential to the formation of multiscale convective wave patterns specifically upper level heating together with low level cooling serves to preferentially excite discrete horizontally propagating wave packets with roughly a full wavelength structure in troposphere and dry phase speeds cn in the range 16 18 m s 1 these wave packets enhance the triggering of new deep convective cloud systems via low level destabilization the new convection in turn caus

the formation of moist vortices and tropical cyclones in idealized simulations abstractthe upscale aggregation of convection is used to understand the emergence of rotating coherent midtropospheric structures and the subsequent process of tropical cyclone formation the cloud model version 1 cm1 is integrated on an f plane with uniform sea surface temperature sst and prescribed uniform background flow deep convection is maintained by surface fluxes from an ocean with uniform surface temperature convection begins to organize simultaneously into moist and dry midtropospheric patches after 10 days after 20 days the patches begin to rotate on relatively small scales moist cyclonic vortices merge eventually forming a single dominant vortex that subsequently forms a tropical cyclone on a realistic time scale of about 5 days radiation that interacts with clouds and water vapor aids in forming coherent rotating structures using the path to genesis provided by the aggregated solution the relationship between thermodynamic changes within the vortex and changes in the character

another look at rare earth elements in shales linear correlation and mass balance considerations indicate that clays are more important than zircon or other heavy minerals in hosting both light and heavy ree in cratonic shales considering the uniformity of the eu anomaly and ree distributions in cratonic shales it seems likely that detritus is thoroughly mixed during weathering and sediment transport and that the ree patterns in shales reflect the average ree pattern of the sources regardless of the ratio of clays to heavy minerals in the shales shales suspended river loads and near shore marine sediments all have broadly similar ree patterns and reported hree depletions in the latter two groups may reflect incomplete dissolution of heavy minerals during sample preparation ree distributions in shales and suspended river loads determined by inna are similar to those in average upper continent crust and ree distributions in shale averages nasc and paas seem to be reasonably representative of the average composition of post archean upper continental crust

the occurrence and geochemistry of arsenic in groundwaters of the newark basin of pennsylvania abstract elevated as concentrations in groundwater in the eastern united states have been recognized predominantly in the accretionary geologic terranes of northern new england a retrospective examination of more than 18 000 existing groundwater samples from the pennsylvania department of environmental protection pa dep drinking water and sampling information system database indicates that elevated groundwater as concentrations occur throughout the northern half of the piedmont province of pennsylvania chemical analyses of 53 samples collected in 2005 from drinking water wells in this area all had detectable as and 23 of these samples contained elevated 133 nmol l or 10 g l concentrations of as elevated concentrations of as in the groundwater samples were most common in the mesozoic sedimentary strata composed of sandstone and red mudstone with interbedded gray shale and gray to black siltstone and shale arsenic was typically not elevated in groundwater of diabase intrusions of the newark basin or in crystalline and calcareous aquifers to the north of the newark basin geochemical parameters such as ph and oxidation reduction potential can indicate mobility mechanisms of as in some regions in this area measured groundwater conditions were predominantly oxidizing eh 50 mv and more than 85 of samples contained arsenate as the dominant as species variations in ph were strongly correlated to the as concentration with highest as concentrations observed at ph values greater than 6 4 the original source of as is most likely the black and gray shales that contain some arsenian pyrite with groundwater concentrations likely to be controlled by adsorption desorption reactions with fe oxides in the red mudstone aquifer materials

tectonics of the southern and central appalachian internides the appalachian orogen was constructed along the ancient precambrian continental margin of eastern north america by a series of compressional events that began in the ordovician and episodically spanned much of the paleozoic era the processes of accretion of suspect and exotic terranes together with terrane collision and ultimately completion of the wilson cycle by continent continent collision resulted in construction of the appalachian orogen figure 1 these paleogeographic elements are rep resented by the various lithotectonic units visible today in the southern and central appalachians figure 2 these subdivisions represent the late precambrian rifted margin and early paleozoic platform that were formed directly upon north american grenvillian basement cumberland allegheny plateau valley and ridge and western blue ridge the offshore north american slope rise assemblage hamburg klippe southern appalachian eastern blue ridge and inner piedmont and higher thrust sheets of the maryland northern virginia piedmont and the exotic carolina or avalon and wilmington terranes the carolina ter rane contains the alleghanian high grade metamorphic core these elements form the basis for this analysis and review of the present state of knowledge of the tectonic history of the southern and central appalachian internides the appalachian orogen has been the subject of study by geologists at least since the early nineteenth century early fundamental concepts such as the geosynclinal theory of mountain building dana 1873 hall 1883

distribution of arsenic and other trace elements in the holocene sediments of the meghna river delta bangladesh geochemical study of the holocene sediments of the meghna river delta chandpur bangladesh was conducted to investigate the distribution of arsenic and related trace and major elements the work carried out includes analyses of core sediments and provenance study by rare earth element ree analysis results showed that the cores pass downward from silty clays and clays into fine to medium sands the uppermost 3 m of the core sediments are oxidized average oxidation reduction potential orp 230 mv and the orp values gradually become negative with depths 45 to 170 mv indicating anoxic conditions prevail in the meghna sediments the ree patterns of all lithotypes in the study areas are similar and are comparable to the average upper continental crust arsenic and other trace elements pb zn cu ni and cr have greater concentrations in the silts and clays compared to those in the sands positive correlation between as and fe was found in the sediments indicating as may be adsorbed on fe oxides in aquifer sediments

