large scale patterns associated with tropical cyclogenesis in the western pacific abstract five characteristic low level large scale dynamical patterns associated with tropical cyclogenesis in the western north pacific basin are examined along with their capacity to generate the type of mesoscale convective systems that precede genesis an 8 yr analysis set for the region is used to identify and create composites for the five characteristic patterns of monsoon shear line monsoon confluence region monsoon gyre easterly waves and rossby energy dispersion this brings out the common processes that contribute to tropical cyclogenesis within that pattern which are described in detail a 3 yr set of satellite data is then used to analyze the mesoscale convective system activity for all cases of genesis in that period and to stratify based on the above large scale patterns it is found that mesoscale convective systems develop in all cases of genesis except one seventy percent of cases developed mesoscale convective systems at more than one time during the genesis period and 44 of

the tectonically controlled emplacement of a vertically sheeted gabbro pyroxenite intrusion feeder zone of an ocean island volcano fuerteventura canary islands abstract the miocene px1 gabbro pyroxenite pluton fuerteventura canary islands is a 3 5 5 5 km shallow level intrusion 0 15 0 2 gpa and 1100 1120 c interpreted as the feeder zone to an ocean island volcano it displays a vertical magmatic banding expressed in five 50 to 100 metre wide nne ssw trending alkaline gabbro sequences alternating with pyroxenites this emplacement geometry was controlled by brittle to ductile shear zones generated by a regional e w extensional tectonic setting that affected fuerteventura during the miocene at a smaller scale the px1 gabbro and pyroxenite bands consist of metre thick differentiation units which suggest emplacement by periodic injection of magma pulses as vertical dykes that amalgamated similarly to a sub volcanic sheeted dyke complex individual dykes underwent internal differentiation following a solidification front parallel to the dyke edges this solidification front may have been favoured by a significant lateral horizontal thermal gradient expressed by the vertical banding in the gabbros the fractionation asymmetry within individual dykes and the migmatisation of the wall rocks pyroxenitic layers result from the fractionation and accumulation of clinopyroxene olivine plagioclase crystals from a mildly alkaline basaltic liquid they are interpreted as truncated differentiation sequences from which residual melts were extracted at various stages of their chemical evolution by subsequent dyke intrusions either next to or within the crystallising unit compaction and squeezing of the crystal mush is ascribed to the incoming and inflating magma pulses the expelled interstitial liquid was likely collected and erupted along with the magma flowing through the newly injected dykes clinopyroxene mineral orientation as evidenced by ebsd and micro x ray tomography investigations displays a marked pure shear component supporting the interpretation of the role of compaction in the generation of the pyroxenites conversely gabbro sequences underwent minor melt extraction and are believed to represent crystallised coalesced magma batches emplaced at lower rates at the end of eruptive cycles clinopyroxene orientations in gabbros record a simple shear component suggesting syn magmatic deformation parallel to observed nne ssw trending shear zones induced by the regional tensional stress field this emplacement model implies a crystallisation time of 1 to 5 years for individual dykes consistent with px1 emplacement over less than 0 5 my a minimum amount of approximately 150 km3 of magma is needed to generate the pluton part of it having been erupted through the central volcanic centre of fuerteventura if the regional extensional tectonic regime controls the px1 feeder zone initiation and overall geometry rates and volumes of magma depend on other source related factors high injection rates are likely to induce intrusion growth rates larger than could be accommodated by the regional extension in this case dyke intrusion by propagation of a weak tip combined with the inability of magma to circulate through previously emplaced and crystallised dykes could result in an increase of non lithostatic pressure on previously emplaced mushy dyke walls thus generating strong pure shear compaction within the pluton feeder zone and interstitial melt expulsion these compaction dominated processes are recorded by the cumulitic pyroxenite bands

response of daily and annual shell growth patterns of the intertidal bivalve phacosoma japonicum to holocene coastal climate change in japan abstract it is well known that the latitudinal distribution of shallow marine mollusks around the japanese islands has changed episodically during the holocene in response to climate change however few studies have investigated the biotic response of individual species to holocene climate change at daily to annual scales of temporal resolution holocene shells of the venerid phacosoma japonicum recovered from various sites in japan preserve lunar daily and annual growth increments in the outer shell layer and hinge plate as also observed in modern shells sclerochronological analysis of 29 shells with known 14 c ages revealed that the life history traits e g length of the growth period and the mean lunar daily growth rate at a given age have changed markedly over the past 8000 years the intra annual patterns of lunar daily increments and shell oxygen isotope records of the fossil shells can be compared with those of modern specimens from various locations which are constrained by annual patterns of seawater temperature and summer autumn precipitation rates furthermore the temporal trends recorded in the fossil shells show a strong correlation with climate change in mid latitude parts of east asia over the past 8000 years indicating that p japonicum has changed its life history traits in response to holocene terrestrial and coastal climate change

modeling compaction of olivine cumulates in the muskox intrusion we have developed numerical models for compaction of olivine cumulates by simultaneous grain boundary diffusion creep and power law creep the simulation is a coupled model of compaction porous medium flow and heat transport that includes latent heat of fusion and advective heat transport by flow of interstitial liquid it also includes precipitation from interstitial pore liquid and partial melting of cumulates caused by changes in temperature or passage of interstitial melt through regions of different temperature compositions and quantities of liquid and precipitated phases are aetermined from a fractional crystallization simulation using the computer program melts we use these models to simulate the accumulation and crystallization of the muskox intrusion simulations suggest that regardless of their initial state compaction will lithify cumulates into a cohesive mass within meters of the depositional interface upward velocity of interstitial liquid is also much too small to suspend or liquify the crystal column the simulations produced rapidly cooled marginal zones at both top and bottom of the intrusion high rates of compaction are found at the tops and bottoms of cyclic units as a result of both high temperature at the boundary and partial melting caused by upward flow of cooler interstitial liquid as it enters hotter compositionally more primitive cumulates above the cyclic unit contact in contrast upward movement of interstitial liquid into cooler cumulates contrib utes to precipitation both in the upper marginal zone and in the middle region of cyclic units the degree of compaction of cumulates is strongly a function of temperature but if temperature is sufficiently high adcumulates can form in the interior of cumulate bodies by compaction alone

physical properties of partly melted tholeiitic basalt melting experiments on centimetre scale blocks of tholeiitic holyoke basalt from the mesozoic hartford basin of connecticut reveal that when this basalt is only 30 crystallized a relatively strong network of crystals exists cubes of the basalt melted to this degree retain their shape as the interstitial liquid drains easily from the crystal network the intrinsic permeability of a sample containing 34 crystals was determined to be 3 10 10 m2 which is similar to that of coarse gravel serial sections through partly melted samples reveal that the network owes its strength to monomineralic strings of plagioclase and pyroxene crystals although these strings are clearly evident once the rock has been partly melted they are difficult to see in thin sections of the initial basalt but they are present the compressive strength of the mush increases dramatically from 336 to 4333 pa as the percentage of crystals increases from 33 to 37 this rapid strengthening is believed to explain why sheets of segregation liquid in tholeiitic flood basalts have compositions that correspond to no more than 35 fractional crystallization of the host basalt these sheets are proposed to form through compaction of the crystal mush in the lower part of thick flows the compaction occurring only while the mush remains weak that is while it has 35 crystals

the eruption environment of multi tiered columnar basalt lava flows field studies on the eruption environment and prevailing cooling conditions of multi tiered lava flows of the type exemplified by the giant s causeway were carried out at localities on the columbia river plateau southern iceland on the islands of mull and staffa and around the giant s causeway ne ireland common features can be recognized in the volcanology of such flows in all the localities examined these include palaeotopographic evidence of river valleys giving conditions conducive to the ponding of flows and the damming of existing drainage evidence of high rainfall regimes or abundant surface water association of interlava lacustrine and fluviatile sediments association of hyaloclastite flow foot breccias within multi tiered basalt lava successions and evidence of large volume lava flows and high eruption rates examination of the petrography of the upper curvi columnar parts of the lava the entablature shows textural signs of quenching compared with the lower more regular columnar zone the colonnade these common field and petrographic features confirm the model of multi tiered flow formation by modification of the cooling regime in the upper part of the flow following inundation of the hot lava surface by displaced river drainage

quantitative measures of textural anisotropy resulting from magmatic compaction illustrated by a sample from the palisades sill new jersey abstract early in the crystallization of many tholeiitic basaltic magmas plagioclase crystals cluster together into a 3 d cellular network which forms a passive marker capable of recording the deformation that accompanies compaction of crystal mush although irregular in detail the overall network is initially isotropic and only becomes anisotropic as a result of compaction we have developed four independent methods to quantify the 3 d textural anisotropy of a basalt sample using at least three non parallel thin sections three of the methods are based on the geometrical properties of digitized maps of the feldspar chain networks one approach focuses on the angular variation of the mean intercept along parallel traverses through the network another examines the orientation and size distribution of individual links and the third considers the average shape of interstitial regions outlined by the plagioclase network the fourth technique approximates the textural anisotropy by the variogram anisotropy of a scanned thin section image we illustrate the methods using five oriented non parallel thin sections from a sample of diabase 146 m above the base of the 300 m thick palisades sill of new jersey compaction of crystal mush in this sill has previously been postulated on the basis of chemical evidence the 3 d feldspar network anisotropy based on the first three approaches suggests nearly uniaxial compaction on the order of 8 6 in a direction within 3 of the intersection of the columnar joints at the sample site a rigorous statistical test based on the statistics of elliptically contoured non normal multivariate distributions documents that the link vector distribution in vertical sections are statistically anisotropic at a 95 confidence level and that the overall compaction is 7 9 2 6 the orientation and magnitude of the 3 d textural anisotropy determined by the image variogram of the non opaque minerals is almost identical to the mean feldspar network anisotropy 8 5 compaction in a direction 10 from the columnar joint intersections the major silicate textural and feldspar network anisotropy axes both plunge almost directly down dip of the sill on the other hand the major axis of the variogram anisotropy of the opaque minerals is approximately parallel to the strike of the sill and to the major axis of the anisotropic magnetic susceptibility the anisotropy of the silicate mineral fabric may reflect down dip flow of a deformable melt rich crystal mush whereas the ams and opaque textural anisotropy reflects the influence of gravitational stresses during the growth of magnetite in the final stages of melt crystallization evidently the palisades sill was not originally horizontal but was intruded in an orientation close to its present attitude

