flux and fate of small mountainous rivers derived sediments into the taiwan strait article i nfo high resolution chirp sonar profiles across the taiwan strait reveal a large silt sand dominated deltaic clinoform up to 50 m thick overlying the postglacial transgressive sea floor across the southeastern central and northern strait delta like configuration and internal depositional sequences indicate a northwestward progradation from western taiwan primarily from the choshui zhuoshui river grain size and mineral data confirm the sediment s taiwanese derivation the chirp profiles together with existing radiocarbon and geomagnetic dates suggest that the clinoform has formed over the past 10 kyr the estimated volume of 375 km 3 of sediment mainly sand and silt suggests a mean annual accumulation of 60 10 6 t yr presumably much of fine mud delivered by taiwanese rivers has been washed away by the local currents and escaped either northeastward into the southern okinawa trough or southward into the south china sea numerous shallow borings onshore over the central western taiwan coastal plain reveal an additional 350 km 3

late pleistocene holocene paleoproductivity circulation in the japan sea sea level control on δ13c and δ15n records of sediment organic material organic carbon and total nitrogen contents and their isotope ratios were determined in a sediment core recovered from the japan sea to investigate the record of organic matter resources and paleoproductivity in a semi enclosed marginal sea 13c 15n relationships show that the composition of sediment organic material resulted from the mixing of terrestrial and marine organic matter we found synchronous down core variations in the carbon and nitrogen isotope records which are explained by surface productivity control on the composition of sediment organic material moreover these variations are related to sea level changes which caused variable surface water inflows last glacial sea level lowering increased continental run off leading to water column stratification in the japan sea anaerobic conditions due to basin water stagnation led to the deposition of laminated clay sediment organic c n and isotope ratios fluctuated markedly in the transitional stage from aerobic to anaerobic conditions the fluctuations are likely to have been caused by large scale oscillations in sea level just before the last glacial maximum

observed dynamics of coastal flow at cape mendocino during coastal waves 1996 abstract airborne in situ and remote meteorological measurements from around cape mendocino california sampled during the coastal waves 1996 field program are analyzed for three different days 7 12 and 26 june 1996 two days conformed to typical summertime conditions with a strong northerly downcoast flow while the wind on the third day was weaker on the first 2 days the flow was supercritical in the sense that the froude number was larger than unity and these 2 days feature expansion fans in the lee of the cape on the third day no such phenomenon was observed all 3 days had a strong thermal wind caused by the marine inversion sloping down toward the coast on the first 2 days the flow aloft was westerly or northerly so that the thermal wind added to the background flow results in a strong jet on the third day the flow aloft was southerly and consequently even with the added thermal wind the northerly flow in the marine layer was too weak to be supercritical the main difference between t

model dependent 10be sedimentation rates for the taiwan strait and their tectonic significance in a new method to estimate the sedimentation rate along continental margins we made use of a model in which the 10 be in the sediment is considered as a mixture of terrigenous and pelagic components this method does not depend directly on radioactive decay it has many advantages over conventional techniques and is especially suitable for areas undergoing rapid deposition sedimentation rates on the continental shelf around taiwan obtained by this method compare favorably with those from 14 c dating our estimated rates for modern basins in the taiwan strait are comparable to the rates in the paleobasins now on land in taiwan this similarity suggests that the arc continent collision on the east side of taiwan has been driving a migration of its western shoreline toward mainland china

a shallow convection parameterization for mesoscale models part ii verification and sensitivity studies abstract formulations describing a new shallow convection parameterization intended for mesoscale models have been described in a companion paper part i in the present paper the convection scheme is tested and evaluated against observed datasets in both marine and continental environments additional experiments explore the sensitivity of the scheme to changes in model vertical resolution key parameters of the closure and the cloud dissipation mechanisms the new shallow convection scheme uses a hybrid mass flux closure that adjusts linearly between two closure options based on i boundary layer turbulent kinetic energy tke for very shallow clouds and ii convective available potential energy cape for deep clouds meanwhile cloud mass detrained from convective updrafts acts as the source for a second class of subgrid clouds having nearly neutral buoyancy which can persist for hours performance of the convection submodel is found to be quite reasonable in four cases covering a range of conditi

tropical cyclone driven erosion of the terrestrial biosphere from mountains the transfer of organic carbon from the terrestrial biosphere to the oceans via erosion and riverine transport constitutes an important component of the global carbon cycle measurements of particulate organic carbon load and composition in the liwu river taiwan during cyclone triggered floods suggest that tropical cyclones may facilitate the delivery of non fossil particulate organic carbon to the ocean and its subsequent burial the transfer of organic carbon from the terrestrial biosphere to the oceans via erosion and riverine transport constitutes an important component of the global carbon cycle1 2 3 4 more than one third of this organic carbon flux comes from sediment laden rivers that drain the mountains in the western pacific region3 5 this region is prone to tropical cyclones but their role in sourcing and transferring vegetation and soil is not well constrained here we measure particulate organic carbon load and composition in the liwu river taiwan during cyclone triggered floods we correct for fossil particulate organic carbon using radiocarbon and find that the concentration of particulate organic carbon from vegetation and soils is positively correlated with water discharge floods have been shown to carry large amounts of clastic sediment6 non fossil particulate organic carbon transported at the same time may be buried offshore under high rates of sediment accumulation7 8 9 we estimate that on decadal timescales 77 92 of non fossil particulate organic carbon eroded from the liwu catchment is transported during large cyclone induced floods we suggest that tropical cyclones which affect many forested mountains within the intertropical convergence zone10 may provide optimum conditions for the delivery and burial of non fossil particulate organic carbon in the ocean this carbon transfer is moderated by the frequency intensity and duration of tropical cyclones

estimation of entrainment rate in simple models of convective clouds a method for estimating lateral entrainment rate in clouds is suggested linking its magnitude to buoyant production of vertical kinetic energy within a cloud updraught in single column model studies the formulation captures the high values of entrainment seen in shallow convection and the values an order of magnitude lower in cases of deep convection as suggested by observational studies and large eddy model simulations together with a realistic vertical variation comparison is made with other recent attempts to parametrize entrainment

upper ocean currents around taiwan abstract current velocity measured by shipboard acoustic doppler current profiler sb adcp during 1991 2000 was used to study the upper ocean the composite and moored currents revealed a branch of the kuroshio that intruded steadily and persistently into the south china sea part of the intruded kuroshio flowed out of the south china sea through the northern luzon strait and re united with the main stream kuroshio the kuroshio had two velocity maximum cores southeast of taiwan but gradually combined into one as the kuroshio flowed north the kuroshio was deflected by the i lan ridge east of taiwan and the zonal running shelf break northeast of taiwan at the shelf break the kuroshio split with one branch intruding onto the shelf west of the luzon strait the kuroshio intruded into the south china sea some water flowed northward into the taiwan strait and re joined the kuroshio currents in the taiwan strait flowed primarily in a northward direction except for the southward current near the coast of mainland china north of the taiwan strait a branch of the northward flow followed the northern coast of taiwan to join the kuroshio the composite current varied consistently from season to season there was generally poor correlation between currents and local winds especially in the deep water regime remote forces were important in the currents around taiwan

terrestrial organic carbon accumulation on the amazon deep sea fan during the last glacial sea level low stand abstract sediment cores from the amazon deep sea fan recovered during r v meteor cruise 16 2 show in detail the modern areal distribution of sedimentary organic carbon stable organic carbon isotopes of the organic matter om as well as variations in the depositional processes in addition we studied up to 300 m long drilled sediment records recovered during odp leg 155 which allow evaluation of temporal variations on the amazon fan our results reveal new evidence for a very rapid change of fan depositional processes and organic carbon source at times of sea level change over the middle and lower amazon fan to estimate the amount of terrestrial organic carbon stored in sediments from the last glacial in the amazon fan we used stable organic carbon isotopes of the om 13 c org organic carbon content corg and age models based on oxygen isotopes faunal data and magnetic excursions following our results the organic carbon accumulation on the amazon deep sea fan is controlled by glacio eustatic sea level oscillations interglacial sea level high stand sediments are dominated by marine om whereas during glacial sea level low stands terrestrial organic carbon is transported beyond the continental shelf through the amazon canyon and deposited directly onto the amazon deep sea fan glacial sediments of the amazon fan stored approximately 73 1015 g terrestrial corg in 20 000 years or 3 7 1012 g terrestrial corg yr 1 equivalent to 7 12 of the riverine organic carbon discharge assuming constant paleo discharge which is about the same amount of terrestrial organic carbon as deposited on the amazon shelf today 3 1 1012 g terrestrial corg yr 1 or 6 10 of the modern riverine organic carbon discharge

