the influence of observations propagated by convectively coupled equatorial waves this paper describes the propagation of the influence of radiosonde observations made during mismo mirai indian ocean cruise for the study of the madden julian oscillation convection onset which was conducted over the indian ocean in the boreal autumn of 2006 the impact of these observations was assessed using an experimental reanalysis called alera that was produced by the local ensemble transform kalman filter with the atmospheric global circulation model for the earth simulator the difference of the analysis ensemble mean between the analysis cycles with and without the mismo observations was used to quantify the influence of these observations on the analysis field which we call impact signals since the impact signals were contaminated by noise probably due to the model s truncated spectral basis a significance test was performed using the analysis ensemble spread and the numerical noise was then successfully eliminated the results indicated that convectively coupled equatorial waves propagated the impact signals to the central pacific to the east and to the african continent to the west in particular the analysis fields around typhoons cimaron chebi and durian over the tropical western pacific were significantly modified by the propagation of the impact signals through the kelvin waves here two factors played important roles 1 the meridional positions of the typhoons and 2 the duration of the observations the equatorial rossby waves also made a significant contribution to the propagation of the impact signals such influences through the waves resulted in the reduction of the analysis spread the shape of the region of reduced spread resembled the matsuno gill pattern with an east west width of more than 20000 km copyright 2011 royal meteorological society

engineering geology and subdivision planning in new zealand abstract the subdivision of land for residential purposes requires the prior identification of hazards to development and engineering geological assessment techniques form an integral part of sound urban planning practices selected examples from south island localities illustrate our engineering geological approach to subdivision planning which involves site mapping test pit logging and limited geotechnical testing and we outline recommended practices for the preparation of scheme and concept plans proposed residential subdivision sites are assessed in terms of those active geomorphic processes that led to their development and the future occurrence of damaging events is quantified in terms of the available historic and or geologic record a site model is also developed to integrate surface and subsurface geology with available geotechnical data thereby identifying those parts of the subdivision that require additional investigation at the detailed design or construction stages and likewise delineating those areas that are unsuitable for residential development because of geologic or topographic constraints

observations of variability on synoptic timescales in the east pacific itcz abstract data obtained in the eastern pacific intertropical convergence zone itcz during the tropical eastern pacific process study tepps show a 3 6 day variability the noaa ship ronald h brown collected surface meteorological observations c band doppler radar volumes atmospheric soundings and rainfall data while on station at 7 8 n 125 w from 8 23 august 1997 the 3 6 day variability was a prominent timescale in the meridional wind and humidity data the maxima of the surface to 700 mb meridional wind anomalies were 5 12 m s 1 maxima of the moisture anomalies at the same levels were 1 3 g kg 1 in phase with the low level southerlies while upper level moisture lagged the southerlies by less than a day the radar indicated a close connection between precipitation in the vicinity of the ship and the meridional wind with the precipitation occurring when the surface southerlies were strongest the meridional and zonal wind components had a maximum of 850 450 mb wind shear during the southerly e

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

engineering geological mapping of tropical soils for land use planning and geotechnical purposes a case study from jamaica west indies abstract an area of a tertiary and cretaceous deposits 100 310 m above sea level and on predominant 20 45 highly dissected concave slopes was investigated to assess its geotechnical characteristics and land use planning implications lithologies include turbidites fluvial conglomerates breccias sandstones mudrocks carbonates granodiorite acid dykes chloritized and epidotized volcanics andesite and holocene fluvial deposits bedrock is highly fractured and sheared hydrothermally altered and highly weathered soils are quite variable with a strong geological control on soil properties soils are generally sandy to gravely with local silts and clays in mudrocks within holocene alluvium or in hydrothermally altered and sheared granodiorites the soils are composed of 0 14 80 00 gravel 5 36 62 50 sand 2 33 50 55 silt 0 17 51 50 clay and total fine content between 2 50 and 94 50 with natural moisture between 4 and 44 during the dry season plastic limit between 6 and 35 liquid limit between 19 and 83 and plasticity index between 1 and 59 sandy soils have residual friction angles between 19 and 39 pi values less than 35 with cohesion between 1 00 and 5 27 kn m 2 for cohesive samples astm classification of soils include soil groups gc gm gw gp sp sm sc sm sc ml cl and ch based on the characteristics of the terrain the geotechnical and land use planning problems include high landslide frequency and susceptibility soil erosion fluvial and reservoir sedimentation high debris flow hazard cut slope failures potentially expansive clays and silts seepage erosion and soil piping differential settlement in interlayered competent and incompetent lithologies high solution erosion and potential subsidence over limestones waste water disposal problems and groundwater pollution and seismic induced settlement and ground failures these phenomena suggest that systematic site investigations should be conducted prior to the utilization of these areas for construction and development in order to minimize the deleterious effects resulting from ground failure

oceanic equatorial waves and the 1991 93 el nino abstract equatorial kelvin and rossby waves associated with the 1991 93 el nino warm event were detected in temperature observations made by the tropical atmosphere ocean tao buoy array intraseasonal kelvin waves were a prominent part of equatorial thermocline depth variability and were well represented by a simple model consisting only of first and second mode baroclinic kelvin waves the second mode was essential to properly represent the observed amplitude thermocline depth variability at 5 n and 5 s was dominated by annual and interannual rossby waves which were found to have been largely wind forced in midbasin with little if any signal associated with eastern boundary reflection an evaluation of the wyrtki buildup hypothesis and the delayed oscillator hypothesis in connection with the 1991 93 events showed that a long lag about two years occurred between the arrival of the downwelling signal in the west and the subsequent initiation of el nino this was considerably longer than suggested

