a simple multicloud parameterization for convectively coupled tropical waves part i linear analysis abstract recent observational analysis reveals the central role of three multicloud types congestus stratiform and deep convective cumulus clouds in the dynamics of large scale convectively coupled kelvin waves westward propagating two day waves and the madden julian oscillation a systematic model convective parameterization highlighting the dynamic role of the three cloud types is developed here through two baroclinic modes of vertical structure a deep convective heating mode and a second mode with low level heating and cooling corresponding respectively to congestus and stratiform clouds a systematic moisture equation is developed where the lower troposphere moisture increases through detrainment of shallow cumulus clouds evaporation of stratiform rain and moisture convergence and decreases through deep convective precipitation a nonlinear switch is developed that favors either deep or congestus convection depending on the relative dryness of the troposphere in particular a dry troposphere

resolving volatile sources along the western sunda arc indonesia we present the chemical and isotope hecn characterization of active fumaroles and hydrothermal gases and waters from the summits and flanks of 19 volcanic centers along the western sunda arc indonesia samples were collected over two field expeditions 1991 and 2010 and cover 13 volcanic centers in sumatra 5 in java and one in bali in addition we present data from three geothermal sites in sumatra associated with active fault systems in between volcanic centers ibvc the overall aim is to resolve volatiles associated with the sub arc mantle subducting slab and mantle wedge from inputs derived from the over riding arc crust the western sunda arc is a prime locality to assess controls on volatile provenance at subduction zones due to changes in composition and thickness of over riding crust and variations in sediment input rates along the strike of the arc the dry gas chemistry of the majority of volcanic samples is dominated by co2 with inert gas variations hearn2 typical of subduction zone gases however there is a strong crustal control on the heco2 isotope and relative abundance systematics on a number of volcanic centers this effect is most clearly observed at flank localities and in water phase samples filtering the entire database for modifications due to air contamination degassing induced fractionation c isotopes and co2 3he ratios and crustal contamination associated with volatile transport within shallow level hydrothermal systems allows recognition of the magmatic volatile signature of individual volcanoes along the arc helium isotopes at all but two volcanic centers talang and dempo on sumatra range from 5 3 ra to 8 1 ra ra air 3he 4he pointing to the mantle wedge as the principal source of he but with a small input of crustal radiogenic he at some localities samples from java and bali span an even more limited range 6 6 to 7 9 ra implying a relatively smaller input of crustal he carbon isotope and co2 3he ratios vary from 1 4 to 6 4 and 4 38 to 150 109 respectively with higher and more variable values to the north of sumatra this latitudinal effect is not apparent in air corrected n isotope values 15nc 3 91 to 5 92 or various elemental ratios such as n2 ar and n2 he the three ibvc sites all located in sumatra have significantly lower 3he 4he ratios 3 6 ra with co2 3he values both higher and lower than volcanic centers their 13c 15nc and gas ratios overlap with the volcanic centers the elemental and isotopic characteristics of carbon and helium have been modified at ibvc sites due to crustal processes however based upon relationships between ch4 and 3he as well as co variations between hecn isotopes the over riding crust and associated sediments add minimal volatiles to volcanic centers throughout the western sunda arc in turn subducted sediment particularly the nicobar fan which supplies himalayan derived sediment to the slab off sumatra exerts a strong control on the magmatic co2 characteristics although it is less influential for n2 in spite of large sections of incoming sedimentary material being off scraped during subduction our data suggest that a significant fraction must enter the trench enhancing fluid melt production in the mantle wedge we propose that subduction related source contamination plays the dominant role over thick old crustal basement in supplying the major volatile output budget of the western sunda arc

the annual cycle in equatorial convection and sea surface temperature abstract the coupled atmosphere ocean system in the equatorial eastern pacific and atlantic exhibits a distinct annual cycle that is reflected in contrasting conditions at the times of the two equinoxes the contrasts are so strong that they dominate the annual march of zonally averaged outgoing longwave radiation for the equatorial belt the march equinox corresponds to the warm season when the equatorial cold tongues in the eastern pacific and atlantic are absent with the onset of summer monsoon convection over colombia central america and west africa in may june northward surface winds strengthen over the eastern pacific and atlantic the equatorial cold tongues reappear and the marine convection shifts from the equatorial belt to the intertropical convergence zones itczs along 8 n as the northern summer program the itczs remain strong and shift northward to new 10 n while sea surface temperature sst continues to drop over the cold tongues and the southern tropics perhaps in response to the

p s velocity and vp vs ratio beneath the toba caldera complex northern sumatra from local earthquake tomography summary in this paper we investigate the crustal and uppermost mantle structure beneath toba caldera which is known as the location of one of the largest cenozoic eruptions on earth the most recent event occurred 74 000 yr bp and had a significant global impact on climate and the biosphere in this study we revise data on local seismicity in the toba area recorded by a temporary passcal network in 1995 we applied the newest version of the lotos 07 algorithm which includes absolute source location optimization of the starting 1 d velocity model and iterative tomographic inversion for 3 d seismicp s or thevp vs ratio and source parameters special attention is paid to verification of the obtained results beneath the toba caldera and other volcanoes of the arc we observe relatively moderate for volcanic areas negative p and s velocity anomalies that reach 18 per cent in the uppermost layer 10 12 per cent in the lower crust and about 7 per cent in the uppermost mantle much stronger contrasts are observed for the vp vs ratio that is a possible indicator of dominant effect of melting in origin of seismic anomalies at a depth of 5 km beneath active volcanoes we observe small patterns 7 15 km size with a high vp vs ratio that might be an image of actual magmatic chambers filled with partially molten material feeding the volcanoes in the mantle wedge we observe a vertical anomaly with low p and s velocities and a high vp vs ratio that link the cluster of events at 120 140 km depth with toba caldera this may be an image of ascending fluids and melts released from the subducted slab due to phase transitions however taking into account poor vertical resolution these results should be interpreted with prudence although the results show clear signatures that are quite typical for volcanic areas low velocity and high vp vs ratio beneath volcanoes we do not observe any specific features in seismic structure that could characterize toba as a super volcano

the structure and annual variation of antisymmetric fluctuations of tropical convection and their association with rossby gravity waves abstract the signature of 4 5 day period rossby gravity waves is searched for in the tropical convection field across the indian pacific oceans the convergence divergence field of these waves in the lower troposphere is anticipated to produce an antisymmetric fluctuation in tropical convection antisymmetric fluctuations of tropical convection are shown to exhibit a pronounced spectral peak at a 4 5 day period only during boreal fall and only within about 30 longitude of the date line the peak amplitude occurs around 7 5 latitude these fluctuations propagate westward at 15 20 m s 1 with zonal wavelength of about 7000 9000 km the fluctuations of convection are coherent and out of phase with the equatorial meridional wind which also exhibits a pronounced spectral peak at a 4 5 day period in the lower troposphere near the date line the antisymmetric zonal wind also is strongly coherent with the antisymmetric convective fluctuations in this region the horizontal distributions of the 4 5 day power an

layered and laterally constrained 2d inversion of resistivity data in a sedimentary environment quasi layered models often can represent the actual geology more accurately than smooth minimum structure models we present a 2d inversion scheme with lateral constraints and sharp boundaries lci for continuous resistivity data all data and models are inverted as one system producing layered solutions with laterally smooth transitions the models are regularized through lateral constraints that tie interface depths or thicknesses and resistivities of adjacent layers a priori information used to resolve ambiguities and to add for example geological information can be added at any point of the profile and migrates through the lateral constraints to parameters at adjacent sites similarly information from areas with well resolved parameters migrates through the constraints to help resolve areas with poorly constrained parameters the estimated model is complemented by a full sensitivity analysis of the model parameters supporting quantitative evaluation of the inversion result a simple synthetic model proves the need for a quasilayered 2d inversion when compared with a traditional 2d minimum structure inversion a 2d minimum structure inversion produces models with spatially smooth resistivity transitions making identification of layer boundaries difficult a continuous vertical electrical sounding field example from sweden with a depression in the depth to bedrock supports the conclusions drawn from the synthetic example a till layer on top of the bedrock hidden in the traditional inversion result is identified using the 2d lci scheme furthermore the depth to the bedrock surface is easily identified for most of the profile with the 2d lci model which is not the case with the model from the traditional minimumstructure inversion

three dimensional implicit stratigraphic model building from remote sensing data on tetrahedral meshes theory and application to a regional model of la popa basin ne mexico remote sensing data provide significant information to constrain the geometry of geological structures at depth however the use of intraformational geomorphologic features such as flatirons and incised valleys often calls for tedious user interaction during 3 d model building we propose a new method to generate 3 d models of stratigraphic formations based primarily on remote sensing images and digital elevation models this method is based on interpretations of the main relief markers and interpolation of a stratigraphic property on a tetahedral mesh covering the domain of study the tetrahedral mesh provides a convenient way to integrate available data during the interpolation while accounting for discontinuities such as faults interpretive expert input may be provided through constrained interactive editing on arbitrary cross sections and additional surface or subsurface data may also be integrated in the modeling we demonstrate this global workflow on a structurally complex basin in the sierra madre oriental northeastern mexico