cloudiness and marine boundary layer dynamics in the astex lagrangian experiments part i synoptic setting and vertical structure abstract a goal of the atlantic stratocumulus transition experiment astex southeast of the azores islands in the east central atlantic ocean during june 1992 was to examine the coupled evolution of cloud dynamical and thermodynamical vertical structure in a marine boundary layer mbl air mass as it advected from cold to warm water in the trade winds in two lagrangian observation periods during astex an unprecedentedly complete view of mbl and cloud evolution was achieved by nearly continuous aircraft coverage of such an air mass for 36 48 hours using three boundary layer aircraft supplemented by satellite ship and balloon observations during the first lagrangian period an accelerated stratocumulus to trade cumulus transition occurred in a clean marine air mass in the second lagrangian period a 200 hpa deep decoupled modified continental mbl persisted with almost no change in structure cumulus rising into intermittent stratocumulus were observed throughout the period the two contrasting a

world wide delivery of river sediment to the oceans new data and new estimates from old data show that rivers with large sediment loads annual discharges greater than about 15 times 10 6 tons contribute about 7 times 10 9 tons of suspended sediment to the ocean yearly extrapolating available data for all drainage basins the total suspended sediment delivered by all rivers to the oceans is about 13 5 times 10 9 tons annually bedload and flood discharges may account for an additional 1 2 times 10 9 tons about 70 of this total is derived from southern asia and the larger islands in the pacific and indian oceans where sediment yields are much greater than for other drainage basins

source mechanism of vulcanian degassing at popocatepetl volcano mexico determined from waveform inversions of very long period signals 1 the source mechanism of very long period vlp signals accompanying volcanic degassing bursts at popocatepetl is analyzed in the 15 70 s band by minimizing the residual error between data and synthetics calculated for a point source embedded in a homogeneous medium the waveforms of two eruptions 23 april and 23 may 2000 representative of mild vulcanian activity are well reproduced by our inversion which takes into account volcano topography the source centroid is positioned 1500 m below the western perimeter of the summit crater and the modeled source is composed of a shallow dipping crack sill with easterly dip of 10 intersecting a steeply dipping crack northeast striking dike dipping 83 northwest whose surface extension bisects the vent both cracks undergo a similar sequence of inflation deflation and reinflation reflecting a cycle of pressurization depressurization and repressurization within a time interval of 3 5 min the largest moment release occurs in the sill showing a maximum volume change of 500 1000 m3 pressure drop of 3 5 mpa and amplitude of recovered pressure equal to 1 2 times the amplitude of the pressure drop in contrast the maximum volume change in the dike is less 200 300 m3 with a corresponding pressure drop of 1 2 mpa and pressure recovery equal to the pressure drop accompanying these volumetric sources are single force components with magnitudes of 108 n consistent with melt advection in response to pressure transients the source time histories of the volumetric components of the source indicate that significant mass movement starts within the sill and triggers a mass movement response in the dike within a few seconds such source behavior is consistent with the opening of a pathway for escape of pent up gases from slow pressurization of the sill driven by magma crystallization the opening of this pathway and associated rapid evacuation of volcanic gases induces the pressure drop pressure recovery in the magma filling the sill is driven by diffusion of gases from the resulting supersaturated melt into bubbles assuming a penny shaped crack at ambient pressure of 40 mpa the observed pressure and volume variations can be modeled with the following attributes crack radius 100 m crack aperture 5 m bubble number density 1010 1012 m 3 initial bubble radius 10 6 m final bubble radius 10 5 m and net decrease of gas concentration in the melt 0 01 wt

transport of terrestrial organic carbon to the oceans by rivers re estimating flux and burial rates this study re estimates one important component in the global carbon cycle the modern global fluviatile organic carbon discharge and burial rates according to these results approximately 430 1012 g of terrestrial organic carbon are transported to the ocean in modern times this amount is higher than the latest estimates but takes into account new data from oceania not previously considered in global flux studies however only the minor amount of 10 or approximately 43 1012 gc year 1 is most likely buried in marine sediments this amount is similar to the burial of marine organic carbon in the coastal ocean 55 1012 gc year 1 adding both estimates gives approximately 100 1012 gc year 1 which is the value calculated by berner 1982 for terrestrial deltaic shelf sediments however the results in this study suggest that on a global scale the organic carbon content in coastal ocean sediments is not solely of terrestrial origin but a mixture of nearly equal amounts of marine and terrestrial organic carbon the major part of the terrestrial organic carbon that enters the ocean by rivers approximately 400 1012 gc year 1 seems to be either a remineralised in the ocean whereas the mechanism by which the terrestrial organic carbon is oxidised in the ocean are unknown or b is dispersed throughout the oceans and accumulates in pelagic sediments

direct observations of atmospheric boundary layer response to sst variations associated with tropical instability waves over the eastern equatorial pacific tropical instability waves tiws with a typical wavelength of 1000 km and period of 30 days cause the equatorial front to meander and result in sst variations on the order of 18 28c vertical soundings of temperature humidity and wind velocity were obtained on board a japanese research vessel which sailed through three fully developed sst waves from 1408 to 1108w along 28n during 21 28 september 1999 a strong temperature inversion is observed throughout the cruise along 28n capping the planetary boundary layer pbl that is 1 1 5 km deep temperature response to tiw induced sst changes penetrates the whole depth of the pbl in response to an sst increase air temperature rises in the lowest kilometer and shows a strong cooling at the mean inversion height as a result this temperature dipole is associated with little tiw signal in the observed sea level pressure slp the cruise mean vertical profiles show a speed maximum at 400 500 m for both zonal and meridional velocities sst based composite profiles of zonal wind velocity show weakened intensified vertical shear within the pbl that is consistent with enhanced reduced vertical mixing causing surface wind to accelerate decelerate over warm cold ssts taken together the temperature and wind soundings indicate the dominance of the vertical mixing over the slp driving mechanism based on the authors measurements a physical interpretation of the widely used pbl model proposed by lindzen and nigam is presented

an observational study of the structure of stratiform cloud sheets part i structure results from six flights with an instrumented aircraft in marine stratiform cloud topped boundary layers are presented the flights took place around the u k in a variety of conditions both during the day and at night the data comprise simultaneous high resolution turbulence cloud microphysics and radiation measurements on five of the flights turbulent mixing in the cloud layer was found to be primarily maintained by convection resulting from cloud top radiative cooling in four cases this mixed layer was observed to be decoupled from the surface i e the cloud induced mixing did not extend down to the surface and the cloud formed part of a detached turbulent layer one flight in high surface wind conditions displayed a significantly different structure possible reasons for this are suggested the mean microphysical features of the different cloud layers are compared as are the measured and theoretically calculated radiation fluxes the latter show good general agreement but some systematic differences are apparent again possible causes of these disparities are discussed features of the turbulent velocity field are presented and a number of similarities between data from the convective cases and cloud free boundary layers driven by heating from below are found values of the entrainment velocity are estimated directly from the measured cloud top water fluxes in all but one case together with an estimate of the errors incurred the measured vertical turbulent fluxes are found to be reasonably well predicted by diagnostic mixed layer models using the measured boundary conditions as long as the heights of the mixed layer boundaries are also specified from observations such a model is also used to help explain the main observed features of the mixed layer structure and the differences between the various cases