on the interaction between convection and crystallization in cooling magma chambers abstract we investigate the interaction of thermal convection and crystallization in large aspect ratio magma chambers because nucleation requires a finite amount of undercooling crystallization is not instantaneous for typical values of the rates of nucleation and crystal growth the characteristic time scale of crystallization is about 10 3 10 4 s roof convection is characterized by the quasi periodic formation and instability of a cold boundary layer its characteristic time scale depends on viscosity and ranges from about 10 2 s for basaltic magmas to about 10 7 s for granitic magmas hence depending on magma viscosity convective instability occurs at different stages of crystallization a single non dimensional number is defined to characterize the different modes of interaction between convection and crystallization using realistic functions for the rates of nucleation and crystal growth we integrate numerically the heat equation until the onset of convective instability we determine both temperature and crystal content in the thermal boundary layer crystallization leads to a dramatic increase of viscosity which acts to stabilize part of the boundary layer against instability we compute the effective temperature contrast driving thermal convection and show that it varies as a function of magma viscosity and hence composition in magmas with viscosities higher than 10 5 poise the temperature contrast driving convection is very small hence thermal convection is weak in low viscosity magmas convective breakdown occurs before the completion of crystallization and involves partially crystallized magma the convective regime is thus characterized by descending crystal bearing plumes and bottom crystallization proceeds both by in situ nucleation and deposition from the plumes we suggest that this is the origin of intermittent layering a form of rhythmic layering described in the skaergaard and other complexes we show that this regime occurs in basic magmas only at temperatures close to the liquidus and never occurs in viscous magmas this may explain why intermittent layering is observed only in a few specific cases

tree ring reconstructions of cool season temperature for far southeastern australia 1731 2007 at the global scale reconstructions of cool season temperature over past centuries are relatively rare here we present 277 year reconstructions of cool season july october temperatures for southern australia based on three different data sets a spatial field reconstruction based on highly resolved temperature data from the australian water availability product data reconstructions for the four southeast australian states based on the berkeley earth mean temperature data for each state and reconstructions for individual stations in southeastern australia from the australian bureau of meteorology s australian climate observations reference network surface air temperature data our reconstructions typically capture 25 50 of the variation over the late twentieth century calibration period and are strongest for the southern state of tasmania and the southeastern part of mainland australia all three use tasmanian tree rings sensitive to cool season temperatures and display similar variability in the context of our reconstructions the persistent warming in the observed record since 1950 is unprecedented while the low frequency variability of winter temperatures is generally in step with that in summer december february temperatures high frequency variability is not illustrating the need for seasonal reconstructions to help improve understanding of variability in inter seasonal dynamics and the historical importance of this on the environment the reconstructions covary with changes in the southern annular mode and may be useful for future reconstructions of this phenomenon

complex layering of the orange mountain basalt new jersey usa the orange mountain basalt of new jersey is a mesozoic formation consisting of three units a single lower inflated sheet lobe about 70 m thick omb1 a middle pillow basalt about 10 to 20 m thick omb2 and an upper compound pahoehoe flow about 20 to 40 m thick omb3 the orange mountain basalt is part of the central atlantic magmatic province quarry and road cut exposures of omb1 near paterson new jersey display some unusual layering that is the focus of this study omb1 exposures displays the typical upper crust core and basal crust layers of sheet lobes but throughout the patterson area also display distinct light gray layers of microvesicular basalt mineralized with albite directly over the basal crust and under the upper crust the lower microvesicular layer is associated with mega vesicular diapirs we propose that the upper and lower microvesicular layers were composed of viscous crust that was suddenly quenched before it could devolatilize immediately before the solidification of the core during initial cooling the bottom of the basal layer was mineralized with high concentrations of calcite and albite during a high temperature hydrothermal event subsequent albitization as well as zeolite prehnite and calcite precipitation events occurred during burial and circulation of basin brine heated by recurring palisades magmatism below the orange mountain basalt some of the events experienced by the orange mountain basalt are unusual and place constraints on the fluid dynamics of thick flood basalt flows in general the late penetration of vesicular diapirs through the entire thickness of the flow interior constrains its viscosity and solidification history

architecture and emplacement of flood basalt flow fields case studies from the columbia river basalt group nw usa the physical features and morphologies of collections of lava bodies emplaced during single eruptions known as flow fields can be used to understand flood basalt emplacement mechanisms characteristics and internal features of lava lobes and whole flow field morphologies result from the forward propagation radial spread and cooling of individual lobes and are used as a tool to understand the architecture of extensive flood basalt lavas the features of three flood basalt flow fields from the columbia river basalt group are presented including the palouse falls flow field a small 8 890 km2 190 km3 unit by common flood basalt proportions and visualized in three dimensions the architecture of the palouse falls flow field is compared to the complex ginkgo and more extensive sand hollow flow fields to investigate the degree to which simple emplacement models represent the style as well as the spatial and temporal developments of flow fields evidence from each flow field supports emplacement by inflation as the predominant mechanism producing thick lobes inflation enables existing lobes to transmit lava to form new lobes thus extending the advance and spread of lava flow fields minimum emplacement timescales calculated for each flow field are 19 3 years for palouse falls 8 3 years for ginkgo and 16 9 years for sand hollow simple flow fields can be traced from vent to distal areas and an emplacement sequence visualized but those with multiple layered lobes present a degree of complexity that make lava pathways and emplacement sequences more difficult to identify

compaction in a mantle mush with high melt concentrations and the generation of magma chambers abstract most compaction models in the partially molten mantle have addressed the case of low intergranular melt concentrations up to a few percent here we develop a mathematical and numerical formalism adapted to the two dimensional modeling of compaction in mushes with higher melt concentrations up to a few tens of percents experimental data on mantle like mushes olivine crystals basaltic melts suggest that the mush viscosity depends in a complex way on the melt concentration three rheological thresholds occur at melt concentrations of about 5 20 and 40 respectively the first threshold corresponds to the establishment of full interconnectivity of the intergranular melt the second to the formation of a very dense suspension of crystals and the last to the development of crystal clusters in the suspension the present models take into account the stiff and drastic viscosity drops associated with these rheological thresholds intergranular melt migration associated with an initial melt pulse generates a horizon of high melt crystal ratio if the melt concentration in the initial pulse presents a local excess the horizon becomes slightly tilted as a consequence melt percolates upslope inside the tilted horizon pools at its summit and generates a pocket like zone due to the higher melt concentration the upward darcy velocity in the pocket markedly exceeds that in the horizon the result is that the pocket like impregnation is rapidly disconnected from the horizon and a new pocket develops at the summit of the partially fragmented horizon eventually the intergranular melt contained in the horizon is completely redistributed into pockets increasing the background melt concentration in the mush from 5 20 and 40 leads to an increase of the maximum melt concentration of 10 40 and 100 in the transient horizons and of 25 60 and 100 in the pockets these models suggest that magma chambers with a kilometer extent naturally result from the compaction of a mantle mush with an initial melt concentration exceeding 5

crystal mush compaction in the cohassett flood basalt flow hanford washington abstract the 40 m thick central part of the cohassett flow which was probably emplaced by inflation of an earlier more ti rich flow exhibits textural evidence of crystal mush compaction during solidification although most of the crystallization started in the roof zone as water circulated through fractures in the crust plumes of dense crystal mush must have dripped from the roof to the floor of the sheet thus displacing upward the colonnade entablature boundary the mush initially consisted of loosely stacked plagioclase crystals and liquid surrounding rapidly grown pyroxene oikocrysts containing radial chadacrysts of plagioclase upon compaction in the floor zone the liquid between the loosely stacked plagioclase crystals was expelled as the crystals packed tightly together to form sub parallel grains wrapped around the pyroxene oikocrysts which recrystallized into granular aggregates of augite and pigeonite stacks of sinking plagioclase crystals and rising liquid accumulated on the upper and lower sides respectively of horizontal plagioclase phenocrysts this asymmetric texture clearly indicates the relative motion of solids and liquid the degree of compaction as determined from variations in the amount of interstitial liquid and quantitative measures of textural anisotropy accounts for the chemical variation through the central part of the flow with compatible elements being concentrated in the lower part of the flow and incompatible elements concentrated in the upper part modeling of the compaction process using the iridium melt infiltration and reaction program of boudreau a 2003 iridium a program to model reaction of silicate liquid infiltrating a porous solid assemblage computers and geosciences 29 423 429 shows that the observed chemical and compaction dilation profiles are to be expected in a 40 m thick sheet of basaltic magma solidifying on the earth s surface compaction of crystal mush should be even more likely in slowly cooled intrusive bodies

comment on philpotts and philpotts 2005 crystal mush compaction in the cohassett flood basalt flow hanford washington flood basalt lava flows have generally been assumed to be homogeneous with little variation in flow composition this concept was reinforced by the ability to map many flows over large distances and thus develop a workable regional stratigraphy as in the columbia river basalt group swanson et al 1979 as detailed studies were carried out on columbia river basalt group flows however it became clear that some lava flows did not fit this model and that considerable variation occurred in some flows e g reidel and fecht 1987 reidel 1998 2000 2005 one of the most complex compositional patterns occurs in the cohassett flow of the sentinel bluffs member grande ronde basalt reidel 2000 2005 philpotts and philpotts 2005 propose that the compositional variation observed in the central portion of the cohassett flow from corehole dc 6 is the result of a process that they have called compaction their conclusions are based on an analysis of textures that were observed in vertically oriented samples complimented by quantitative modeling of the compositional profile the purpose of my comment is to provide an alternative explanation for the compositional pattern ob

satellite measurements reveal persistent small scale features in ocean winds four year averages of 25 kilometer resolution measurements of near surface wind speed and direction over the global ocean from the quikscat satellite radar scatterometer reveal the existence of surprisingly persistent small scale features in the dynamically and thermodynamically important curl and divergence of the wind stress air sea interaction over sea surface temperature fronts throughout the world ocean is evident in both the curl and divergence fields as are the influences of islands and coastal mountains ocean currents such as the gulf stream generate distinctive patterns in the curl field these previously unresolved features have important implications for oceanographic and air sea interaction research

geochemical reversals within the lower 100 m of the palisades sill new jersey transects through the lower part of the palisades sill were made at fort lee and alpine new jersey in order to characterize the petrologic signature of previously proposed reversals in the normal tholeiitic differentiation trend petrographic and geochemical data include 1 modal and grain size analyses 2 bulk rock major and trace element concentrations by dcp aes and 3 augite orthopyroxene magnetite and olivine compositions by electron microprobe analysis anomalous horizons defined by increased bulk rock mg cr ni and co concentrations and abrupt modal and grain size changes occur at 10 m the well known olivine zone 27 m 45 m and 95m above the basal contact thermal models coupled with estimates of the emplacement rate and total magma volume indicate that the olivine zone oz is an early stage feature related to the emplacement of initial magma into the palisades chamber stoke s law calculations indicate that the settling velocity of average sized olivine crystals in a high titanium quartz normative htq magma is too slow for significant gravity settling to have occurred prior to the solidification of the basal 20 m of the sill it is suggested that the oz resulted from the emplacement of a heterogeneous initial magma from a compositionally stratified sub palisades storage chamber located within the upper crust however heterogeneity may have been derived directly from the mantle or during rapid ascent geochemical models indicate that the oz contains accumulated olivine that is not in cotectic or constant proportions with the other cumulus phases suggesting a mechanical sorting process magma chamber recharge is proposed to have occurred at the 27 m and 45 m levels when a slightly more primitive htq magma was injected into the palisades sill chamber zones of elevated mg and cr 6 to 10 m thick at these two horizons may indicate the thickness of the hybrid magma formed by the mixing of these two compositions geochemical models indicate that the rocks at these levels have accumulated excess orthopyroxene relative to samples from the rest of the sill normal faulting in the fort lee area at the 95 m level has caused repetition of the stratigraphic section and hence the sharp reversal observed at this level

