diurnal variation in vertical motion over the central equatorial pacific from vhf wind profiling doppler radar observations at christmas island 2 n 157 w wind profiling doppler radars measure vertical motions along a vertically directed beam by averaging over long periods it is possible to measure very small mean vertical motions long term measurements at christmas island have been analyzed to determine the diurnal variation in the vertical motion field the outstanding feature that emerges from the analysis is a pronounced diurnal cycle in the subsiding motion of the main troposphere 4 10 km and an equally pronounced diurnal cycle in upward motion centered around the altitude of the tropopause the possibility of radiative forcing of the observed diurnal cycle is considered in the context of the diurnal variation of atmospheric diabatic heating and cooling rates

the old alluvium of singapore and the extinct drainage system to the south china sea in both sand quarry faces and boreholes the old alluvium of singapore is a matrix supported pebbly sand with minor beds of better sorted sands and clays the beds can be grouped into four textural classes pebbles coarse sand with fine pebbles medium to coarse sand clay and silt each with characteristic sedimentary structures the deposit appears to be the proximal facies of an ancient braided river alluvium of possible pleistocene age this widespread but scattered alluvium is found both on land and offshore on the sunda shelf in southeast asia it is believed to have been deposited during low sea levels in singapore the mineralogy of the grains forming the old alluvium suggests a mixed provenance of granitic and low grade metamorphic origin the volume and freshness of the deposited material indicate an environment of considerable relief seasonal rainfall and extremely active erosional processes conditions considerably different from the current ones the old alluvium was probably deposited by seasonal rivers which experienced periodic large floods such regional conditions could have prevailed over much of southeast asia at the time of deposition of the old alluvium

vertical velocity characteristics of deep convection over darwin australia abstract continuous vertical velocity measurements using a 50 mhz wind profiler located at darwin in northern australia during periods of active convection have been analyzed this dataset is dominated by continental type convection numerous examples of shallow deep and decaying convection were seen and it is shown that only the deep systems have substantial tilts to the draft structure the most intense updrafts occur above the freezing level but shallow convection also produces large amplitude vertical motions the strength of these updrafts in this dataset is very similar to other tropical oceanic data that observation is consistent with the idea that the magnitude of the updrafts is much less in the tropics than for intense midlatitude convection because the convective available potential energy is distributed over a much deeper layer in the tropics although more intense updrafts may be present at other tropical locations such as the tiwi islands north of darwin the size of the cores however

late quaternary tropical lowland environments on halmahera indonesia abstract results of a case study of landform development and sedimentation in humid tropical lowland environments on halmahera island eastern indonesia are presented with the aim to better characterise tropical lowland environments in the context of late quaternary environmental change studies first the geologic morphologic and environmental settings of the two areas the interior kao river plain and the kao coastal zone n halmahera are presented subsequently data concerning late pleistocene and holocene landform development sedimentation and coastal processes are discussed pleistocene landform development involved volcaniclastic sedimentation base levelling of coastal lowlands prolonged weathering and crust formation coastal uplift and eustatic sea level change a conspicuous ferricrete crust in the subsoil of the coastal plain is tentatively dated with 14 c ams analysis and isotopes of organic matter encapsulated in the soil ferricrete have been determined due to interacting sea level change neotectonic uplift climatic hydrologic and vegetational change unequivocal evidence for anomalous late pleistocene or holocene environmental conditions is difficult to obtain during the mid late holocene a low energy fluvial systems and swamps existed in the interior kao river plain a dense open swamp swamp forest vegetation contributed to extremely high sedimentation rates in this depositional basin palynological analysis of the organic swamp deposits indicates little or no change in sedimentary environmental settings and swamp vegetations and indications for early human presence in the area in the coastal area accretion and delta progradation occurred after the early mid holocene formation of a marine erosion cliff tentative evidence for early human presence in the kao area is derived from charcoal particle frequencies in sediments and the existence of natural grasslands in the coastal zone as most of the geologic and environmental characteristics of the tropical lowlands in the kao area are common in eastern indonesia the study provides useful information for ongoing research in the region

critical levels and mixing layers induced by convectively generated gravity waves during cepex we study data from the central equatorial pacific experiment in particular the soundings providing temperature pressure wind and ozone profiles and we link them to the large scale conditions deduced from the analyses of the european centre for medium range weather forecasts to the west of the date line the mean wind shows a strong shear at the tropopause between the easterlies of the upper troposphere and the westerlies of the lower stratosphere these are conditions propitious to the formation of critical levels for quasi stationary gravity waves generated by deep convection the measured wind profiles show the main characteristics of the encounter of a wave with its critical level and in the ozone and potential temperature profiles the existence of a conspicuous mixing layer in the vicinity of this critical level our interpretation that the mixing layer is a consequence of the critical level is supported by numerical simulations with a nonlinear time dependent two dimensional model the occurrence of a mixing layer in the tropopause structure seems to be characteristic of large scale equatorial convective areas during westerly phases of the quasi biennial oscillation