lagrangian evolution of the northeast pacific marine boundary layer structure and cloud during cset abstractflight data from the cloud system evolution over the trades cset campaign over the pacific stratocumulus to cumulus transition are organized into 18 lagrangian cases suitable for study an

the coastal depositional system of a small mountainous river a perspective from grain size distributions abstract tseng wen river is a small mountainous river on a wave dominated coast of taiwan the spatial distribution patterns of 17 individual grain sizes offshore near the river mouth show strong morpho textural relationships with the bathymetry which also vary considerably according to the grain size the influence of seven hypothetical factors that could affect the observed grain size patterns were examined individually by using a methodology that combines filtering concept and a multivariate analysis technique eof these factors include the sediments discharged by the river offshore palimpsest sediments sediments eroded from a submarine sand ridge and the remnant river delta the effect of wave sorting and the northward and southward littoral drift the study results indicate that the tseng wen river is the most important source for modern sediments in the study area the reworking of offshore palimpsest sediments is also an important sediment source the agitation by waves is an important sorting mechanism in the study area and the net sediment transport in the study area is northward the findings based on grain sizes are also corroborated by short term observations of the near bed sediment dynamics and transport during the flood season of the tseng wen river

the structure of gradually transforming marine stratocumulus during the astex first lagrangian experiment summary an analysis of the mean and turbulent structure of the planetary boundary layer is presented using aircraft data obtained during the atlantic stratocumulus transition experiment e rst lagrangian experiment the analysis of the mean vertical structure relies mostly on slant proe le data however part of the analysis also uses socalled porpoise runs in the vicinity of the cloud top the analysis of the turbulence structure utilizes all of the data horizontal eight legs as well as slant proe les and presents both scaled turbulence statistics and a spectral analysis the purpose is to investigate details in the temporal development of the e rst lagrangian experiment and to study the turbulent structure in order to e nd scale relations that can be utilized in improved modelling of the stratocumulus capped boundary layer the hypothesis is that so called cloud decoupling has a signie cant impact on the turbulence scaling the measured cloud water is corrected to become consistent between the two participating aircraft the corrected maximum cloud water is more constant in time than in previous studies of the erst lagrangian it is suggested that previously analysed temporal variability may be an artefact of using two different instruments to measure cloud water the cloud top jump in equivalent potential temperature is positive in the erst three eights sufe ciently large for a stable cloud top but decreases and becomes negative for the last two eights in line with the breaking up of the cloud eeld the upper part of the boundary layer warms and dries more rapidly than the lower suggesting entrainment to be a dominant factor in the development of the cloud the analysis of the porpoise e ight legs illustrates how sharp features at the cloud top inversion are smoothed out while analysing several proe les eight legs or even entire eights rather than normalizing each proe le with the height to the local cloud top scaling of the turbulent e uxes and the velocity variances shows that the cloud layer is decoupled throughout almost the entire erst lagrangian it is also shown that while surface layer scaling is appropriate for the marine atmospheric boundary layer mabl the cloud layer turbulence scales with convective scaling the lowfrequency spectrum has no spectral gap with the exception of the vertical velocity and continues to increase with decreasing frequency with only a change in slope this indicates the presence of mesoscale motions the cospectra of the turbulent euxes are very noisy throughout when averaging several spectra into height intervals the scales of the turbulence as indicated by the peak in the averaged spectra appear to vary with height above the surface in the mabl but to be height independent in the cloud layer an attempt to calculate a dissipation length scale shows scatter but is consistent with a dissipation length scale increasing linearly with height in the mabl but being roughly constant or possibly parabolic with height in the cloud layer

dynamics of cumulus rising into stratocumulus as observed during the first lagrangian experiment of astex the atlantic stratocumulus transition experiment took place during june 1992 in the eastern atlantic ocean in an area extending south east of the azores to madeira one of the goals of this experiment was to study the physical processes responsible for the transition from stratocumulus to shallow cumulus clouds the cloud type most frequently observed was cumulus rising into stratocumulus two lagrangian experiments were carried out to study the evolution of the boundary layer and to observe any transition in the cloud characteristics downstream here we concentrate on the last flight of the first lagrangian experiment during which cumulus cloud was penetrating thin and broken stratocumulus from below the immediate cause of the cumulus convection was condensation at the top of the well mixed surface based boundary layer the lifting condensation level was observed to be at about 500 m and above this height there was a conditionally unstable layer up to 1600 m in the upper part of the conditionally unstable layer the horizontally averaged thermodynamical variables showed that the air was very close to saturation indicating that the upper part of the cloud deck consisted of broken clouds the vertical structure of mean variables variances fluxes and turbulent kinetic energy budget is discussed one of the findings is that the cumulus convection is an important factor in counteracting the gradual dissipation of the stratocumulus deck in that it supplies moisture to the latter furthermore the net longwave radiative loss at cloud top was observed to be about 40 15 w m 2 which tended to destabilize the cloud layer from above the skewness factor s showed that the upward convection was quite intense owing to the rising cumuli the factor s reaching a maximum of about 2 0 7 in the middle of the cloud layer the skewness was found to be slightly negative near the cloud top

regional model simulations of marine boundary layer clouds over the southeast pacific off south america part ii sensitivity experiments abstract the sensitivity of a regional climate model to physical parameterizations and model resolution is investigated in terms of its simulation of boundary layer stratocumulus scu clouds over the southeast pacific specifically the physical schemes being tested include shallow cumulus convection subgrid vertical mixing cloud droplet number concentration cdnc and drizzle as described in part i the model with standard settings captures the major features of the boundary layer in the region including a well mixed marine boundary layer a capping temperature inversion scu clouds and the boundary layer regime transition from the well mixed layer near the coast of south america to a decoupled cloud layer over warmer water to the west turning off the shallow cumulus parameterization results in a dramatic increase in the simulated scu clouds while the boundary layer structure becomes unrealistic losing the decoupled regime over warm water with reduced penetrative mixing at the top of shallow cu

burial of terrestrial organic matter in marine sediments a re assessment 1 calculations based on recent observations indicate that approximately one third of the organic matter presently being buried in marine sediments may be of terrestrial origin with the majority of this terrestrial organic matter tom burial occurring in muddy deltaic sediments these calculations further suggest that the remineralization of terrestrial organic matter in the oceans is also much less efficient than that of marine organic matter these two underappreciated observations have important implications in terms of our understanding of the controls on the global carbon cycle from a paleoceanographic perspective the results presented here also suggest that changes in tom burial on glacial interglacial timescales have the potential to impact the global carbon cycle i e atmospheric co2 levels

a buoyancy based mixing length proposal for cloudy boundary layers the parametrization of boundary layer clouds is approached here using a turbulence kinetic energy closure in conservative variables for non precipitating processes and through a new proposal for the turbulence mixing length a subgrid condensation scheme able to treat partially saturated conditions in a model grid cell is also necessary an extension of the buoyancy based bougeault lacarrere mixing length is proposed to take into account moist processes and specifically the effects of phase changes the asymmetry between upward and downward mixing processes is also considered for partial cloudiness conditions the new proposal is tested for stratocumulus capped marine boundary layers and for shallow cumulus convection both over land and sea the validation ismade against large eddy simulation results obtained from model intercomparison cases for stationary regimes as a first step and then for the diurnal evolution of marine stratocumulus and shallow convection over land copyright 2004 royal meteorological society

diagnosing monthly mean boundary layer properties from reanalysis data using a bulk boundary layer model abstract the mixed layer approach to modeling the planetary boundary layer pbl is particularly well suited to inversion topped pbls such as the stratocumulus topped boundary layer found off the west coast of america in the subtropical pacific ocean at northern and southern latitudes however a strong temperature inversion near 850 hpa the trade wind inversion is not confined to the stratocumulus regimes but has been observed over most parts of the subtropical tropical pacific ocean in this paper the authors test the ability of a simple bulk boundary layer model bblm to diagnose entrainment velocity cumulus mass flux and surface latent heat flux from monthly mean reanalysis data the pbl depth is estimated from geoscience laser altimeter system data the model is based on the conservation equations for mass total water mixing ratio and moist static energy the bblm diagnoses entrainment velocities between 1 and 8 mm s 1 in the stratocumulus and trade wind regions with increasing rates towar