compaction of igneous cumulates when initially deposited mafic igneous cumulates consist of a solid matrix of mineral phases plus 50 60 interstitial liquid due to its greater density the matrix compacts squeezing the interstitial liquid upward a numerical fluid mechanical model of this process indicates that if the cumulate deposition rate is constant compaction occurs in one of two distinct models for rapid deposition the system is permeability controlled with compaction occurring only at the base of the cumulate pile for slowly deposited cumulates an additional compaction zone that is partially viscosity controlled develops at the top of the pile if the extent of compaction and thickness of this zone are known for a real system the model can be used to estimate the permeability and effective viscosity of the compacting cumulates such calculations yield a permeability of 1 5 times 10 3 a 2 f 3 1 f 2 for olivine cumulates in the muskox intrusion reliable viscosity estimates await an empirical law relating ma

the formation of plagioclase chains during convective transfer in basaltic magma the basaltic rock in the lower part of the thick holyoke lava flow in connecticut and massachusetts has been shown to have a remarkable texture with crystals of feldspar linked together in a continuous three dimensional network of chains1 heating experiments have revealed that this network persists to temperatures where the rock is 75 liquid2 and therefore the network was interpreted to have formed at an early stage of crystallization and to have played an important role in the compaction of crystal mush in the lower part of the flow3 4 despite the texture s importance to our understanding of how such basalt flows form the origin of the texture has remained uncertain1 2 3 here we show that although the network is present in the lower third of the flow it was actually formed in the upper solidification front and was transported down in plumes of dense crystal mush convection of this type has been postulated for intrusive magma chambers but corroborative field evidence has been equivocal especially in lava lakes and flows preservation of the roof generated texture in the lower part of a thick flood basalt flow therefore constitutes important evidence for the role of convection in the solidification and differentiation of a simple magma sheet

experimental constraints on the sound velocities of cementite fe3c to core pressures abstract sound velocities of cementite fe3c have been measured up to 1 5 mbar and at 300 k in a diamond anvil cell using the nuclear resonant inelastic x ray scattering nrixs technique from the partial phonon density of states pdos and equation of state eos of fe3c we derived its elastic parameters including shear modulus compressional v p and shear wave v s velocities to core pressures a pressure induced spin pairing transition in the powdered fe3c sample was found to occur gradually between 10 and 50 gpa by the x ray emission spectroscopy xes measurements following the completion of the spin pairing transition the v p and v s of low spin fe3c increased with pressure at a markedly lower rate than its high spin counterpart our results suggest that the incorporation of carbon in solid iron to form iron carbide phases fe3c and fe7c3 could effectively lower the v s but respectively raise the poisson s ratio by 0 05 and 0 07 to approach the seismically observed values for the earth s inner core the comparison with the preliminary reference earth model prem implies that an inner core composition containing iron and its carbon rich alloys can satisfactorily explain the observed seismic properties of the inner core

differentiation and compaction in the skaergaard intrusion igneous differentiation processes are constrained from bulk compositions densities and mineral modes of 116 cumulate gabbro samples in a new reference profile through the layered series of the skaergaard intrusion east greenland the stratigraphic distribution of p u and rb in cumulates and residual magma modeled by rayleigh fractionation constrains the final porosities or trapped liquid contents to 30 52 in lza troctolites decreasing to 4 12 at the top of lzb olivine gabbros and remaining low 1 13 4 middle dot 6 on average in the oxide gabbros of lzc mz and uz local variations in trapped liquid content are associated with modal layering leucocratic low density rocks have higher proportions of trapped melt than adjacent melanocratic high density rocks these observations are explained by varying degrees of compaction compaction was most important after the onset of fe ti oxide crystallization because of the high densities of the crystal matrix here computed rates of compaction exceed the rate of crystal accumulation in layers that are metres to a few tens of metres thick in the basal section lza the crystal pile was too thin and the density of the crystal matrix too low to drive the rate of compaction above the high rate of crystal accumulation promoted by initial cooling through the intrusion floor in the overlying section lzb the efficiency of compaction gradually increased as a result of thickening of the crystal pile and lowering of the rate of crystal accumulation the modeling constrains the p2o5 content of the residual magma to 1 middle dot 7 wt at the level of apatite in suggesting that the magma contained 49 wt sio2 and followed a trend of iron enrichment compaction of the uppermost metres to tens of metres of crystal mush at the top of the cumulate pile was an efficient means of differentiation and resulted in layers with variable final porosities and trace element contents depending on the mineralogy and density of the crystal matrix

millimeter scale modal layering and the nature of the upper solidification zone in thick flood basalt flows and other sheets of magma abstract water flooding the surface of the holyoke flood basalt flow of connecticut and massachusetts was probably responsible for its entablature developing quench textures to depths of 80 m beneath the flow s surface despite the rapid cooling from above the entablature colonnade boundary is displaced above the center of the flow which can only mean that crystal mush sank from the roof zone to the floor of the flow during solidification the entablature of the holyoke flow exhibits a subtle quasi horizontal millimeter scale modal layering with sheets of ophitic pyroxene plagioclase clusters alternating with discontinuous sheets of residual liquid the layering is believed to have formed by repeated nucleation of pyroxene plagioclase clusters in a rapidly advancing thermal boundary layer the alternating layers of crystals and residual liquid produced a mush with planes of weakness along which the dense crystal mush could separate from the roof the layering parallels the cuspate entablature colonnade boundary which must therefore be a primary magmatic feature rather than simply where downward and upward propagating fractures met the modal layering has been found in other flood basalt flows but also in the roof zone of the palisades sill this texture may therefore be common in the roof zones of many sheet like bodies of magma

satellite data analysis and numerical simulation of tropical cyclone formation 1 forecast of tropical cyclone tc formation has long been a great challenge owing to lack of reliable observations over vast open oceans recent satellite products provide a unique opportunity to reveal detailed atmospheric wave structures prior to tc formation using the quikscat surface wind and the tropical rainfall measurement mission microwave image data we document temporal and spatial structures of rossby wave trains induced by energy dispersion from a pre existing tc and easterly wave propagation characteristics prior to cyclogenesis in the western north pacific using a baroclinic model we further simulate cyclogenesis processes associated with the tc energy dispersion and easterly waves

physical processes controlling earlier and later onset of a typhoon season in the western north pacific the interannual variability of typhoon onset date in western north pacific wnp during 1979 2015 is investigated the average date in the earlier later onset group is early april late july a diagnosis of the genesis potential index shows that the key factor affecting the earlier and later onset lies in the background moisture field according to their evolution feature the earlier onset cases are further divided into two sub groups in the first sub group positive specific humidity anomalies were confined in the western wnp and caused primarily by circulation anomalies associated with a la nina in the equatorial eastern pacific in the second sub group positive specific humidity anomalies were confined in the eastern wnp and caused by anomalous convection associated with the pacific meridional mode pmm in the tropical and subtropical eastern pacific in the later onset composite negative specific humidity anomalies appear in the wnp and were accompanied by an anomalous anticyclone in situ and a v shape negative ssta pattern in the western pacific in addition the change of background vertical wind shear vws also influences the tc onset date a decrease increase in the vws magnitude and an easterly westerly shear anomaly occur in the earlier later onset composite physically it is argued that both the magnitude of the vws and the sign of anomalous zonal wind shear may affect tc formation in the wnp

climatic impact of the a d 1783 asama japan eruption was minimal evidence from the gisp2 ice core abstract assessing the climatic impact of the a d 1783 eruption of mt asama japan is complicated by the concur rent eruption of laki iceland estimates of the stratospheric loading of h2so 4 for the a d 1108 eruption of asama derived from the so42 time series in the gisp2 greenland ice core in dicate a loading of about 10 4 tg h2so 4 with a resulting stratospheric optical depth of 0 087 assuming sulfur emis sions from the 1783 eruption were only one third of the 1108 event yields a h2so 4 loading value of 3 5 tg and a strato spheric optical depth of only 0 029 these results suggest minimal climatic effects in the northern hemisphere from the 1783 asama eruption thus any volcanically induced cooling in the mid 1780s is probably due to the laki eruption introduction asama volcano 36 5on 138 9oe honshu japan has erupted many times over the last 1000 years aramaki 1956 1957 1963 but only two of these events have been large enough to definitely warrant a volcanic explosivity index

rossby waves in zonally opposing mean flow behavior in northwest pacific summer monsoon abstract the interactions between monsoon circulations and tropical disturbances in the northwest pacific where the low level mean flow is westerly in the west and easterly in the east are studied with a barotropic model the authors model results suggest that the scale contraction by the confluent background flow the nonlinear dynamics the effect and the large scale convergence are important for the energy and enstrophy accumulation near the region where the zonal flow reverses the energy enstrophy accumulation can be maintained with a continuous rossby wave emanation upstream the largest accumulation occurs when the emanating zonal wavelength is around 2000 km longer rossby waves experience less scale contraction and nonlinear effects while shorter rossby waves cannot hold a coherent structure against dispersive effects the nonlinear energy enstrophy accumulation mechanism is significantly different from previous linear energy accumulation theories in the linear theories this is primarily a

crystal capture sorting and retention in convecting magma the mystery of producing strong compositional diversity among suites of comagmatic igneous rocks is investigated by considering the dynamic evolution of basaltic magma in a sheet like chamber a central conclusion is that inward progressing crystallization produces strong viscosity and temperature gradients that promote convection only near the leading edge of the upper thermal boundary layer convection is apparently confined to an essentially isoviscous isothermal region that hugs the downward growing roof zone strong changes in viscosity with crystallization divide the upper and lower thermal boundary layers into regions of decreasing viscosity and crystallinity n called rigid crust n 0 5 mush 0 5 n 0 25 and suspension n 0 25 the strong increase in viscosity near the mush suspension interface acts as a capture front that overtakes and traps slowly settling crystals initial phenocrysts mostly escape capture but crystals nucleated and grown in the suspension zone can escape only if the capture front slows to a critical rate attainable only in bodies thicker than about 100 m escaping crystals are redistributed and sorted by convection driven by the advance of the capture front itself crystal laden plumes traverse the central hot core of the body and deposit partially resorbed and sorted crystals within the lower suspension zone convection is never vigorous but is part of an overall intimate balance between roofward heat loss rigid crust growth crystallization kinetics and transport and sorting of sinking escaped crystals there is a strong similarity between these processes and those producing both varves and saline pan deposits it is clear that lavas lava lakes and sills are indeed examples of true magma chambers strongly exhibiting certain aspects of this over all process these aspects commonly also characterize the large mafic magmatic bodies because strong compositional changes in the residual melt occur largely outward that is at lower temperatures and higher crystallinities of the capture front which is immobile and mostly within rigid crust the possible range in comagmatic compositions available for eruption anywhere within the active magma is very limited this is in broad agreement with the compositional range observed in basaltic lava lakes sills and plutons like skaergaard the tuning of convection crystallization kinetics and phase equilibria in chambers of this type can produce a variety of textures and layering but not a diversity of compositions