multidomain petrophysically constrained inversion and geology differentiation using guided fuzzy c means clustering abstractgeophysical inversion methods are used as part of an interpretation process that seeks to differentiate geologic units to improve the reliability of geologic differentiation based on recovered images from geophysical inversions we have developed a multidomain clustering inversion algorithm that can incorporate statistical petrophysical data into a deterministic geophysical inversion framework through the use of the fuzzy c means clustering technique petrophysical data are treated in the parameter domain in the same way that geophysical data are treated in the spatial domain and these two different types of data are simultaneously inverted in their respective domains through the minimization of a single common objective function the resulting physical property model honors the geophysical and petrophysical data and therefore can represent the earth better than geophysical inversion models that solely honor the geophysical data geophysical inversion and geology differentiation are generally tr

seismic vp and vp vs structure of the geothermal area around tarutung north sumatra indonesia derived from local earthquake tomography abstract a passive seismic experiment with 42 short period stations was setup for 10 months from may 2011 within a 20 30 km radius covering the tarutung basin and the northern part of the sarulla graben along the seismically active sumatran fault north sumatra indonesia the objective of the project is to investigate the geothermal setting based on the vp and vp vs structures and the distribution of seismicity we recorded 2856 local earthquakes by at least 8 stations which were reduced to 809 events having gap angle less than 180 the initial earthquake locations were determined using simultaneous inversion for hypocenters and 1d velocity structure followed by 3d tomographic inversion the resulting seismicity distribution vp and vp vs structure reveal systematic differences between the tarutung basin and the sarulla graben the tarutung pull apart basin is characterized by a complex structure reflected by a broader distribution of seismicity compared with the very narrow rather vertical hypocenter distribution in the sarulla graben which was formed by fault perpendicular extension and not by pull apart tectonics high vp vs values near to the surface are imaged within the sarulla graben and northeast of the tarutung basin these features are interpreted as fluid bearing sediments with fracturing indicating potentially favorable conditions for geothermal exploitation the localized fluid flow northeast of tarutung could be explained by the releasing step over structure of the pull apart basin and resulting dilatational stress regime in this part of the basin heat sources are assumed to be located at greater depth in association with magmatic activities accompanying the subduction process and the heat is transported along the sumatran fault to shallow depth

gravity waves generated by a tropical cyclone during the step tropical field program a case study overflights of a tropical cyclone during the australian winter monsoon field experiment of the stratosphere troposphere exchange project step show the presence of two mesoscale phenomena a vertically propagating gravity wave with a horizontal wavelength of about 110 km and a feature with a horizontal scale comparable to that of the cyclone s entire cloud shield wavelength of 250 km or greater the larger feature is fairly steady though its physical interpretation is ambiguous the 110 km gravity wave is transient having maximum amplitude early in the flight and decreasing in amplitude thereafter its scale is comparable to that of 100 to 150 km diameter cells of low satellite brightness temperatures within the overall cyclone cloud shield these cells have lifetimes of 4 5 to 6 hours aircraft flights through the anvil show that these cells correspond to regions of enhanced convection higher cloud altitude and upwardly displaced potential temperature surfaces a three dimensional transient linear gravity wave simulation shows that the temporal and spatial distribution of meteorological variables associated with the 110 km gravity wave can be simulated by a slowly moving transient forcing at the anvil top having an amplitude of 400 600 m a lifetime of 4 5 6 hours and a size comparable to the cells of low brightness temperature the forcing amplitudes indicate that the zonal drag due to breaking mesoscale transient convective gravity waves is definitely important to the westerly phase of the stratopause semiannual oscillation and possibly important to the easterly phase of the quasi biennial oscillation there is strong evidence that some of the mesoscale gravity waves break below 20 km as well the effect of this wave breaking on the diabatic circulation below 20 km may be comparable to that of above cloud diabatic cooling

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

the abundance of seafloor massive sulfide deposits the possibility of mining seafl oor massive sulfide deposits has stirred debate about the sustainable use of this new resource and whether commercial development is worth the risk among the outstanding questions is how many deposits might be accessible to deep sea mining more than 300 sites of high temperature hydrothermal venting have been identifi ed since the discovery of black smokers but signifi cant massive sulfide accumulation has been found at only 165 of these sites estimates of the total number of vent fields and associated mineral deposits based on plume studies and deposit occurrence models range from 500 to 5000 we have used new deposit occurrence data from 10 000 km of ridge arc and backarc spreading centers to estimate the amount of massive sulfide in the easily accessible neovolcanic zones of the global oceans the total accumulation in these areas is estimated to be on the order of 6 108 tonnes containing 3 107 tonnes of copper and zinc this is similar to the total discovered copper and zinc in cenozoic massive sulfi de deposits mined on land but is insuffi cient to satisfy a growing global demand for these metals

inversion of seismic refraction and wide angle reflection traveltimes for three dimensional layered crustal structure summary we present a method for the determination of crustal structure by simultaneous inversion of seismic refraction and wide angle reflection traveltimes for 3 d interface geometry and layer velocity crustal structure is represented by layers in which velocity varies linearly with depth separated by smooth interfaces with a cubic b spline parametrization lateral variations in structure are therefore represented by variations in interface depth only the model parametrization we have chosen means that ray paths consist of piecewise circular arc segments for which analytic expressions of trajectory and traveltime are calculated the two point problem of finding the first arrival ray path and traveltime of a specified phase between a given source and receiver is solved using a shooting technique a subspace inversion method is used to solve the inverse problem which is formulated as a non linear optimization problem in which we seek to minimize an objective function that consists of a data residual term and a regularization term before performing the inversion each data pick must be assigned as a refraction or reflection from a particular layer or interface since our method represents structure in terms of interfaces fewer parameters would generally be used in a reconstruction compared to an equivalent 3 d variable velocity inversion the method is well suited to wide angle surveys that consist of many sources and relatively few receivers or vice versa such as marine shot lines used in conjunction with land based receivers data coverage in this kind of survey is often sparse and especially if near offset ray paths are unavailable highly variable a 3 d synthetic test with an array consisting of eight sources lying within a three sided square of 79 receivers is described the test model consists of a three interface structure that includes a layer pinch out and the synthetic data set comprises 987 refraction and 930 reflection travel times contaminated with 75 ms of data noise six iterations of an 18 d subspace method demonstrate that the method can produce an accurate reconstruction that satisfies the data from a 1 d starting model we also find that estimates of a posteriori model covariance and resolution obtained from linear theory are useful in analysing solution reliability despite the non linear nature of the problem application of the method to data collected as part of the 1995 tasgo project in tasmania shows that the method can satisfy 1345 refraction and reflection traveltime picks with a geologically reasonable and robust 254 parameter three interface model the inversion results indicate that the moho beneath nw tasmania varies in depth from 27 km near the coast to 37 km near central tasmania with the major increase in depth occurring across the arthur lineament

modulation of seasonal precipitation over the tropical western central pacific by convectively coupled mixed rossby gravity waves abstractthe relationship between the interannual variations of the activity of convectively coupled equatorial waves and seasonal mean precipitation in the tropical western to central pacific ocean is investigated it is found that the convectively coupled mixed rossby gravity mrg waves are highly and negatively correlated with the seasonal precipitation near the equator in boreal summer it is suggested that the mrg waves which have convection centers off the equator suppress the equatorial precipitation the relation is insignificant in the other seasons when the interannual variation of sea surface temperature near the equator is greater than in boreal summer also a similar relation is not found in the eastern pacific in any season

an evaluation of plate tectonic models for the development of sumatra abstract over the past two decades models have been developed which suggest that the asian continent has been formed since the late palaeozoic by the accretion of continental blocks derived from the northern margin of gondwana sumatra forming the southwestern margin of the southeast asian promontory sundaland is considered to be composed of fragments of continental plates and magmatic arcs which were derived from gondwana during the late palaeozoic and mesozoic the indochina block forms the core of sundaland extending into the eastern part of the malay peninsula the greater part of sumatra is considered to form part of the sibumasu block which accreted to the indochina block along the bentong raub suture in the triassic a model has been proposed in which the southern part of the sibumasu block in the western part of the malay peninsula and sumatra is divided into malacca and mergui microplates by the mutus assemblage which represents another triassic suture a review of the permo triassic stratigraphy of malaya and sumatra provides no support for this model comparison of the permo carboniferous stratigraphy and palaeontology of northern sumatra with that of the malay peninsula and peninsular thailand and in particular the occurrence of tillites links sumatra firmly to the rest of the sibumasu block to the north comparison with the permo carboniferous stratigraphy of bonaparte gulf region of northwest australia shows a mirror image relationship suggesting that the sibumasu block separated from this part of the gondwanan margin in the mid permian on the other hand permo carboniferous rocks in central sumatra contain a cathaysian fauna and flora which relates this area to the indochina block rather than to sibumasu this anomaly was recognised early in the study of the geology of sumatra and led to the proposal of a djambi nappe thrust over sumatra from the east the cathaysian fauna and flora is associated with an early permian volcanic arc it has been suggested that this was an independent island arc accreted to the western margin of sibumasu but from the relationships of the volcanic rocks to permian sediments and the underlying basement it is most probable that this arc was developed on the margin of the cathaysian block the most recently accreted pre tertiary unit on sumatra is the woyla group a jurassic early cretaceous oceanic volcanic arc which together with its associated accretionary complex of oceanic crustal material was thrust over the western margin of sumatra in the mid cretaceous earlier plate models for the development of sumatra are reviewed and a revised model is proposed however there are still many difficulties in interpreting the stratigraphy and the tectonic development of sumatra which will require further detailed study aimed at resolving the many outstanding problems