observations of tropical convection events using indian mst radar first results mesoscale convective events associated with severe weather play a significant role in troposphere stratosphere coupling processes deep convection occurs very often at tropical latitudes the convection events result in the transport of energy from the lower troposphere to the upper troposphere and stratosphere and may also affect global circulation in the indian tropical region meteorological convection events are a common occurrence during the months of may to december in the present study very high frequency radar located at gadanki 13 45 n 79 18 e a tropical station in india is used to make observations of winds turbulence and stable layer structures during the passage of convective events over the radar site under different synoptic situations radar observations of vertical velocity show enhanced up and down draughts during the passage of convection events height and time cross sections of radar observed signal to noise ratio clearly show distinct regions of enhanced signal intensity indicating height and time structures of enhanced atmospheric turbulence associated with the convection it is also noted that stable layer structures associated with the tropical tropopause are not well defined during the passage of convection this suggests weakening of stable layer structures during the convective activity the present observations also show enhanced mass flux both in upward and downward directions through the tropopause indicating mass exchange between troposphere and stratosphere during the period of convective activity

arkose subarkose quartz sand and associated muds derived from felsic plutonic rocks in glacial to tropical humid climates abstract in the range of climates from high latitude glacial to equatorial tropical the mineral and chemical compositions of over 600 modern nonmarine first cycle sands and muds produced from felsic crystalline basement provenance in various tectonic settings were studied under glacial conditions sediments are developed by mostly mechanical weathering and thus are mineralogically and chemically similar to their source rocks humid tropical climates yield quartz rich sands kaolinite rich muds along with si mg ca na and k in solution between these extremes a wide range of detrital sediment compositions are developed in arid to wet climates in arid climate and semi arid climate sands feldspar is commonly more abundant than quartz and plagioclase k feldspar except in the cases of granite source rocks the muds are feldspathic with smectite dominant in the clays with increasing temperature and moisture in temperate to subtropical climates mafic silicates and feldspars are destroyed so that the sands range from arkoses with plagioclase as the major feldspar to subarkoses with dominant k feldspar through this range of climate muds become more kaolinitic and thus more aluminous with increasingly severe weathering typically feldspathic sands are associated with feldspathic muds with decreasing feldspar in sands there is less feldspar in muds with increasingly intense chemical weathering rare earth elements ree are more fractionated into muds typically sands contain 150 ppm ree with much of the ree in heavy minerals abundance differences are greatest between humid tropical sands and muds in many samples the ree are mostly in monazite allanite sphene and apatite more intensely weathered samples contain more xenotime and zircon evidenced by yb enrichment

equatorial weathering landform development and the formation of white sands in north western kalimantan indonesia abstract the morphology and geochemistry of weathering profiles in miocene granodiorites from the coastal lowlands of nw kalimantan indonesia 1 n lat indicate long term weathering rates landform development and mechanisms for the formation of white sands found widely in valleys and depressions samples are analysed from convex hill piedmont glacis and valley slope profiles all profiles above the saturated zone are strongly gibbsitic but kaolinite minerals are dominant below the water table the profiles are interpreted as expressions of the perhumid equatorial climate rainfall 3000 mm y 1 acting within a dynamic regime of landscape lowering during the neogene the current profiles being largely quaternary 0 4 0 6 ka possible effects of quaternary tectonic and environmental changes are considered including those caused by a late pleistocene drier climate when there was greater water table fluctuation and surface erosion landform evolution is a form of dynamic etchplanation with a long term rate of landscape and weathering profile lowering of ca 50 mm ka 1 within this regime some of the white sands may be residual weathering products locally redistributed by colluvial or alluvial processes they originated in the podzolising environment of the weathering profile and later experienced post depositional diagenetic changes within the hydromorphic regime of the valley floor