a low level circulation in the tropics abstract deep convective tropical systems are strongly convergent in the midtroposphere horizontal wind measurements from a variety of rawinsonde arrays in the equatorial pacific and caribbean are used to calculate the mean dynamical divergence profiles of large scale arrays 1000 km in diameter in actively convecting regions somewhat surprisingly the magnitude of the midtropospheric divergence calculated from these arrays is usually small in principle the midlevel convergence of deep convective systems could be balanced on larger scales either by a vertical variation in the radiative mass flux of the background clear sky atmosphere or by a divergence from shallow cumuli the vertical variation of the clear sky mass flux in the midtroposphere is small however so that the offsetting divergence must be supplied by shallow cumuli on spatial scales of 1000 km the midlevel convergent inflow toward deep convection appears to be internally compensated or screened by a divergent outflow from surr

the influence of sediment recycling and basement composition on evolution of mudrock chemistry in the southwestern united states this paper reports systematic changes in mudrock composition through time on a single con tinental cmstal block the changes reflect both sediment recycling processes and changes through time in the composition of crystalline material being added to the sedimentary system and are related to tectonic evolution as the block matures from a series of accreted arc terranes to a stable craton the major and trace element distributions reflect different aspects of the provenance of the mudrocks in this study major elements record sediment recycling processes as well as changing proportions of sedi mentary and first cycle source rocks with the exceptions of kzo which tends to increase and sioz and a o3 which show no trend most major oxides tend to decline in relative abundance in younger mud rocks patterns shown by the index of compositional variability fe03 kro naao cao mgo mno tiojialro and by k20 a1203 indicate that the major oxide trends are due to decreasing proportions of nonclay silicate minerals and a concomitant increase in the proportion of clay minerals probably due to decreasing input of first cycle detritus coupled with recycling of sedimentary material excursions from progressive trends marked by increases in mgo k20 and cao reflect episodes of large scale input of nonclay first cycle minerals from crystalline source rocks due to large scale basement uplift the chemistry of low solubility trace elements in contrast is not sensitive to recycling effects and reflects the composition of first cycle input incompatible elements are progressively enriched relative to compatible elements in younger mudrocks and values for chondrite normalised rare earth elements also increase in addition the eu anomaly becomes systematically more negative in younger samples these trends cmnot be explained by diagenetic or weathering processes and therefore indicate that the proportion of fnc tionated granitic first cycle detritus being added to the sedimentary system becomes greater with time these results confirm the importance of tectonic setting in controlling mudrock chemistry and also demonstrate that there is a dynamic relationship between the tectonic evolution of a continental block and the composition of its sedimentary mantle

late proterozoic rift control on the shape of the appalachians the pennsylvania reentrant the pennsylvania reentrant the most prominent deviation in the trend of the appalachians is the product of late proterozoic rifting the peters creek formation pennsylvania maryland piedmont contains rift gene rated deep water turbidite deposits of late proterozoic cambrian age these rocks are an extension of the westminster terrane and lie well to the northeast of the southern appalachian late proterozoic cambrian rift basin lynchburg chilhowee group basin the basin into which the peters creek formation was deposited may have connected the southern rift basin with one to the north the preservation of the peters creek formation and other age equivalent units within the pennsylvania reentrant indicates that the new york promontory acted as a buttress to paleozoic orogenic activity

on large scale circulations in convecting atmospheres the dominant thinking about the interaction between large scale atmospheric circulations and moist convection holds that convection acts as a heat source for the large scale circulations while the latter supply water vapour to the convection we show that this idea has led to fundamental misconceptions about this interaction and offer an alternative paradigm based on the idea that convection is nearly in statistical equilibrium with its environment according to the alternative paradigm the vertical temperature profile itself rather than the heating is controlled by the convection which ties the temperature directly to the subcloud layer entropy the understanding of large scale circulations in convecting atmospheres can therefore be regarded as a problem of understanding the distribution in space and time of the subcloud layer entropy we show that the subcloud layer entropy is controlled by the sea surface temperature the surface wind speed and the large scale vertical velocity in the convecting layer and demonstrate how the recognition of this control leads to a simple physically consistent view of large scale flows ranging from the hadley and walker circulations to the 30 50 day oscillation in particular we argue that the direct effect of convection on large scale circulations is to reduce by roughly an order of magnitude the effective static stability felt by such circulations and to damp all of them