coherent fluctuations of extratropical geopotential height and tropical convection in intraseasonal time scales abstract coherent fluctuations between extratropical circulation and tropical conviction in the intraseasonal time scale are studied possible relationships between 500 mb height field and outgoing longwave radiation olr are examined using correlation complex eof and composite techniques results show that in the 20 70 day bands data there is a systematic evolution of extratropical wavetrains from eurasia across the pacific to north america and the north atlantic in the time scale of 5 to 10 days over the tropics the dominant mode of intraseasonal variation in convection is an east west dipole like feature which propagates from the western indian ocean eastward to the dateline with a quasi period of 40 50 days the space time evolution of these extratropical wavetrains is found to he coherent with the tropical dipolar convection and with the strongest convection over indonesia central pacific in approximate quadrature with the peak phase of the eurasia and pacific north america wavetrains while the

synoptic scale disturbances near the equator abstract a spectral analysis of winds analyzed and initialized at the european centre for medium range weather forecasts reveals an abundance of power in the 850 mb meridional wind along the equator with periods near four days the power is mostly in the westward propagating component using high pass filtered data it is shown that the waves have westward phase and eastward group propagation relative to the mean wind the longest wavelengths are found over the pacific ocean while the shortest are found over the convectively variable regions of indonesia south america and africa mean phase speeds at 850 mb are positively correlated with the mean wind on the equator at 500 mb and below and negatively correlated with the mean wind above that level the effective advecting zonal wind of the disturbances seems to be the density weighted average of the lower troposphere the structure of the disturbances bears resemblance to the expected structure of an equatorially trapped mixed rossby gravity wave over t

horizontal and vertical structure of easterly waves in the pacific itcz abstract outgoing longwave radiation olr and low level wind fields in the atlantic and pacific intertropical convergence zone itcz are dominated by variability on synoptic time scales primarily associated with easterly waves during boreal summer and fall this study uses spectral filtering of observed olr data to capture the convective variability coupled to pacific easterly waves filtered olr is then used as an independent variable to isolate easterly wave structure in wind temperature and humidity fields from open ocean buoys radiosondes and gridded reanalysis products the analysis shows that while some pacific easterly waves originate in the atlantic most of the waves appear to form and strengthen within the pacific pacific easterly waves have wavelengths of 4200 5900 km westward phase speeds of 11 3 13 6 m s 1 and maximum meridional wind anomalies at about 600 hpa a warm moist boundary layer is observed ahead of the waves with moisture lofted quickly through the troposphere by deep co

vertical coupling from the lower atmosphere to the ionosphere observations inferred from indian mst radar gps radiosonde ionosonde magnetometer olr noaa and saber timed instrument over gadanki

the madden julian oscillation recorded in early observations from the tropical rainfall measuring mission trmm a satellite data analysis is performed to explore the madden julian oscillation mjo focusing on the potential roles of the equatorial rossby er and kelvin waves measurements from the tropical rainfall measuring mission trmm precipitation radar pr and visible infrared scanner virs are analyzed in the frequency wavenumber domain to identify and ultimately filter primary low frequency modes in the tropics the space time spectrum of deep storm fraction estimated by pr and virs exhibits notable kelvin wave signals at wavenumbers 5 8 a distinct mjo peak at wavenumbers 1 7 and periods of about 40 days and a signal corresponding to the er wave these modes are separately filtered to study the individual modes and possible relationship among them in the time longitude space in 10 cases analyzed here an mjo event is often collocated with a group of consecutive kelvin waves as well as an intruding er wave accompanied with the occasional onset of a stationary convective phase the spatial and temporal relationship between the mjo and kelvin wave is clearly visible in a lag composite diagram while the ubiquity of the er wave leads to a less pronounced relation between the mjo and er wave a case study based on the geostationary meteorological satellite gms imagery together with associated dynamic field captures the substructure of the planetary scale waves a cross correlation analysis confirms the mjo related cycle that involves surface and atmospheric parameters such as sea surface temperature water vapor low clouds shallow convection and near surface wind as proposed in past studies the findings suggest the possibility that a sequence of convective events coupled with the linear waves may play a critical role in mjo propagation an intraseasonal radiative hydrological cycle inherent in the local thermodynamic conditions could be also a potential factor responsible for the mjo by loosely modulating the envelope of the entire propagation system

joint inversion of gravity and magnetic data for two layer models gravity and magnetic data are inverted jointly in terms of a model consisting of an interface separating two layers having a constant density and magnetization contrast a damped least squares inversion is used to determine the topography of the interface the inversion requires knowledge of the physical property contrasts across the interface and its average depth since the relationship between model parameters and data is weakly nonlinear a constant damped least squares inverse is used during the iterative solution search the effect of this inverse is closely related to a downward continuation of the field to the average interface depth the method is used to map the base of the sept iles mafic intrusion quebec canada and the shape of the central uplift at the chicxulub impact crater yucatan mexico at sept iles the intrusion reaches a thickness of 7 km coincident with the maximum gravity anomaly south of the intrusion center at chicxulub the top of the central uplift is modeled to be 3

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

gravity waves in the tropical lower stratosphere a model study of seasonal and interannual variability a model study is presented to clarify the relationship between gravity wave properties observed in the stratosphere and the sources for the waves presumed to be in the troposphere the observations are balloon borne radiosondes launched from cocos island in the tropical indian ocean 12 s 97 e and the analysis of these data is described in a companion paper vincent and alexander this issue the dominant time variations in the observed gravity wave activity are annual and quasi biennial patterns in the zonal momentum flux and kinetic energy density the background zonal winds at this site vary with the same periods and these are known to be capable of causing dramatic variations in the observable properties of the waves even if the sources for the waves are constant in time the results presented here clarify 1 the nature of the sources for the gravity waves observed in the stratosphere 2 the limitations of the observations for observing the full range of gravity wave perturbations potentially present in the atmosphere and 3 the role the observed waves can play in forcing the quasibiennial oscillation qbo in the zonal winds at this latitude the stratospheric waves appear to originate near the height of the tropopause so the source is apparently related to deep convection no seasonal or interannual variations in the convection need be assumed to understand the observations the waves at the tropopause appear to have a phase speed distribution that is narrowly confined near zero phase speed relative to the ground the source is likely related to slowly propagating tropospheric convection and the wind near the tropopause variations observed in the stratospheric data are caused by both the wind shear in the stratosphere and the ability of waves with these characteristics to propagate vertically without severe dissipation higher phase speed waves may be present and could carry significant momentum flux vertically into the stratosphere and mesosphere but would be extremely difficult to see in these radiosonde data the observed waves can contribute substantially to the descent of the eastward shear zones characteristic of the westerly phase of the qbo in the lower stratosphere zonal winds

the association of the evolution of intraseasonal oscillations to enso phase abstract the pacific ocean intraseasonal kelvin wave is a leading oceanic mode that links intraseasonal tropical atmospheric variations with interannual variations in the coupled ocean atmosphere system this study considers the premise that these waves may evolve differently with their associated weather patterns during different phases of el nino southern oscillation enso if atmospheric and oceanic intraseasonal modes interact and evolve differently during various stages of enso this result may provide useful information with regard to the role of these intraseasonal processes in enso evolution this work utilizes signals of the oceanic kelvin wave as a statistical basis for a simple composite averaging technique that is applied during different phases of enso to objectively analyze the evolution of oceanic and the associated portions of atmospheric intraseasonal oscillations results confirm the above premise and suggest that coupling between kelvin waves and atmospheric convection evolves differen

the intraseasonal 30 50 day oscillation of the australian summer monsoon abstract the tropical intraseasonal 30 50 day oscillation manifests itself in the australian summer monsoon by a pronounced modulation of the monsoonal westerlies these 30 50 day fluctuations of the monsoonal westerlies are coherent with rainfall and olr across northern australia the olr fluctuation originates in the indian ocean and systematically propagates eastward at 5 m s 1 consistent with previous studies of the intraseasonal oscillation the detailed evolution of the intraseasonal oscillation of the monsoon is studied via composites of upper air data in and about the australian tropics during the summer periods 1957 87 91 events were identified at darwin australia the composite oscillation at darwin has a very deep baroclinic structure with westerlies extending up to 300 mb the westerly phase lasts about ten days and lags a similar duration rainfall event by about four days during the westerly phase the upper troposphere is warm and the extreme lower troposphere is cool this structure

the influences of convectively coupled kelvin waves on multiscale rainfall variability over the south china sea and maritime continent in december 2016 abstractwe studied the scale interactions of the convectively coupled kelvin waves kws over the south china sea scs and maritime continent mc during december 2016 three kws were observed nea

organization of convection within the madden julian oscillation convection associated with the madden julian oscillation mjo is organized over a broad range of time and space scales within a large scale envelope of activity the large scale envelope of convection is characterized as an eastward propagating disturbance predominantly of zonal wavenumber 2 which is confined over the warmest waters of the indian and western pacific oceans large scale convection is shifted toward the disturbance s temperature anomaly which appears to result from frictional effects in the boundary layer synoptic and mesoscale convective activity is enhanced within the wet phase of the large scale envelope the increase at synoptic scales occurs uniformly over all scales but little difference in the character of the variability is observed between dry and wet phases the enhanced mesoscale activity within the wet phases exhibits a marked tendency to be organized into westward propagating clusters with periods near 2 days and half wavelengths of about 1000 km the role of these modes for the evolution of the mjo is discussed