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

upscale impact of mesoscale disturbances of tropical convection on 2 day waves abstractwestward propagating 2 day waves with embedded mesoscale disturbances contribute a large portion of synoptic variability of tropical convection over the western pacific it is of crucial im

circulation anomalies associated with tropical convection during northern winter abstract lagged cross correlations between outgoing longwave radiation olr and national meteorological center global analyses are utilized to isolate the preferred upper level and surface circulation anomalies associated with tropical convection during northern winter three intraseasonal time scales are studied 30 70 14 30 and 6 14 days in the 30 70 day band the upper level circulation signals are zonally elongated with zonal wavenumbers 0 2 dominant higher frequency signals are dominated by zonal wavenumbers 5 and 6 in the 14 30 day band convection over the eastern hemisphere is associated with upper level anticyclones in the subtropics and appears to be linked in some cases to midlatitude wave trains the strongest signals are for convection over africa australia and the eastern indian ocean only weak signals are seen for convection over indonesia in these regions of upper level easterlies olr anomalies peak prior to the maximum anomalies in wind suggesting forcing of the circulation b

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

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

observation of a quasi 2 day wave during toga coare abstract detailed structure of the quasi 2 day oscillation observed in the active phase of the madden julian oscillations during the intensive observation period of tropical ocean and global atmosphere coupled ocean atmosphere response experiment toga coare iop was described a variety of observational platforms is used including high resolution gms infrared histogram rain rate estimate from toga and mit radar measurements upper air soundings and boundary layer profiler winds from the integrated sounding system and surface data from the imet buoy the quasi 2 day mode had a westward propagation speed of 12 15 day 1 a horizontal wavelength of 25 30 longitude a coupling with the westward propagating n 1 inertio gravity waves was hypothesized from the space time power spectral distribution of the cloud field the wind disturbance structure was consistent with the hypothesis the vertical wave structure had an eastward phase tilt with height below 175 hpa and vice versa above indicating the wav

upper tropospheric waves in the tropics part ii association with clouds in the wavenumber frequency domain abstract the relationship between the large scale transient wave disturbances at the 200 mb level and the associated cloud field is studied in the latitude belt 20 s to 40 n based on wind and satellite measured brightness data for the period june august 1967 space time cross spectral analysis is used to examine the degree of association of the wind and cloud fields in the wavenumber frequency domain the total time variance of the brightness field has a well defined maximum near 10 n corresponding to a belt of sea surface temperature maximum the divergence and relative vorticity as well as the brightness have a pronounced spatial scale of zonal wavenumber s 10 at this latitude the major component contributing to this scale is westward moving disturbances with a period 5 days there is high coherence between the brightness and divergence fields at these scales in addition high coherence is found for s 3 6 and a period 5 days of westward moving disturbances corresponding to the wavenumber and p

variations in precipitating convective feature populations with itcz width in the pacific ocean abstractmany recent studies have aimed to better understand changes in the characteristics of the intertropical convergence zone itcz including itcz location width and precipitation intensity

convective momentum transport in a simple multicloud model for organized convection abstractconvective momentum transport cmt is the process of vertical transport of horizontal momentum by convection onto the environmental flow the significance of cmt from mesoscale to synoptic and planetary scale organized cumulus convection has been established by various theoretical and observational studies a new strategy mimicking the effect of unresolved mesoscale circulation based on the weak temperature gradient wtg approximation with a gaussian profile to redistribute the heating due to parameterized cumulus convection at the subgrid scale is adopted here to construct a cmt parameterization for general circulation models gcms two main regimes of cmt are considered an upscale squall line regime and a downscale non squall line regime an exponential probability distribution is used to select which of these two effects is active conditional on the state of the large scale shear the shear itself is used as a measure of the persistence of mesoscale organized circulation due to the presen

geoscientific maps for planning in semi arid regions valencia and gran canaria spain abstract two case studies of the application of geoscientific maps for planning in semi arid regions are presented one for the mediterranean province of valencia and another for the island of gran canaria canaries both regions are very dynamic from the point of view of population growth and urban touristic industrial development and they suffer from a serious degree of environmental degradation the provincial island governments have undertaken programmes of geoscientific mapping and assessment to serve as a basis for the establishment of guidelines for future planning two map sets have been made 1 200 000 in valencia and 1 50 000 in gran canaria based on initial maps of homogeneous integrated units these represent a series of hierarchical land subdivisions progressively smaller and more detailed morphodynamic environments systems units elements defined on the basis of morphostructure climate lithology surficial deposits landforms topography active processes soils vegetation and human influence each individual map unit is described by means of a form which includes 114 items summarising its environmental features morphodynamic units have been evaluated in terms of qualities significant for planning and a series of derivative maps has been developed geologic hazards soil capability present degree of erosion potential erodibility quality for conservation a final map shows the most advisable types of uses and the main limitations for human activities mainly due to engineering geological factors this is a synthesis document which can be used directly by planners