deep convective cloud top heights and their thermodynamic control during crystal face 1 infrared 11 m radiances from goes 8 and local radiosonde profiles collected during the cirrus regional study of tropical anvils and cirrus layers florida area cirrus experiment crystal face in july 2002 are used to assess the vertical distribution of florida area deep convective cloud top height and test predictions as to its variation based on parcel theory the highest infrared tops z11 reached approximately to the cold point at 15 4 km though these are uncertain by about 1 km due to unknown cloud environment temperature differences since lidar shows that visible tops are generally 1 km or more above z11 visible cloud tops frequently penetrated the lapse rate tropopause 15 km further since tropospheric ice concentrations were typically present up to 1 km above the visible tops lofting of moisture through the mean cold point was probably common morning clouds and those near key west rarely penetrated the tropopause as in previous studies nonentraining parcel theory fails to explain either of these results though it does show promise in explaining day to day variations over the peninsula moisture variations above the boundary layer account for much of the day to day z11 variability especially over the oceans in all locations a 20 increase in mean mixing ratio between 750 and 500 hpa was associated with about 1 km deeper maximum cloud penetration other things being equal this sensitivity is too large to explain by simple dilution of parcel buoyancy through mixing implying microphysical or dynamical feedbacks on cloud development the evident influence of midtropospheric humidity on the depth of the tropical troposphere suggests an interesting climate feedback possibility for stabilizing midtropospheric relative humidity

the drying tendency of shallow meridional circulations in monsoons shallow meridional overturning circulations are superimposed on the deep circulations that produce precipitation in nearly all monsoon regions and these shallow circulations transport subtropical mid tropospheric dry air into the tropical monsoon precipitation maxima here horizontal moisture advection produced by shallow meridional circulations is characterized in the monsoon regions of west africa south asia australia and southern africa during local summer horizontal flow in the upper and lower branches of the shallow meridional circulations consistently dries and moistens air respectively in the continental precipitation maxima of each region the peak drying by horizontal advection occurs at a lower altitude than peak winds in the upper branch of the shallow circulations consistent with the small scale height of water vapor advection of time mean moisture by time mean wind dominates horizontal moisture advection in south asia and west africa while most horizontal moisture advection in australia and southern africa is produced by transient eddies much of the transient eddy advection can be accurately represented as a first order horizontal diffusion with a constant globally uniform diffusivity these results suggest that horizontal moisture advection in theoretical and conceptual models of seasonal mean monsoons can be adequately represented in terms of time mean winds plus a simple horizontal moisture diffusion finally interannual variations in the summer mean regional averages of monsoon precipitation and horizontal advective drying in the lower free troposphere are shown to be negatively correlated in most regions consistent with the hypothesis that advective drying by shallow meridional circulations inhibits monsoon precipitation

quantitative filling model for continental extensional basins with applications to early mesozoic rifts of eastern north america in many half graben strata progressively onlap the hanging wall block of the basins indicating that both the basins and their depositional surface areas were growing in size through time based on these constraints we have constructed a quantitative model for the stratigraphic evolution of extensional basins with the simplifying assumptions of constant volume input of sediments and water per unit time as well as a uniform subsidence rate and a fixed outlet level the model predicts 1 a transition from fluvial to lacustrine deposition 2 systematically decreasing accumulation rates in lacustrine strata and 3 a rapid increase in lake depth after the onset of lacustrine deposition followed by a systematic decrease when parameterized for the early mesozoic basins of eastern north america the model s predictions match trends observed in late triassic age rocks significant deviations from the model s predictions occur in early jurassic age strata in which markedly higher accumulation rates and greater lake depths point to an increased extension rate that led to increased asymmetry in these half graben the model makes it possible to extract from the sedimentary record those events in the history of an extensional basin that are due solely to the filling of a basin growing in size through time and those that are due to changes in tectonics climate or sediment and water budgets

integrated analyses constraining the provenance of sandstones mudstones and conglomerates a case study the laojunshan conglomerate qilian orogen northwest china the qilian orogenic belt in the northern tibetan plateau connects the altaids to the north with the tethyan orogenic system to the south and occupies a key tectonic position in the evolution and assembly of asia the belt con tains a wide range of subduction accretion related petrotectonic units the early middle devonian laojunshan con glomerate deposited unconformably upon cambrian silurian strata along the northern margin of the north qilian terrane contains a record of the late paleozoic tectonism of the qilian orogen its provenance and tectonic setting are critical in understanding not only the tectonic evolution of tibetan plateau but paleozoic global reconstructions as well the composition of clastic conglomerates and heavy mineral assemblages of sandstones suggests that coeval mafic felsic metamorphic and sedimentary rocks were the main sources the geochemistry of volcanic clasts and paleocurrent and paleogeographic data suggest derivation from subduction accretion complexes in the north qilian terrane the geochemistry of siltstones and mudstones indicates that the laojunshan conglomerate was derived from an arc and accumulated in an active continental margin geochemical data of granitoid clasts suggest that they were de rived from ordovician silurian subduction related magmatic rocks mafic and ultramafic clasts chromite and magne tite decrease upwards in the stratigraphy whereas metamorphic sedimentary and granitoid clasts and garnet increase these data imply that mafic rocks were the predominant source during initial deposition regional studies suggest that the north china plate subducted southwards and produced subduction related arc magmatism along the southern margin of the north qilian terrane during the early middle devonian therefore we interpret the laojunshan conglomerate as a fore arc basin fill