squall lines and convectively coupled gravity waves in the tropics why do most cloud systems propagate westward abstractthe coupling between tropical convection and zonally propagating gravity waves is assessed through fourier analysis of high resolution 3 hourly 0 5 satellite rainfall data results show the familiar enhancement in power along the dispersion curves of equatorially trapped inertia gravity waves with implied equivalent depths in the range 15 40 m i e pure gravity wave speeds in the range 12 20 m s 1 here such wave signals are seen to extend all the way down to zonal wavelengths of around 500 km and periods of around 8 h suggesting that convection wave coupling may be important even in the context of mesoscale squall lines this idea is supported by an objective wave tracking algorithm which shows that many previously studied squall lines in addition to 2 day waves can be classified as convectively coupled inertia gravity waves with the dispersion properties of shallow water gravity waves most of these disturbances propagate westward at speeds faster than the background flow to under

observations of a convectively coupled kelvin wave in the eastern pacific itcz abstract a case study of a convectively coupled kelvin wave in the eastern pacific intertropical convergence zone itcz is presented as observed during the 1997 pan american climate studies pacs tropical eastern pacific process study tepps the large scale convective envelope associated with this disturbance with a zonal scale of approximately 1000 2000 km propagates eastward at 15 m s 1 along the mean convective axis of the itcz this envelope consists of many smaller scale westward moving convective elements with zonal scales on the order of 100 500 km as the convectively coupled kelvin wave disturbance propagates eastward it exerts a strong control on local convection radar and vertical profiler data collected aboard the noaa r v ronald h brown during the wave passage show that convection deepens rapidly as the kelvin wave approaches from the west progressing from isolated shallow cumuli to organized deep convective features within just 12 h initially rainfall in the vicinity of the s

the internal structure of an active sea floor massive sulphide deposit the hydrothermal circulation of sea water through permeable ocean crust results in rock water interactions that lead to the formation of massive sulphide deposits these are the modern analogues of many ancient ophiolite hosted deposits1 4 such as those exposed in cyprus here we report results obtained from drilling a series of holes into an actively forming sulphide deposit on the mid atlantic ridge a complex assemblage of sulphide anhydrite silica breccias provides striking evidence that such hydrothermal mounds do not grow simply by the accumulation of sulphides on the sea floor indeed the deposit grows largely as an in situ breccia pile as successive episodes of hydrothermal activity each form new hydrothermal precipitates and cement earlier deposits during inactive periods the collapse of sulphide chimneys dissolution of anhydrite and disruption by faulting cause brecciation of the deposit the abundance of anhydrite beneath the present region of focused hydrothermal venting reflects the high temperatures 150 c currently maintained within the mound and implies substantial entrainment of cold sea water into the interior of the deposit these observations demonstrate the important role of anhydrite in the growth of massive sulphide deposits despite its absence in those preserved on land

joint inversion of surface and three component borehole magnetic data the inversion of magnetic data is inherently nonunique with respect to the distance between the source and observation locations this manifests itself as an ambiguity in the source depth when surface data are inverted and as an ambiguity in the distance between the source and boreholes if borehole data are inverted joint inversion of surface and borehole data can help to reduce this nonuniqueness to achieve this we develop an algorithm for inverting data sets that have arbitrary observation locations in boreholes and above the surface the algorithm depends upon weighting functions that counteract the geometric decay of magnetic kernels with distance from the observer we apply these weighting functions to the inversion of three component magnetic data collected in boreholes and then to the joint inversion of surface and borehole data both synthetic and field data sets are used to illustrate the new inversion algorithm when borehole data are inverted directly three component data are far more usefu

a simulation study of kelvin waves interacting with synoptic events during december 2016 in the south china sea and maritime continent abstractthis study evaluates the model simulation of interaction between convectively coupled tropical disturbances in the south china sea scs and maritime contin mc the model for prediction a

first measurement of ice bedrock interface of alpine glaciers by cosmic muon radiography the shape of the bedrock underneath alpine glaciers bears vital information on the erosional mechanism related to the flow of ice so far several geophysical exploration methods have been proposed to map the bedrock topography though with limited accuracy here we illustrate the first results from a technology called cosmic ray muon radiography newly applied in glacial geology to investigate the bedrock geometry beneath the aletsch glacier situated in the central swiss alps for this purpose we installed new cosmic muon detectors made of emulsion films at three sites along the jungfrau railway tunnel and measured the shape of the bedrock under the uppermost part of aletsch glacier jungfraufirn our results constrain the continuation of the bedrock ice interface up to a depth of 50 m below the surface where the bedrock underneath the glacier strikes ne sw and dips at 45 5 this documents the first successful application of this technology to a glaciated environment

hybrid optimization for lithologic inversion and time lapse monitoring using a binary formulation we have developed a hybrid optimization algorithm for binary inversion of geophysical data associated with lithologic inversion and time lapse monitoring the binary condition is designed to invert geophysical data for well defined physical properties within discrete lithologic units such as a salt body within a sedimentary host or temporal changes in physical property associated with dynamic processes such as the density and conductivity change in an oil and gas reservoir or groundwater aquifer the solution of such inverse problems with discrete model values requires specialized optimization algorithms to meet this need we develop a hybrid optimization algorithm by combining a genetic algorithm with quenched simulated annealing the former allows for easy incorporation of prior geologic information and rapid buildup of large scale model features whereas the latter guides genetic algorithm to faster evolution by rapidly adjusting the finer model features in examining the performance of the hybrid

hydrothermal minerals and microstructures in the silangkitang geothermal field along the great sumatran fault zone sumatra indonesia detailed study of core samples of silicic tuff recovered from three geothermal wells along the strike slip great sumatran fault zone near silangkitang north sumatra supports a model for enhanced hydrothermal circulation adjacent to this major plate boundary fault two wells a and c were drilled nearly vertically 1 km southwest of the eastern i e the principal fault trace and the third directional well b was drilled eastward from the site of well a to within 100 m of the principal fault trace the examined core samples come from depths of 1650 2120 m at measured well temperatures of 180 320 c the samples collected near the principal fault trace have the highest temperatures the largest amount of secondary pore space that correlates with high secondary permeability and the most extensive hydrothermal mineral development secondary permeability and the degree of hydrothermal alteration decrease toward the southwestern margin of the fault zone these features indicate episodic localized flow of hot possibly co 2 rich fluids within the fault zone the microstructure populations identified in the core samples correlate to the subsidiary fault patterns typical of strike slip faults the geothermal reservoir appears to be centered on the fault zone with the principal fault strands and adjoining highly fractured and hydrothermally altered rock serving as the main conduits for vertical fluid flow and advective heat transport from deeper magmatic sources

origin of convectively coupled kelvin waves over south america convectively coupled kelvin waves over the south american continent are examined through the use of temporal and spatial filtering of reanalysis satellite and gridded rainfall data they are most prominent from november to april the season analyzed herein the following two types of events are isolated those that result from preexisting kelvin waves over the eastern pacific ocean propagating into the continent and those that apparently originate over amazonia forced by disturbances propagating equatorward from central and southern south america the events with precursors in the pacific are mainly upper level disturbances with almost no signal at the surface those events with precursors over south america on the other hand originate as upper level synoptic wave trains that pass over the continent and resemble the cold surges documented by garreaud and wallace as the wave train propagates over the andes it induces a southerly low level wind that advects cold air to the north precipitation associated with a cold front reaches the equator a few days later and subsequently propagates eastward with the characteristics of a kelvin wave the structures of those waves originating over the pacific are quite similar to those originating over south america as they propagate to eastern south america and into the atlantic south america kelvin waves that originate over neither the pacific nor the midlatitudes of south america can also be identified in a composite sense these form over the eastern slope of the andes mountains close to the equator there are also cases of cold surges that reach the equator yet do not form kelvin waves the interannual variability of the pacific originating events is related to sea surface temperatures in the central eastern pacific ocean when equatorial oceanic conditions are warm there tends to be an increase in the number of disturbances that reach south america from the pacific

convectively coupled kelvin waves in cmip5 coupled climate models this study provided a quantitative evaluation of convectively coupled kelvin waves cckws over the indian ocean and the pacific ocean simulated by 20 coupled climate models that participated in coupled model intercomparison project phase 5 the two leading empirical orthogonal function eof modes of filtered daily precipitation anomalies are used to represent the eastward propagating cckws in both observations and simulations the eigenvectors and eigenvalues of the eof modes represent the spatial patterns and intensity of cckws respectively and the lead lag relationship between the two eof principle components describe the phase propagation of cckws a non dimensional metric was designed in consideration of all the three factors i e pattern amplitude and phase propagation for evaluation the relative rankings of the models based on the skill scores calculated by the metric are conducted for the indian ocean and the pacific ocean respectively two models noresm1 m and mpi esm lr are ranked among the best 20 for both the regions three models inmcm4 mri cgcm3 and hadgem2 es are ranked among the worst 20 for both the regions while the observed cckw amplitude is greater north of the equator in the pacific some models overestimate the cckw ampliutde in the southern hemisphere this bias is related to the mean state precipitation bias along the south pacific convergence zone