from oxisols to spodosols and histosols evolution of the soil mantles in the rio negro basin amazonia abstract the upper rio negro basin under a constantly humid equatorial climate is a low altitude peneplain of more than 165 000 km 2 prevailing soils are oxisols and spodosols and their distribution is usually related to the lithology of the parent materials spodosols being generally associated with sandy deposits after exploratory surveys in this extensive region six major soil geomorphic units have been identified in which selected toposequences have been studied by means of micromorphological chemical and mineralogical analyses detailed field analysis of the horizonation of the soil mantle has been carried out in three sequences consisting of oxisols ultisols and spodosols results show that sharp transitions within distances of less than one hundred meters separate the oxisols from the spodosols however the arrangement of the horizons in the soil mantle and similarities in micromorphological features chemical composition and mineral components between the adjacent horizons are evidences that genetic relationships link contiguous profiles the authors propose an alternative explanation for this soil distribution based on the lateral transformation of oxisols and ultisols into spodosols and on the lateral evolution of the giant spodosols into histosols peat and waterlogged ultisols interpretative models of landscape evolution as consequence of soil evolution are thus proposed

late quaternary sediment fluxes from tropical watersheds abstract inherited saprolite stores and continued weathering in quaternary time juxtapose abundant clay and fresh rock in tropical landscapes this influences sediment fluxes and affects the interpretation of sediment sequences derived from tropical watersheds detrital kaolinites derive from inherited saprolite sources as well as from soil clays and appear in delta and ocean sediments these sediments appear to correspond with sub milankovitch millennial scale cycles of climate change but may also record century scale episodes of rapid warming dansgaard oeschger events destabilisation of sediment sources and increased sediment fluxes in the late quaternary followed millennia of climatic deterioration cooling aridity and vegetation change and led to altered patterns of sedimentation during the last glacial maximum lgm sediment yield from slopes increased 10 around the lgm when rainfall was reduced by 30 60 and led to fan building and braided channels rainfall increased 40 80 from the lgm to the early holocene maximum and this led to channel cutting and major sediment fluxes to delta and ocean sinks vegetation recovery lagged the rapid warming by several millennia and was interrupted by younger dryas yd aridity influencing slope and stream behaviour holocene sedimentation has been by both vertical and lateral accretion increasing floodplain sediment stores

studies of quasi horizontally propagating gravity waves in the troposphere using the piura st wind profiler vhf profiler observations of the troposphere obtained over a flat desert in northern peru show the presence of strong quasi sinusoidal oscillations in the vertical wind velocity with periods of around 8 18 min these oscillations are a very typical feature of the vertical velocities over piura this paper presents an overview of the wave characteristics obtained at piura until this point including results obtained using two additional antennas built a few hundred meters to the west and south of the main antenna to measure horizontal wavelengths and phase velocities briefly the piura waves appear to have horizontal wavelengths of 1 3 km with either westward or eastward phase velocities in a ground based reference frame of 0 5 4 m s 1 their occurrence appears to be causally related to the magnitude of the easterly wind which blows over the andean cordillera some 60 km to the east of the site

an ensemble study of wet season convection in southwest amazonia kinematics and implications for diabatic heating dual doppler radar data from the tropical rainfall measuring mission large scale biosphere atmosphere experiment in amazonia trmm lba field campaign are used to determine characteristic kinematic and reflectivity vertical structures associated with precipitation features observed during the wet season in the southwest region of amazonia case studies of precipitating systems during trmm lba as well as overarching satellite studies have shown large differences in convective intensity associated with changes that develop in low level easterly flow east regime er and westerly flow west regime wr this study attempts to examine the vertical kinematic and heating structure of convection across the spectrum of precipitation features that occurred in each regime results show that convection in the er is characterized by more intense updrafts and larger radar reflectivities above the melting level in agreement with results from lightning detection networks these regime differences are consistent with contrasts in composite thermal buoyancy between the regimes above the boundary layer the environment in the er is characterized by a greater virtual temperature excess for near surface rising parcels both regimes showed a peak in intensity during the late afternoon hours as evidenced by radar reflectivity and

tropical stone lines and podzolized sand plains as paleoclimatic indicators for weathered cratons abstract stone lines and podzolized white sand plains are characteristic features of the regolith in many low latitude cratonic landscapes but nevertheless often seem to be out of phase with the present pedogenic and geomorphic regimes of the humid tropics and subtropics consideration of contemporary environments where the genetic processes related to these features can be observed implies several conditions for prior events in landscape evolution 1 tropical stone lines may be interpreted as winnowed mudflows or lag deposits that reflect morphoclimatic events of brief duration torrential rains within an arid or semi arid phase of pronounced global cooling 2 within the present zone of the prevailing westerlies stone lines may reflect periglacial activity during brief interstade fluctuations 3 in lower latitudes the principal stone line which commonly truncates saprolites appears to be late wisconsinan wurmian in age coinciding more or less with the pleniglacial phase 4 the podzolized sands represent leached residuals and accordingly reflect extended intervals of leaching during the pleistocene and 5 the nature and distribution of podzolized sand plains indicates a pedogenic history of considerable variety and no brief episodicity as implied with stone lines