geological and geochemical examination of arsenic contamination in groundwater in the holocene terai basin nepal geological and geochemical study has been carried out to investigate arsenic contamination in groundwater in nawalparasi the western terai district of nepal the work carried out includes analyses of core sediments provenance study by rare earth elements analyses 14c dating and water analyses results showed that distribution of the major and trace elements are not homogeneous in different grain size sediments geochemical characteristics and sediment assemblages of the arsenic contaminated nawalparasi and uncontaminated bhairahawa area have been compared geochemical compositions of sediments from both the areas are similar however water chemistry and sedimentary facies vary significantly extraction test of sediment samples showed significant leaching of arsenic and iron chemical reduction and contribution from organic matter could be a plausible explanation for the arsenic release in groundwater from the terai sediments

application of ree geochemical signatures for mesozoic sediment provenance to the gettysburg basin pennsylvania rift basins adjacent to accreted terranes provide accommodation space for sediments eroded from these terranes despite similar depositional environments and geologic age rocks of the triassic gettysburg basin have approximately half the arsenic concentrations of the adjacent newark basin quartz feldspar lithics qfl diagrams and rare earth element ree geochemical signatures can inform sediment provenance here we investigate ree geochemical signatures of the sedimentary rocks in the triassic gettysburg rift basin with the goal of distinguishing the main sources of siliciclastic sediment among the appalachian foreland in the rift footwall from piedmont arc and iapetan continental margin rocks exposed in the hanging wall and ultimately understanding the geochemical cycling of arsenic to the gettysburg basin shale normalized ree spider diagrams and mann whitney tests on trace element ratios suggest that the gettysburg basin samples show patterns that most closely resemble those of the iapetus continental slope rise iapetus rift volcanic and accretionary complex deposits mann whitney rank sum analysis suggest that the iapetus continental slope rise terrane is the main source of sediments to the basin which confirms results from prior qfl analysis and shows the utility of ree fingerprinting in provenance analysis the main sources of sediment have smaller minimum and maximum arsenic concentrations than other terranes and the newark basin sediments additionally suggesting the source of arsenic to the gettysburg basin is based upon specific terranes

self aggregation and large scale control of tropical deep convection a modeling study abstract the pennsylvania state university national center for atmospheric research mesoscale model version 5 mm5 is used to investigate whether superclusters represent a mode of self aggregation of tropical deep convection that occurs spontaneously under horizontally uniform boundary conditions and large scale forcings the nonhydrostatic version of mm5 is run with prescribed domain averaged vertical velocity and periodic boundary conditions in both east west and north south directions domain averaged horizontal winds are relaxed to a specified reference wind profile two vertical profiles of mean ascent are used one has an elevated maximum at the upper troposphere and near zero vertical velocity in the lower troposphere the other peaks at the midtroposphere representing the vertical velocity distribution of convective towers only simulations with the same initial conditions but two different forcings show significant differences in convective organization the run with elevated forcing develops l

organized convective systems in the tropical western pacific as a process in general circulation models a toga coare case study we examine the large scale effects of organized convective systems in the tropical western pacific observed during the tropical ocean global atmosphere coupled ocean atmosphere response experiment toga coare in a case study approach we examine realizations of a supercluster associated with the onset of the december 1992 westerly wind burst in the t213 operational medium range weather forecasting model of the european centre for medium range weather forecasts ecmwf we idealize a supercluster as a hierarchy of three interacting scales namely organized cumulonimbus c 1 mesoscale convective systems c 2 and the supercluster component c 3 it is shown that the ecmwf model represents this hierarchy as a c 3 like surrogate whose influence dominates the effect of parametrized convection this causes over prediction of the model tendencies which in the case of zonal momentum is explained in elementary terms the structure of the resolved scale momentum flux is explained by moncrieff s 1992 archetypal theory of organized convection which has been verified against observations and cloud resolving model data sets the parametrization of subgrid scale convective momentum flux in the ecmwf model based on a momentum mixing concept produces subgrid scale tendencies that are physically different from transports associated with cumulonimbus convection in a shear flow we outline a strategy for parametrizing the momentum flux by the c 1 component based on the archetypal model the c 2 component which is part resolved and part parametrized is at odds with the assumptions of scale separation underpinning parametrization it is argued that this component should be represented as part of the prognostic treatment of convectively generated cirrus finally we suggest cloud resolving modelling studies to further quantify the structure and large scale impact of superclusters in a westerly wind burst environment ranging from idealized models to models having data assimilation capability

observed evolution of northward propagating intraseasonal variation over the western pacific a case study in boreal early summer abstractthis report describes the in situ observed evolution of the atmospheric profile during an event of the boreal summer intraseasonal variation bsisv in the tropical western pacific ocean the convectively active region of the bsisv proceeded northward over the sounding and radar network over the array the situation changed from a convectively inactive period to an active period inspection of the sounding data revealed the gradual moistening of the lower troposphere during the convectively inactive period the sounding derived heat and moisture budget analyses indicated that both the convective and large scale processes caused moistening of the lower and middle troposphere where the radar echo tops were observed most frequently this study is the first to identify such a preconditioning process for the bsisv in the western pacific using detailed in situ observational data during the preconditioning an increase in cape was observed as in previous studies of the mjo an increase of moisture