kelvin wave time scale propagation features of the madden julian oscillation mjo as measured by the chen mjo index 1 kelvin wave time scale propagation features in an indexed measure of the strength of the madden julian oscillation mjo are investigated examination of reanalysis data and chen mjo index data for three 14 may to 21 september periods shows that recurring events near sumatra frequently associated with convectively coupled cc kelvin waves tend to correspond in a time lagged manner with increases in indexed mjo strength at various longitudes the events characterized by low level divergence within a cyclonic circulation off the west coast of sumatra combined with northward advances in the dynamic equator tend to lag increases in indexed mjo strength by several days in the indian ocean and maritime continent and to lead such increases farther to the east maximum time lagged correlation coefficients between increases in indexed mjo strength and a measure of the strength of the divergence events near sumatra are consistent with a disturbance propagating eastward at kelvin wave phase speeds a similar signal is demonstrated in a 32 year data set of the chen mjo index by examining time lagged correlations between increases in indexed mjo strength at various longitudes and corresponding increases for selected events at 80 e and 160 e the results suggest an enhanced rate of increase in mjo strength as the apparent kelvin wave signal passes roughly marking the beginning of an extended period of mjo growth potential limitations of the current analysis are discussed a look at a particular mjo episode provides evidence consistent with the statistical results while supporting a role of sequential cc kelvin wave passages in the propagation of the mjo

multiscale phenomena in the tropical atmosphere over the western pacific abstract multiscale variabilities in the atmosphere over the tropical western pacific during the 1979 northern hemisphere winter are studied with an aim at identifying possible interactions between phenomena of different spatial and temporal scales based on the convection index information derived from satellite measurements two intra seasonal oscillations isos are identified within the equatorial belt between 0 and 10 s in the analyzed period the two isos accompanied by both rotational and divergent circulations propagate eastward from the indian ocean to the western pacific over the warm pool in the western pacific the isos develop into quasi stationary systems with an enhanced rotational circulation characterized by a strong westerly jet in the lower troposphere the isos appear to interact with a number of regional and synoptic scale phenomena in the maritime continent and western pacific region for example the onset of the monsoon coincides with the arrival of the first iso at northern a

sharp boundary inversion of 2d magnetotelluric data we consider 2d earth models consisting of laterally variable layers boundaries between layers are described by their depths at a set of nodes and interpolated laterally between nodes conductivity within each layer is described by values at a set of nodes fixed within each layer and is interpolated laterally within each layer within the set of possible models of this sort we iteratively invert magnetotelluric data for models minimizing the lateral roughness of the layer boundaries and the lateral roughness of conductivities within layers for a given level of data misfit this stabilizes the inverse problem and avoids superfluous detail this approach allows the determination of boundary positions between geological units with sharp discontinuities in properties across boundaries while sharing the stability features of recent smooth conductivity distribution inversions we compare sharp boundary inversion results with smooth conductivity distribution inversion results on a numerical example and on inversion of field data from the columbia river flood basalts of washington state in the synthetic example where true positions and resistivities are known sharp boundary inversion results determine both layer boundary locations and layer resistivities accurately in inversion of columbia flood basalt data sharp boundary inversion recovers a model with substantially less internal variation within units and less ambiguity in both the depth to base of the basalts and depth to resistive basement

structural controls on a geothermal system in the tarutung basin north central sumatra abstract the sumatra fault system provides a unique geologic setting to evaluate the influence of structural controls on geothermal activity whereas most of the geothermal systems in indonesia are controlled by volcanic activity geothermal systems at the sumatra fault system might be controlled by faults and fractures exploration strategies for these geothermal systems need to be verified because the typical pattern of heat source and alteration clays are missing so that conventional exploration with magnetotelluric surveys might not provide sufficient data to delineate favorable settings for drilling we present field geological structural and geomorphological evidence combined with mapping of geothermal manifestations to allow constraints between fault dynamics and geothermal activity in the tarutung basin in north central sumatra our results indicate that the fault pattern in the tarutung basin is generated by a compressional stress direction acting at a high angle to the right lateral sumatra fault system nw se striking normal faults possibly related to negative flower structures and nnw sse to nne ssw oriented dilative riedel shears are preferential fluid pathways whereas ene wsw striking faults act as barriers in this system the dominant of geothermal manifestations at the eastern part of the basin indicates local extension due to clockwise block rotation in the sumatra fault system our results support the effort to integrate detailed field geological surveys to refined exploration strategies even in tropical areas where outcrops are limited

an observational study of tropical midlatitude interaction on intraseasonal time scales during winter abstract eight northern hemisphere winters of five and ten day average midlatitude 500 mb heights and tropical outgoing ir are used in a correlative study of tropical midlatitude interaction the seasonal cycle and interannual variability are removed so that only intraseasonal variability remains results indicate that energy predominantly propagates from midlatitudes to the tropics for both five and ten day averaged data although the propagation is more apparent in five day averaged data this is evidenced by the fact that the largest tropical ir patterns are southeastward of the 500 mb point with which the ir field is correlated the result is interpreted in terms of a quasi stationary rossby wave which has an eastward component of group velocity the southwest northeast tilt of the 500 mb height correlation patterns indicating poleward momentum transport or equatorward wave propagation also supports the hypothesis that midlatitude flow drives the tropics lead and lag correlations show that when 5

analysis of convectively coupled kelvin waves in the indian ocean mjo abstract the active convective phase of the madden julian oscillation hereafter active mjo comprises enhanced moist deep convection on its own temporal and spatial scales as well as increased variance in convection associated with higher frequency modes synoptic scale cloud superclusters apparently associated with convectively coupled kelvin waves occur within the active convective envelopes of most mjo events these convectively coupled kelvin waves also occur during the suppressed convective phase of the mjo hereafter suppressed mjo this observational study presents an analysis of outgoing longwave radiation and reanalysis data to determine how these waves behave differently as they propagate through the active and suppressed mjo time indices of the mjo and kelvin waves are derived for over the equatorial indian ocean dates of local extrema in these indices are used to composite data to discern how the waves and associated circulations behave on average then further composites are made based o

a climatology of waves in the equatorial region abstract propagating anomalies of moisture and moist deep convection in the tropics are organized into a variety of large scale modes these include but are not limited to the so called intraseasonal oscillations convectively coupled waves similar to those predicted by shallow water theory on the equatorial beta plane and tropical depression type disturbances along with the annual and diurnal cycles these modes act and interact to control much of the variance of tropical convection analyses of 10 yr of outgoing longwave radiation olr and precipitable water pw data are carried out to develop comparative climatologies of these wavelike modes the analysis relaxes the commonly used cross equatorial symmetry constraints which allows study of the portions of the wavelike processes that are asymmetric across the equator mean background states are found for olr and for pw as functions of day of the year examination of anomalies together with the background reveals much about how the waves are affec

physical analog modeling of pull apart basin evolution abstract pull apart basins are structural depressions formed by localized extension along strike slip fault systems typically at releasing bends or steps in the fundamental strike slip system analog modeling is used to evaluate the sequence of structural evolution of pull apart basins and factors that control their degree of structural asymmetry and geometry basin evolution internal structure and overall symmetry are investigated for oblique releasing step angles and with varying rates of displacement between brittle and ductile crust on opposing sides of the strike slip system while maintaining relative rates between brittle crust on opposing sides of the basin pull apart basin evolution is separated into three stages incipient early and mature incipient pull apart basins are characterized by formation of a normal fault bounded graben or half graben parallel to the oblique step between main strike slip zones in the early stage of formation additional normal faults form toward the basin interior from the original bounding faults and cross basin strike slip faults cut diagonally across the basin interior basin bounding normal fault systems are characterized by lateral variations of fault throw and localized relay ramps in the mature stage of evolution strike slip and normal faults join to completely bound the pull apart basin analog model results indicate that displacement associated with cross basin faults causes development of a through going strike slip fault that links the two main strike slip displacement zones ultimately resulting in a decline in normal fault activity asymmetric symmetric and hybrid pull apart basins all follow the same overall deformation sequence just described the asymmetry of a pull apart basin is controlled by the degree of decoupling between brittle and ductile crust beneath the two crustal blocks in relative motion this is modeled by maintaining a constant relative rate of motion between opposing fault blocks in all models but varying the rate between the blocks and the fixed model basement absolute rate models in which one side of the detachment is fixed with respect to the basement form asymmetric pull apart basins defined by a half graben with the master fault on the mobile side in models where opposing sides of the fault system are equally decoupled from the basement symmetrical pull apart basins form defined by horst and graben structures and master fault dominance switching sides along the length of the basin fault segmentation associated with relatively immature pull apart basins may be capable of arresting earthquake rupture late linkage of main strike slip zones by a cross basin fault could extend potential rupture area dramatically increasing the possibility for large magnitude earthquakes

multiscale interactions in an idealized walker cell analysis with isentropic streamfunctions abstracta new approach for analyzing multiscale properties of the atmospheric flow is proposed in this study for that the recently introduced isentropic streamfunctions are employed here for scale decomposition with haar wavelets this method is applied subsequently to a cloud resolving simulation of a planetary walker cell characterized by pronounced multiscale flow the resulting set of isentropic streamfunctions obtained at the convective meso synoptic and planetary scales capture many important features of the across scale interactions within an idealized walker circulation the convective scale is associated with the shallow congestus and deep clouds which jointly dominate the upward mass flux in the lower troposphere the synoptic and planetary scales play important roles in extending mass transport to the upper troposphere where the corresponding streamfunctions mainly capture the first baroclinic mode associated with large scale overturning circulation the intermediate scale features of