short lived u and th isotope distribution in a tropical laterite derived from granite pitinga river basin amazonia brazil application to assessment of weathering rate we have analyzed samples of a 15 m thick profile weathered from the madeira granite located in the pitinga basin river north of manaus in the state of amazonia brazil this profile consists essentially of a yellow red saprolite covered by a soil u and th concentrations are particularly high in the granite 20 and 80 g g respectively normalized element to th concentrations indicate that th is most resistant to chemical weathering except to some extent in the top soil higher concentrations in the saprolite compared to the granite comprise a relative enrichment resulting from a loss of mass the saprolites are initially generated by a descending weathering front which alters the granite to a yellow red saprolite a second front close to the top turns the saprolite into a soil weathering has led to leaching of u the 234u 238u and 230th 238u isotopic ratios are in radioactive disequilibrium numerous nodules are present and apparently started to form at the base of the saprolite these nodules achieve more developed form during their relative ascent until they are reached by the descending top front where they undergo dissolution the th and pb are concentrated in the nodules close to the top front the u being more mobile is strongly leached by the first front and most of the remainder freed by the second engages in a descending flux which supplies the underlying saprolite using the data an attempt is made to model the isotopic distribution in the profile we conclude that the first front has descended at a rate of 5 cm 1000 yt and that the time needed to create the saprolite must have been around 300 000 yr

soils as a useful tool for reconstructing geomorphic dynamics in high mountain environments the case of the buscagna stream hydrographic basin lepontine alps abstract the soil formation its development and its preservation in high mountain environments are largely determined by topography and geomorphological dynamic therefore soil development in alpine areas is often non linear over time and characterized by phases of progressive and regressive evolution the interaction among soil forming factors is preserved in soils as physical chemical properties and pedological features in particular the action of surface geomorphological processes can be observed as stone lines or sequences of buried surfaces in this light exhaustive investigation of soils and paleosols could provide enough information to reconstruct past environmental conditions and spatio temporal changes in denudation deposition processes the main aim of this study is to assess the role of soil as a useful archive for retracing the geomorphological processes that are responsible for the landscape evolution during the late holocene in a typical alpine catchment such as the buscagna stream hydrographic basin veglia devero natural park lepontine alps the asymmetry in valley slopes due to lithology and structural control generates a great variety of geomorphic processes and landforms therefore seven soil profiles were selected along the two slopes in different morphological contexts to reveal the influence of the different active geomorphic processes in soil development soils were investigated by means of field and laboratory analyses and geomorphological maps of the area surrounding the profiles were made on the southeastern slope characterized by calcschist substratum the soil profiles are composed of two superimposed pedological units separated by an instability hiatus on the northwestern slope characterized by gneiss and ultramafic rocks and on the valley bottom the soils record instability phases in different ways fitting well with the geomorphological context in this mountain environment the close relationship between soil development and geomorphic processes allows us to confirm the role of soil as a useful archive to potentially reconstruct the past geomorphological conditions

what do yellowish brown soils and stone layers tell us about late quaternary landscape evolution and soil development in the humid tropics a field study in the serra dos orgaos southeast brazil abstract the occurrence spatial distribution and properties of yellowish brown soils and stone layers allow deriving conclusions about landscape evolution and soil development in the humid tropics in this study standard soil profiles and saprolite and subsoil samples along an altitudinal gradient from the high mountain ranges 1500 m a s l to the lowlands 8 m a s l in the serra dos orgaos mountain range in the brazilian state of rio de janeiro are analyzed field mapping techniques and laboratory methods are used to analyze the samples and reconstruct late quaternary landscape and soil development processes it is suggested that the formation of stone layers is polygenetic with dissolution processes geogenic bioturbation pedogenic and slope processes including coverage of terrace gravels geomorphic as possible mechanisms yellowing of the upper soil horizons is assumed to be the result of bio chemical processes xanthization chelation which took and take place in periods of wet climate conditions and closed forest cover in the late quaternary it can be distinguished between pre colonial and modern yellowish brown colluvial deposits with or without stone layer s it is suggested that the deposition of pre colonial colluvial soils primarily took place in dryer periods and forest retreat during the late pleistocene and holocene however it is proposed that the model of cyclic changes between geomorphic activity with colluviation on the one hand and stability and pedogenesis on the other hand need to be further differentiated due to small scale temporal and spatial climatic changes and sensitive vegetation responses to these fluctuations moreover it is suggested that due to the very steep relief and intense rainfall in the central mountain ranges of the serra dos orgaos accelerated displacement of soil material by landslides and mudslides took also place under closed forest cover in the late holocene modern colluvial deposits have originated from deforestation and land use intensification processes within the last 300 years they cover wide parts of the lower slopes foothills and depressions and indicate massive erosion and deposition processes since the european colonization