the hadley circulation as a radiative convective instability abstract hadley cell simulations over a tropical ocean are reported that suggest that the emission and absorption of thermal radiation by clouds plays an important role in the dynamics of the hadley circulation in particular inclusion of interactions between clouds and radiation causes the tropical atmosphere to become unstable to large scale convective circulations driven by differential radiative heating between cloudy and clear regions even when the sea surface temperature and the solar forcing do not vary with latitude or time zonally symmetric circulations take the form of an equatorially asymmetric convective cell with ascent in one hemisphere and descent in the other this may explain why there is usually only one intertropical convergence zone that is located away from the equator even when the sea surface temperature maximum is on or near the equator the conclusions of this paper are tentative because the treatments of convection radiation and cloudiness are highly simplified however if

gravity waves compensating subsidence and detrainment around cumulus clouds abstract gravity waves play an important role in the redistribution of heat and moisture in a deep convecting cloud field we explore this role in a two dimensional numerical experiment on a simple moist convecting system consisting of an isolated long lasting nonprecipitating cloud in a calm atmosphere with no surface forcing the cloud develops a horizontally averaged density variation with height which is neutrally buoyant with respect to a moist adiabatic the buoyancy difference between the cloud and the undisturbed sounding produces circulations that can be understood as spreading gravity waves which adjust the environmental buoyancy to be equal to the cloud buoyancy by compensating subsidence unlike the circulations inside clouds this adjustment takes place without turbulent mixing hence the buoyancy adjustment time t1 during which the environment comes into rough buoyant equilibrium with the clouds is much shorter than the mixing time t2 which it takes a tracer initially concentrated at s

cloud resolving modeling of tropical circulations driven by large scale sst gradients this paper considers interactions between the moist atmospheric convection and the large scale flow driven by the large scale gradient of sea surface temperature a two dimensional computational framework is used with the horizontal domain size of 4000 km in which both the convective dynamics and the large scale flow are resolved rotational effects are not considered simulations are performed using either a prescribed temperature tendency mimicking the effects of radiative processes or a fully interactive radiation transfer model the simulations are performed for a period of 60 days with quasi equilibrium conditions attained after about a month the time mean large scale flow in the simulations features an ascending branch occupied by moist convection over a warm ocean and a cloud free descending branch over a cold ocean the time mean flow for the prescribed radiation case features a complex vertical structure characterized by two somewhat decoupled circulations in the lower and upper troposphere this is in stark contrast with the predominant first baroclinic mode structure typical of the observed large scale tropical circulations which is characterized by a single cell an idealized dry model featuring prescribed convective heat source suggests that the complex vertical structure is directly related to the deviation of the model temperature profile from the climatology quasi two day oscillations are a major transient feature of the simulations the oscillations are associated with radiation of gravity waves from the convective branch into the descending branch inclusion of the interactive radiation results in a significant modification of the large scale flow and has a dramatic impact on the strength and horizontal extent of convection water vapor and cloud condensate strongly interact with radiative processes to induce these paramount effects on the tropical large scale circulations

rare earth element distributions among minerals in a granodiorite and their petrogenetic implications a study of the distribution of lanthanide rare earths in a granodiorite from the eastern peninsular ranges batholith southern california reveals that a large fraction of the ree in this rock resides in the accessory phases sphene and allanite the minerals plagioclase alkali feldspar biotite epidote and apatite each contribute approximately 1 or less of each ree to the whole rock with the exception of eu for which plagioclase contributes 7 sphene and allanite together contain 80 to 95 of each ree each of these phases is zoned in ree concentration with substantial decreases from core to margin textural observations argue for relatively early saturation and precipitation of sphene and allanite in the magma ree zoning trends in sphene and allanite and unexpectedly low ree concentrations in largely later crystallizing minerals such as feldspar indicate that the precipitation of sphene and allanite significantly reduced ree concentrations in residual melts these results illustrate the potential that sphene and allanite have for controlling the behavior of ree in granitic magmas available information collectively suggest that the sampled granodiorite existed as a complete melt that the ree contained in the assemblage of phases were derived by direct crystallization from the melt and that the melt behaved essentially as a closed system once crystallization of the phases now present began close correspondences between the major and trace element chemistries of the granodiorite and phenocryst poor lavas from similar tectonic settings support these conclusions the ree pattern of the granodiorite melt appears to have originated at depth and is characteristic of its source regions and derivation mechanism the high liquidus temperature of a granodiorite melt 1000 c indicates the importance of mantle derived components within the sources of batholithic magmas in the peninsular ranges