morphology and sedimentation in caribbean montane streams examples from jamaica and puerto rico abstract this paper presents a summary description of the morphology sedimentation and behaviour of the montane streams of eastern jamaica and eastern puerto rico the area is located within a 200 km wide seismically active zone of neogene left lateral strike slip deformation which defines the plate boundary between the caribbean and north american plates tropical storms occasionally strengthening up to hurricane force affect the region periodically this is an area of steep mass movement scarred hillslopes which supply a large amount of coarse sediment to the rivers from the description presented we have constructed a model for the rivers of this region controlled by both neotectonics and periodic large floods the drainage density is low with a near rectangular stream network the gradients are steep with boulder accumulations in the channels their location at times related to the presence of large past landslides on hillslopes narrow steep and confined channels occur in the mountains but in wider sections and lower down near coastal plains flood depositional forms appear in coarse valley alluvium small scale deviations from the general pattern occur locally controlled by variations in lithology neotectonism seasonality in flow etc this model for caribbean montane streams differs considerably from the standard descriptions of alluvial rivers for which a number of detailed studies are available

convectively coupled kelvin waves and tropical cyclogenesis in a semi lagrangian framework abstractthis study examines how convectively coupled kelvin waves interact with the semi lagrangian circulation of easterly waves to modulate tropical cyclogenesis recent studies have shown that fewer tropical cyclones form in the three days before passage of the kelvin wave s peak convection and more develop in the three days thereafter separately other studies have identified the recirculation of moisture and vorticity within easterly waves using a semi lagrangian frame of reference that framework is achieved by subtracting the easterly wave phase speed from the earth relative winds this study combines these recent findings by testing whether the equatorial westerlies from kelvin waves can help close the semi lagrangian circulation past studies have shown that kelvin waves tilt westward with height in the troposphere such that equatorial westerlies build upward from the surface in the days following the convective peak this study shows that the easterly wave s semi lagrangian closed circulation gr

geological and geotechnical engineering aspects of low cost roads in mountainous terrain abstract the paper is concerned with design and construction of mountain roads in areas of high relief and steep mountain slopes where the principal soil types are transported rather than residual and the landscape is shaped mainly by active erosion processes in order to simplify the wide range of ground conditions encountered the geology and geomorphology of typical mountain terrain are described and related to a five zone model geotechnical features within each zone are then considered so that the application of various investigation and construction techniques can be appreciated the paper is primarily concerned with low cost but well trafficked primary roads where closure time due to slope failures or lack of maintenance are intended to be minimal village feeder roads and steep mountain haul roads for example those used in forestry are not the prime concern of the paper three aspects which distinguish mountain roads from typical lowland roads are the difficult ground access with numerous slope instability problems the greater use of very local construction materials and the greater need for off site drainage and erosion protection measures in remote rugged terrain access for wheeled traffic may not exist this severely curtails the use of conventional site investigation techniques such as drilling and means that greater emphasis is placed on remote sensing and on the surface assessment of ground conditions several relatively new low cost techniques applicable to the investigation of mountain regions are described a rational approach to alignment selection is developed which stresses the importance of stable ascent corridors and practical guidelines are offered on the selection of the road cross section and on the variety of techniques available to stabilise the cross section chosen the use of local construction materials is dictated largely on economic grounds and may place heavy constraints on construction standards and structural design the use of gabion structures is a major construction technique examined in the paper drainage and erosion protection methods are important in areas of high relief and erosion potential and a range of design approaches are described the bulk of stabilisation and control works described can only be attempted by labour

urban geology a case study of tongchuan city shaanxi province china abstract urban geology is the study of urban geologic environments to provide a scientific basis for rational land use planning and urban development this paper examines the major geotechnical and environmental geologic problems arising from the characteristics topography geology and soil types including their properties and areal distribution and human engineering activities slope excavation underground mining of tongchuan city the main factors restricting urban development are steep slopes landslides the wide distribution of problematic soils flooding and surface subsidence caused by underground mining information theory has been applied to predict the slope susceptibility the area of surface subsidence caused by mining at present and in the future is delimited using a finite element method the factors closely related to land use planning are slope susceptibility and landslides flooding collapsible soils surface subsidence related to mining and the low bearing capacity of a bearing layer these are combined to produce uniform engineering geological units the result of a suitability assessment of the study area is illustrated in the form of a rational land use planning map

horizontal and vertical structure of observed tropospheric equatorial rossby waves equatorial rossby er waves are identified in an 8 year data set of national meteorological center operational analyses the westward moving waves have symmetric circulations about the equator and eastward energy dispersion with maximum zonal wind perturbations along the equator and meridional wind maxima roughly 10 15 off the equator they have maximum amplitude in the lower troposphere and are associated with convective signals at roughly the mean latitude of the tropical convergence zones the circulations thus possess many of the features of the equatorially trapped n 1 rossby modes derived by matsuno 1966 they are generally around zonal planetary wavenumber 6 scale and have a deep nearly equivalent barotropic structure up to 100 mbar this is in contrast with the madden julian oscillation and mixed rossby gravity waves which generally have a first baroclinic mode vertical structure during the intensive observing period iop of the tropical ocean global atmosphere toga coupled ocean atmosphere response experiment coare and in other years westward propagating er disturbances along the equator are observed by using 6 to 30 day filtered circulation data at 850 mbar zonal wind anomalies at 850 mbar are preferentially associated with like signed anomalies in a deep layer at this frequency as was observed during coare the er waves are most common during northern winter in the central pacific although they can be detected sporadically over the other ocean basins and in other seasons as well one source for the equatorial rossby waves appears to be upper level extratropical rossby wave activity propagating into the eastern pacific although the equatorial waves are sometimes present during the northern summer when the extratropical source is absent we cite evidence that propagation of er wave activity from the central into the western pacific is related to occurrences of westerly wind bursts