equatorial waves in the lower stratosphere ii annual and interannual variability the annual and interannual variability of idealized linear equatorial waves in the lower stratosphere is investigated using the temperature and velocity fields from the ecmwf 15 year re analysis dataset peak kelvin wave activity occurs during solstice seasons at 100 hpa during december february at 70 hpa and in the easterly to westerly quasi biennial oscillation qbo phase transition at 50 hpa peak rossby gravity wave activity occurs during equinox seasons at 100 hpa during june august september november at 70 hpa and in the westerly to easterly qbo phase transition at 50 hpa although neglect of wind shear means that the results for inertio gravity waves are likely to be less accurate they are still qualitatively reasonable and an annual cycle is observed in these waves at 100 hpa and 70 hpa inertio gravity waves with n 1 are correlated with the qbo at 50 hpa but the eastward inertio gravity n 0 wave is not due to its very fast vertical group velocity in all background winds the relative importance of different wave types in driving the qbo at 50 hpa is also discussed the strongest acceleration appears to be provided by the kelvin wave while the acceleration provided by the rossby gravity wave is negligible of the higher frequency waves the westward inertio gravity n 1 wave appears able to contribute more to the acceleration of the 50 hpa mean zonal wind than the eastward inertio gravity n 1 wave

structure coupled 3 d imaging of magnetotelluric and wide angle seismic reflection refraction data with interfaces magnetotelluric mt and wide angle seismic reflection refraction surveys play a fundamental role in understanding the crustal rheology and lithospheric structure of the earth in recent years the

robust 3d gravity gradient inversion by planting anomalous densities we have developed a new gravity gradient inversion method for estimating a 3d density contrast distribution defined on a grid of rectangular prisms our method consists of an iterative algorithm that does not require the solution of an equation system instead the solution grows systematically around userspecified prismatic elements called seeds with given density contrasts each seed can be assigned a different density contrast value allowing the interpretation of multiple sources with different density contrasts and that produce interfering signals in real world scenarios some sources might not be targeted for the interpretation thus we developed a robust procedure that neither requires the isolation of the signal of the targeted sources prior to the inversion nor requires substantial prior information about the nontargeted sources in our iterative algorithm the estimated sources grow by the accretion of prisms in the periphery of the current estimate in addition only the columns of the sensitivity matrix corresponding to the prisms in the periphery of the current estimate are needed for the computations therefore the individual columns of the sensitivity matrix can be calculated on demand and deleted after an accretion takes place greatly reducing the demand for computer memory and processing time tests on synthetic data show the ability of our method to correctly recover the geometry of the targeted sources even when interfering signals produced by nontargeted sources are present inverting the data from an airborne gravity gradiometry survey flown over the iron ore province of quadrilatero ferrifero southeastern brazil we estimated a compact iron ore body that is in agreement with geologic information and previous interpretations

the diurnal cycle of tropical convection the diurnal cycle of tropical convection is investigated with global cloud imagery constructed from 11 m radiance measurements taken aboard six satellites four harmonics of the diurnal cycle are resolved in the cloud imagery with about 50 km horizontal resolution to isolate deep convective activity from other processes which cause diurnal fluctuations in longwave radiance an index of deep convective activity is constructed by thresholding to brightness temperatures less than 230 k significant diurnal amplitude of deep convection is found only over tropical landmasses over the tropical oceans the diurnal cycle is weak and is barely discernible from the background red spectrum of convective variance nonetheless oceanic convection exhibits a systematic diurnal fluctuation with maximum intensity in the early morning nocturnal subsidence along the cloud free equator is postulated to play a role in forcing diurnal variation in the intertropical convergence zones other mechanisms are also implied to contribute as a similar early morning maximum in deep convection is seen even where no adjoining cloud free regions occur the diurnal cycle of deep convection is found to be organized on planetary scales predominantly in nonmigrating modes i e modes with phase speeds not equal to that of the sun the nonmigrating modes are postulated to be produced by the nonuniform distribution of convective centers the nonmigrating zonally symmetric component is found to be especially large while the role of this mode in forcing diurnal variations of the tropospheric circulation e g the hadley cell is questionable its role in modulating the ionospheric electric potential is well established discrepancies with the traditional notion that cloud to ground lightning is the dominant mechanism by which the earth is negatively charged are discussed in particular the probable role of nonlightning producing clouds e g the stratiform portion of convective complexes in diurnally modulating the negative charge on earth is discussed

velocity model inversion using parametric curves summary the use of parametric curves to define velocity models in seismic traveltime tomography is proposed this approach provides increased flexibility in shaping the velocity models because it allows inversion for both velocity and grid point adjustments the method is applied to a data set generated from a 1 d profile having sharp discontinuities the results are compared with those obtained from other methods currently in use for traveltime tomography it is found that large gradients and discontinuities can be retrieved with improved accuracy and that instabilities caused by non optimal prior selection of the inversion grid can be avoided the results appear to be robust when the sizes of both data and model space are reduced which makes the method appealing for the solution of large scale tomographic problems

multiple level set joint inversion of traveltime and gravity data with application to ore delineation a synthetic study abstractwe have developed a multiple level set method for simultaneous inversion of gravity and seismic traveltime data the method recovers the boundaries between regions with distinct physical properties assumed constant and known creating structurally consistent models of two subsurface properties p wave velocity and density in single level set methods only two rock units can be considered background and inclusion such methods have been applied to examples representing various geophysical scenarios including in the context of joint inversion in multiple level set methods several units can be considered which make them far more applicable to real earth scenarios recently a multiple level set method has been proposed for inversion of magnetic data we extend the multiple level set formulation to joint inversion of gravity and traveltime data improving upon previous work and we investigate applicability of such an inversion method in ore delineation in mineral exploration environments trad

the sipoholon geothermal field and adjacent geothermal systems along the north central sumatra fault belt indonesia reviews on geochemistry tectonics and natural heat loss abstract the sipoholon system in the tarutung basin is one of five geothermal systems associated with a c 100 km stretch of the sumatra fault system sfs in north central sumatra indonesia that exhibits parallel sets of dextral strike slip faults associated with seismic activity characteristics of discharged thermal fluids differ significantly between the systems the gas rich sipoholon field transfers only c 19 mw heat by ca so4 hco3 springs with sio2 fluid equilibria pointing to temperatures of 50 80 c at intermediate depths most of its thermal springs t in contrast all four thermal systems in the sarulla block concession to the southeast of the sipoholon field are convective high temperature systems that transfer significant heat to the surface fumaroles steaming ground thermal springs hot pools and thermal lakes discharge at least 50 mw heat at three of the four prospects where the temperatures of springs and fumaroles often reach boiling point many hot springs of the sarulla block systems discharge dominantly na hco3 cl type waters with partially equilibrated cation compositions a result of fluid rock equilibration and mixing processes sio2 fluid equilibria indicate 130 to c 200 c with cation geothermometers pointing to a high reservoir temperature 200 260 c for all four systems this was confirmed by the first deep exploratory wells drilled c 20 years ago in three prospects that encountered t 250 c at bottom hole 1 5 km depth the structural setting of the five geothermal fields is complex at tarutung it is associated with the narrow tarutung basin filled with volcanic debris and ash the basin exhibits a partly exposed dextral strike slip fault along its ne margin and can be interpreted in terms of a trans tensional pull apart basin two of the adjacent sarulla block systems are associated with large volcanic debris basins namora i langit and silangkitang that exhibit half graben structures in profiles normal to two large active faults of the sumatra fault system sfs the other two systems donotasik and sibualbuali are hosted by an elongated graben structure parallel and within the sfs and by a stratovolcano respectively

convectively coupled equatorial waves 1 convectively coupled equatorial waves ccews control a substantial fraction of tropical rainfall variability their horizontal structures and dispersion characteristics correspond to matsuno s 1966 solutions of the shallow water equations on an equatorial beta plane namely kelvin equatorial rossby mixed rossby gravity and inertio gravity waves because of moist processes the tilted vertical structures of ccews are complex and their scales do not correspond to that expected from the linear theory of dry waves the dynamical structures and cloud morphology of ccews display a large degree of self similarity over a surprisingly wide range of scales with shallow convection at their leading edge followed by deep convection and then stratiform precipitation mirroring that of individual mesoscale convective complexes ccews have broad impacts within the tropics and their simulation in general circulation models is still problematic although progress has been made using simpler models a complete understanding of ccews remains a challenge in tropical meteorology

modulation of the convectively coupled kelvin waves over south america and the tropical atlantic ocean in association with the madden julian oscillation abstractin this study evidence of the strong modulation of the convectively coupled kelvin wave cckw activity by the madden julian oscillation mjo is presented with a particular focus over the south america and tropical atlantic region the mjo impacts on cckws over this region as noted in anomalous fields of rainfall as well as vertical profiles of wind moisture and temperature are primarily through the modulation of kelvin wave amplitude with secondary effects on vertical structure and little impact on wavenumber cckw activity is enhanced during mjo phases 8 1 and 2 and damped during mjo phases 4 5 and 6 further analyses reveal that the strong modulation of the mjo on the cckw activity could be largely through two factors namely the vertical zonal wind shear and the lower to middle tropospheric specific humidity the cckw activity tends to be enhanced during mjo phases when the easterly vertical wind shear and positive low to midtroposphere moisture anomalies are present and vice ve

development characteristics and dynamic structure of tropical intraseasonal convection anomalies abstract the development and dynamical structure of intraseasonal low frequency convection anomalies in the equatorial region are investigated using 10 years 1975 85 of outgoing longwave radiation olr and 7 years 1979 85 of 200 and 850 mb wind data the composite olr anomalies for 36 cases show a four stage development process initiation over equatorial africa rapid intensification when passing through the indian ocean mature evolution characterized by a weakening in the maritime continent and redevelopment over the western pacific and dissipation near the date line in moderate events or emanation from the equator toward north america and southeastern pacific in strong events a noticeable feature in vertical structure is that the 850 mb convergence leads convection and midtropospheric upward motion by about 30 degrees longitude in both developing and mature phases equatorial upper lower level easterly westerly anomalies and associated twin anomalous anticyclonic cyclonic circulation an