regional sediment sources versus the indus river system the plio pleistocene of the peshawar basin nw pakistan abstract sedimentary archives within the peshawar basin in northwest pakistan preserve a record of siliciclastic supply patterns during the plio pleistocene epoch the basin fill consists of fluvial floodplain clays overlain by thick lacustrine glaciofluvial rhythmites with deposits of multiple alluvial fans in the southern parts of the basin and topped by loess deposits in ideal vertical successions framework mineralogical composition and bulk sediment geochemical proxies of these sediments indicate detritus derivation from dominantly acidic igneous sources with contribution from medium grade metamorphic rocks there appears to be no significant contribution from ultramafic mafic or very high grade metamorphic sources in addition sediments from the southern part of the basin support supply from low grade metamorphic rocks and carbonate sediments overall sedimentation occurred in an active continental margin setting under conditions of insignificant chemical weathering the uplift of the attock cherat range during the late pliocene 2 8 ma restricted the indus river from shedding its detritus into the basin therefore the sediments of the peshawar basin do not reflect signatures of the indus river siliciclastics and thus lack the basic igneous geochemical signal which is otherwise typical for the himalayas hinterland on the contrary the geochemical signatures of these sediments favour predominant detritus flux from the acidic rocks of the peshawar plain alkaline igneous complex ppaic and associated metasediments therefore the kabul swat river and other local tributaries of this smaller river system that originated within the ppaic and associated mountains are considered the major transporting agents which contributed siliciclastics into the peshawar basin during the plio pleistocene additionally in the southern part of the basin the uplifting attock cherat range appeared to have contributed detritus in the form of alluvial fluvial fan deposits

two dimensional convection in non constant shear a model of mid latitude squall lines numerical simulations of two dimensional deep convection are analysed using analytical models extended to include shallow downdraughts and non constant shear the cumulonimbus are initiated by low level convergence created by a finite amplitude downdraught these experiments have constant low level shear and differ only in the profile of mid and upper level winds quasi steady convenction is produced if the mid and upper level flow has small shear and the low level shear is large the surface precipitation ismaximized for no intial relative relative flow aloft if stationary this storm p o can give prodigious locilized rainfall p o is the two dimentisonal equivalent of the supercell these results are placed in context with previous two dimensional simulations attention is drawn to the similiarity with previous two dimensional simulations attention is drawn to the similarity with squall lines in central and eastern u s a storm p o is analysed by construction of time averaged fields of streamfunction vorticity teperature and height deviation the smoothness of these fields suggests a conceptual model of the storm dynamics which involves cooperation between distinct charcteristic flows an overturning updraught a jump type updraught a shallow downdraught a low level rotor and a boundary layer an idealized analytical model is described by solution of the equations for steady convection these solutions for the remote flow are derived from energy conversation mass continuity and a momentum budget and they give relationships between the non dimensional parameteres of the problem it is apparent that the convection is a high froude or low richardson number flow demanding the existence of a cross storm pressure gradient inherent in this idealized model is a vortex sheet between updraught and down draught and it is considered that the dynamical instability of this sheet is related to complexities in the numerical simulation furthermore these results show that in two dimensions both non constant shear and a shallow downdraught are necessary to maintain steady convection

dynamics of the intertropical convergence zone of the east pacific abstract the dynamical factors controlling the mean state and variability of the east pacific intertropical convergence zone itcz and the associated cross equatorial boundary layer flow are investigated using observations from the east pacific investigation of climate epic2001 project the tropical east pacific exhibits a southerly boundary layer flow that terminates in the itcz this flow is induced by the strong meridional sea surface temperature sst gradient in the region away from the equator and from deep convection it is reasonably well described on a day to day basis by an extended ekman balance model variability in the strength and northward extent of this flow is caused by variations in free tropospheric pressure gradients that either reinforce or oppose the pressure gradient associated with the sst gradient these free tropospheric gradients are caused by easterly waves tropical cyclones and the madden julian oscillation convergence in the boundary layer flow is often assumed to be r

tectonic environment of the devonian gramscatho basin south cornwall framework mode and geochemical evidence from turbiditic sandstones the portscatho formation within the allochthonous unit of the middle and upper devonian gramscatho group is a thick sequence of deep water sandstones and interbedded slates deposited by southerly derived turbidity currents into the gramscatho basin of south cornwall throughout an approximately 3 5 km thick sequence the portscatho formation is petrographically and chemically coherent except that the upper section shows a higher proportion of metamorphic clasts high but variable cr and low uniform zr abundances complementary framework mode and bulk geochemistry indicate that the sandstones were derived from a dissected continental magmatic arc of predominantly acidic composition similar to average upper continental crust but with an admixture of minor intermediate basic material flysch deposition took place in a fore arc setting the presence of an arc to the south of cornwall during the devonian implies that there was subduction at the margin of the gramscatho basin whose ultimate closure was accommodated by the northward stacking of flysch ophiolite nappes

vertical temperature structure associated with evaporation of stratiform precipitation in idealized wrf simulations abstracta recent study based on observations has shown that after precipitation over tropical oceans rather shallow temperature structures occur in the lower troposphere and that their magnitude de