the interaction of easterly waves orography and the intertropical convergence zone in the genesis of eastern pacific tropical cyclones the interaction of an idealized easterly wave with an orographic feature representing the sierra madre of mexico and a large scale meridionally sheared zonal flow representing the itcz in the eastern north pacific is examined through numerical integration of the shallow water equations on an equatorial beta plane channel the model simulations show that as a wave approaches the orography from the east the relative vorticity in the lee increases due to the wave being modified by the orography this relative vorticity maximum increases the northward advection of the itcz in the lee of the mountain that occurs due to the influence of the mountain anticyclone the result of this interaction is the development of a localized region of enhanced cyclonic vorticity that moves parallel to the contours of the model orography there is a minimal increase in the amplitude of the vorticity occuring during interactions between the wave and orography itcz and orography and wave and itcz the position of the incident wave upstream of the orography at the time that the disturbance in the lee begins to develop and the subsequent motion of the leeside vorticity maximum are in agreement with an observed case of eastern pacific tropical cyclogenesis which is also presented

reply to comment on philpotts and philpotts 2005 crystal mush compaction in the cohassett flood basalt flow hanford washington

the origin and dispersion characteristics of the observed tropical summertime synoptic scale waves over the western pacific abstract the origin initiation and dispersion behavior of the observed summertime synoptic scale disturbances in the tropical western pacific are studied these westward propagating disturbances have the strongest growth rate over the region of 130 160 e off the equator the three dimensional wave activity flux associated with a wave packet in the vicinity of this region is computed in general wave activity is directed westward there is accumulation of activity flux which gives rise to the amplification of waves in the low levels such accumulation can be attributed to the convergence of both the mean flow and the intrinsic group velocity diabatic forcing also contributes to the growth of disturbances and is most important in the 500 600 hpa layer along the east west oriented storm tracks of the synoptic scale disturbances there are two different dynamical regimes west of 150 e enhanced convection is associated with increased specific humidity at the top of the planetary boundary layer an

vortex rossby waves in a numerically simulated tropical cyclone part i overall structure potential vorticity and kinetic energy budgets abstract the asymmetric structure in the inner core of a numerically simulated tropical cyclone is analyzed in this study the simulated tropical cyclone is found to be highly asymmetric in the inner core in the mid lower troposphere the asymmetry in the core is dominated by azimuthal wavenumber 1 and wavenumber 2 vortex rossby waves these waves propagate azimuthally upwind against the azimuthal mean cyclonic tangential flow around the eyewall and thus have a much longer cyclonic rotation period by a factor of 2 than the period of a parcel moving with the cyclonic mean tangential flow around the circumference they also propagate outward against the boundary layer inflow of the azimuthal mean cyclone the waves are only visible within a radius of about 60 km from the cyclone center beyond this distance the radial gradient of potential vorticity pv of the azimuthal mean cyclone is too weak to support the vortex rossby waves although the divergent motion remains strong the geopotential height an

microstructural evolution of silicate immiscible liquids in ferrobasalts an experimental study of the microstructural evolution of an immiscible basaltic emulsion shows that the fe rich liquid forms homogeneously nucleated droplets dispersed in a continuous si rich liquid together with droplets heterogeneously nucleated on plagioclase magnetite and pyroxene heterogeneous nucleation is likely promoted by localised compositional heterogeneities around growing crystals the wetting angle of fe rich droplets on both plagioclase and magnetite increases with decreasing temperature droplet coarsening occurs by a combination of diffusion controlled growth and ostwald ripening with an insignificant contribution from coalescence characteristic microstructures resulting from the interaction of immiscible fe rich liquid with crystal grains during crystal growth can potentially be used as an indicator of liquid unmixing in fully crystallised natural samples in magma bodies 10 m in size gravitationally driven segregation of immiscible fe rich droplets is unlikely to be significant

downstream development in the southern hemisphere monsoon during fgge wmonex abstract evidence is presented of a downstream development mechanism operating across the entire longitudinal span of the 1978 79 southern hemisphere monsoon observationally it is seen as progressive cyclonic and anticyclonic vorticity increases that develop eastward in the monsoon trough at a speed of approximately 5 m s 1 the process results in many tropical cyclone and tropical depression formations over northern australia and the south pacific it is shown that the downstream development process is generally consistent with linearized barotropic dynamics and that the southern hemisphere monsoon because of an intrinsic westerly basic state is a particularly suitable region for downstream events it is also shown that some apparent contradictions in previous observational studies can be rationalized by the theory the interactions between the regional components of the monsoon indonesian australian and south pacific sectors can also he better understood we further suggest that the process has i

large scale influences on tropical cyclogenesis in the western north pacific abstract objectively analyzed data from the european centre for medium range weather forecasts are used to examine the large scale aspects of the formation of tropical cyclones it is hypothesized that tropical cyclogenesis occurs when external atmospheric forcing on the synoptic or larger scale provides uplift through a deep layer enhancing convection in a region with environmental conditions favorable for genesis emphasis is placed on the roles of upper level troughs low level wind surges preexisting tropical cyclones and propagating wave disturbances in triggering tropical cyclogenesis composites of the 200 hpa and 850 hpa flows reveal the presence of both upper level troughs and low level wind surges respectively prior to genesis in the composites the wind surges also appear to be related to the presence of a prior circulation located approximately 2000 km to the west of the genesis location an examination of the individual cases demonstrates that approximately 85 of all storms had either

roles of the synoptic scale wave train the intraseasonal oscillation and high frequency eddies in the genesis of typhoon manyi 2001 abstractexperiments using the weather research and forecasting wrf model were conducted to investigate the effects of multiscale motions on the genesis of typhoon manyi 2001 in the western north pacific the precursor signal associated with this typhoon genesis was identified as a northwest southeast oriented synoptic scale wave train swt the model successfully simulated the genesis of the typhoon in the wake of the swt further experiments were conducted to isolate the effects of the swt the intraseasonal oscillation iso and high frequency shorter than 3 days eddies in the typhoon formation removing the swt in the initial and boundary conditions eliminates the typhoon genesis this points out the importance of the swt in the typhoon genesis it was noted that the swt strengthened the wake cyclone through southeastward energy dispersion the strengthening wake cyclone triggered multiple episodes of strong sustained convective updrafts leading to aggregation of vertical vorticity and formatio

systematic variation of summertime tropical cyclone activity in the western north pacific in relation to the madden julian oscillation abstract the variability of observed tropical cyclone tc activity i e genesis track and landfall in the western north pacific wnp is examined in relation to the various categories of the madden julian oscillation mjo during summer june september for the period 1979 2004 the mjo categories are defined based on the empirical orthogonal function analysis of outgoing longwave radiation data the number of tcs increases when the mjo related convection center is located in the wnp the axis of a preferable genesis region systematically shifts like a seesaw in response to changes in the large scale environments associated with both the eastward and northward propagation of the mjo and the intraseasonal variability of the wnp subtropical high furthermore the authors show that the density of tc tracks in each mjo category depends on the systematic shift in the main genesis regions at first order also the shift is affected by the prevailing large scale steering flows in each mjo category when th

influence of the north pacific victoria mode on western north pacific tropical cyclone genesis the victoria mode vm is defined as the second empirical orthogonal function mode eof2 of sea surface temperature anomalies sstas in the north pacific north of 20 n this study examines the influence of the spring vm on the tropical cyclone tc genesis over the western north pacific wnp during summer may august for the period 1960 2016 our analysis demonstrates that the spring vm exhibits a good relationship with the following summer tropical cyclone frequency tcf over the wnp characterized by positive correlations over the eastern wnp ewnp and negative correlations over the western wnp wwnp during strongly positive vm cases the sstas in the north pacific 5 20 n associated with the spring vm persist until summer via the wind evaporation sst wes feedback the low level convergence divergence caused by the vm related sstas combined with a strengthened weakened wnp monsoon trough as well as a weakened strengthened west pacific subtropical high wpsh result in the enhanced suppressed tc genesis over the ewnp wwnp it appears that the spring vm may be a useful predictor for the wnp tcs in summer

ocean currents evident in satellite wind data satellite mounted radar scatterometers designed to quantify surface winds over the ocean actually measure the relative motion between the air and the ocean surface estimates of the wind stress from conventional surface wind measurements are usually derived neglecting ocean currents however when the relative motion is used the differences in the estimated stress can be as large as 50 near the equator and may even reverse sign during an el nino this assertion is supported by the strong relationship between the surface currents measured by the tropical atmosphere ocean tao array in the pacific ocean and the differences between the winds estimated from scatterometer data and those measured by tao anemometers the fact that the scatterometer measures relative motion and not wind alone makes scatterometer derived stress a more accurate representation of the boundary condition needed for both atmospheric and oceanic models than stress fields derived neglecting ocean currents

plagioclase chain networks in slowly cooled basaltic magma plagioclase crystals in the slowly cooled interior of the thick holyoke flood basalt flow of connecticut linked to form monomineralic chains at an early crystallization stage partial melting experiments reveal that when the quartz tholeiite was only 25 crystallized the chains had already linked to form a continuous 3 d network at such an early stage of crystallization the network was weak highly permeable and easily deformed consequently the mush of plagioclase chains and interstitial pyroxene crystals underwent compaction in the lower third of the flow with the expelled liquid rising to the center of the flow where it crystallized to form coarse grained sheets of fractionated basalt plagioclase chains are most easily seen in the basalt after it has been partly melted and the late crystallizing minerals converted to glass the chains are several crystals wide the crystals which are approximately 0 5 mm long are attached together randomly normal zoning patterns indicate crystals had a brief period of growth before linking together the chains branch every few millimeters to form the 3 d network which was mapped using serial polished sections and x ray ct scans the chain frequency measured along vertical and horizontal traverses decreases toward the center of the flow in the compaction zone the frequency in the vertical direction is greater than in the horizontal making the reasonable assumption that these frequencies were initially the same the difference is used to calculate the degree of compaction the resulting pattern through the flow matches almost exactly the pattern indicated by variations in the incompatible elements plagioclase chains are also found in some coarser grained plutonic rocks if they are common their fabric may provide a new direct means of measuring the degree of compaction in crystal mushes