simulation of seasonal variation of marine boundary layer clouds over the eastern pacific with a regional climate model abstractthe seasonal cycle of marine boundary layer mbl clouds over the eastern pacific ocean is studied with the international pacific research center iprc regional atmospheric model iram the results show that the model is capable of simulating not only the overall seasonal cycle but also the spatial distribution cloud regime transition and vertical structure of mbl clouds over the eastern pacific although the modeled mbl cloud layer is generally too high in altitude over the open ocean when compared with available satellite observations the model simulated well the westward deepening and decoupling of the mbl the rise in cloud base and cloud top of the low cloud decks off the peru and california coasts and the cloud regime transition from stratocumulus near the coast to trade cumulus farther to the west in both the southeast and northeast pacific in particular the model reproduced major features of the seasonal variations in stratocumulus decks off the peru and california coasts includin

deep sea terrigenous organic carbon transfer and accumulation impact of sea level variations and sedimentation processes off the ogooue river gabon abstract sedimentary isotopic and bulk geochemical proxies measured in sediment samples of five gravity cores collected in the distal part of the ogooue turbidite system around 4000 m depth were used to develop a conceptual model to describe the accumulation of terrigenous organic matter om during the last 200 000 yrs bp in the eastern part of the gulf of guinea this model takes into account the influence of the different depositional processes turbiditic vs hemipelagic sedimentation geomorphological features and sea level variations total organic carbon toc and the stable organic carbon isotopes of the om 13 c variability follow the highstand lowstand interglacial glacial cyclicity with a very low accumulation rate of terrigenous om during periods of high sea level and higher accumulation rate during period of low sea level a sea level of 80 120 m below present day seems to favor the transfer of terrigenous sediments to the deep offshore environment through the turbidite system and thanks to the connection of the canyons heads with the river system presently located at the shelf edge at 120 m water depth in this system terrigenous om matter delivered by the river accumulate in the sediments via two main processes indeed a part of the terrigenous om settles in combination with the finest particles forming hemipelagites while another part formed of very well preserved land plant debris is transported and deposited far offshore with turbidity currents the proportion of terrigenous om accumulated due to turbidity currents is important as it can represent more than 70 of the carbon accumulated during sea level lowstand moreover terrigenous om seems to preferentially accumulate in the levees and the lobes of the system notably due to the higher frequency of organic rich turbidites this study demonstrates that gravity flows influenced by the sea level variations can significantly affect the terrigenous om budget of the deep offshore atlantic margins and that channel levee complexes as well as turbidite lobes can be regarded as good sink for terrestrial organic carbon these processes should be taken into consideration in the context of source rocks exploration but also for the estimation of the general carbon accumulation in ocean sediment

geomorphic tectonic control of sediment discharge to the ocean the importance of small mountainous rivers analysis of data from 280 rivers discharging to the ocean indicates that sediment loads yields are a log linear function of basin area and maximum elevation of the river basin other factors controlling sediment discharge e g climate runoff appear to have secondary importance a notable exception is the influence of human activity climate and geology on the rivers draining southern asia and oceania sediment fluxes from small mountainous rivers many of which discharge directly onto active margins e g western south and north america and most high standing oceanic islands have been greatly underestimated in previous global sediment budgets perhaps by as much as a factor of three in contrast sediment fluxes to the ocean from large rivers nearly all of which discharge onto passive margins or marginal seas have been overestimated as some of the sediment load is subaerially sequestered in subsiding deltas before the proliferation of dam construction in the latter half of this century rivers

the vertical turbulence structure of the coastal marine atmospheric boundary layer the vertical turbulence structure in the marine atmosphere along a shoreline has been investigated using data from tower and aircraft measurements performed along the baltic coast in the southeast of sweden two properties make the baltic sea particularly interesting it is surrounded by land in all directions within moderate advection distances and it features a significant annual lag in sea surface temperature as compared with inland surface temperature the present data were collected mostly during spring or early summer when the water is cool i e with a stably or neutrally stratified marine boundary layer usually capped by an inversion substantial daytime heating over the land area results in a considerable horizontal thermal contrast measurements were made on a small island on a tower with a good sea fetch and with an airborne instrument package the profile data from the aircraft is from 25 slant soundings performed in connection to low level boundary layer flights the results from the profiles are extracted through filtering techniques on individual time space series individual profiles applying different normalization and finally averaging over all or over groups of profiles the land based data are from a low tower situated on the shoreline of a small islandmore with a wide sector of unobstructed sea fetch several factors are found that add to the apparent complexity of the coastal marine environment the state of the sea appears to have a major impact on the turbulence structure of the surface layer jet shaped wind speed profiles were very common at the top of the boundary layer in about 50 of the cases and distinct layers with increased turbulence were frequently found well above the boundary layer in about 80 of the cases the present paper will concentrate on a description of the experiment the analysis methods and a general description of the boundary layer turbulence structure over the baltic sea 40 refs 16 figs 2 tabs less

observations of diurnal variation in a cloud capped marine boundary layer abstract observations are presented of the turbulent structure of a cloud capped boundary layer during the 1987 fire marine stratocumulus project the measurements were made from san nicolas island off the coast of california using instruments attached to the cable of a tethered balloon a marked diurnal variation is demonstrated through a direct comparison of observations made around local noon and approximately 12 hours later emphasis is given to the decoupling of the boundary layer during the morning into a separate cloudy layer and surface mixed layer

marine stratocumulus layers part 1 mean conditions abstract the mean radiational dynamical and thermodynamical structure of the marine stratocumulus topped mixed layers of the california coast is described for two days in june 1976 using data from the ncar electra aircraft we suggest that the synoptic conditions found may be typical of about half of the shallow stratocumulus topped boundary layers that occur in this region during summer the inversion was low near the coast and increased in height to the west consistent with the average westward increase in sea surface temperature north south inversion height change was largely due to entrainment and mean mesoscale vertical motions below the inversion strong winds 12 20 m s 1 from the north and horizontal inhomogeneities resulted in large advection terms in mean field equations the sloping inversion often produced large vertical shears of the actual and geostrophic wind velocities across the inversion because of low liquid water contents 0 1 g kg 1 temperature and water vapor could be measure

accumulation of terrestrial organic carbon on an active continental margin offshore southwestern taiwan source to sink pathways of river borne organic particles abstract sediment samples 213 sites collected from the tectonic active continental margin offshore southwestern taiwan were analyzed for grain sizes organic carbon nitrogen and carbon isotopic composition to obtain mass accumulation rate of terrestrial organic carbon and carbon budget to evaluate fate of terrestrial organic carbon from small mountainous rivers on the continental margin offshore southwestern taiwan terrestrial organic carbon accumulation rates range from 0 29 to 45 6 g c m 2 yr 1 with a total accumulation budget of 0 063 mt yr 1 which accounts for less than 13 of total river particulate organic carbon loads exported from the adjacent rivers the gaoping a k a kaoping erhjen and tsengwen rivers this low burial efficiency of terrestrial organic carbon demonstrated that a majority of river borne particles together with organic materials was moved away from the study area for the river borne particles from the gaoping river a pair of depocenters in the upper slope flanking the gaoping submarine canyon are the locations where the maximum tc org accumulation rate were observed which hold up to 45 0 016 mt yr 1 of the calculated accumulation found in the study region on the other hand the occurrence of higher fraction terrestrial organic carbon in the upper and middle gaoping submarine canyon suggests that a majority of particulate organic carbon of the gaoping river was transported directly into the deep sea basin through the gaoping submarine canyon our results demonstrated that active margin with narrow shelf and slope is not an efficient sink for the large amount of terrigenous organic carbon supplied by the small rivers but a transient environment for these river derived particles

