remote trigger of deep convection by cold outflow over the taiwan strait in the mei yu season a modeling study of the 8 june 2007 case abstractin this study the heavy rainfall event over central taiwan during the mei yu season on 8 june 2007 is investigated with an emphasis on the triggering mechanism for the deep convection that produced the rain observations indicate that there existed two lines of forcing with convection prior to the rain one over the northern taiwan strait along the mei yu front and the other over the southern taiwan strait yet the convection in question developed over the central strait between these two lines in an unstable environment with strong westerly vertical wind shear this motivated the authors to carry out the present study the cloud resolving storm simulation cress of nagoya university was used and the event was reproduced at a horizontal grid size of 2 km including the initiation of new convection over the central strait at the correct location and time the model results suggest a crucial role played by the series of active persistent and propagating storms in the southern strait along the

an analytical study of the sea breeze abstract in this paper we present theoretical results concerning the sea breeze intensity and its inland penetration as a function of latitude and friction we produce solutions for the spatial structure of the streamfunction and momentum components and for their line behavior in the case of a step function forcing of finite duration and in the case of periodic forcing results show that the sea breeze initially has an aspect ratio equal to unity and that earth rotation and friction aged its intensity but they are unimportant in determining its early geometry the sea breeze has a characteristic time scale which is a combination of the inertial period and the e folding time due to friction for a time larger than this characteristic time scale the inland penetration of the sea breeze is confined by a rossby deformation radius which includes a frictional effect in fact friction and inertia reduce not only the intensity but also the horizontal scale of motion at the equator the controlling parameter

khvalynian transgression of the caspian sea was not a result of water overflow from the siberian proglacial lakes nor a prototype of the noachian flood abstract the paper presents a critical review of the hypothesis that the khvalynian transgression resulted from abundant inflow of meltwater from siberian proglacial lakes through the aral sea and along the uzboi channel into the caspian sea had a catastrophic character and could be considered as a prototype of the biblical noachian flood a thorough analysis of evidence cited by the proponent of the hypothesis revealed the lack of factual substantiation 1 there are no data indicative of aral drainage 2 there is no evidence that siberian proglacial water was inflowing into the caspian sea 3 taxonomic and spatial distribution of molluscs in khvalynian sediments do not indicate that transgression was essentially influenced by thawing of ice sheets on the russian plain 4 there is no evidence that the khvalynian transgression was catastrophic sea level rose by few centimeters per year over several thousands of years 5 there are no data indicating that khvalynian water overflowing through the manych spillway into the neoeuxinian lake was significant inflow could increase the level and salinity of the lake by 30 m and 5 respectively thus there is no evidence that the khvalynain transgression could serve as a reliable source for the biblical noachian flood

an investigation of local scale human landscape dynamics in the endorheic alluvial fan of the murghab river turkmenistan abstract endorheic or inland deltas commonly found across the deserts of central asia represent unique and dynamic ecotones that are still not fully understood these regions of environmental and landscape transition as well as social liminality straddle the line between fertile sustainable environments and less productive desertic regions less capable of sustaining significant human occupation because such boundary areas are dynamic and often unpredictable they are excellent case studies through which to study the complex processes that have characterized human environmental relationships throughout the late holocene this paper focuses on the local variability that characterizes these relationships in one such region the terminal fan of the murghab river in turkmenistan populated since at least the late 5th millennium bp and likely earlier the region has been variously described as an oasis environment in which desertic processes have been more or less stagnant throughout the late holocene or alternatively as a fertile continuously occupied and heavily cultivated alluvial fan in which desertification was a relatively late process intensifying only in the mid 4th millennium bp this paper presents geoarchaeological data from a series of test pits in the distal portion of the terminal fan to show that local scale analysis indicates a far more complex interpretation one shaped by the continuous and non uniform interaction of aeolian and alluvial depositional environments and one that bears substantially on human landscape dynamics in the region the late holocene development of the distal fan is examined using proxy data from granulometric analysis loss on ignition loi and geochemical analysis as well as a series of new osl dates that refines the depositional chronology of the region ultimately we show that landscape change throughout the holocene has been characterized by pronounced variability at the local level not fully described by regional scale approaches while differential aeolian encroachment non uniform alluvial processes and climatic conditions bear significantly on the initial conditions for human occupation human environmental processes are ultimately co evolutionary in nature