observations of sst induced perturbations of the wind stress field over the southern ocean on seasonal timescales the surface wind stress response to sea surface temperature sst over the latitude range 308 608 si n the southern ocean is described from the national aeronautics and space administration s quikscat scatterometer observations of wind stress and reynolds analyses of sst during the 2 yr period august 1999 to july 2001 while ocean atmosphere coupling at midlatitudes has previously been documented from several case studies this is the first study to quantify this relation over the entire southern ocean the spatial structures of the surface wind perturbations with wavelengths shorter than 108 latitude by 308 longitude are closely related to persistent spatial variations of the sst field on the same scales the wind stress curl and divergence are shown to be linearly related respectively to the crosswind and downwind components of the sst gradient the curl response has a magnitude only about half that of the divergence response this observed coupling is consistent with the hypothesis that sst modification of marine atmospheric boundary layer mabl stability affects vertical turbulent mixing of momentum inducing perturbations in the surface winds the nonequivalence between the responses of the curl and divergence to the crosswind and downwind sst gradients suggests that secondary circulations in the mabl may also play an important role by producing significant perturbations in the surface wind field near sst fronts that are distinct from the vertical turbulent transfer of momentum the importance of the wind stress curl in driving ekman vertical velocity in the open ocean implies that the coupling between winds and sst may have important feedback effects on upper ocean processes near sst fronts

mixed rossby gravity waves and western pacific tropical cyclogenesis part i synoptic evolution abstract a large amplitude mixed rossby gravity wave packet is identified in the western pacific using 6 10 day bandpass filtered winds individual disturbances of 2300 3000 km wavelength propagated westward as the packet moved slowly eastward the packet first appeared and subsequently amplified within a region of active convection associated with the madden julian oscillation mjo which was isolated by low pass filtered outgoing longwave radiation the packet lasted about 5 weeks then rapidly dispersed as the active mjo moved away from it to the east west of 150 e individual disturbances within the packet turned northwestward away from the equator indicating an apparent transition from mixed rossby gravity waves to off equatorial tropical depression td type disturbances cyclones filled with cloud and anticyclones cleared during the transition nevertheless convective structure consistent with mixed rossby gravity waves remained outside the circulation centers and three tropical cyclones for

are multiple tropical cyclone events similar among basins abstractthe present study intercompares multiple tropical cyclone event mtce characteristics among each global tropical cyclone tc basin using best track data specific focus is placed on examining the number of mtces and tcs during mtces the zonal distance between tcs during mtces and the spatiotemporal separation between genesis events during mtces the results suggest that the ratio of mtces relative to single tcs is substantially higher in the eastern north pacific enp western north pacific wnp and south indian ocean si basins compared to the north atlantic na and south pacific sp the prolific nature of enp wnp and si mtce activity results in approximately half of tcs occurring during mtces during new tc genesis the majority of preexisting tcs are generally located westward at a consistent zonal distance from new tc genesis for mtces within each basin with median values between 1620 and 1961 km tc induced rossby wave dispersion may set this zonal length scale as implied by it

petrologic evolution of a nipigon diabase sill ontario canada insights from compositional and textural profiles petrographic and geochemical profiles collected through a 250 m thick nipigon diabase sill near black sturgeon lake ontario constrain the complex emplacement and differentiation processes that controlled the magmatic evolution of these rocks several nested reinjections of phenocryst bearing magma compactiondriven redistribution of mildly evolved interstitial liquids in the central portion of the sill and segregation of highly evolved interstitial liquids into micropegmatitic veins near the upper contact these processes impact not only the silicate mineralogy of the rocks but also distribution of sulfide phases both petrographic and geochemical data demonstrate that the sill was gradually inflated via several discrete injections of olivine bearing magma plagioclase crystal size trends exhibit several reversals that are correlated with increases in olivine abundance and bulk rock mgo content these textural and compositional reversals are attributed to reinjections of olivine bearing magma into partially solidified magma from earlier injections mixing between evolved resident magma and reinjections of less evolved magma is commonly proposed as a mechanism for triggering sulfide mineralization in this sill which contains no significant mineralization localized minor enrichments and depletions in copper content are associated with the margins of a well constrained reinjection horizon chemical differentiation of the magma was controlled by three distinct processes flow differentiation crystal mush compaction and solidification front instability although the mineralogy of the sill is dominated by plagioclase and clinopyroxene major oxide compositional variations are largely controlled by the mechanical concentration of olivine via flow differentiation or phenocryst redistribution within the individual reinjection pulses this redistribution of phenocryst phases is the primary factor controlling the major element composition of the rocks in most of the sill in the central portion of the sill the abundances of incompatible trace elements are influenced by the compaction of partially crystalline mush and the expulsion of incompatible rich interstitial liquid this is recognized by a negative correlation between the alignment of plagioclase crystals and concentrations of incompatible trace elements such as zr finally there is a 2 5 m thick silicic segregation approximately 32 m below the upper contact whose composition is consistent with residual liquid after 65 to 85 fractional crystallization of magma with a composition equivalent to that of the marginal rocks similar veins and patches are common throughout the upper 50 m of the sill indicating that this segregation process was common and widespread during the cooling and crystallization of the sill the complexity of intrusion and differentiation in this sill despite its generally unremarkable texture and composition suggests that many diabase sills may have experienced a range of processes that have previously been recognized to impact the petrologic evolution of larger igneous systems and that these processes can be identified in minor intrusions such as sills and dikes using simple and robust analytical techniques

quantitative modeling of compaction in the holyoke flood basalt flow hartford basin connecticut compaction in the holyoke flood basalt flow is modeled using a quantitative phase equilibrium routine based on the melts algorithm that is coupled with compaction driven heat and mass transport equations for a crystal liquid mush that is cooling from both the top and the bottom the compaction is qualitatively different in the upper and lower parts of the flow the solid fraction in the lower part increases as a result of concurrent compaction and solidification in contrast cooling from the upper boundary results in an increase in viscosity and a decrease in permeability toward the top this causes the velocity of the solid matrix to increase downward and the upper part to undergo dilation of the solid matrix the result is an s shaped profile for compatible elements and an inverse profile for incompatible elements the region of modeled maximum dilation matches the location of segregation sheets in the holyoke flow discrepancy between observed deformation as calculated from textural deformation of plagioclase chain networks versus compositional profiles suggest some crystal accumulation and or compaction prior to the formation of the plagioclase chains

influence of equatorial waves on the genesis of super typhoon haiyan 2013 abstractthe influence of equatorial wave disturbances on the genesis of super typhoon haiyan 2013 is investigated through spectral composite and ensemble sensitivity analysis of various observational datasets in combination with predictions from an operational ensemble under the favorable large scale environmental conditions of the asian monsoon combined with the madden julian oscillation mjo the incipient haiyan develops from a cyclonic disturbance that originates from a train of westward propagating mixed rossby gravity mrg waves haiyan eventually develops in the monsoon trough region at the leading edge of the moist mjo phase that has strong low level convergence high moisture content and weak shear along with high sea surface temperature these favorable environmental conditions promote the intensification of deep moist convection that facilitates the development of the cyclonic disturbance from an mrg wave into a tropical depression which later intensifies rapidly into super typhoon ha

tropical cyclogenesis associated with rossby wave energy dispersion of a preexisting typhoon part i satellite data analyses abstract the structure and evolution characteristics of rossby wave trains induced by tropical cyclone tc energy dispersion are revealed based on the quick scatterometer quikscat and tropical rainfall measuring mission trmm microwave imager tmi data among 34 cyclogenesis cases analyzed in the western north pacific during 2000 01 typhoon seasons six cases are associated with the rossby wave energy dispersion of a preexisting tc the wave trains are oriented in a northwest southeast direction with alternating cyclonic and anticyclonic vorticity circulation a typical wavelength of the wave train is about 2500 km the tc genesis is observed in the cyclonic circulation region of the wave train possibly through a scale contraction process the satellite data analyses reveal that not all tcs have a rossby wave train in their wakes the occurrence of the rossby wave train depends to a certain extent on the tc intensity and the background flow whether or not a rossby wave train can finally lead to cy

three centuries of winter temperature change on the southeastern tibetan plateau and its relationship with the atlantic multidecadal oscillation long term high resolution proxy records containing cold season temperature signals are scarce on the southeastern tibetan plateau tp limiting our understanding of regional climate and the potential driving forces in this study we present a nearly three centuries long reconstruction of winter december february mean temperature for the central hengduan mountains southeastern tp the reconstruction is derived from a composite tree ring width chronology of pinus yunnanensis franch from two high elevation sites 3000 m above sea level our reconstruction passes all standard calibration verification schemes and explains nearly 73 of the variance of the original instrumental data however we were constrained to calibrate our full period 1718 2013 reconstruction of december february mean temperature on the calibration period from 1959 to 1992 only due to a decrease in temperature sensitivity of tree ring index exhibited after 1992 spatial correlation analysis shows that our reconstruction represents large scale temperature variations in southwest china and the eastern tp our reconstructed december february mean temperature shows a close association with the atlantic multidecadal oscillation amo over the past three centuries with warm cold periods coinciding with the positive negative phases of the amo this persistent relationship suggests that the amo may have been a key driver of multidecadal winter temperature variations on the southeastern tp

stratigraphy and petrogenesis of the grande ronde basalt from the deep canyon country of washington oregon and idaho deep canyons cut by the snake salmon grande ronde and imnaha rivers near the point where washington oregon and idaho join expose 800 m of grande ronde basalt flows the grande ronde basalt erupted 16 5 to 14 5 m y b p makes up 85 vol of the columbia river basalt group an area enclosing 1 000 km 2 of the deep canyon country dominated by this basalt was mapped and samples from 16 measured sections in the grande ronde basalt were analyzed for major minor and trace elements three magnetostratigraphic units r 1 n 1 and r 2 were helpful in mapping the area using physically distinct flows the magnetostratigraphic units and certain chemical variations a detailed flow by flow stratigraphy was developed and the lateral extent of many individual flows was traced the number of flows and thickness of each stratigraphic unit decrease from west to east these tholeiitic flows are fine grained and aphyric clinopyroxene and plagioclase are the predominant minerals but olivine orthopyroxene pigeonite and accessory minerals are minor but important phases the flows are primarily of the low mg chemical type with lesser amounts of the high mg chemical type a cyclical trend in the over all major and trace element chemistry through the stratigraphic section is dominated by a ca rich clinopyroxene chemistry rare earth elements show significant light over heavy enrichment but overall patterns remain similar from flow to flow a small negative eu anomaly is present in many flows three models employing fractional crystallization schemes and one combining fractional crystallization and partial melting were tested using least squares modeling a petrogenetic model is proposed wherein partial melting of a heterogeneous clinopyroxene dominated mantle supplied magma that ascended to the crust was temporarily stored and recurrently erupted during storage new basaltic melt with slightly different isotopic and trace element abundances was added and mixed into the liquid that remained after previous eruptions orthopyroxene plagioclase and to a lesser extent olivine fractionated from these temporarily stored liquids upon eruption clinopyroxene and plagioclase with accessory minerals crystallized at the surface