a new boundary layer mixing scheme part i scheme description and single column model tests a new boundary layer turbulent mixing scheme has been developed for use in the ukmo weather forecasting and climate prediction models this includes a representation of nonlocal mixing driven by both surface fluxes and cloud top processes in unstable layers either coupled to or decoupled from the surface and an explicit entrainment parameterization the scheme is formulated in moist conserved variables so that it can treat both dry and cloudy layers details of the scheme and examples of its performance in single column model tests are presented

a cloud resolving model with an adaptive vertical grid for boundary layer clouds abstractaccurate cloud resolving model simulations of cloud cover and cloud water content for boundary layer clouds are difficult to achieve without vertical grid spacing well below 100 m especially for inversion topped stratocumulus the need for fine vertical grid spacing presents a significant impediment to global or large regional simulations using cloud resolving models including the multiscale modeling framework mmf in which a two dimensional or small three dimensional cloud resolving model is embedded into each grid cell of a global climate model in place of more traditional cloud parameterizations one potential solution to this problem is to use a model with an adaptive vertical grid i e a model that is able to add vertical layers where and when needed rather than trying to use a fixed grid with fine vertical spacing throughout the boundary layer this article examines simulations with an adaptive vertical grid for three well studied stratocumulus cases based on observations from the sec

finescale structure and microphysics of coastal stratus observations were made of unbroken marine stratus off the coast of oregon using the combined capabilities of in situ probes and a 95 ghz radar mounted on an aircraft reflectivity and doppler velocity measurements were obtained in vertical and horizontal planes that extend from the flight lines data from three consecutive days were used to examine echo structure and microphysics characteristics the clouds appeared horizontally homogeneous and light drizzle reached the surface in all three cases radar reflectivity is dominated by drizzle drops over the lower two thirds to four fifths of the clouds and by cloud droplets above that cells with above average drizzle concentrations exist in all cases and exhibit a large range of sizes the cells have irregular horizontal cross sections but occur with a dominant spacing that is roughly 1 2 1 5 times the depth of the cloud layer doppler velocities in the vertical are downward in all but a very small fraction of the cloud volumes the cross correlation between reflectivity and vertical doppler velocity changes sign at or below the midpoint of the cloud indicating that in the upper parts of the clouds above average reflectivities are associated with smaller downward velocities this correlation and related observations are interpreted as the combined results of upward transport of drizzle drops and of downward motion of regions diluted by entrainment the in situ measurements support these conclusions

boundary layer moisture regimes data from fifty two aircraft flight legs 100 150m above ground from hapex and fife are analysed to estimate characteristics of boundary layer moisture fluctuations in boundary layers with different bulk stability and surface energy regimes in hapex considerable effort was devoted to the quality of measurement of moisture fluctuations the data include repeated 120km flight legs flown at 150m over the same relatively homogeneous terrain allowing statistical examination of motion characteristics on horizontal scales up to 10km this study finds two prototype boundary layer regimes with significant boundary layer instability relatively weak surface evaporation and drier air aloft the entrainment drying boundary layer may develop this boundary layer is characterized by vertical divergence of the moisture flux and significant diffusion of dry air from the top downwards top down in this type of boundary layer dry air occasionally reaches the lower boundary layer leading to negative moisture skewness in spite of positive temperature and vertical velocity skewness associated with warm moist updraughts in contrast the moistening boundary layer associated with greater surface evaporation is characterized by positive moisture skewness near the surface in addition to the above turbulent moisture fluctuations some of the above data are characterized by 10km moisture variations with horizontal gradients often concentrated in narrow zones of horizontal convergence since corresponding signatures of vertical velocity and temperature are weaker these zones are referred to as mesoscale moisture fronts as a more general feature moisture variations on scales of 5km and greater are negatively correlated with temperature variations associated with cool moist regions and warm dry regions on scales of tens of kilometres and greater such negative correlation may be due to inhomogeneity of the surface energy budget the negative moisture temperature correlation leads to large mesoscale variations of relative humidity and the lifted condensation level

holocene tectonic uplift deduced from elevated shorelines eastern coastal range of taiwan abstract this paper is concerned with the tectonic trends that can be deduced from the holocene raised shorelines between ch eng kung and hsin she along a 65 km long coastal sector in the eastern coastal range of taiwan sequences of up to eight superimposed shorelines have been identified in a single section twelve new radiocarbon dates six of which were obtained by accelerator mass spectrometry of in situ marine samples up to 40 m in altitude have confirmed a holocene age however it is difficult to define clearly the upper marine boundary in the highest holocene coastal terraces which have been uplifted to 65 70 m but have been capped by and often also interfingered with alluvial deposits high uplift rates ranging from 2 5 3 0 to over 8 mm yr have been inferred along the coast providing evidence of differential uplift in some cases uplift movements appear to have occurred by steps probably spasmodically recurrence periods of fast uplifts seem to be of the order of at most 1000 yr this means that a new spasmodic movement may be imminent because the last displacement 4 6 m has been dated about 1000 yr bp

organic carbon fluxes to the ocean from high standing islands the transfer of terrestrially derived yet poorly quantified organic carbon to the oceans is an important yet unagreed upon proportion of the world s carbon budget the few data that exist suggest that high standing oceanic islands in the southwest pacific may make important contributions to the overall terrestrial flux of particulate organic carbon poc to the oceans we have determined the poc flux from several streams in new zealand with those data and previous measurements from taiwan and papua new guinea we estimate the poc flux from high standing islands in the southwest pacific to be 48 1012 g c yr 1 a value slightly lower than previous estimates these islands which make up only 3 of earth s landmass contribute 17 35 of the estimated poc entering the world s oceans annually and thus may be important sources of terrestrial carbon to the ocean anthropogenic activities especially deforestation and forest harvesting have probably exacerbated the natural flux few to no data exist for many of these islands and thus a more detailed assessment awaits further measurements

the structure of radiatively driven convection in stratocumulus data from a series of five research flights in marine stratocumulus are used to investigate the structure of radiatively driven free convective layers conditional sampling methods are used to determine the properties of the primary convective elements negatively buoyant downdraughts the turbulent velocity data are also subjected to spectral analysis and the turbulent kinetic energy tke balance is evaluated for each case results from each case are found to be very similar if scaled using appropriate mixed layer quantities downdraughts are selected using a criterion based on vertical velocity the distributions of their intersected widths at cloud top and the velocity spectra are consistent with downdraughts occupying narrow regions 0 1 0 15 h wide h being the mean mixed layer depth around the periphery of larger regular 0 5 h 0 75 h diameter updraughts as suggested by cellular patterns observed in the cloud tops downdraughts are found to carry over half of the total turbulent fluxes of heat and water substance within cloud and also transport variance down the mean gradients their thermodynamic properties are consistent with their containing a small fraction of air from above cloud top although their negative buoyancy is almost entirely due to the incorporation of radiatively cooled air the properties of the downdraughts near cloud top suggest they are formed primarily as a result of the local horizontal convergence of upwelling motions constrained by the inversion while being cooled radiatively these quasi horizontal motions scour the base of the inversion incorporating some drier air before being forced downwards in relatively narrow zones comparisons with other convective layers over land or sea suggest that convection in stratocumulus proceeds with a greater mass flux and correspondingly reduced differences between convective elements and the environment possibly reflecting the improved ventilation possible at an inversion interface compared with much rougher surfaces the tke balance divides into three main regions and is consistent with the interpretations given above the pressure transport is implied to be the largest source term close to cloud top comparisons with model results reveal some important differences

a field study of nocturnal stratocumulus ii turbulence structure and entrainment tethered balloon borne instrumentation has been used to study the small scale air motion and temperature variations occurring within a layer of nocturnal stratocumulus the observations indicate a very sharp and intermittently turbulent entrainment interfacial layer with some evidence for a characteristic entrainment scale of about 10m within the cloud layer convective motions are apparent and these take the form of cold downward moving plumes which increase in scale away from cloud top they are generated by the large radiative loss from the upper part of the cloud some statistical features of the turbulence field in cloud are discussed and compared with other observations from stratocumulus and the daytime convective boundary layer