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

to an improved method for hydrofracture induced microseismic event detection and phase picking fuxian song h sadi kuleli m nafi toksoz erkan ay and haijiang zhang geophysics 75 no 6 a47 a52

remote influences on the indian monsoon low level jet intraseasonal variations a strong low level jet llj also known as the findlater jet develops over the arabian sea during the indian summer monsoon this jet is an essential source of moisture for monsoonal rainfall over the densely populated indian subcontinent and is a key contributor to the indian ocean oceanic productivity by sustaining the western arabian sea upwelling systems the llj intensity fluctuates intraseasonally within the 20 to 90 day band in relation with the northward propagating active and break phases of the indian summer monsoon our observational analyses reveal that these large scale regional convective perturbations only explain about half of the intraseasonal llj variance the other half being unrelated to large scale convective perturbations over the indian ocean we show that convective fluctuations in two regions outside the indian ocean can remotely force a llj intensification four days later enhanced atmospheric deep convection over the northwestern tropical pacific yields westerly wind anomalies that propagate westward to the arabian sea as baroclinic atmospheric rossby waves suppressed convection over the eastern pacific north american monsoon region yields westerly wind anomalies that propagate eastward to the indian ocean as dry baroclinic equatorial kelvin waves those largely independent remote influences jointly explain 40 of the intraseasonal llj variance that is not related to convective perturbations over the indian ocean i e 20 of the total with the northwestern pacific contributing twice as much as the eastern pacific taking into account these two remote influences should thus enhance the ability to predict the llj

eocene fan delta submarine fan deposition in the wagwater trough east central jamaica the wagwater trough is a fault bounded basin which cuts across east central jamaica the basin formed during the late palaeocene or early eocene and the earliest sediments deposited in the trough were the wagwater and richmond formations of the wagwater group these formations are composed of up to 7000 m of conglomerates sandstones and shales six facies have been recognized in the wagwater group facies i unfossiliferous massive conglomerates facies ii channelized non marine conglomerates sandstones and shales facies iii interbedded fossiliferous conglomerates and sandstones facies iv fossiliferous muddy conglomerates facies v channelized marine conglomerates sandstones and shales and facies vi thin bedded sheet sandstones and shales the wagwater and richmond formations are interpreted as fan delta submarine fan deposits facies associations suggest that humid region fan deltas prograded into the basin from the adjacent highlands and discharged very coarse sediments on to a steep submarine slope at the coast waves reworked the braided fluvial deposits of the subaerial fan delta into coarse sand and gravel beaches sediments deposited on the delta front slope were frequently remobilized and moved downslope as slumps debris flows and turbidity currents at the slope basin break submarine fans were deposited the submarine fans are characterized by coarse inner and mid fan deposits which grade laterally into thin bedded turbidites of the outer fan and basin floor

evidence of the existence and eastward motion of superclusters at the equator abstract a numerical experiment with an atmospheric general model gcm indicate that moist convection in the equatorial region is spontaneously organized into a form of supercluster which is an area of precipitation with a spatial extent of about 2000 km and an eastward propagation speed of about 1 5 m s 1 in this article the existence of superclusters in the real atmosphere is shown through a comparison between satellite observations and the gcm results it is argued that eastward motion of convective activity occurs not only as the well known property of the 30 60 day oscillation but as a property of synoptic scale disturbances at the equator

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

feasibility of monitoring hydraulic fracturing using time lapse audio magnetotellurics abstracthydraulic fracturing is widely used for initiating and subsequently propagating fractures in reservoir strata by means of a pressurized fluid to release oil and gas or to store industry waste downhole or surface microseismic monitoring is commonly used to characterize the hydraulically induced fractures however in some cases downhole microseismic monitoring can be difficult due to the limitation imposed by boreholes surface microseismic monitoring often faces difficulties acquiring high signal to noise ratio data because of the on site noise from hydraulic fracturing process research and field observations indicate that injecting conductive slurry or water into a strata may generate distinct time lapse electromagnetic anomalies between pre and posthydraulic fracturing these anomalies provide a means for characterizing the hydraulic fracturing using time lapse electromagnetic methods we examined the time lapse variation over an hour one day one month and two years of observed audio magn