the interplay of geomorphic processes and soil development in an upland environment calabria south italy abstract five representative soil profiles outcropping in the area around the cecita lake calabria south italy were characterised by field work chemical and mineralogical analyses optical and scanning electron microscopy interactions among weathering pedogenesis and geomorphic processes are emphasised in an attempt to link the results obtained at different scales of observation the important role of topography in controlling soil development or removal by erosive processes is discussed in relation to the natural geomorphological context and the effects of human pressure both present day and relict features were recognised in the studied soils and discussed in terms of environmental conditions and climatic changes the chemical composition of volcanoclastic components identified in some soil horizons with andosol like field appearance coupled with pedogenetic features contributed useful chronological constraints for the reconstruction of late quaternary geomorphic events

mineral distribution and feldspar weathering in a saprolite from northeastern nigeria abstract mineral composition was analysed within a saprolite profile from ne nigeria the determination of identifiable feldspar phases is only based on x ray powder diffractograms representative k feldspar fragments were selected for detailed sem scanning electron microscope studies and edx energy dispersive x ray analysis from the profile the analytical data indicate a significant contrast in weathering states between the lower and the upper profile section this contrast reflects a different weathering history the feldspars from the lower section exhibit weathering features that are characteristic for decomposition below the water table when raised above the water table another type of decomposition attacked only the feldspars within the upper section while those in the lower section still preserve the older weathering state

late cretaceous to early tertiary structural elements of west kalimantan abstract recent geological and geophysical mapping in west kalimantan has allowed the definition of three domains with distinct geological and geophysical characteristics which were imprinted on the region by early cretaceous to eocene convergent tectonic events subduction related granitoids intruded low grade regional metamorphic rocks during the early cretaceous forming the schwaner mountains domain extending east west across the southern and central part of west kalimantan this is flanked in the northwest by a complex sequence of sedimentary and volcanic rocks ranging in age from late carboniferous to cretaceous which comprise the northwest kalimantan domain deformed cretaceous flysch deposits east of the northwest kalimantan domain form an accretionary complex representing the southern continuation of the extensive dominantly tertiary accretionary wedge in sarawak the boundary between the cretaceous accretionary domain and rocks of the northwest kalimantan domain is a fault which we interpret as a transform that marked the western limit of late cretaceous southward subduction beneath west kalimantan growth of the accretionary complex resulted in uplift of a ridge of melange and flysch deposits on which a half graben extensional basin formed and accumulated thick lacustrine deposits a sedimentary basin developed between continental rocks to the south and the emergent ridge comprising accretionary complex rocks and outer shelf deposits to the north in the position of a forearc basin as accretion proceeded the locus of underthrusting migrated northward and a second melange ridge and sedimentary basin developed farther to the north the evidence for accretionary processes and the association of these with sedimentary basin formation supports the hypothesis that an ancient south dipping subduction zone existed in the eastern part of west kalimantan during late cretaceous to early tertiary times

did panthera pardus linnaeus 1758 become extinct in sumatra because of competition for prey modeling interspecific competition within the late pleistocene carnivore guild of the padang highlands sumatra abstract on the island of sumatra the leopard panthera pardus became extinct during the late pleistocene several theories exist about the reasons why leopards could not subsist in sumatra while today national parks still bear tigers panthera tigris and asiatic wild dogs cuon alpinus one often debated theory is that the competition for prey was the reason for the extinction of leopards in sumatra the aim of our study is to model the impacts of competition for prey in the carnivore guild of the padang highlands in sumatra to test if competition pressure was sufficient to force the leopard to extinction in the first step we reconstructed the carnivore guild of the padang highlands based on fossils collected by dubois in the three cave sites of sibrambang djamboe and lida ajer in the second step we developed and applied an agent based model based on population density prey spectrum and daily meat intake and simulated different scenarios of competition among the sumatran predators we simulated the reconstructed guild and further tested scenarios with the absence of guild members to see under which circumstances leopards could have survived in sumatra simulation of the reconstructed carnivore guild revealed that in fact the leopard could have been driven to extinction by competition from other carnivores excluding one of the competing medium sized cats or the asiatic wild dog leads to the survival of the leopard in our simulations interestingly our model demonstrates that humans and tigers were not the strongest competitors for leopards because their exclusion from the scenarios does not conclude with the survival of leopards in our simulations according to our results the presence of two medium sized cats and the asiatic wild dog in combination with the small litter size of the leopard were the main reasons why the leopard could not tolerate the competition for prey in the padang highlands in sumatra and thus became extinct in sumatra