the influence of sea surface temperature gradients on stratiform cloudiness along the equatorial front in the pacific ocean abstract satellite observations of visible cloudiness and sea surface temperature sst are used to test the hypothesis that the configuration of cool low level winds blowing across a sharp sst front in the equatorial eastern pacific gives rise to stratiform clouds on the warm downstream side of the front the results show that there is a maximum in low clouds over the equatorial front during the cold season of 1988 when the front and cross isotherm winds were strong the low cloud maximum was reduced in the warm el nino year of 1987 consistent with the weakening of the front instability waves along the equatorial front were pronounced during the summer and autumn of 1988 the results show a strong association between visible cloud and the sst waves with enhanced reduced cloudiness in the warm troughs cold crests of the waves

tropical cyclogenesis associated with rossby wave energy dispersion of a preexisting typhoon part ii numerical simulations abstract the cyclogenesis events associated with the tropical cyclone tc energy dispersion are simulated in a 3d model a new tc with realistic dynamic and thermodynamic structures forms in the wake of a preexisting tc when a large scale monsoon gyre or a monsoon shear line flow is present maximum vorticity generation appears in the planetary boundary layer pbl and the vorticity growth exhibits an oscillatory development this oscillatory growth is also seen in the observed rainfall and cloud top temperature fields the diagnosis of the model output shows that the oscillatory development is attributed to the discharge and recharge of the pbl moisture and its interaction with convection and circulation the moisture convection feedback regulates the tc development through controlling the atmospheric stratification raindrop induced evaporative cooling and downdraft pbl divergence and vorticity generation on one hand ascending motion associated with deep convection transports moisture upward and le

reconstruction of early spring temperature for central japan from the tree ring widths of hinoki cypress and its verification by other proxy records 1 we describe the results of a dendroclimatic study in central japan using ring width data from living trees of hinoki cypress february april temperatures were reconstructed for the period ad 1719 1961 this reconstruction from which five cooling events were determined for the late little ice age was validated against other climate proxies there is a reasonable agreement with cold periods previously estimated from documentary records in japan and china a notably good agreement is also found for a dendroclimatic reconstruction for korea suggesting that the annual activity of the winter monsoon in the western pacific rim persisted longer in the 19th century than at present records of prolonged famines and unusual climatic phenomena support the reconstruction of the cold periods in the 1780s 1810s and 1830s it is thus revealed that the hinoki chronology has enough potential to reconstruct the climatic variability further into the past

origin of the summertime synoptic scale wave train in the western north pacific abstract the origin of the summertime synoptic wave train in the western north pacific is investigated with a multilevel nonlinear baroclinic model a realistic three dimensional summer mean state is specified and eigenvectors are calculated by introducing small perturbation initially to the model numerical experiments indicate that the origin of the synoptic wave train may arise from instability of the summer mean flow in the presence of a convection frictional convergence cfc feedback in the lack of the cfc feedback the summer mean flow supports only a least damped mode characterized by a northwest southeast oriented wave train pattern with a zonal wavelength of 2500 km in the presence of both the realistic summer mean flow and the cfc feedback the model reproduces a fast growing mode whose structure and propagation characters are similar to the observed sensitivity experiments with different initial perturbation patterns indicate that the model solution is not sensitive to initial conditions

on the westward turning of hurricane sandy 2012 effect of atmospheric intraseasonal oscillations abstracthurricane sandy 2012 experienced an unusual westward turning and made landfall in new jersey after its northward movement over the atlantic ocean the landfall caused severe casualties an

the columbia river basalts between 17 million and 6 million years ago 200 000 square kilometers of the american northwest were flooded by basaltic lava that erupted through fissures in the crust up to 150 kilometers long larger individual eruptions covered over a third of the columbia plateau in a few days the lavas represent partial melts of the earth s mantle that were only slightly modified by near surface upper crustal processes the abundant chemical and mineralogical data now available offer an opportunity to study mantle composition and the processes involved in the evolution of the earth s crust

structures textures and cooling histories of columbia river basalt flows flood basalt flows of the columbia river basalt group commonly exhibit well developed colonnade and entablature structures formed during cooling of individual flows the colonnade refers to the well defined columnar structure of many flows which appears in the lowermost 10 to 30 and in places the uppermost 10 to 20 entablature refers to those parts of a flow that have smaller column diameters and more irregular pattern fractures than those of colonnade entablature commonly occupies the central 60 to 70 of a flow in some cases however the entablature is interrupted by colonnade in such cases the entablature and colonnade may be repeated once or twice within a single flow in other cases flows may lack an entablature entirely petrographic examination reveals a pronounced correlation between structural and textural features thin sections of colonnade basalt have relatively coarse cruciform or octahedral fe ti oxide crystals and 20 glassy mesostasis the central entablature basalt in contrast has much more mesostasis as much as 60 and has textural features such as feathery fe ti oxide crystals indicative of more rapid cooling these features are the reverse of what might be expected for normal conductive cooling because cooling rates at the flow margins should be greater than those in the flow interior we reconciled the observed basalt textures with thermal models by taking into account rainfall and deranged drainage during crystallization of the flow downward migration of water through cracks would cause convective cooling of underlying unsolidified lava this effect and its consequences have been modeled numerically in order to clarify the physical constraints on the mechanism by which the central part of the lava can be quenched we have found that a water infiltration front can explain the presence of a thick quenched flow interior provided that the infiltration front moves downward just behind the lava solidification front despite heavy rainfall on hawaii for example 250 cm yr at kilauea iki exposed prehistoric lava flows on that island exhibit only colonnades we deduce from this that heavy rainfall alone is inadequate to quench flow interiors extensive flooding by deranged drainage or perhaps extremely heavy rainfall 250 cm yr is apparently required to produce entablatures the model also can be used to explain the occurrence of repeated entablature and colonnade by considering the effects of intermittent inundation the imposition of boundary conditions that mimic the removal and reoccurrence of flooding yields cooling histories that are consistent with the development of multiple colonnades and entablatures

enso phase dependent td and mrg wave activity in the western north pacific the three dimensional structure and evolution characteristics of tropical depression td and mixed rossby gravity wave mrg type disturbances in the tropical western north pacific during el nino and la nina summers are investigated based on observational and reanalysis data a clear mrg to td transition was observed during el nino summers while such a transition is unclear during la nina summers the vertical structure of the td mrg waves appears equivalent barotropic during el nino but becomes tilted eastward with height during la nina the diagnosis of barotropic energy conversion shows that both the rotational and divergent components of the background flow change associated with e1 nino southern oscillation enso are responsible for energy conversion from the mean flow to the td mrg perturbations a further examination of the pure mrg mode shows that its intensity does not vary between el nino and la nina while its phase speed does a faster slower westward propagation speed during la nina el nina is attributed to enhanced reduced mean easterlies in the western equatorial pacific the heating associated with the mrg wave appears more anti symmetric during la nina than during el nino in contrast to the mrg waves the amplitude of the td waves depends greatly on the enso phase the enhanced suppressed td disturbances during el nino la nina is attributed to greater less barotropic energy conversion associated with the background flow change the vertical structure of the td waves appears quasi barotropic in the geopotential height field but baroclinic in the divergence field

two stage vesiculation in the cohassett flow of the grande ronde basalt south central washington the cohassett flow in south central washington is considered a possible host for a nuclear waste repository at the hanford site and is being investigated as part of the basalt waste isolation project the cohassett flow of the grande ronde basalt contains two vesicular zones separated by 24 m of dense sparsely vesicular basalt the vesicular zones represent accumulations of upward migrating bubbles sequentially frozen in by the downward passage of the upper solidification front the separation of the two zones suggests a hiatus in the exsolution of aqueous vapor from the lava the flow top vesicular zone formed during and immediately following emplacement of the flow from vapor bubbles nucleated during ascent and eruption whereas the internal vesicular zone formed after emplacement from bubbles apparently nucleated at the lower solidification front homogeneous nucleation of vapor was probably initially driven by large oversaturation pressures in the erupting lava after emplacement heterogeneous nucleation of vapor was probably initiated by crystallization in the margins of the flow

cluster analysis of typhoon tracks part ii large scale circulation and enso abstract a new probabilistic clustering method based on a regression mixture model is used to describe tropical cyclone tc propagation in the western north pacific wnp seven clusters were obtained and described in part i of this two part study in part ii the present paper the large scale patterns of atmospheric circulation and sea surface temperature associated with each of the clusters are investigated as well as associations with the phase of the el nino southern oscillation enso composite wind field maps over the wnp provide a physically consistent picture of each tc type and of its seasonality anomalous vorticity and outgoing longwave radiation indicate changes in the monsoon trough associated with different types of tc genesis and trajectory the steering winds at 500 hpa are more zonal in the straight moving clusters with larger meridional components in the recurving ones higher values of vertical wind shear in the midlatitudes also accompany the straight moving tracks compared to

the graveyard point intrusion an example of extreme differentiation of snake river plain basalt in a shallow crustal pluton the graveyard point intrusion is the only known example of a wellexposed differentiated mafic pluton associated with the late miocene pleistocene magmatism of the western snake river plain srp it is exposed in a 6 km by 4 km area adjacent to the oregon idaho border and exposures range in thickness from 20 to 160 m the thicker parts of the intrusion are strongly differentiated and contain a 25 60 m thick section of well laminated cumulus textured gabbros that grade upward into pegmatoidal ferrogabbro evolved liquids formed sheets of fe rich siliceous granophyre at least two injections of magma are indicated by abrupt discontinuities in the rock and mineral compositions and by the lack of mass balance between the bulk intrusion and its chilled borders the laminated gabbros are interpreted to have formed from a tongue of augite and plagioclase crystals that were carried in with the second pulse of magma following the final emplacement of the intrusion in situ differentiation proceeded through a two stage process the ferrogabbros are explained as interstitial liquids forced out of the crystal mush by compaction and the siliceous granophyres are interpreted to be residual liquids that migrated out of the partly crystallized ferrogabbros in response to the exsolution of volatiles because the geochemical trend inferred for the mafic to intermediate composition liquids in the graveyard point intrusion is similar to the trend for many western snake river plain lavas the pluton may be a good model for shallow sub volcanic magma chambers elsewhere in the srp however some western srp lavas contain anomalously high concentrations of p2o5 which are best explained by mixing within the active crustal mush column or with partial melts of previously formed differentiated mafic intrusions