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

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

some aspects of western hemisphere circulation and the madden julian oscillation abstractalthough the greatest variance in convection associated with the madden julian oscillation mjo occurs over the indo pacific warm pool the mjo is associated with substantial circulation patterns in the tropics and the extratropics of the western hemisphere reanalysis data suggest that upper tropospheric easterly wind anomalies on the equator between 40 and 140 w precede 86 of active convective phases of mjo events greater than one standard deviation in amplitude over the indian ocean basin during the northern hemisphere winter composites of those mjo events that are preceded by westerly wind anomalies and those events preceded by easterly wind anomalies are compared results show that those events that are preceded by westerly wind anomalies fail to thrive and do not yield the amplitude in convection or the canonical atmospheric circulation response that is associated with those preceded by easterly wind the composite of events preceded by easterly winds reveals that these winds amplify coi

neotectonics of the caribbean a compilation of earthquake focal mechanism solutions together with the interpretation of inclined intermediate depth seismic zones neogene strike slip faults fault controlled basins and volcanism is used to test three existing models for the neotectonic i e neogene or post oligocene development of the caribbean the current models although based on different hypotheses using different data sets are similar and suggest varying degrees of convergence between the caribbean and either north or south american plates or convergence between the caribbean plate and continental fragments of the northwestern corner of south america using model 1 previous workers have interpreted the disposition of fracture zones and magnetic anomalies in the central and south atlantic as indicating that the caribbean plate is being compressed by north south convergence between the americas with the result that it is being driven eastward relative to the americas along strike slip faults while producing east west trending subductionlike convergent zones along northern and southern plate margins using model 2 previous workers have interpreted the azimuths of active strike slip faults and focal mechanism solutions and closure of three plate velocity circuits as indicating that the south american plate converges in a west northwesterly direction on the southern margin of the caribbean plate and has produced compressional features while strike slip motion dominates along the northern boundary using model 3 previous workers have interpreted focal mechanism solutions and the pattern of strike faulting and basin development in northwestern south america to suggest right lateral displacement of the northwestern corner of south america relative to the craton with convergence and compression in the south central caribbean our integration of geologic information on faults basins and volcanism considerably extends the limited record of plate interactions known from historical reports of the past few hundred years and recorded earthquakes and suggests that 1 relative motion between the north american and caribbean plates is dominantly east west strike slip motion although areas of complex internal deformation associated with restraining bend or compressional strike slip fault segments have been identified in jamaica hispaniola and central america 2 relative motion between the south american and caribbean plates is dominantly east west strike slip motion although an area of restraining bend deformation has been identified in the araya peninsula of venezuela 3 relative motion between a triangular continental fragment of northwestern south america the maracaibo block ranges from northwest to northeast along the south central margin of the caribbean and appears to be driven mostly by the late miocene pliocene collision of the panama arc although additional driving forces may include the collision of the carnegie ridge and or oblique subduction to the northeast in ecuador and 4 relative motion internal deformation may be occurring at a very slow rate between fault bounded blocks within the caribbean plate as a result of the convergence of the maracaibo block and or eastward motion of the caribbean plate relative to a continental promontory of north america in northern central america because the caribbean margins are composed mainly of anisotropic easily deformed continental and arc lithosphere plate boundaries are zones of diffuse deformation and it is difficult to assess the degree of convergence between the americas although data from the caribbean itself suggest that it may be smaller than the amount inferred by some workers using model 1 fracture zone and magnetic anomalies in the atlantic some of the compressional features cited as evidence for the relative convergence of the americas may be instead related to the convergence between the maracaibo block relative to the southern margin of the caribbean many aspects of caribbean neotectonics remain less than completely understood but more integration of seismic and geologic studies particularly exploratory fault trenching of onshore faults and seismic profiling of offshore faults should lead to rapid advances

focusing of elastic waves for microseismic imaging microseismic events generate compressive waves and shear waves which can be recorded at receivers we present a theory that shows how elastic p and s waves separately backpropagate to the original source location these refocused p and s wavefields are free of singularities we also demonstrate a technique that enhances the ability to image the spatial focus for each wave type using elastic waves the improved spatial focus obtained is achieved in a velocity model for which the interface boundaries are approximate but where the mean slowness is correct deconvolution designs a signal to be rebroadcasted from the receivers using only the waves recorded at each receiver such that the wavefield has an optimal temporal focus at the source location we demonstrate theoretically and numerically that improved temporal focusing of elastic waves leads to improved spatial focusing for each wave type this proposed technique only involves a simple preprocessing step to the recorded data and its cost is hence negligible compared to the total cost of microseismic imaging

horizontal structure and seasonality of large scale circulations associated with submonthly tropical convection the relationship between deep tropical convection and large scale atmospheric circulation in the 6 30 day period range is examined regression relationships between filtered outgoing longwave radiation at various locations in the tropics and 200 and 850 mb circulation are mapped for the standard seasons and the spatial structure and seasonal dependence of the results are interpreted in view of the basic state circulation in regions where the convection is embedded in upper level easterlies anomalous equatorial easterly flow is typically present at 200 mb within and to the west of the convective signal along with patterns of meridional outflow into subtropical anticyclonic perturbations lagged relationships suggest that the convection is forcing the circulation in many of these cases the outflow and subtropical circulations are strongest into the winter hemisphere during the solstitial seasons with more symmetric signals about the equator seen in the equinoctial seasons the longitudinal positioning of the subtropical features with respect to the convection varies but is generally located due poleward or just to the east of the convection there tends to be a first baroclinic mode vertical structure to these circulations such that equatorial westerlies are present at 850 mb within the convection with closed circulations on either side of the equator resembling equatorial rossby modes especially common over the atlantic and pacific sectors as a contrast in regions located within upper level westerlies or along the margin of influence of upper westerly disturbances convection appears to be forced by upper level wave energy propagating into the deep tropics with the heating located in the upward motion region ahead of upper level troughs this occurs over the atlantic and eastern pacific sectors during northern winter and spring and over australia the south pacific and south america during southern summer when upper westerlies are at relatively low latitudes where they can interact with deep tropical convection the results confirm theoretical and modeling ideas that suggest that rossby wave energy is able to propagate into the deep tropics in regions where upper level westerlies exist in the tropics