the numerical representation of entrainment in parameterizations of boundary layer turbulent mixing abstract problems have been identified with parameterizations of convective boundary layers in particular with their numerical treatment of the capping inversion it is shown that the turbulence scheme can combine with the numerical representation of subsidence to produce unphysical entrainment as was also identified by lenderink and holtslag a correction is proposed for the lock et al boundary layer parameterization in which a discontinuous inversion is diagnosed from the mean thermodynamic profiles every time step this then allows a consistent treatment of subgrid scale processes in the region of the inversion in particular the parameterized turbulent entrainment flux can be adjusted to allow for the spurious entrainment arising from the conflicting representations of turbulent mixing and vertical advection it also allows a direct coupling between the turbulent and radiative fluxes to ensure that cloud top radiative cooling is correctly distributed between the inversion grid level and the mixed

the impact of vertical resolution upon gcm simulations of marine stratocumulus the impact of increased vertical resolution in the hadley centre climate model upon the simulation of stratocumulus is investigated in experiments using single column scm and general circulation gcm model configurations a threefold enhancement of vertical resolution in the boundary layer leads to improvements in the vertical structure of the cloud topped boundary layer produced by the scm and gcm in both well mixed and decoupled situations however single and decoupled mixed layers in the marine stratocumulus subsidence regions are still too shallow and despite increasing layer cloud amounts remain generally too low moreover closer examination of gcm data and scm timeseries reveals an underlying sensitivity to vertical resolution in model interactions between boundary layer and convection processes which appears unrealistic stratocumulus simulation is thus unlikely to improve significantly as a result of enhanced resolution alone and further work is being undertaken to improve the hadley centre model s boundary layer scheme and in particular its interaction with the convection scheme nevertheless this study shows that the full benefit of an improved boundary layer scheme will not be realized if the boundary layer structure is constrained by the rather poor lower troposphere resolution of the standard 19 level climate model future hadley centre model versions will seek to combine the added flexibility of a better resolved structure with improvements to the subgrid boundary layer parametrizations

numerical simulations and a conceptual model of the stratocumulus to trade cumulus transition abstract a two dimensional eddy resolving model is used to study the transition from the stratocumulus topped boundary layer to the trade cumulus boundary layer the 10 day simulations use an idealized lagrangian trajectory representative of summertime climatological conditions in the subtropical northeastern pacific the sea surface temperature is increased steadily at 1 5 k day 1 reflecting the southwestward advection of the subtropical marine boundary layer by the trade winds while the free tropospheric temperature remains unchanged results from simulations with both a fixed diurnally averaged shortwave radiative forcing and a diurnally varying shortwave forcing are presented a two stage model for the boundary layer evolution consistent with these simulations is proposed in the first stage decoupling is induced by increased latent heat fluxes in the deepening boundary layer after decoupling cloud cover remains high but the cloudiness regime changes from a single stratocumulus layer to sporadic

dynamics of sheared convective boundary layer entrainment part i methodological background and large eddy simulations abstract the reported study examines the dynamics of entrainment and its effects on the evolution of the dry atmospheric convective boundary layer cbl when wind shear is present the sheared cbl can be studied by means of direct measurements in the atmosphere laboratory studies and numerical techniques the advantages and disadvantages of each technique are discussed in the present paper which also describes the methodological background for studying the dynamics of entrainment in sheared cbls for the reported study large eddy simulation les was chosen as the primary method of convective entrainment investigation twenty four les runs were conducted for cbls growing under varying conditions of surface buoyancy flux free atmospheric stratification and wind shear the simulations were divided into three categories cbl with no mean wind ns cbl with a height constant geostrophic wind of 20 m s 1 gc and cbl with geostrophic wind shear gs in the simulated cases the sheared cbls grew fastes

observations of the interaction between cumulus clouds and warm stratocumulus clouds in the marine boundary layer during astex abstract decoupling of the marine boundary layer beneath stratocumulus clouds and the formation of cumulus clouds at the top of a surface based mixed layer sml have frequently been observed and modeled when such cumulus clouds penetrate the overlying stratocumulus layer the cloud microphysics and hence the radiative properties of the cloud are altered locally observations made during a series of lagrangian experiments in the azores as part of the atlantic stratocumulus transition experiment astex june 1992 have been analyzed to ascertain how the properties of a stratocumulus layer with which cumulus clouds are interacting differ from those of an unaffected cloud layer the results suggest that in regions where cumulus clouds penetrate the cloud layer the stratocumulus is thickened as the cumuli spread out into its base transport of air from the sml into the cloud by convective updrafts is observed and the increase in available moisture within the penetrating cumulus clouds results in increased

a moist pbl parameterization for large scale models and its application to subtropical cloud topped marine boundary layers abstract a new general purpose boundary layer parameterization that permits realistic treatment of stratocumulus capped boundary layers scbls with coarse vertical resolution is described it combines a 1 5 order turbulent closure model with an entrainment closure at the boundary layer top three different implementations of the entrainment closure in which the boundary layer height is respectively prognosed reconstructed from thermodynamic values at the grid points or restricted to lie on a flux level of the host model grid are tested in a single column modeling framework at both fine and coarse vertical resolution the first two approaches permit a stratocumulus top and base to lie between grid levels and evolve continuously with time but are more complicated to implement in a three dimensional model the model performs very well in cases of dry convection whatever the inversion implementation and the vertical resolution with 15 mb or better vertical resolution all approaches properly simulate

clay mineral compositions of sediments in the gaoping river sea system implications for weathering sedimentary routing and carbon cycling abstract small mountainous rivers smrs play a crucial role in the global sediment and carbon cycle by rapid transfer of huge particulate and dissolved loads into the sea gaoping river sea system is a good representative of smrs in oceania having an extreme high denudation rate 15 000 t km 2 yr 1 and a high burial efficiency of terrestrial particulate organic carbon poc in the gaoping submarine canyon gpsc however it is contentious whether silicate weathering or poc burial plays more important role in long term carbon cycling in such a high active orogen clay minerals of fluvial sediments not only act as an important carrier of poc but also encode valuable information of weathering regimes on land and dispersal routes in the seas to uncover these informations surface and core sediments are systematically collected from the gaoping river sea system for clay mineral analysis comparative studies are carried out on the basis of new results and vast published data to better understand weathering processes and products in oceanian islands and southeast asian continent we find that clay mineral compositions in the gaoping river gpr and other taiwan rivers are a legacy from provenance rocks in the alpine reach characterized by predominant illite and chlorite and limited compositional change throughout the river courses these sharply contradict the downstream increase in compositional complexity rich in kaolinite and smectite and chemical weathering intensity in southeast asian large rivers because of strong hydrolysis and active sediment recycling at the lowland reach with extensive floodplains high consistency of clay mineral compositions is also observed in the interior and exterior of gpsc careful examination shows that a slight offshore decrease in cumulative illite and chlorite content is accompanied by a slight increase in exotic clay mineral inputs by ocean circulations the combination of this finding with previously reported data on the offshore change in 13corg and 14corg values suggests that petrogenic poc predominates in the river dominated gaoping continental margin with high preservation efficiency due to its tight bandage with clay minerals moreover a tardy response of chemical weathering fluxes to high elevated physical erosion rates is remarkably examined in the oceanian and global river gauging data we therefore postulate that rapid transfer and high burial efficiency of terrestrial poc in the tectonically active high standing islands and their adjacent continental margins play much more important role in the long term carbon cycle than silicate weathering

an extreme cold air outbreak over the labrador sea roll vortices and air sea interaction abstract observational data from two research aircraft flights are presented the flights were planned to investigate the air sea interaction during an extreme cold air outbreak associated with the passage of a synoptic scale low pressure system over the labrador sea during 8 february 1997 this is the first such aircraft based investigation in this remote region both high level dropsonde and low level flight level data were collected the objectives were twofold to map out the structure of the roll vortices that cause the ubiquitous cloud streets seen in satellite imagery and to estimate the sensible and latent heat fluxes between the ocean and atmosphere during the event the latter was achieved by a lagrangian analysis of the flight level data the flights were part of the labrador sea deep convection experiment investigating deep oceanic convection and were planned to overpass a research vessel in the area the aircraft observed roll vortices had a characteristic wavelength of 4 5 km particular