sedimentary facies and depositional environments of early mesozoic newark supergroup basins eastern north america abstract the early mesozoic newark supergroup consists of continental sedimentary rocks and basalt flows that occupy a ne trending belt of elongate basins exposed in eastern north america the basins were filled over a period of 30 40 m y spanning the late triassic to early jurassic prior to the opening of the north atlantic ocean the sedimentary rocks are here divided into four principal lithofacies the alluvial fan facies includes deposits dominated by 1 debris flows 2 shallow braided streams 3 deeper braided streams with trough crossbeds or 4 intense bioturbation or hyperconcentrated flows tabular unstratified muddy sandstone the fluvial facies include deposits of 1 shallow ephemeral braided streams 2 deeper flashflooding braided streams with poor sorting and crossbeds 3 perennial braided rivers 4 meandering rivers 5 meandering streams with high suspended loads 6 overbank areas or local flood plain lakes or 7 local streams and or colluvium the lacustrine facies includes deposits of 1 deep perennial lakes 2 shallow perennial lakes 3 shallow ephemeral lakes 4 playa dry mudflats 5 salt encrusted saline mudflats or 6 vegetated mudflats the lake margin clastic facies includes deposits of 1 birdfoot deltas 2 stacked gilbert type deltas 3 sheet deltas 4 wave reworked alluvial fans or 5 wave sorted sand sheets coal deposits are present in the lake margin clastic and the lacustrine facies of carnian age late triassic only in basins of south central virginia and north and south carolina eolian deposits are known only from the basins in nova scotia and connecticut evaporites and their pseudomorphs occur mainly in the northern basins as deposits of saline soils and less commonly of saline lakes and some evaporite and alkaline minerals present in the mesozoic rocks may be a result of later diagenesis these relationships suggest climatic variations across paleolatitudes more humid to the south where coal beds are preserved and more arid in the north where evaporites and eolian deposits are common fluctuations in paleoclimate that caused lake levels to rise and fall in hydrologically closed basins are preserved as lacustrine cycles of various scales including major shifts in the late triassic from a wet carnian to an arid norian in contrast fluvial deposits were mainly formed in response to the tectonic evolution of the basins but to some extent also reflect climatic changes the newark supergroup illustrates the complexity of rift basin sedimentation and the problems that may arise from using a single modern analog for sedimentary deposition spanning millions of years it also shows that a tremendous wealth of depositional climatic and tectonic information is preserved in ancient rift basin deposits which can be recovered if the depositional processes of modern rift basin deposits are understood

an intraseasonal oscillation composite life cycle in the ncar ccm3 6 with modified convection abstract the ncar ccm3 6 with microphysics of clouds with relaxed arakawa schubert convection produces an intraseasonal oscillation that is highly dependent on lower tropospheric moistening by surface convergence model intraseasonal convection is most highly correlated with surface convergence at zero lag causing enhanced convection to be associated with 850 mb easterly anomalies where surface convergence is strongest the tendency for surface convergence to maximize within 850 mb easterly anomalies is consistent with meridional frictional convergence into equatorial surface pressure troughs associated with planetary scale tropical wave circulations anomalous vertical advection associated with meridional surface convergence influences model convection by moistening the lower troposphere observed madden julian oscillation mjo convection and lower tropospheric specific humidity are also significantly correlated with surface convergence although correlations are weaker than in the model and converge

mechanisms of meridional teleconnection observed between a summer monsoon system and a subtropical anticyclone part i the pacific japan pattern abstract summertime atmospheric circulation over the midlatitude western north pacific wnp is influenced by anomalous convective activity near the philippines this meridional teleconnection observed in monthly anomalies and known as the pacific japan pj pattern is characterized by zonally elongated cyclonic and anticyclonic anomalies around the enhanced convection center and to its northeast respectively in the lower troposphere with an apparent poleward phase tilt with height the authors idealized two layer linear model whose basic state consists of a zonal subtropical jet and a pair of a monsoon system and a subtropical anticyclone can simulate a pj like response against diabatic heating located between the pair each of the observed and simulated patterns can gain energy through barotropic and baroclinic conversions from the zonally varying baroclinic mean flow in an efficiency comparable with that of energy generation due to the anomalous diabatic heating indicating a characteristic of

large scale organization of tropical convection in two dimensional explicit numerical simulations effects of interactive radiation we examine interactions among radiative processes water vapour clouds and the multi scale organization of tropical convection in two dimensional idealized cloud resolving simulations using planetary scale horizontal domains we extend our earlier study where radiative cooling was prescribed therein deep convection spontaneously organized into two primary scales westward travelling mesoscale convective systems on a scale of a few hundred kilometres and the eastward propagating envelopes of convection spanning thousands of kilometres these envelopes represented large scale convectively coupled gravity waves two dimensional non rotating analogues of equatorially trapped kelvin waves interactive radiation introduces a new mechanism of large scale convective organization weak overturning circulations steered by the mean wind and of a few thousand kilometres in scale gradually develop this overturning is a manifestation of the baroclinic response to horizontal gradients of radiative heating established between the moist and dry regions which causes a spontaneous positive feedback among large scale dynamics water vapour clouds and radiation the mechanism is as follows the convective systems maintain the humidity vapour and cloud in the ascending branch which in turn maintains the differential radiative heating conversely the large scale overturning provides the large scale dynamical forcing that maintains the deep convection this quantifies recent idealized studies that applied convective parametrizations the radiatively driven overturning and the deep convection are modulated by large scale convectively coupled gravity waves responsible for the large scale envelopes reported earlier a series of sensitivity tests including the effects of environmental shear demonstrate the robustness of these results copyright 2002 royal meteorological society