mesoscale convective systems 1 mesoscale convective systems mcss have regions of both convective and stratiform precipitation and they develop mesoscale circulations as they mature the upward motion takes the form of a deep layer ascent drawn into the mcs in response to the latent heating and cooling in the convective region the ascending layer overturns as it rises but overall retains a coherent layer structure a middle level layer of inflow enters the stratiform region of the mcs from a direction determined by the large scale flow and descends in response to diabatic cooling at middle to low levels a middle level mesoscale convective vortex mcv develops in the stratiform region prolongs the mcs and may contribute to tropical cyclone development the propagation of an mcs may have a discrete component but may further be influenced by waves and disturbances generated both in response to the mcs and external to the mcs waves of a larger scale may affect the propagation velocity by phase locking with the mcs in a cooperative mode the horizontal scale of an mcs may be limited either by a balance between the formation rate of convective precipitation and dissipation of stratiform precipitation or by the rossby radius of the mcv the vertical redistribution of momentum by an mcs depends on the size of the stratiform region while the net vertical profile of heating of the large scale environment depends on the amount of stratiform rain regional variability of the stratiform rain from mcss affects the large scale circulation s response to mcs heating

upscale impact of mesoscale disturbances of tropical convection on synoptic scale equatorial waves in two dimensional flows abstractsuperclusters on the synoptic scale containing mesoscale systems are frequently organized by convectively coupled equatorial waves ccews present day global models struggle to simulate multiscale tropical convection and the upscale effects of mesoscale systems are not well understood a simple two dimensional multiscale model with prescribed two scale heating and eddy transfer of momentum and temperature drives the synoptic scale circulation successfully reproduces key features of flow fields with a front to rear tilt and compares well with results from a cloud resolving model crm in the scenario with an elevated upright mean heating the tilted vertical structure of synoptic scale circulation is still induced by the upscale impact of mesoscale disturbances in a faster propagation scenario the upscale impact becomes less important as a result of competing effects of eddy transfer of momentum and temperature while the synoptic scale circulation response to mean heating dominates in agre

distribution of gypsiferous soil using geoinformatics techniques for some aridisols in garmian kurdistan region iraq the paper deals with techniques of image classification developed to distinguish gypsiferous soils using the integration of field observation and remote sensing and more specific landsat etm imagery a landsat image was assembled and used in this study the image was acquired by the etm landsat 7 sensor which was acquired on august 2012 two main data have been used in this research i field and ii satellite data the amount of gypsum is different from location to other may be due to the parent material of some locations of the study area which is rich with gypsum minerals and there is evidence of gypsic indopedon horizon the results indicated that the amount of organic matter decreases with increasing the amount of gypsum in general the study area is rich with total lime these results reflect the effect of decalcification and calcification processes caused the formation of illuvial subsurface calcic horizon in some location of the study area the ph values were around neutral to slightly alkaline due to the effect of calcareous parent material and type of climatic conditions the low ece values indicate that the soil was non saline reflected by low values of ece the soil classes of the study area are belonging to haplogypsids haplocalcids haplocambids calciargids and haplargids two maps were prepared to show the distribution of gypsiferous in the study area the first one is map which shows the output of supervised classification and maximum like hood for specific and the second is the thermal based classification thermal based map could predict the gypsiferous area in a better way than the classification based only on spectral properties of non thermal bands

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

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

characteristics of tropical convection over the ocean near kwajalein radar observations have been analyzed to determine characteristics of convection over the oceanic region around kwajalein in the tropical western pacific generally the echo areas heights and durations exhibited lognormal distributions heights were greater under conditions of higher midtropospheric humidity and correlated with echo area with a wide spread of values mergers and splits often truncated echo lifetimes the most surprising result was the distribution of orientation angles of echo lines which statistically verify the shear parallel and shear normal modes of convective line organization seen elsewhere over tropical oceans the two modes typically coexisted within the area of radar coverage indicating a potential difficulty in predicting line orientation in terms of large scale variables the largest members of the echo population were mesoscale convective systems mcss which had large stratiform components they occurred in environments of increased humidity and higher midlevel buoyancy associated with westward propagating synoptic scale disturbances mcss moved with the easterlies in low to midlevels and exhibited the jump updraft overturning updraft and subsiding midlevel inflow characteristic of tropical oceanic mcss the kwajalein experiment kwajex radar echo population resembles that of the eastern tropical atlantic in terms of the shapes of the distributions of area height and lifetime the prevalence of echo mergers and splits and the tendency to form shear parallel and shear normal lines these characteristics appear to be endemic to oceanic convective populations large scale conditions appear to modulate these basic population characteristics rather than qualitatively alter them