production consumption and migration of methane in accretionary prism of southwestern taiwan to systematically quantify the production consumption and migration of methane along a continental margin 210 sediment cores were collected from offshore southwestern taiwan and analyzed for their gas and aqueous geochemistry these data combined with published results were used to calculate the diffusive methane fluxes across different geochemical transitions and to develop scenarios of mass balance to constrain deep microbial and thermogenic methane production rates within the accretionary prism the results showed that methane diffusive fluxes ranged from 2 71 10 3 to 2 78 10 1 and from 1 88 10 1 to 3 97 mmol m 2 d 1 at the sulfate methane transition zone smtz and sediment seawater interfaces respectively high methane fluxes tend to be associated with structural features suggesting a strong structural control on the methane transport a significant portion of ascending methane 50 is consumed by anaerobic oxidation of methane at the smtz at most sites indicating effective biological filtration gas compositions and isotopes revealed a transition from the predominance of microbial methane in the passive margin to thermogenic methane at the upper slope of the active margin and onshore mud volcanoes methane production and consumption at shallow depths were nearly offset with a small fraction of residual methane discharged into seawater the flux imbalance arose primarily due to the larger production of methane through deep microbial and thermogenic processes at a magnitude of 1 512 43 096 tg myr 1 methane and could be likely accounted for by the sequestration of methane into hydrate forms and clay absorption

cloud aerosol and boundary layer structure across the northeast pacific stratocumulus cumulus transition as observed during cset abstractduring the cloud system evolution in the trades cset field study 14 research flights of the national science foundation g v sampled the stratocumulus cumulus transition between northern

turbulence structure in decoupled marine stratocumulus a case study from the astex field experiment the average and turbulence structure of two marine stratocumulus layers from the atlantic stratocumulus transition experiment are analyzed these layers were in adjacent air masses with different

diurnal evolution of the cloud topped marine boundary layer part i nocturnal stratocumulus development abstract the structure and evolution of the extratropical marine atmosphere boundary layer mabl depend largely on the variability of stratus and stratocumulus clouds stratus clouds are generally associated with a well mixed mabl whereas daytime observations of stratocumulus topped boundary layers generally indicate that the cloud and subcloud layers are decoupled in the atlantic stratocumulus transition experiment aircraft measurements show a surface based mixed layer separated from the base of the stratocumulus by a layer that is stable to dry turbulent mixing this layer forms due to shortwave heating of the stratocumulus clouds cumulus clouds often develop in this transition layer and they play a fundamental role in the redistribution of heat in the decoupled stratcumulus capped boundary layer they are however very sensitive to small changes in the heat and moisture in the boundary layer and are generally transient features that depend directly on the surface sensible and latent heat fluxes

terrestrial sedimentation and the carbon cycle coupling weathering and erosion to carbon burial this paper examines the linkages between the carbon cycle and sedimentary processes on land available data suggest that sedimentation on land can bury vast quantities of organic carbon roughly 1015 g c yr 1 to evaluate the relative roles of various classes of processes in the burial of carbon on land terrestrial sedimentation was modeled as a series of 864 scenarios each scenario represents a unique choice of intensities for seven classes of processes and two different global wetland distributions comparison was made with presumed preagricultural conditions the classes of processes were divided into two major component parts clastic sedimentation of soil derived carbon and organic sedimentation of autochthonous carbon for clastic sedimentation masses of sediment were considered for burial as reservoir sediment lake sediment and combined colluvium alluvium and aeolian deposits when the ensemble of models is examined the human induced burial of 0 6 1 5 1015 g yr 1 of carbon on land is entirely plausible this sink reaches its maximum strength between 30 and 50 n paddy lands stand out as a type of land use that warrants future study but the many faces of rice agriculture limit generalization in an extreme scenario paddy lands alone could be made to bury about 1 1015 g c yr 1 arguing that terrestrial sedimentation processes could be much of the sink for the so called missing carbon is reasonable such a hypothesis however requires major redesign of how the carbon cycle is modeled unlike ecosystem processes that are amenable to satellite monitoring and parallel modeling many aspects of terrestrial sedimentation are hidden from space

observed lagrangian transition of stratocumulus into cumulus during astex mean state and turbulence structure aircraft measurements made during the first lagrangian of the atlantic stratocumulus transition experiment astex between 12 and 14 june 1992 are presented during this lagrangian experiment an air mass was followed that was advected southward by the mean wind five aircraft flights were undertaken to observe the transition of a stratocumulus cloud deck to thin and broken stratocumulus clouds penetrated by cumulus from below from the horizontal aircraft legs the boundary layer mean structure microphysics turbulence structure and entrainment were analyzed the vertical profiles of the vertical velocity skewness are shown to illustrate the transition of a cloudy boundary layer predominantly driven by longwave radiative cooling at the cloud top to one driven mainly by convection due to an unstable surface stratification and cumulus clouds during the last flight before the stratocumulus deck was observed to be broken and replaced by cumuli the total water flux the virtual potential temperature flux and the vertical velocity variance in the stratocumulus cloud layer were found significantly larger compared with the previous flights to analyze the cloud top stability the mean jumps of conserved variables across the inversion were determined from porpoising runs through the cloud top these jumps were compared with cloud top entrainment instability criteria discussed in the literature it is suggested that enhanced entrainment of dry air is a key mechanism in the stratocumulus cumulus transition

water and sediment discharge from small mountainous rivers taiwan the roles of lithology episodic events and human activities national science council of taiwan nsc96 2628 m 001 028 u s national science foundation and naval oceanographic office

boundary layer depth entrainment and decoupling in the cloud capped subtropical and tropical marine boundary layer abstract estimates of marine boundary layer mbl depth and degree of decoupling for two regions of the subtropical and tropical east pacific are presented using satellite observations from the moderate resolution imaging spectroradiometer modis and the tropical rainfall measuring mission trmm microwave imager tmi these data are combined in a novel way with ncep reanalysis data and a mixing line parameterization to estimate the mean entrainment rate we over the two regions mean entrainment rates vary geographically and have maxima just downwind of the californian coast we 4 5 mm s 1 and also in the core of the equatorial east pacific cold tongue where mean we exceeds 6 mm s 1 entrainment exceeds subsidence by 30 or less in the subtropical stratocumulus regions north of the equatorial cold tongue entrainment greatly exceeds subsidence producing a rapid deepening of the mbl as air flows over a marked sst gradient shallow mbls zi 500 700 m are found to be well mixed in general the deco

a continental outbreak of air during the second aerosol characterization experiment ace 2 a lagrangian experiment a mesoscale meteorological model is used to simulate the continental outbreak of air that occured over north atlantic ocean during the second aerosol characterization experiment ace 2 comparison with meteosat 6 visible images shows that the model is able to reproduce most of the observed cloud features in the entire modeling domain including a frontal system orographic clouds over the pyrenees and the iberian peninsula boundary layer clouds in the ace 2 region and cloud free areas in the dry air outflow off the portuguese coast the model reproduces correctly the temperature humidity wind speed and direction cloud water content and light precipitation events observed by the aircraft during the lagrangian experiment while following a tagged boundary layer air parcel over a 28 hour long period a passive tracer introduced in the model at the time corresponding to the balloon launch followed the balloon track with an error in position that is smaller than 1 after 24 hours with about 20 higher speed an estimate of the boundary layer entrainment velocity is obtained based on observed boundary layer growth rates and modeled vertical wind speed the average entrainment velocity of 1 28 cm s for the 28 hour lagrangian period agrees with experimentally derived entrainment velocities