the gravity wave response above deep convection in a squall line simulation abstract high frequency gravity waves generated by convective storms likely play an important role in the general circulation of the middle atmosphere yet little is known about waves from this source this work utilizes a fully compressible nonlinear numerical two dimensional simulation of a midlatitude squall line to study vertically propagating waves generated by deep convection the model includes a deep stratosphere layer with high enough resolution to characterize the wave motions at these altitudes a spectral analysis of the stratospheric waves provides an understanding of the necessary characteristics of the spectrum for future studies of their effects on the middle atmosphere in realistic mean wind scenarios the wave spectrum also displays specific characteristics that point to low physical mechanisms within the storm responsible for their forcing understanding these forcing mechanisms and the properties of the storm and atmosphere that control them are crucial first steps toward developing

horizontally propagating quasi sinusoidal tropospheric waves observed in the lee of the andes vhf profiler observations of the troposphere obtained over a flat desert in northern peru show the presence of strong quasi sinusoidal oscillations in the vertical wind velocity with periods of around 8 18 minutes these oscillations are a very consistent feature of the vertical velocities over piura and are also observed at other profiler locations this paper presents an overview of the wave characteristics obtained at piura until this point including results obtained using a second antenna built a few hundreds meters to the west of the main antenna to measure horizontal wavelengths and phase velocities briefly the piura waves appear to have horizontal wavelengths in the zonal direction of 5 10 m with either westward or eastward phase velocities in a ground based reference frame of 5 15 m s 1 their occurrence appears to be causally related to the magnitude of the easterly wind which blows over the andean cordillera some 60 km to the east of the site

observed structure of mesoscale convective systems and implications for large scale heating mesoscale convective cloud systems that produce large amounts of rain in mid latitudes and most of the rain in the tropics consist of a combination of convective and stratiform cloud the convective regions contain numerous deep cells that are often but not always arranged in lines the stratiform region is an outgrowth of the convective ensemble it lies adjacent to the convective region and is seeded by ice particles detrained from convective towers sometimes it lies to the rear of a propagating convective line while on other occasions it surrounds the convection the heating of the large scale environment by a mesoscale convective system is affected by both the convective and stratiform regions although processes such as melting and radiation are important the net heating by a system is dominated by condensation and evaporation associated with vertical air motions this paper reviews recent observational evidence regarding the mean vertical motion profiles in the convective and stratiform regions of mesoscale convective systems and the implications of these mean motions for the vertical distribution of heating of the large scale environment in both the convective and the stratiform regions vertical motions have been determined by various techniques including composites of rawinsonde and aircraft wind data single and dual doppler precipitation radar analyses and wind profiler observations in stratiform regions these data consistently show mean vertical velocity that is upward in the upper troposphere and downward in the lower troposphere the level separating upward from downward motion is located from 0 to 2 km above the 0 c level depending on location within the stratiform region diagnostic calculations show that these vertical motion profiles imply heating of the upper troposphere and cooling of lower levels by stratiform region processes data on vertical motions in the convective regions are less consistent from case to case these data sometimes indicate that the mean vertical velocity in convective regions is maximum in the lower troposphere in other cases the data indicate a maximum in the high troposphere diagnostic calculations show that heating profiles diagnosed from these two types of profile are quite different the first having a maximum of heating in the lower troposphere while the second has a maximum in the middle troposphere although it is difficult to determine whether or not the differences in estimates arise from different types of observations analysis methods or sampling strategies it seems likely that they stem from differences in the large scale environment of the different mesoscale systems the ubiquitous occurrence of stratiform regions in mesoscale convective systems and hurricanes together with their consistent heating profiles which systematically concentrate heating in upper levels while cooling lower levels are a major consideration in evaluating the interaction of mesoscale systems with the large scale environment however the consistency of the stratiform profiles from case to case indicates that the variability of net convective plus stratiform heating profiles from case to case lies primarily in the variation of the convective region profiles from one case to another it is suggested that future work should focus on the convective region vertical profiles of vertical motion and heating and on the large scale environmental factors that may control the variation of these profiles from case to case