proposing a framework to combine geological and geotechnical information for city planning in sanandaj iran abstract a proposed framework that combines geological and geotechnical characteristics is very useful in planning and designing construction activities in a large area such as a city a step by step process of the proposed framework is presented for the city of sanandaj iran sanandaj was developed on cretaceous rock units as well as quaternary alluviums identifying engineering variables related to these rock units and alluvial deposits is essential for determining their behavior in construction projects in the presented research first all rock types and alluvial layers in sanandaj were determined and their properties including their formation and origin were described and then the area was geologically classified a database including the results of 211 geotechnical boreholes at sanandaj was compiled and data were completed and validated through the excavation of 9 pits in different locations around sanandaj finally a geological and geotechnical framework was proposed for sanandaj to identify the city s underlying geological layers

geotechnical mapping for alluvial fan deposits controlled by active faults a case study in the erzurum ne turkey erzurum the biggest city of eastern anatolia region in the turkey is located in karasu plain karasu plain located on the central segment of the erzurum fault zone is an intermountain sedimentary basin with a miocene quaternary volcanic basement andesitic basaltic lava flows and fissure eruptions of basaltic lava it was filled in the early quaternary by lacustrine fan delta deposits the basin is characterized by nne ssw trending sinistral wrench faults on its eastern margin and ene wsw trending reverse faults on its southern margin both systems of active faults intersect very near to erzurum which is considered to be the most likely site for the epicenter of a probable future large earthquake historical records of destructive earthquakes morphotectonic features formed by paleo seismic events and instrument seismic data of region indicate to a very high regional seismicity the residential areas of erzurum are located on thick alluvial fan deposits forming under the control of faults on the central segment of the erzurum fault zone which is one of the most active fault belts of the east anatolian region over time the housing estates of city such as yenisehir and yildizkent have been expanded toward to the west and southwest part of erzurum as a consequence of rapid and massive construction during the last 30 years geotechnical investigation has therefore been undertaken the residential areas of city in order to characterize geotechnical properties over the varied lithologies examine the potential for geotechnical mapping and assess the foundation conditions of the present and future settlement areas the geological field observations and operations have been performed to make the soil sampling and characterize the lateral and vertical changes in thickness of the alluvial deposits in trenches excavations and deep holes with 6 12 m sections the soil samples have been subjected to a series of tests under laboratory conditions to obtain physical and mechanical properties furthermore the standard penetration tests have been applied to the soils under field conditions the geological field observations geotechnical data and distribution of bearing capacity have been considered for the geotechnical mapping based on the geotechnical map there are five geotechnical zones distinguished in the study area

a mechanism of chemical weathering of mudstone in a mountainous area abstract the chemical weathering of marine mudstone in humid mountainous areas of japan is dominated by the oxidation of pyrite a common mineral in marine sedimentary rocks this process occurs at the oxidation front that is the base of the oxidized zone and sulfuric acid is formed chlorite is transformed into smectite due to the oxidizing and acidic conditions as sulfuric acid migrates downward from the oxidation front minerals are dissolved and components are leached out from the underlying dissolved zone whose lower boundary is the dissolution front the oxidation and dissolution fronts migrate downward as weathering progresses in mountainous areas

engineering geomorphology of the widentobel catchment appenzell and sankt gallen switzerland a geomorphologuical inventory system applied to geotechnical appraisal of slope stability abstract the paper presents a method of applied and detailed 1 2000 scale geomorphological and geotechnical surveying developed in alpine areas and tested to its engineering consulting value in the widenbach valley appenzell and st gallen switzerland the investigation was carried out by a pair of geomorphologists trained in high relief terrain and well versed in mass movement characteristics a programme of wildbachverbauung the controlling of fluviatile erosion by the erection of dams was already undertaken in the twenties but this first generation of wooden dams is now being replaced by concrete constructions the widenbach valley situated in the marls and sandstones of the folded molasse zone untere susswasserzone was subjected to glacial scouring and deposition by a branch of the rhine glacier transfluencing westwards across the stosspass separating the widenbach valley at 940 m a s l from the appenzell depression postglacially various earthflows have originated from the instable morainic deposits as well as from the weathered marls and sandstones underlying the glacially oversteepened valley flanks they have built a two km long earthflow complex filling the widenbach valley to considerable depth the townships of eichberg and altstatten situated at the outlet of the system have since historic times experienced damage to forest and grazing land houses and roads in the midstream and upstream valley sections the widenbach is flowing on the earthflow morphology while the downstream part already constrained by new dams founded in exposed hard rock is controlled by fluvial processes the mass movement dynamics of the midstream and upstream sectors make a completely different engineering approach necesssary when this was made clear by the geomorphological reconnaissance the lack of data could only be filled by a detailed 1 2000 scale geomorphological site investigation as time and funds for long lasting monitoring of the earthflow system were not available this geomorphological survey contained the following elements pre field airphoto interpretation mapping of micro terrainforms classification of materials types and order of movement it placed emphasis on the behaviour of the various discontinuity planes expressed in the terrain

fine structure of cloud patterns within the intraseasonal oscillation during toga coare abstract the relationship of satellite derived cloud motions to actual convective systems within a convectively active phase of the intraseasonal oscillation is examined by using both cloud scale properties produced by a cloud resolving model and field observations to clarify what is going on at shorter time and space scales each convective system has a life cycle of up to 1 2 days described in terms of active convection the system consists of successive precipitation cells generated ahead of the gust front described in terms of its cloud shield the system is more continuous when easterly winds prevail above 2 km both precipitating clouds and upper tropospheric anvil clouds move westward with about the same phase speed 10 m s 1 however during the westerly wind period precipitating clouds move eastward with a phase speed of 10 m s 1 which is better represented by the radar observations and surface precipitation the westward movement of cloud patterns viewed from the satellite images is mos