an explosive convective cloud system and its environmental conditions in mjo initiation observed during dynamo an unusually large explosive convective cloud system was observed over the equatorial indian ocean on 28 november 2011 during the dynamo dynamics of the madden julian oscillation mjo field campaign the significance of this mesoscale convective system mcs is its size and explosive development of cold cloud tops 96 c during the initiation of a strong mjo event observations from the dynamo show that the large mcs developed within a well defined synoptic scale cyclonic circulation associated with an equatorial low pressure system with characteristics of a mixed rossby gravity wave that dominated the flow in the dynamo array prior to the development of the mcs the equatorial flow was characterized by strong vertical wind shear with low level westerlies and upper level easterlies a region of decreased wind shear and enhanced upper level divergence emerged concurrently with the passage of the westward moving mixed rossby gravity wave related low pressure system and convective activity in situ sounding observations suggest that widespread deep convection upstream of the large mcs may have contributed to the reduction of the upper level easterlies through vertical momentum transport and convective outflow both the reduction in vertical wind shear and enhanced low level convergence induced by the equatorial low pressure system created a favorable environment for the rapid development of the mcs this study examines the development of the mcs and the associated synoptic scale equatorial low pressure system within the large scale mjo circulation using in situ sounding observations from dynamo which provide new insights into the interaction between convection and environmental flow during mjo initiation over the equatorial indian ocean

transtensional faulting patterns ranging from pull apart basins to transform continental margins an experimental investigation abstract seventeen small scale experiments were performed to study the deformation induced in brittle ductile models by a releasing stepover between two transform faults and by intersection between transform and divergent plate boundaries in both cases faulting depends on the rheological layering presence and strength of a ductile layer at depth and the width of the basal stepover successive types of pull apart basins are observed in the first set of experiments which are compared with natural examples firstly a lazy z shaped basin appears which is bounded by y faults above transform boundaries and r faults propagating from each corner of the stepover then r faults replace r faults leading to a rhomb shaped graben at every stage the basin length to width ratio remains between 2 2 and 3 8 suggesting that scale independence of pull apart basins is related to the geometrical shape of bounding faults in a second set of experiments deformation at the end of a transform boundary is characterized by a horsetail splay bounding a divergent basin within the horsetail splay block tilting and block rotation about vertical axes lead to a surface slope perpendicular to the slope of the divergent basin a feature that can be compared with marginal ridges at transform margins

the tectonic framework of the sumatran subduction zone the great aceh andaman earthquake of december 26 2004 and its tragic consequences brought the sumatran region and its active tectonics into the world s focus the plate tectonic setting of sumatra has been as it is today for tens of millions of years and catastrophic geologic events have likely been plentiful the immaturity of our understanding of great earthquakes and other types of geologic hazards contributed to the surprise regarding the location of the 2004 earthquake the timing however is probably best understood simply in terms of the inevitability of the infrequent events that shape the course of geologic progress our best hope is to improve understanding of the processes involved and decrease our vulnerability to them

observation of 3 6 day meridional wind oscillations over the tropical pacific 1973 1992 horizontal structure and propagation abstract twenty years of rawinsonde data 1973 1992 were examined in conjunction with european centre for medium range weather forecasts ecmwf analyses and outgoing longwave radiation olr in 1980 1989 to determine the horizontal structure propagation and convective coupling of 3 6 day meridional wind oscillations over the tropical pacific wave properties from ecmwf data determined by lag correlation with respect to rawinsonde or ecmwf principal components were consistent with what could be determined from the sparse rawinsonde network alone gridded analyses allowed a clearer distinction between equatorially trapped rossby gravity waves rgw and off equatorial tropical depression td disturbances so that the contrasting properties of these waves including their seasonal and interannual variation could be studied in better detail significant correlations with olr were found increasing in magnitude from eastern to western pacific the apparent group propagation of disturbances was equator

convectively coupled equatorial waves within the mjo during cindy dynamo slow kelvin waves as building blocks this study examines the relationship between the mjo and convectively coupled equatorial waves ccews during the cindy2011 dynamo field campaign using satellite borne infrared radiation data in order to better understand the interaction between convection and the large scale circulation the spatio temporal wavelet transform stwt enables us to document the convective signals within the mjo envelope in terms of ccews in great detail through localization of space time spectra at any given location and time three mjo events that occurred in october november and december 2011 are examined it is in general difficult to find universal relationships between the mjo and ccews implying that mjos are diverse in terms of the types of disturbances that make up its convective envelope however it is found in all mjo events that the major convective body of the mjo is made up mainly by slow convectively coupled kelvin waves these kelvin waves have relatively fast phase speeds of 10 13 m s 1 outside of and slow phase speeds of 8 9 m s 1 within the mjo sometimes even slower eastward propagating signals with 3 5 m s 1 phase speed show up within the mjo which as well as the slow kelvin waves appear to comprise major building blocks of the mjo it is also suggested that these eastward propagating waves often occur coincident with n 1 wig waves which is consistent with the schematic model from nakazawa in 1988 some practical aspects that facilitate use of the stwt are also elaborated upon and discussed

the influence of amazon rainfall on the atlantic itcz through convectively coupled kelvin waves abstract using outgoing longwave radiation olr and tropical rainfall measuring mission trmm daily rain rate data systematic changes in intensity and location of the atlantic intertropical convergence zone itcz were detected along the equator during boreal spring it is found that the changes in convection over the tropical atlantic may be induced by deep convection in equatorial south america lagged regression analyses demonstrate that the anomalies of convection developed over the land propagate eastward across the atlantic and then into africa the eastward propagating disturbances appear to be convectively coupled kelvin waves with a period of 6 7 5 days and a phase speed of around 15 m s 1 these waves modulate the intensity and location of the convection in the tropical atlantic and result in a zonal variation of the atlantic itcz on synoptic time scales the convectively coupled kelvin wave has substantial signals in both the lower and upper troposphere both a reanalysis dataset and the qui

stochastic inversion of magnetotelluric data using a sharp boundary parameterization and application to a geothermal site we developed a bayesian model to invert magnetotelluric mt data using a 2d sharp boundary parameterization we divided the 2d cross section into layers and considered the locations of interfaces and resistivity of the regions formed by the interfaces as random variables we assumed that those variables are independent in the vertical direction and dependent along the lateral direction whose spatial dependence is described by either pairwise difference or multivariate gaussian priors we used a parallel adaptive finite element algorithm to rapidly forward simulate frequency domain mt responses of the 2d resistivity structure and used markov chain monte carlo methods to draw many samples from the joint posterior probability distribution we applied the bayesian model to a synthetic case that mimics a geothermal exploration scenario our results demonstrated that the developed method is effective in estimating the resistivity and depths to interfaces and in quantifying uncertainty on the estimates we also applied the developed method to the field mt data collected from the darajat geothermal site in indonesia we compared our inversion results with those obtained from a deterministic inversion of 3d mt data they are consistent even if the two inversion methods are very different and the amount of information used for inversion is different

inversion of coeval shear and normal stress of piton de la fournaise flank displacement the april 2007 eruption of piton de la fournaise was the biggest volcano eruptive crisis of the 20th and 21st centuries interferometric synthetic aperture radar insar captured a large coeruptive seaward displacement on the volcano s eastern flank which continued for more than a year at a decreasing rate coeruptive uplift and posteruptive subsidence were also observed while it is generally agreed that flank displacement is induced by fault slip we suggest that this flank displacement might have been induced by a sheared sill based on observations of sheared sills at piton des neiges to test this hypothesis we develop a new method to invert a quadrangular curved source submitted to simultaneous pressure and shear stress changes this method based on boundary elements is applied to data acquired along six envisat orbits covering a 14 month period subsequent to the april 2007 eruption posteruptive displacement is well explained by closure and slip of a large 5 km by 8 km and shallow 500 m trapezoidal fracture parallel to the flank and probably coincident with a lithological discontinuity we investigate whether thermal contraction or degassing of a coeruptive sill can explain the displacement such a sill would have to be 10 times thicker than inferred from the coeruptive uplift and solidification time 10 times shorter 20 days than the duration of the posteruptive subsidence 24 to 33 months instead we propose that the posteruptive eastern flank displacement is due to the compaction and ongoing slow slip on a shallow detachment fault

atlantic tropical cyclogenesis a three way interaction between an african easterly wave diurnally varying convection and a convectively coupled atmospheric kelvin wave abstractthis paper explores a three way interaction between an african easterly wave aew the diurnal cycle of convection over the guinea highlands ghs and a convectively coupled atmospheric equatorial kelvin wave cckw these interactions resulted in the genesis of tropical storm debby over the eastern tropical atlantic during late august 2006 the diurnal cycle of convection downstream of the ghs during the month of august is explored convection associated with the coherent diurnal cycle is observed off the coast of west africa during the morning later convection initiates over and downstream of the ghs during the afternoon these convective features were pronounced during the passage of the pre debby aew the superposition between the convectively active phase of a strong cckw and the pre debby aew occurred shortly after merging with the diurnally varying convection downstream of the ghs the cckw aew interaction preceded tropical cyclogenesis by 18 h the cckw provided a favorable environment