steady state large eddy simulations to study the stratocumulus to shallow cumulus cloud transition abstractthis study presents a series of steady state large eddy simulations less to study the stratocumulus to shallow cumulus cloud transition to represent the different stages of what can be interpreted as an eulerian view of the transition each simulation is assigned a unique sea surface temperature sst and run until statistically steady the les runs are identical in every other aspect these idealized boundary driven steady state less allow for a simple parametric assessment of cloud controlling factors in isolation from initial conditions and time lag effects inherent in the lagrangian view of the transition the analysis of the thermodynamic energy budget reveals that as the cloud regime transitions from stratocumulus to shallow cumulus changes in the cloud radiative cooling term are balanced by changes in the subsidence warming term this leads to a linear regression between the cloud fraction cf and an integral that scales to a first order approximation as the lower tropospheric stabi

observed microphysical structure of midlevel mixed phase clouds abstract this paper analyzes airborne measurements of six midlevel clouds observed over the great plains of the united states in late 1999 and early 2000 during the fifth of the complex layered cloud experiments clex 5 data show that these innocuous looking clouds display complicated microphysical and thermodynamic structures five of the six cases exhibit mixed phase conditions in temperatures ranging from near 0 to 31 c at altitudes of 2400 to 7200 m msl four of the cases consist of a single cloud layer while the other two are multilayered systems in the thin mixed phase single layered clouds that the authors observed there is an increase of liquid water content with altitude whereas the ice water content maximizes in the mid to lower part of the clouds this contrasts the two multilayered systems the authors observed in which significant amounts of ice occur in the top as well as the bottom of the individual layers of each system a lack of significant temperature inversions or wind shea

summertime post cold frontal marine stratocumulus transition processes over the eastern north atlantic abstractmarine boundary layer mbl cloud morphology associated with two summertime cold fronts over the eastern north atlantic ena is investigated using high resolution simulations from the weat

factors influencing cloud area at the capping inversion for shallow cumulus clouds large eddy simulations of marine cumulus clouds are performed aspects of the simulations are varied in order to identify those parameters that play a role in determining when the cumulus clouds spread out under the capping inversion into stratocumulus these include the strength of the surface fluxes which also affects the strength of the cumulus mass transport the strength of the capping inversion the moisture content of the free atmosphere the strength of cloud top radiative cooling and whether there is significant precipitation or sedimentation of cloud drops tests are also performed to evaluate sensitivity to the model resolution as in previous studies having sufficient resolution at the capping inversion is found to be important for robust simulation of any stratiform cloud that forms there in addition the cloud cover is found to be sensitive to many of the physical processes investigated in the end though a clear and robust dependence emerges on the cloud top entrainment instability parameter for large a typical small shallow cumulus cloud cover is seen for below the threshold for buoyancy reversal the cumulus spreads into a solid sheet of stratocumulus beneath the inversion consistent with previous studies there is no abrupt transition and the cloud cover decreases smoothly as increases the conclusion is reached that varying other parameters in the simulations affects the cloud cover through their impact on the size of the jumps across the inversion and thence the implications for turbulent mixing parametrizations in general circulation models are discussed crown copyright 2009 reproduced with the permission of hmso published by john wiley sons ltd

relationships between mineral surfaces and organic carbon concentrations in soils and sediments abstract relationships between mineral specific surface area and organic carbon oc concentration are examined for sediments and soil a horizons from throughout the world i found published elsewhere that continental shelf sediments from many different regions exhibit downcore loss of oc to a refractory background level which shows a consistent relationship with mineral surface area slope 0 86 mg m 2 oc this trend is equivalent to a monolayer of organic matter over all surfaces and is termed the monolayer equivalent me level sediments and soils from other environments are compared to this empirically derived relationship several continental slope areas show extension of this relationship to considerable depth marked excesses of oc above this trend which persist downcore were found in sediments with high carbonate mineral content or slope sediments with low dissolved oxygen concentrations in the overlying water column about half of the soils examined also adhered to this relationship while soils with high carbonate content low ph or poor drainage showed oc concentrations higher than the me level oc concentrations below the me level are found in deltaic regions and areas with low organic matter delivery such as the deep sea or arid soils the nature of mineral surfaces was examined using n2 adsorption desorption isotherms and most surface area was found to be present as pores with

surface area control of organic carbon accumulation in continental shelf sediments the relationship between organic carbon oc and grain size found in most continental shelf sediments is here reinterpreted in terms of the surface area of the sediments cores from many north american shelf environments show downcore decreases in oc to similar refractory background concentrations if expressed relative to the surface area of the sediments this consistent concentration is 0 86 mg oc m 2 which is equivalent in concentration to a monolayer of organic matter coating all mineral surfaces a more global collection of sediment water interface samples show that this relationship is even more extensive with exceptions occurring in areas of very high riverine sediment input organic pollution or low oxygen water columns density separations indicate that organic matter is largely adsorbed to mineral grains the microtopography of surfaces was examined with n2 sorption and most surface area was found to be inside pores of 10 nm width these data lead to a hypothesis that organic matter is protected by its location inside pores too small to allow functioning of the hydrolytic enzymes necessary for organic matter decay such protection would likely work in concert with other protection mechanisms such as humification this consistent surface area correlation with oc concentration may explain control of spatial and temporal variations in oc burial rates by sedimentation rates the pore protection hypothesis provides a causal mechanism for this observed control

sediment trapping in deltas of small mountainous rivers of southwestern taiwan and its influence on east china sea sedimentation abstract taiwan s setting of high mountains steep gradients frequent earthquakes erodible lithology and heavy rainfall represents an ideal site to focus on sedimentary processes of the deltas of small mountainous rivers smrs several smrs in southwestern taiwan have deposited a thick sedimentary succession in the composite southwest taiwan delta swtd since the middle holocene evidence from the swtd can help to determine its trapping efficiency and assess the role of smrs in sediment transport to the sea we used historical nautical charts bathymetric data satellite radar data and 14c dates to calculate the sediment volume of the swtd on millennial and decadal scales the 14c dates of core samples indicate deposition of thick deltaic sediment in subsiding areas since the time of the maximum flooding surface about 7 cal ka bp the paleo shoreline changes of the swtd suggest a steady westward progradation since 7 cal ka bp in contrast the nautical charts suggest minor volume reduction of the offshore part of the swtd with a deepening trend and retreating shorelines during the last seven decades the results show that at least 201 72 13 90 km3 3 23 105 mt of sediment has been trapped in the swtd since 7 cal ka bp and that the delta has shifted to a destructive phase during the past seven decades as human influences such as construction of reservoirs dams and weirs in the hills have reduced the sediment supply the birth of the taiwan warm current and following continuous sediment supply from the western rivers of taiwan to the east china sea since 7 3 cal ka bp have played a crucial role in the sedimentation of the east china sea particularly in the okinawa trough and the japan sea through the tsushima warm current

mesoscale shallow convection in the atmosphere this paper is a review of the observational experimental theoretical and numerical studies of mesoscale shallow convection msc in the atmosphere typically msc is 1 to 2 km deep has a horizontal length scale of a few to a few tens of kilometers and takes distinctive planforms linear and hexagonal the former is called a cloud street roll or band while the latter is called mesoscale cellular convection mcc comprising three dimensional cells msc is characterized by its shape horizontal extent convective depth and aspect ratio the latter is the ratio of the horizontal extent to that in the vertical for cells the horizontal extent is their diameter whereas for rolls it is their spacing rolls usually align along or at angles of up to 10 from the mean horizontal wind of the convective layer with lengths from 20 to 200 km widths from 2 to 10 km and convective depths from 2 to 3 km the typical value of aspect ratio ranges from 2 to 20 rolls may occur over both water surface and land surfaces mesoscale convective cells may be divided into two types open and closed open cell circulation has downward motion and clear sky in the cell center surrounded by cloud associated with upward motion closed cells have the opposite circulation both types of cell have diameters ranging from 10 to 40 km and aspect ratios of 5 to 50 and both occur in a convective layer with a depth of about 1 to 3 km both the magnitude and direction of horizontal wind in the convective layer change little with height msc results from a complex and incompletely understood mix of processes these processes are outlined and their interplay is examined through a review of theoretical and laboratory analyses and numerical modeling of msc