sea breezes shallow and deep on the california coast abstract analyses of doppler lidar data reveal sea breezes occurring on two different depth and time scales at monterey bay california on a day with offshore gradient flow indicated before sunrise and after sunset the lidar data used in this study consist of vertical cross sections and profiles of the westerly onshore wind component u in the morning after 0900 pst a shallow sea breeze formed which reached a depth of 300 m by noon starting in early afternoon a deeper sea breeze layer formed in the lowest kilometer and by late afternoon the shallow sea breeze blended into the deeper sea breeze and was no longer evident maximum speeds of 6 m s 1 in the shallow sea breeze occurred at the surface whereas those in the deep sea breeze also 6 m s 1 were about 300 m above the surface it is hypothesized that the shallow sea breeze is a local phenomenon responding to a more local temperature contrast between the sea and the region between the ocean and the mountain ranges the deeper sea breeze on the

mapping the interactions between rivers and sand dunes implications for fluvial and aeolian geomorphology article i nfo the interaction between fluvial and aeolian processes can significantly change earth surface morphology when riversandsanddunes meet theinteractionofsedimenttransportbetweenthetwosystemscanleadtochangein eitherorboth systems however these two systemsare usuallystudied independently which leavesmanyques tions unresolved in terms of how they interact this paper carries out a global inventory using satellite imagery to identify 230 sites where there are significant fluvial aeolian interactions at each location key attributes such as wind river direction net sand transport direction fluvial aeolian meeting angle dune type and river channel pattern were identifiedand relationshipsbetween each factorwere analysed from thesedata six different types of interaction were classified that reflect a shift in dominance between the fluvial and aeolian systems results from this classification confirm that only certain types of interaction were significant the meeting angle and dunetype themeeting angle and interaction type and finally thechannel pattern andinteraction type however the findings also indicate the difficulties of classifying dynamic geomorphic systems from snapshot satellite images

a dual doppler radar study of longitudinal mode snowbands part i a three dimensional kinematic structure of meso γ scale convective cloud systems within a longitudinal mode snowband abstract observations of snowstorms were carried out around ishikari bay hokkaido japan from december 1991 to february 1992 on 15 january 1992 a longitudinal mode snowband was observed by a dual doppler radar system the snowband was composed of meso scale 20 km convective cloud systems the three dimensional kinematic structures and organization processes of the meso scale systems were studied in detail strong band parallel winds appeared in the upper north rear of the meso scale systems since their speed was faster than that of the cellular radar echoes the winds formed rear to front currents increasing in volume and speed the rear to front currents developed into meso scale and penetrated toward the lower front and lower south of the systems consequently the rear to front currents caused strong meso scale convergence and the enhancement of updrafts at their leading edges the transport of the band parallel momentum greatly contributed to the successive development of new convec

co2 ecbm field tests in the ishikari coal basin of japan abstract the feasibility of extracting gas from coal seam while storing carbon dioxide underground was evaluated in japan a co2 ecbm project had begun near the town of yubari on the island of hokkaido in northern japan the primary coal seam of interest was a 5 6 m thick yubari coal seam located at the depth of 900 m a micro pilot test with a single well and multi well co2 injection tests involving an injection and production wells were carried out in the period between may 2004 and october 2007 there were a variety of tests conducted in the injection well including an initial water injection fall off test and a series of co2 injection and fall off tests although gas production rate was obviously enhanced by co2 injection water production rate was not clearly affected by co2 injection several injection tests suggested that injectivity of co2 into the virgin coal seam saturated with water was eventually increased as the water saturation near the injector was decreased by the injected co2 it was estimated that low injectivity of co2 was caused by the reduction in permeability induced by coal swelling n2 flooding test was performed in 2006 to evaluate the effectiveness of n2 injection on improving well injectivity the n2 flooding test showed that daily co2 injection rate was boosted but only temporarily moreover the permeability did not return to the initial value after co2 and n2 were repeatedly injected it was also indicated that the coal matrix swelling might create a high stress zone near to the injection well

contributions of geoarchaeology and remote sensing to the study of holocene hunter gatherer and agro pastoral groups in arid margins the case of north gujarat northwest india the present work aims at setting the bases for the critical study of settlement patterns and resource management among holocene hunter gatherer and agro pastoral groups in arid margins the case study is set on the sw margin of the thar desert in n gujarat an ecotone sensitive to the slightest shifts in precipitation patterns indian summer monsoon the potential significance of published and newly acquired archaeological information is discussed in the light of physiographical data collected from satellite imagery and field exploration the review of available and newly acquired records includes a the integration of field and remote observation of regional traits and b the definition of active morphological processes that may bias archaeological preservation and visibility a synthetic geoarchaeological map of the study area is proposed that integrates physiographical and archaeological evidence at the regional scale the potential significance of the archaeological evidence in the region i e presence absence concentration of archaeological materials in different physiographical units is discussed in terms of preservation and visibility at this stage results are considered at the regional level of macroscopic units the results constitute the first step towards the full multi scalar integration of landscape architectures stratified archaeological sites and surface sediments at regional and local levels