effect of stratiform heating on the planetary scale organization of tropical convection abstractit is widely recognized that stratiform heating contributes significantly to tropical rainfall and to the dynamics of tropical convective systems by inducing a front to rear tilt in the heating profile precipitating stratiform anvils that form from deep convection play a central role in the dynamics of tropical mesoscale convective systems the wide spreading of downdrafts that are induced by the evaporation of stratiform rain and originate from in the lower troposphere strengthens the recirculation of subsiding air in the neighborhood of the convection center and triggers cold pools and gravity currents in the boundary layer leading to further lifting here aquaplanet simulations with a warm pool like surface forcing based on a coarse resolution gcm of approximately 170 km grid mesh coupled with a stochastic multicloud parameterization are used to demonstrate the importance of stratiform heating for the organization of convection on planetary and intraseasonal scales when the model paramet

transport of rare earth elements by hydrocarbon bearing brines implications for ore deposition and the use of rees as fluid source tracers abstract low temperature 100 160 c hydrocarbon bearing brines mobilize ree at concentrations up to several thousand ppm total rare earth elements ree at el hammam morocco the major element chemistry na ca mg and temperature of the fluids in this system are consistent with those of oil field brines in contrast ree concentrations in the fluid suggest a significant element input from a magmatic source spatially related lamprophyres predating the formation of el hammam share a similar trace element signature therefore hydrocarbon bearing basinal brines seem to have leached some of these elements through fluid rock interaction from the lamprophyres supporting the ability of oil field brines to mobilize not only base metals as in mississippi valley type mvt deposits but also rare earth elements the stability constants of ree aqueous complex at temperatures of 100 160 c the chemistry of oil field brines worldwide and the partitioning behavior of ree between fluorite and water at el hammam indicate that acetate carbonate and fluoride are likely to be major contributors to ree mobilization in these settings the direct implications of the low temperature transport of ree by oil bearing brines is that in systems where these kind of fluids occur the ree signature observed may not reflect the source of the fluid as much as a combination of fluid source and fluid rock interaction in addition oil field brines can efficiently scavenge transport and deposit ree leading to anomalously high accumulations such as the el hammam fluorite deposit and may also contribute to ree mobilization and concentration in other systems

arsenic iron and organic matter in sediments and groundwater in the pannonian basin hungary in the central part of the pannonian basin factors controlling the distribution of as in sediments and groundwater of the upper 500 m were studied in core samples the amounts of as fe and mn extractable with hydroxylamine hydrochloride nh2oh hcl in 25 acetic acid the proportion of the 0 063 mm size fraction and the sediment organic c corg contents were measured in the groundwaters concentrations of as humic substances and selected major chemical components were determined in most core samples extractable fe as feooh and corg are correlated but some samples have excess fe or organic matter in cases where either excess fe or excess organic matter is found the amount of as is also elevated the spatial distribution of as in the groundwater and the lack of a consistent correlation of as with a single component indicate that there is no single factor controlling the concentration of dissolved as over the entire study area the only consistent feature is enrichment of as relative to fe in the groundwater compared to the sediments this suggests that the dissolution of fe minerals which primarily adsorb as is not congruent in reducing conditions fe iii oxyhydroxides together with adsorbed as dissolve and siderite with little or no as precipitates when sub regions are separated and studied individually it can be shown that hydrogeological features of the sediments the proportions of fe minerals and sedimentary organic matter and the concentration of dissolved humic materials all influence the accumulation and mobilization of as the significance of the different mobilizing processes however and the mean concentration of as is different in the recharge through flow and discharge areas

the early mesozoic birdsboro central atlantic margin basin in the mid atlantic region eastern united states the early mesozoic birdsboro basin new name was a single elongate depositional trough in the present mid atlantic area of the eastern united states extending northeastward from central virginia across maryland pennsylvania and new jersey into southern new york what now remains after erosion comprises the barboursville culpeper gettysburg and newark remnants some 7 km of late triassic and early jurassic continental sediments of varying provenances entered and spread across in the birdsboro basin in several depositional environments the five resulting sedimentary lithosomes include feldspathic sandstone quartzose sandstone red silty mudstone gray shale and fanglomerate the extensive interbedding intertonguing and lateral gradation among these lithosomes suggest that they were contemporary and closely interrelated the feldspathic sandstone lithosome contains sediment with a southeastern provenance that accumulated in a bajada environment extending the length of the southeastern side of the basin sediment in the quartzose sandstone lithosome had a northwestern provenance the coarse grained fraction formed regional alluvial fans at the mouths of four major input centers the finer grained fraction was deposited in the distal reaches of these fans and in the playa environments in the interfan areas this fraction formed the red silty mudstone lithosome gray black shales and argillites of the gray shale lithosome accumulated in lacustrine environments in the interfan areas the fanglomerate lithosome comprises numerous small lobate deposits of poorly sorted sediment along both basin margins the location and time of activity of the northwest input centers largely determined the distribution and areal extent of the various depositional environments and consequent lithosomes along the length and across the width of the basin the birdsboro basin was deformed tilted faulted and folded sometime after the deposition of the youngest preserved rocks early sinemurian the deformation varied along the length of the basin producing differences in the amount of tilting structural elevation and subsequent erosion the present erosional remnants create the illusion of four originally separate depositional basins