compaction of igneous cumulates part ii compaction and the development of igneous foliations quantitative petrofabric analysis of 66 samples from olivine bearing zones iii and iv of the middle banded series of the stillwater complex montana was conducted to allow direct comparison among textural and chemical variations systematic variations in foliations with stratigraphic height are observed in both zones statistical analysis of the orientations of inequant grains was used to calculate an alignment factor af corresponding to the extent of the development of the foliation both petrofabric and petrographic evidence indicates that the foliation is best explained by compaction of the crystal pile comparison of afs with estimates of the amount of compaction based on whole rock compositions shows approximate agreement variations in mole fraction cl of interstitial apatite mimic the observed trends in the af indicating that local concentrations of fluids exsolved from interstitial liquid were important in the development of strong foliations we conclude that 1 differing amounts of co

prediction of tropical cyclogenesis using scatterometer data in the present work a new technique based on the data mining approach has been discussed for the prediction of tropical cyclogenesis using the ocean wind vectors derived from the sea winds scatterometer on quikscat satellite the technique is based on similarity of given wind pattern with wind vector signatures of developing systems available from the past observations a database has been formed in this work using the quikscat observed vector wind patterns associated with the early stages of tropical cyclones that developed in the north indian basin during the years 2000 2008 the prediction of possibility of cyclogenesis in a given scene is determined by matching it with all the archived scenes in a database using vector block matching algorithm the system is predicted as developing if its matching index exceeds the predetermined threshold value 0 5 the prediction of cyclo genesis can be made 24 96 h prior to its classification as a tropical storm by the joint typhoon warning centre the probability of detection of the technique is determined using the equivalent of the jackknife approach in the database as 0 93 the algorithm is tested with a continuous wind data of years 2007 2009 for active cyclone months excluding the scenes archived in a database all the 14 tropical disturbances that developed into tropical storms during the test period were predicted using the discussed method and two false alarms were found

magnetic anisotropy as a tracer of crystal accumulation and transport middle banded series stillwater complex montana abstract fabric studies of layered mafic intrusions have led to improved understanding of the mechanical processes operating in large magma chambers including crystal accumulation and crystal mush deformation such studies however are typically limited by a tradeoff between breadth number of sites studied characteristic of field focused work and sensitivity ability to discern subtle fabric elements characteristic of laboratory fabric analyses magnetic anisotropy if analyzed in a systematic way and supported by single crystal and petrofabric measurements permits relatively rapid characterization of magmatic fabrics for large numbers of samples here we present the results of a study of remanence and susceptibility anisotropy from three transects through the middle banded series of the stillwater complex montana all three transects exhibit a magnetic foliation that increases with stratigraphic height up to the top of olivine bearing zone iii consistent with crystal mush compaction perhaps more importantly each transect is characterized by a subtle lineation in the anisotropy of magnetic susceptibility with a consistent direction within that transect the magnetic lineation directions which generally coincide with crystallographic preferred orientations of silicate minerals likely record a pre compaction fabric lineation directions differ from one transect to another implying that the process generating the lineation either slumping of a semiconsolidated crystal mush or magma transport acted on length scales of at most a few km these results demonstrate the sensitivity of magnetic anisotropy to petrofabric in mafic rocks

monsoonal interactions leading to sudden tropical cyclone track changes abstract sudden poleward track changes of tropical cyclones embedded in monsoon gyres in the western north pacific are documented during these track changes which are generally not well forecast the cyclones are often accompanied by a separate comma shaped area of gale force winds and deep convection along the eastern periphery this monsoon surge is distinct from the tropical cyclone synoptic analyses often reveal a building anticyclone to the east or southeast of the monsoon gyre the hypothesis that the sudden track change is initiated by a binary interaction of the tropical cyclone and monsoon gyre is tested with a nondivergent barotropic model tropical cyclone scale vortices with initial positions within the eastern semicircle of a larger monsoon gyre scale vortex initially coalesce with the monsoon gyre and then exhibit sudden poleward track changes that are similar to the observations during the coalescence phase the large and relatively weak monsoon gyre undergoes a induced dispersion in

large scale vapor transport of remotely evaporated seawater by a rossby wave response to typhoon forcing during the baiu meiyu season as revealed by the jra 55 reanalysis the modulation of large scale moisture transport from the tropics into east asia in response to typhoon induced heating during the mature stage of the baiu meiyu season is investigated using the japanese 55 year reanalysis jra 55 aided by a rayleigh type global isotope circulation model icm we highlighted the typhoons that migrate northward along the western periphery of the north pacific subtropical high and approach the vicinity of japan anomalous anticyclonic circulations to the northeast and southeast of typhoons and cyclonic circulation to their west become evident as they migrate toward japan which could be interpreted as a rossby wave response to typhoon heating these resultant anomalous circulation patterns form moisture conveyor belt mcb stretching from the south asian monsoon region to east asia via the confluence region between the monsoon westerlies and central pacific easterlies the icm results confirm that the well defined nature of the mcb leads to penetration of the indian ocean south china sea philippine sea and pacific ocean water vapors into western japan the typhoons have the potential to accumulate large amounts of moisture from distant tropical oceans through the interaction of their rossby wave response with the background flow in the case of a typical typhoon the total precipitable water around the typhoon center as it approaches japan is maintained by the moisture supply from distant oceans rather than from the underlying ocean which indirectly leads to the occurrence of heavy rainfall over western japan

multiple reinjections and crystal mush compaction in the beacon sill mcmurdo dry valleys antarctica the beacon sill a member of the jurassic ferrar group of the transantarctic mountains south victoria land is a 150 m thick tholeiitic diabase intrusion uniform on a field and macroscopic scale it displays chemical and textural variability indicative of a sustained and complex history of emplacement and differentiation emplacement of the sill consisted of at least two and probably four discrete massive injections of magma each averaging 35 m thick over a time span of 100 years the final injection event is marked by a 30 m thick interval of significantly finer grained rock at the sill center these fine grained textures can be successfully reproduced by combining the results of thermal and crystal growth models but only if the sill was a multiple intrusion with the exception of a minor reinjection event captured in the chilled margin of the sill earlier reinjection events are not evident texturally most probably because of textural overprinting during prolonged cooling after initial crystallization the dominant process involved in the postemplacement differentiation of the beacon sill was compactiondriven redistribution of interstitial liquid transfer of residual liquid from the compacting lower solidification front to the dilating upper solidification front resulted in characteristic chemical and mineralogical effects such as the depletion of the lower half of the sill and the enrichment of the upper half of the sill in incompatible elements e g tio2 zr and modal granophyre based on thermodynamic models most of the compaction occurred at a crystallinity of roughly 33 geochemical profiles are distinctly segmented suggesting that the sill was repeatedly split and reinjected with fresh magma near the center after compaction had redistributed the interstitial liquid within the partially solidified magma the recognition of evidence for reinjection and compaction in a macroscopically uniform relatively quickly cooled sill suggests that these processes may be common in the construction of sills and other mesoscale igneous intrusions in general

surface morphology of columnar joints and its significance to mechanics and direction of joint growth columnar joints in basaltic lava flows display conspicuous bands oriented normal to column axes new observations show that each band contains a single plumose structure and thus represents an individual crack or joint segment formed during a discrete growth event analysis of plumose structure and intersections of cracks leads to a new kinematic model of columnar jointing and provides the first direct proof that columnar joints grow incrementally from exterior to interior regions of solidifying magma bodies columnar joints form by nucleation and growth of new cracks on the edges of older cracks each new crack begins at a point and propagates mostly normal to column axes and along the leading edge of a developing column face where thermal stress is concentrated inward propagation of cracks toward hotter regions is limited by a decrease of thermal stress and by the brittle ductile transition of lava outward and lateral propagation is limited by mechanical interaction with previous cracks and by low thermal stress in already fractured lava cracks often diverge slightly from the planes of previous cracks probably because of spatial and temporal changes in directions of local principal stresses mechanical interaction causes a diverging crack to overlap curve toward and usually intersect the previous crack behind its edge leaving a blind tip that points in the overall growth direction of the columnar joints this and other directional criteria are applied to determine joint growth patterns in several lava flows of the western united states in two tiered and multi tiered flows downward growing columnar joints usually meet upward growing joints well below the middle of the flows which indicates very rapid cooling of upper portions relative to lower portions this supports the idea that convection of water in columnar joints connected to the surface may be an important mechanism for cooling the upper portions of these flows whereas conduction is probably the dominant cooling mechanism at the bases

development of synoptic scale disturbances over the summertime tropical northwest pacific abstract this study addresses the origin of the synoptic scale disturbances that occur in the tropical western north pacific ocean wp region in northern hemisphere summer these have been called easterly waves and tropical depression type td disturbances this analysis uses the national center for environmental prediction national center for atmospheric research reanalysis dataset by performing a regression analysis on several terms in the vorticity equation at 850 hpa it is shown that the td disturbances propagate approximately as barotropic rossby waves at 850 hpa given this ray tracing calculations and the wave activity diagnostic introduced by plumb are used to show that wave accumulation is a promising candidate for the initial development mechanism of the td disturbances the expected local growth rate from this mechanism is simply the convergence of the group velocity which reaches values corresponding to a growth timescale of 3 days this convergence is dominated by but somewhat lar

origins and mechanisms of eastern pacific tropical cyclogenesis a case study the genesis of hurricane hernan 1996 in the eastern pacific was investigated using gridded analyses from the european centre for medium range weather forecasts and gridded outgoing longwave radiation hernan developed in association with a wave in the easterlies that could be tracked back to africa in longitude time plots of the filtered y component of the wind 2 6 day period at 700 mb the wave crossed central america near lake nicaragua with little change in its southwest northeast tilt but the most intense convection shifted from near the wave axis in the caribbean to west of the wave axis in the pacific the wave intensified as it moved through a barotropically unstable background state defined by a low pass filter with a 20 day cutoff in the western caribbean and eastern pacific a surge in the southwesterly monsoons and enhanced convection along 108n occurred to the west of the 700 mb wave in the pacific and traveled with the wave this had the effect of enhancing low level vorticity over a wide region ahead of the 700 mb wave available evidence suggests that additional low level vorticity was produced by enhanced flow from the north through the isthmus of tehuantepec as the 700 mb wave approached depression formation did not occur until 6 12 h after the 700mb wave reached this region of large low level vorticity in the gulf of tehuantepec eastern pacific sst and vertical wind shear magnitude are typically favorable for tropical cyclone development in northern hemisphere summer and early fall because the favorable mountain interaction and the surge in the low level monsoons appear to relate directly to the wave in the easterlies it is argued that the strength of such waves reaching central america from the east is the single most important factor in whether subsequent eastern pacific cyclogenesis occurs possible parallels with western pacific cyclogenesis are discussed