high resolution measurements of vertical velocity with the european incoherent scatter vhf radar 1 motion field characteristics and measurement biases european incoherent scatter vhf radar measurements of vertical velocities were made under polar mesopause summer echo pmse conditions enabling spatial and temporal resolution of 300 m and 2 s and accuracies of 0 1 ms 1 or better our observations revealed vertical motions with periods ranging from hours to tens of seconds and vertical wave structure exhibiting both ducted and vertically propagating behavior significant correlations were found between the low pass vertical velocity and velocity uncertainties velocity variances at high frequencies radar backscatter power and radar spectral widths specifically upward motions at lower frequencies correlated with larger uncertainties high frequency variances and radar spectral widths while downward motions correlated best with larger backscatter power we show these correlations to lead to biases in the determination of mean vertical motions when data are thresholded by any of the above quantities we also suggest that these correlations arise from a tendency for turbulence to be associated primarily with the upward phase of wave motions at lower frequencies a companion paper by fritts and hoppe presents a spectral analysis of this same data set

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

weathering and pedogenesis in the sila grande massif calabria south italy from field scale to micromorphology abstract weathering and soil features in the upland landscapes developed on granitic terrains of the sila grande massif calabria south italy have been studied in this work the attempt to link field scale and micromorphological observations in order to better understand the main weathering processes and their controlling factors is revealed to be very powerful six soil profiles in the area around the cecita lake representative of different geomorphological units were characterised by field work optical microscopy and sem eds analysis a strong influence on weathering and pedogenesis by micro scale features of primary minerals and parent rock fabrics is shown key roles are played also by relief in the development and preservation or stripping of regolith soil mantles in relation to natural and man induced phenomena by time controlling rates and degree of development of the main weathering features by climate in terms of type and intensity of dominant processes

podzols in amazonia summary in the area near manaus amazonia brazil soil sequences including oxisols ultisols and spodosols podzols are widely distributed such toposequences occur on slopes leading down into valleys cut in a nearly level plateau the geochemistry of the organic and mineral components of one of these sequences has been investigated spodosols develop on quartzose sands which may be the results of an intense hydrolysis of clays and or an impoverishment of clays through eluviation or selective erosion large analogies with podzolization in the temperate zone were found especially in the organic matter dynamics as the clay content decreases more organic compounds with increased aromaticity and more polycondensed structures were allowed to move forming the bh horizons or reaching the water streams an in situ experimentation was also performed to characterize presently active soil forming processes it was found that podzolization in amazonia was mainly active during the rainy season

first frequency domain interferometry observations of large scale vertical motion in the atmosphere the spatiotemporal distribution of the vertical velocity at synoptic and subsynoptic scales is key to the patterns of weather and climate on earth on these scales the vertical velocity is on the order of one to a few centimeters per second typically about three orders of magnitude smaller than typical horizontal wind velocities because of the smallness of large scale vertical velocities relative to typical horizontal velocities a direct observation of the large scale vertical air velocity is extremely difficult in a case study on observational material obtained during a 68 h experiment using the sousy very high frequency vhf radar in the harz mountains in germany the authors present the first intercomparison between three different sources of physical information that can provide large scale vertical wind velocities i the doppler shifts observed with a vertically pointing vhf radar ii the rates of change of the altitudes of refractiveindex discontinuities as identified with frequency domain interferometry fdi which is still a relatively unexplored technique in meteorology and iii the output of a regional numerical weather prediction model nwpm which has been set up to model the meteorological situation during the observational period there are several phenomena that have been known to possibly cause significant biases in mean vertical velocities retrieved from the doppler shifts measured with vertically pointing clear air vhf radars i stationary or nonstationary gravity waves with vertical velocity amplitudes up to the order o f1ms 21 ii stationary or horizontally advected tilted refractive index discontinuities that are aspect sensitive in the vhf regime and iii a correlation between the radar reflectivity fluctuations and the vertical velocity fluctuations within a vertically propagating gravity wave on the basis of an intercomparison between the vertical velocities retrieved from i standard doppler vhf radar observations ii vhf fdi observations and iii the nwpm output the authors present first evidence that under ideal conditions vhf fdi can be used to directly monitor large scale vertical motion

grus weathering mantles problems of interpretation abstract grus is an ill defined product of deep weathering of coarse grained rocks whose relationships to other weathering changes remain unclear this paper attempts to address this issue by reviewing a number of examples of coarse saprolites from a variety of climatic and topographic settings grus is the category of weathering mantle that possesses the following characteristics sand gravel 75 100 silt clay