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

landslide processes and landslide susceptibility analysis from an upland watershed a case study from st andrew jamaica west indies abstract rainfall induced landslides are common geomorphic events on the steeper slopes of upper st andrew and cause severe environmental engineering social and economic repercussions in the area a geotechnical study was initiated to identify a past present and potential landslide types and sites for landslides b to examine the nature of geological geomorphological and geotechnical conditions under which failures can take place and c the potential landslide hazard in the area 886 failures were mapped more than 80 of which were located in soils a total of 1 55 km2 9 80 of the total area had failed approximately 59 failures per km2 were mapped with the highest density within elastic sedimentary units and weathered granodiorite 789 failure were mapped on slopes between 20 45 with no failure on slope less than 10 481 failures were mapped along twelve major roadways 46 6 km of road with approximately 10 failures km of road analysis of eighteen geotechnical units within nine geological formations revealed that the highest susceptibility for failure was within old landslide deposits with granular nonplastic to low plasticity soils and on slopes between 20 and 30 the lowest susceptibility was found within white limestones and recent alluvium and terrace deposits granular nonplastic to low plasticity soils are generally more susceptible than fine soils especially on slopes between 30 and 45 while granular and expansive clay soils demonstrate similar susceptibilities but on slopes between 30 and 45 and 20 and 45 respectively clastic sedimentary rocks are more susceptible that igneous lithologies an increase in slope angle increases the susceptibility to failures but only on slopes up to 45 an increase in the degree of weathering of soils and bedrock and fracturing of bedrock as well as road construction increases the landslide susceptibility in the area

organized convection parameterization for the itcz abstractmesoscale convective systems mcss are of fundamental importance in the dynamics of the atmospheric circulation and the climate system they are often observed to develop over significant terrain in ambient shear flows in midlatitudes and embedded within the madden julian oscillation mjo and convectively coupled equatorial wave ccew envelopes as well as in the intertropical convergence zone itcz yet general circulation models gcms fail to resolve these systems and their underlying convective parameterizations are not directed to represent organized circulations shear parallel mcss which are common in the itcz have a three dimensional structure and as such present a serious modeling challenge here a previously developed multicloud model mcm is modified to parameterize mcss one of the main modifications is the parameterization of stratiform condensation to capture extended stratiform outflows which characterize mcss resulting from strong upper level jets linear analysis show

vertical mode decompositions of 2 day waves and the madden julian oscillation abstract vertical structures of 2 day waves and the madden julian oscillation mjo are projected onto vertical normal modes for a quiescent tropical troposphere three modes capture the gross tropospheric structure of 2 day waves while only two modes are needed to represent most of the baroclinic structure of the mjo deep circulations that project onto the first baroclinic mode are associated with deep cumulonimbus and stratiform rainfall shallow circulations that project onto higher wavenumber modes are associated with precipitating shallow cumulus and congestus and stratiform rainfall for both disturbances the horizontal divergence contributed by shallow modes is an important factor in the column integrated moist enthalpy budget these modes converge moist static energy for a time prior to when deep circulations export moist static energy these results highlight the importance of properly representing the effects of shallow cumulus congestus and stratiform precipitation in theories of convective

two day disturbances in the equatorial western pacific from november 1992 to february 1993 westward propagating disturbances with scales of 1000 1500 km frequented the equatorial western pacific they propagated at about 16 m s 1 and their passage was accompanied by a two day oscillation in high cloudiness their convection was most intense when the lower troposphere was cool and the level of free convection was relatively low the disturbances propagated westward at about 18 m s 1 faster than the lower tropospheric flow this rapid propagation may have been the result of a coupling between the disturbance s convection and the 20 m s 1 vertical mode the signal of this mode was apparent in vertical profiles of temperature and wind and the most intense convection began when the mode dynamically cooled the lower troposphere lowering the level of free convection

convectively coupled kelvin waves from linear theory to global models abstractthe authors analyze composite structures of tropical convectively coupled kelvin waves cckws in terms of the theory of raymond and fuchs using radiosonde data 3d analysis and reanalysis model output and annual integrations with the ecmwf model on the full planet and on an aquaplanet precipitation anomalies are estimated using the noaa interpolated olr and trmm 3b42 datasets as well as using model olr and rainfall diagnostics derived variables from these datasets are used to examine assumptions of the theory large scale characteristics of wave phenomena are robust in all datasets and models where kelvin wave variance is large indices from the theory representing column moisture and convective inhibition are also robust the results suggest that the cckw is highly dependent on convective inhibition while column moisture does not play an important role

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