mechanisms of differentiation in the skaergaard intrusion thanks to its magnificent exposures and extraordinary petrologic development the skaergaard intrusion provides an excellent test for three basic mechanisms of crystal liquid fractionation diffusive exchange compaction convective exchange 1 diffusive exchange at the solidification front does not seem to have played a major role for no obvious difference is seen in the behavior of components of widely differing diffusivities the effects of diffusion were probably masked by porous flow of the interstitial liquid 2 compaction and 9filter pressing9 of residual liquids can be tested by comparing concentrations of incompatible elements in parts of the intrusion that crystallized in different orientations with respect to gravity the contrast between the large concentrations of these elements in the upper border series and consistently smaller abundances in the layered series long thought to be due to contamination of the upper levels with crustal rocks is more likely a result of compaction that took place at the floor but not under the roof 3 convective exchange driven by differences in the compositional densities of the main magma and interstitial liquids seems to have been important at the steep walls and to a lesser degree under the roof it may also have been responsible for a large compositional anomaly near the centre of the layered series where an iron rich liquid percolated down through parts of lower and middle zones at later stages of crystallization when density relations were reversed a buoyant liquid rich in volatiles and incompatible elements rose from the layered series and permeated the upper part of the intrusion a liquid of this latter kind could have caused the pervasive metasomatic alteration seen in much of the layered series in both compaction and convective exchange re equilibration and reactions between migrating liquids and early formed crystals augmented permeabilities and brought about extensive compositional and textural changes although inhomogeneities in the initial magma could account for some of the compositional variations the main trend of differentiation can be ascribed to a combination of compaction and convective fractionation the convective flow was of two kinds one of descending iron rich liquids and another of more evolved rising liquids and fluids with low densities and large concentrations of incompatible elements in the early stages the proportions of iron rich liquids were much greater than those of the silica rich variety and until the crystallization fronts converged at the sandwich horizon the former made the greatest contribution to evolution of the main body of magma as crystallization advanced however light silica rich liquids became more important they permeated the upper border series and much of the upper part of the layered series this late stage liquid continued to differentiate after the crystallization fronts met a secondary sandwich horizon was formed where incompatible elements reach maximum concentrations in the lower part of the upper border series

a comprehensive mass flux scheme for cumulus parameterization in large scale models abstract observational studies indicate that a mass flux approach may provide a realistic framework for cumulus parameterization in large scale models but this approach through the introduction of a spectral cloud ensemble leads normally to rather complex schemes in this paper the question is addressed whether much simpler schemes can already provide realistic values of the thermal forcing by convection under various synoptic conditions this is done through verifying such a scheme first on data from field experiments for periods of tropical penetrative convection gate marshall islands tradewind cumuli atex bomex and extratropical organized convection sesame 79 and then in a nwp model the scheme considers a population of clouds where the cloud ensemble is described by a one dimensional bulk model as earlier applied by yanai et al in a diagnostic study of tropical convection cumulus scale downdrafts are included various types of convection are represented i e penetrative convection in c

scale interactions during the formation of typhoon irving the development of typhoon irving is investigated using a variety of data including special research aircraft data from the tropical cyclone motion tcm 92 experiment objective analyses satellite data and traditional surface and sounding data the development process is treated as a dry adiabatic vortex dynamics problem and it is found that environmental and mesoscale dynamics mutually enhance each other in a cooperative interaction during cyclone formation synoptic scale interactions result in the evolution of the hostile environment toward more favorable conditions for storm development mesoscale interactions with the low level large scale circulations and with other midlevel mesoscale features result in development of vorticity in the midlevels and enhancement of the low level vorticity associated with the developing surface cyclone multiple developments of mesoscale convective systems after the storm reaches tropical depression strength suggests both an increase in low level confluence and a tendency toward recurrent development of associated mesoscale convective vortices this is observed in both aircraft data and satellite imagery where subsequent interactions including mergers with the low level tropical depression vortex are observed a contour dynamics experiment suggests that the movement of mesoscale convective systems in satellite imagery corresponds well to the movement of their associated midlevel vortices results from a simple baroclinic experiment show that the midlevel vortices affect the large scale low level circulation in two ways 1 initially interactions between midlevel vortices produce a combined vortex of greater depth 2 interaction between midlevel vortices and the low level circulation produces a development downward of the midlevel vorticity this strengthens the surface vortex and develops a more cohesive vortex that extends from the surface through the midtroposphere

volcanic diapirs in the orange mountain flood basalt new jersey usa abstract diapir shaped structures 4 30 m high consisting of vesicular basalt have intruded into the interior of a 50 70 m thick subaerial orange mountain basalt flow exposed at several rock quarries in northern new jersey the basalt flowed onto a travertine encrusted mudflat saturated with alkali salts we propose that pressurized alkali vapors trapped under the lava created a vesicular and viscous flow bottom layer about 10 m thick vesicle coalescence within this layer increased its buoyancy where it locally accumulated into diapirs and displaced overlying lava large bubbles within the diapirs expanded upon intrusion into hot flow interiors where they explosively escaped leaving lenses of breccia some early diapirs reached the base of the upper lava crust these diapirs document vapor driven convection of large blobs of contaminated lava into the lava core of the orange mountain flow

northwestward propagating wave patterns over the tropical western north pacific during summer abstract the possible relationship between northwestward propagating wave disturbances and tropical cyclones over the tropical western north pacific during summer is studied using data assimilated by the navy s global model during may september 1989 91 a multiple set canonical correlation mcc analysis is applied to the 850 hpa meridional v component over a core domain covering the western pacific the analysis seeks the maximal geometrically averaged correlation between 12 consecutive twice daily fields two mcc components with a 90 phase difference and comparable variances that combine to nearly one third of the total variance describe the northwestward propagating pattern with a period near 8 9 days upstream of this steady northwestward propagating pattern there is a weaker westward propagation along 5 n that may be traced back to 170 e the surface pressure cell advancing east of the philippines is consistent with low level winds for a circulation in gradient wind balance it has a zonal wave

emplacement and crystallization time for the bushveld complex the bushveld complex formed by the crystallization of successive basaltic magmatism may be of the order of several million years for example the columbia river basalts hooper injections of magma which were sufficiently closely spaced in time that each previous magma had not cooled and differentiated 1988 were erupted in the period 17 12 ma with minor eruptions for a further 5 my although most outpouring significantly before the addition of the next one to constrain the emplacement and crystallization times a thermal model is presented occurred within the first 2 my it is now recognized that large intrusions were not emplaced in a single pulse but which permits the investigation of the rate of cooling of magma in an intrusion repeatedly subjected to magma addition and subresult from multiple magma injection the question is how rapidly were magma chambers such as the bc traction such modelling indicates that magmas injected into the bushveld complex were emplaced within 75 000 years at that filled and how much magma was involved answers are relevant to the dynamics of melt production storage and time injection into the complex ceased the volume of rock in the eastern and western limbs is 370 000 600 000 km however transport in the mantle and crust this paper describes a thermal modelling technique not previously applied a quantitative evaluation of the cr budget in the formation of chromitite layers indicates that large volumes of magma cannot be to magma chambers which can be used to analyse this process and to obtain an estimate of the emplacement accounted for in the preserved rock sequence similarly an evaluation of the incompatible trace element abundances such as those for zr time to present this model it is necessary to discuss the stratigraphy size and connectivity of the different limbs and k suggests that the chamber was open and that large volumes of differentiated magma escaped the volume of magma therefore of the bushveld complex and to consider the extent of tapping of the magma chamber as well as its filling greatly exceeded the preserved volume of cumulate rocks giving an estimated magma volume of over 1 10 km an average the term bushveld complex has been given several meanings in the literature and according to the south emplacement rate of 13 km year is indicated by these calculations african commission on stratigraphy 1980 includes not only the ultramafic mafic layered rocks but also the sills beneath the intrusion volcanic rocks which pre date the

on bimodal differentiation by solidification front instability in basaltic magmas part 1 basic mechanics extensive coarse grained silicic lenses are common in the upper portions of large diabase sills lava lakes and gabbroic intrusions these lenses which often contain up to 10 wt more silica than their host rocks record a clear process of bimodal differentiation that may play a fundamental role in generating significant quantities of silicic magma in predominantly basaltic systems the spatial compositional textural and contact relations suggest that these silicic segregations form by infilling of tears formed during gravitational instability of the upper solidification front this process is investigated in some detail by exploring the thermal and mechanical conditions leading to internal failure of the front and segregation formation as the upper solidification front grows inward and thickens the local strength of the developing crystalline network must increase upward through the front sufficiently fast to offset the increasing weight of the front itself this necessary local variation in strength dictates how crystallinity must vary to prevent failure but the actual variation in crystallinity is determined by phase equilibria which in general varies in a fashion that is noncovariant with that required for mechanical stability it is this mismatch that apparently leads to failure and formation of silicic segregations the rate of filling of the tears by porous flow of interstitial melt from below regulates the rate of tear opening and the overall size of the tears is regulated by the local rate of advance of the solidification front segregations therefore thicken downward as the growth of the front slows and then die out altogether with approach of the lower solidification front this process irreversibly introduces siliceous noise into basaltic systems the silicic signal can be enhanced through subsequent reprocessing of the host rock to form volumetrically important masses of silicic magma this process may be fundamental to achieving the strong compositional diversity of the igneous rocks to yielding continental masses and to the differentiation of earth itself

a matter of divergence tracking recent warming at hemispheric scales using tree ring data 1 no current tree ring tr based reconstruction of extratropical northern hemisphere enh temperatures that extends into the 1990s captures the full range of late 20th century warming observed in the instrumental record over recent decades a divergence between cooler reconstructed and warmer instrumental large scale temperatures is observed we hypothesize that this problem is partly related to the fact that some of the constituent chronologies used for previous reconstructions show divergence against local temperatures in the recent period in this study we compiled tr data and published local regional reconstructions that show no divergence against local temperatures these data have not been included in other large scale temperature reconstructions utilizing this data set we developed a new completely independent reconstruction of enh annual temperatures 1750 2000 this record is not meant to replace existing reconstructions but allows some degree of independent validation of these earlier studies as well as demonstrating that tr data can better model recent warming at large scales when careful selection of constituent chronologies is made at the local scale although the new series tracks the increase in enh annual temperatures over the last few decades better than any existing reconstruction it still slightly under predicts values in the post 1988 period we finally discuss possible reasons why it is so difficult to model post mid 1980s warming provide some possible alternative approaches with regards to the instrumental target and detail several recommendations that should be followed in future large scale reconstruction attempts that may result in more robust temperature estimates

barotropic aspects of itcz breakdown abstract in satellite images the itcz intertropical convergence zone is sometimes observed to undulate and break down into a series of tropical disturbances tropical cyclones may later develop within these disturbances and move into higher latitudes allowing the itcz to reform it has been proposed that itcz breakdown results from a convectively modified form of combined barotropic and baroclinic instability of the mean flow an unstable mean flow can be produced by itcz convection in just a couple of days in this sense the itcz produces favorable conditions for its own instability and breakdown in this study a nonlinear shallow water model on the sphere is used to simulate barotropic aspects of itcz breakdown in the shallow water model the itcz is simulated by a prescribed zonally elongated mass sink near the equator the mass sink produces a cyclonic potential vorticity pv anomaly that has a reversed meridional pv gradient on its poleward side according to the ripa theorem a flow that has a