tropical spodosols in northeastern amazonas state brazil abstract the white sand formation found in northeastern amazonas state in brazil showed three horizons e b and c the superficial horizon e was formed by sandy friable material of grayish to whitish colour with accumulations of organic matter in the form of wavy bands the b horizon remained essentially sandy but showed a pale yellowish to orangish colour the c horizon was friable with pink to creamy clayey sandy materials in the contact zone between horizons b and c occurred an enrichment of organic matter forming ortsteins the profile structure the upward increasing of quartz grains corrosion and the predominance of quartz in the e horizon and thus of io 2 instead of kaolinite al 2 o 3 fe 2 o 3 and tio 2 that were more abundant in the c horizon suggest that the white sands are the product of podzolization soil horizonation and accumulation of organic matter are governed by the active decomposition of the forest litter these data also allow us to relate the spodosols with the mottled and the saprolitic horizons of truncated lateritic profiles of the alter do chao formation this process of podzolization which continues up to the present moment is very aggressive since the studied profiles have developed in less than 3000 years and beneath the modern forest

micromorphology and chemical weathering of a k rich trachyandesite and an associated sedimentary cover parkes se australia abstract the micromorphology composition and sequential formation of weathering products of a k rich trachyandesite and an associated sedimentary cover at parkes se australia are described this has been achieved using a combination of mineralogical optical x ray microdiffraction and sem edxa microanalysis and chemical x ray fluorescence techniques the weathering profiles have developed in a low altitude relatively flat landscape setting the following processes are dominant a weathering of primary minerals notably feldspars and micas to transient poorly crystalline oxyhydroxide patches smectite and ultimately kaolinite b weathering of sediments in a zone of intense solution activity and redox reactions resulting in development of mottles and ferruginous nodules and c greater thickness up to 350 cm and compositional differences between the soil over weathered sediments and in situ weathered bedrock the dominant profile microsystems evolved under a past humid climate later modified by the prevailing semi arid to arid conditions

average vertical motions in the tropical atmosphere observed by a radar wind profiler on pohnpei 7 n latitude 157 e longitude abstract average vertical profiles of the vertical wind obtained under clear sky conditions as weal as under conditions of both light to moderate and heavy rainfall am presented from data obtained using a radar wind profiler located on the island of pohnpei latitude 7 n longitude 157 e the average profiles for the precipitation conditions were obtained insofar as possible under conditions similar to those present within the stratiform and convective regions of tropical mesoscale convective complexes comparison between the vertical wind profiles obtained from the wind profiler and vertical wind profiles obtained earlier by wore conventional methods i e deduced from the convergence divergence of mesoscale horizontal winds shows that while the general features of the profiles obtained by both techniques are similar the profiler results exhibit somewhat more detail the profiler is able to resolve long term average vertical motions down to the cm s 1 subsidence that occurs under clear air condi

kelvin helmholtz instability around the tropical tropopause observed with the equatorial atmosphere radar 1 in november 2001 the equatorial atmosphere radar 0 20 s 100 32 e observed a continuous strong eastward wind shear 10 50 m s 1 km 1 westward wind 2 27 m s 1 and the radar echo layer tilted downward to the west in the region 0 1 km above the tropopause during the same period the richardson number calculated with hourly averaged horizontal wind and radiosonde temperature data was almost continuously 0 5 and sometimes 0 25 which seems to indicate that the kelvin helmholtz instability khi frequently occurs in that region the existence of the tilted radar echo layer can be explained by khi billows a spurious updraft caused by the khi induced tilted echo layer and by the strong westward wind was also observed in the region

changes in shear wave splitting before the 2010 eyjafjallajokull eruption in iceland summary we use shear wave splitting sws above microearthquakes to monitor stress variations before the 2010 march and april flank and summit eruptions of eyjafjallaj okull volcano in iceland sws time delays before eyjafjallaj okull show characteristic variations similar to those seen before earthquakes the time delays display a nearly linear increase before the eruption an abrupt change of slope and a rapid nearly linear decrease until the flank eruption begins similar variations before earthquakes are interpreted as stress accumulation increases and stress relaxation decreases as microcracks coalesce onto the eventual fault plane the changes in sws before eyjafjallaj okull are interpreted as a similar stress accumulation increase as magma penetrates the crust and stress relaxation decrease as microcracks coalesce onto the magma conduit prior to magma release we suggest that the remarkable similarity between stress changes before eruption and earthquake is strong evidence for the new geophysics of a critically microcracked crust