eastward propagating 2 to 15 day equatorial convection and its relation to the tropical intraseasonal oscillation anomalies of outgoing longwave radiation olr in 1980 1989 were examined in a narrow latitude band about the equator to elucidate the propagation and interaction of tropical intraseasonal oscillations tios and synoptic scale convective activity hovmoller diagrams of olr data reconstructed from two frequency bands corresponding to periods of 30 60 days and 2 15 days respectively revealed a clear distinction between the phase speed of eastward moving tios 3 7 m s 1 and that of eastward synoptic scale convection 10 13 m s 1 coherent propagation of tios from the indian to the western pacific oceans was often observed with temporary diminution of amplitude over the maritime continent propagation of high frequency anomalies was generally confined to an individual basin dominance of eastward propagating synoptic scale convection in the equatorial zone contrasts sharply with the westward propagation of off equatorial convergence zones interaction between the tio and high frequency activity resolved by daily olr was visible as a modest enhancement of eastward synoptic scale events and of high frequency activity in general during the convectively active phase of the tio

using constrained inversion of gravity and magnetic field to produce a 3d litho prediction model geologically constrained inversion of gravity and magnetic field data of the victoria property located in sudbury canada was undertaken in order to update the present three dimensional geological model the initial and reference model was constructed based on geological information from over 950 drillholes to constrain the inversion in addition downhole density and magnetic susceptibility measured in six holes were statistically analysed to derive lower and upper bounds on the physical properties attributed to the lithological units in the reference model constrained inversion of the ground gravity and the airborne magnetic data collected at the victoria property were performed using grav3d and mag3d respectively a neural network was trained to predict lithological units from the physical properties measured in six holes then the trained network was applied on the three dimensional distribution of physical properties derived from the inversion models to produce a three dimensional litho prediction model some of the features evident in the lithological model are remnants of the constraints where the data did not demand a significant change in the model from the initial constraining model e g the thin pair of diabase dykes however some important changes away from the initial model are evident for example a larger body was predicted for quartz diorite which may be related to the prospective offset dykes a new zone was predicted as sulfide which may represent potential mineralisation and a geophysical subcategory of metabasalt was identified with high magnetic susceptibility and high density the litho prediction model agrees with the geological expectation for the three dimensional structure at victoria and is consistent with the geophysical data which results in a more holistic understanding of the subsurface lithology

a study of fuzzy c means coupling for joint inversion using seismic tomography and gravity data test scenarios abstractjoint inversion the inversion of multiple geophysical data sets containing complementary information about the subsurface has the potential to significantly improve inversion results by reducing the nonuniqueness of the inverse problem one of the challenges of joint inversion is deciding how to couple the multiple physical property models if a coupling approach is used that is inconsistent with the physical truth then inversion artifacts can occur and may lead to incorrect interpretations in this paper we investigated the fuzzy c means fcm clustering approach to provide a lithological coupling of the seismic velocity and density models in joint 2d inversions of first arrival traveltimes and gravity data even though this coupling approach has been used in previous works recommendations for its effective use have not yet been developed we conducted a suite of joint inversion tests on synthetic data generated from a geologically realistic model based on magmatic massive sulfide deposits

the mjo and convectively coupled waves in a coarse resolution gcm with a simple multicloud parameterization abstract the adequate representation of the dominant intraseasonal and synoptic scale variability in the tropics characterized by the madden julian oscillation mjo and convectively coupled waves is still problematic in current operational general circulation models gcms here results are presented using the next generation ncar gcm the high order methods modeling environment homme as a dry dynamical core at a coarse resolution of about 167 km coupled to a simple multicloud parameterization the coupling is performed through a judicious choice of heating vertical profiles for the three cloud types congestus deep and stratiform that characterize organized tropical convection important control parameters that affect the types of waves that emerge are the background vertical gradient of the moisture and the stratiform fraction in the multicloud parameterization which set the strength of large scale moisture convergence and unsaturated downdrafts in the wake of deep convection respectively three

inversion of magnetotelluric data for 2d structure with sharp resistivity contrasts we have developed a linearized algorithm to invert noisy 2 d magnetotelluric data for subsurface conductivity structures represented by smooth boundaries defining sharp resistivity contrasts we solve for both a fixed number of subsurface resistivities and for the boundary locations between adjacent units the boundary depths are forced to be discrete values defined by the mesh used in the forward modeling code the algorithm employs a lagrange multiplier approach in a manner similar to the widely used occam method the main difference is that we penalize variations in the boundary depths rather than in resistivity contrasts between a large number of adjacent blocks to reduce instabilities resulting from the breakdown of the linear approximation we allow an option to penalize contrasts in the resistivities of adjacent units we compare this boundary inversion method to the smooth occam inversion for two synthetic models one that includes a conductive wedge between two resistors and another that includes a resistive wedge between two conductors the two methods give good agreement for the conductive wedge but the solutions differ for the more poorly resolved resistive wedge with the boundary inversion method giving a more geologically realistic result application of the boundary inversion method to the resistive gemini subsalt petroleum prospect in the gulf of mexico indicates that the shape of this salt feature is accurately imaged by this method and that the method remains stable when applied to real data

multicloud models for organized tropical convection enhanced congestus heating abstract despite the recent advances in supercomputing the current general circulation models gcms poorly represent the large scale variability associated with tropical convection multicloud model convective parameterizations based on three cloud types congestus deep and stratiform introduced recently by the authors have been revealed to be very useful in representing key features of organized convection and convectively coupled waves here a new systematic version of the multicloud models is developed with separate upper and lower troposphere basis functions for the congestus and stratiform clouds it naturally leads to a new convective closure for the multicloud models enhancing the congestus heating in order to better pinpoint the congestus preconditioning and moistening mechanisms the models are studied here for flows above the equator without rotation effects first the new model results consist of the usual synoptic scale convectively coupled moist gravity wave packets moving at 15 20 m

3d gravity analysis in the spatial domain model simulation by multiple polygonal cross sections coupled with exponential density contrast an automatic 3d modeling technique is developed in the spatial domain to analyze the gravity anomalies produced by a concealed density interface with mass density contrast differing exponentially with depth the sedimentary column above the interface is described with a stack of multiple vertical polygonal sections of unit thickness each for such a case the depth ordinates of the vertices of the cross sections become the unknown parameters to be estimated from gravity data forward solution of the model space is realized in the spatial domain by a technique that combines both analytic and numeric approaches initial depths to the interface are calculated based on the bouguer slab approximation and subsequently improved iteratively based on the ratio of the product of the observed gravity anomaly and existing depth parameter to the corresponding model gravity response the iterative process continues until one of the predefined termination criteria is accomplished unlike the existing methods the advantage of the proposed method is that the observed gravity anomalies need not necessarily be sampled available at regular spatial grid intervals the applicability of the proposed model is exemplified with a set of noisy gravity anomalies attributable to a synthetic structure before being applied to a real world gravity data in the case of the synthetic example the method has yielded a structure that was compatible with the assumed structure even in the presence of random noise application of the proposed method to the gravity data set from the los angeles basin california using a prescribed exponential density function has yielded a model that concurs reasonably well with the published models

a model for convectively coupled tropical waves nonlinearity rotation and comparison with observations abstract recent observational analysis of both individual realizations and statistical ensembles identifies moist convectively coupled kelvin waves in the tropics with supercluster envelopes of convection this observational analysis elucidates several key features of these waves including their propagation speed of roughly 15 m s 1 and many aspects of their dynamical structure this structure includes anomalously cold temperatures in the lower troposphere and warm temperatures in the upper troposphere below 250 hpa within and sometimes leading the heating region and strong updrafts in the wave and an upward and westward tilting structure with height below roughly 250 hpa other key features in the wave are that anomalous increases in convective available potential energy cape and surface precipitation lead the wave while the trailing part of the supercluster is dominated by stratiform precipitation the main result in this paper is the development of a simple model convective parameterization with n

observations of cloud cluster hierarchies over the tropical western pacific infrared radiance measurements at cloud top by the japanese geostationary meteorological satellite gms were used to study the structure and propagation of tropical convective systems over the equatorial western pacific results indicate that tropical convection in this region possesses three fundamental periodicities 1 day 2 3 days and 10 15 days cloud clusters within these convective systems interact to produce a hierarchy of collective motions covering all of these three basic time scales the 10 to 15 day time scale is closely related to the intraseasonal or 30 60 day oscillations that propagate from the indian ocean to the western pacific along the equator all year round large convective complexes known as supercloud clusters scc are found to organize in the 10 to 15 day time scale especially over the open warm water of the western central pacific 160 e to 180 the sccs generally propagate eastward although occasionally they can also propagate westward the zonal propagation can occur either continuously or intermittently in both cases the scc is found to be made up of several well organized cloud clusters which are generated at 2 to 3 day intervals and propagate in the opposite direction to the scc the diurnal variation is most pronounced over the maritime continent although significant amplitudes are also found over the open ocean the amplitude of the diurnal cycle is strongly modulated by the 2 to 3 day and 10 to 15 day oscillations advanced spectral analysis methods applied to convective indices derived from the radiance data confirm this hierarchical structure in cloud clusters in the tropical western pacific in addition to the embedding of well organized clusters within a scc in the spatial domain there is also a similar embedding by successive longer scales in the time domain interactions between the major frequency groups appear also to give rise to intermediate frequency variations a discussion of the present results in the context of equatorial wave dynamics of the moist tropical atmosphere is also presented