numerical modelling of the offshore extent of sea breezes two and three dimensional versions of a nonlinear atmospheric model were used to investigate environmental controls on the offshore influence of sea breeze circulations the temperature of the water surface relative to the atmospheric temperature had a small effect when the water was colder than the overlying air and a greater effect when the water temperature was high enough to create convective mixing in the planetary boundary layer over the water ambient thermal stratification including elevated inversions with thermal stratification similar to trade wind inversions had a small influence the predicted offshore extent of the sea breeze was substantially affected by latitude the effects of both ambient stratification and latitude were generally consistent with predictions of linear theory prevailing synoptic winds were also found to have a significant effect on the sea breeze offshore with offshore influence greatly suppressed by onshore large scale flow curvature of the coastline produces slightly stronger winds offshore for a concave coast than for a convex coast the subsidence offshore also extends further over the water for a concave coast than for a convex coast the model predictions were compared with previous investigations which used linear theory it was found that the present results agreed with the linear theory of r rotunno with regard to the effects of latitude and ambient thermal stability linear theory is less suitable for explaining the effects of water temperature owing to the simplified treatment of turbulent exchange necessary for a tractable linear model

evolution of the monterey bay sea breeze layer as observed by pulsed doppler lidar abstract as part of the land sea breeze experiment lasbex to study the sea breeze at monterey bay the pulsed doppler lidar of the noaa erl wave propagation laboratory performed vertical and nearly horizontal scans of the developing sea breeze on 12 days analyses of doppler velocity data from these scans revealed details on the growth of the sea breeze layer and on the horizontal variability of the sea breeze resulting from inland topography two days were selected for study when the ambient flow was offshore because the onshore flow of the sea breeze was easy to discern from the background flow sequences of vertical cross sections taken perpendicular to the coast showed the beginnings of the sea breeze beneath the land breeze at the coast and the subsequent growth of the sea breeze layer horizontally and vertically on one of the days a transient precursor a minor sea breeze appeared and disappeared before the main sea breeze began in midmorning other issues that the lidar was well suited to stud

swelling induced volumetric strains internal to a stressed coal associated with co2 sorption abstract it is generally accepted that typical coalbed gases methane and carbon dioxide are sorbed both adsorbed and absorbed in the coal matrix causing it to swell and resulting in local stress and strain variations in a coalbed confined under overburden pressure the swelling interactions of gases within the coal matrix and the resultant changes in the permeability sorption gas flow mechanics in the reservoir and stress state of the coal can impact a number of reservoir related factors these include effective production of coalbed methane degasification of future mining areas by drilling horizontal and vertical degasification wells injection of co2 as an enhanced coalbed methane recovery technique and concurrent co2 sequestration such information can also provide an understanding of the mechanisms behind gas outbursts in underground coal mines the spatio temporal volumetric strains in a consolidated pittsburgh seam coal sample were evaluated while both confining pressure and carbon dioxide co2 pore pressure were increased to keep a constant positive effective stress on the sample the changes internal to the sample were evaluated by maps of density and atomic number determined by dual energy x ray computed tomography x ray ct early time images as soon as co2 was introduced were also used to calculate the macroporosity in the coal sample scanning electron microscopy sem and photographic images of the polished section of the coal sample at x ray ct image location were used to identify the microlithotypes and microstructures the co2 sorption associated swelling and volumetric strains in consolidated coal under constant effective stress are heterogeneous processes depending on the lithotypes present in the time scale of the experiment vitrite showed the highest degree of swelling due to dissolution of co2 while the clay kaolinite and inertite region was compressed in response the volumetric strains associated with swelling and compression were between 15 depending on the location although the effective stress on the sample was constant it varied within the sample as a result of the internal stresses created by gas sorption related structural changes sem images and porosity calculations revealed that the kaolinite and inertite bearing layer was highly porous which enabled the fastest co2 uptake and the highest degree of compression

a late holocene record of human impacts on tropical environments from non pollen palynomorphs albertine rift western uganda non pollen palynomorphs and elemental geochemistry data from lake kifuruka in western uganda provide evidence of environmental change in the tropical african region since the beginning of the holocene the multi proxy record presented here shows that dry conditions dominated the end of the pleistocene evidenced by calcium enriched sediments and suppressed fungal taxa activity moist conditions dominated the early holocene and persisted until just after 1960 cal yr bp elevated frequencies of individual fungal spore taxa associated with herbivory and soil erosion including sordaria type sporormiella type chaetomium type and glomus type about 4300 cal yr bp suggests a significant environmental change that could be linked to human activities a convergence of multiple proxy data including microscopic charcoal elemental geochemistry and fungal spores strongly support the occurrence of anthropogenic forest disturbance in the albertine rift about 4300 cal yr bp

winter monsoon convection in the vicinity of north borneo part i structure and time variation of the clouds and precipitation abstract radar and satellite observations in the vicinity of northern borneo obtained during the international winter monsoon experiment wmonex showed that the convection in that region underwent an extremely regular diurnal cycle over the sea to the north of borneo the general level of convective activity was increased during monsoon surges and during the passages of westward propagating near equatorial disturbances convective activity was decreased during monsoon lulls the diurnal cycle was well defined regardless of whether the general level of convective activity was enhanced or suppressed by synoptic scale events the cycle of convection over the sea was especially well documented it was typically initiated at about midnight when an offshore low level wind began where this wind met the monsoonal northeasterly flow usually just off the coast convective cells formed after midnight the convection continued to develop and by 0800 lst it had evolved into an organized mesoscale system with a

horizontal convective rolls determining the environmental conditions supporting their existence and characteristics abstract data from the convection and precipitation electrification cape project as well as results from numerical simulations are used to study horizontal convective rolls the environmental conditions necessary for sustaining rolls and for influencing the aspect ratio ratio of roll wavelength to convective boundary layer cbl depth and orientation are examined observations and numerical model simulations both suggest that a moderate surface sensible heat flux and some vertical wind shear are necessary for roll existence unlike some previous studies however it is shown that rolls occurred within very low cbl shear conditions 2 10 3 s 1 in addition the low level i e 200 m shear seems to be more important than the shear through the depth of the cbl in roll sustenance the aspect ratio is shown to be proportional to the cbl instability measured in terms of the monin obukhov length the roll orientation is similar to the wind direction at 10 m agl the cbl wind direction the inversio

holocene oscillations of the caspian sea and forecasts based on palaeogeographical reconstructions abstract investigation of deltas and terraces adjacent to the caspian sea has indicated the pattern of holocene fluctuations in level since the initiation of the earliest holocene transgression the surface of the caspian sea has varied between 20 and 32 m below modern sea level six transgressive episodes are recognized in the holocene record separated by regressive episodes when the level fell below 28 m a s l the modal holocene level of the caspian sea is estimated at 28 2 m a s l beginning in 1929 water levels fell rapidly in the caspian sea reaching 29 m a s l the lowest value in 400 years in 1977 however the water level began to rise a trend which has continued to the present currently the caspian sea surface stands at approximately 27 m a s l throughout the past 2500 years the level has not exceeded 25 m a s l and it is not anticipated to exceed this value in the near future the fluctuations recorded since 1929 fall within the range of variations expected from natural environmental factors which have operated since the early holocene

onset of hudson strait heinrich events in the eastern north atlantic at the end of the middle pleistocene transition 640 ka 1 heinrich events are well documented for the last glaciation but little is known about their occurrence in older glacial periods of the pleistocene here we report scanning xrf and bulk carbonate 18o results from integrated ocean drilling program site u1308 reoccupation of deep sea drilling project site 609 that are used to develop proxy records of ice rafted detritus ird for the last 1 4 ma ca sr is used as an indicator of ird layers that are rich in detrital carbonate i e heinrich layers whereas si sr reflects layers that are poor in biogenic carbonate and relatively rich in detrital silicate minerals a pronounced change occurred in the composition and frequency of ird at 640 ka during marine isotope stage mis 16 coinciding with the end of the middle pleistocene transition at this time hudson strait heinrich layers suddenly appeared in the sedimentary record of site u1308 and the dominant period of the si sr proxy shifted from 41 ka prior to 640 ka to 100 ka afterward the onset of heinrich layers during mis 16 represents either the initiation of surging of the laurentide ice sheet lis off hudson strait or the first time icebergs produced by this process survived the transport to site u1308 we speculate that ice volume i e thickness and duration surpassed a critical threshold during mis 16 and activated the dynamical processes responsible for lis instability in the region of hudson strait we also observe a strong coupling between ird proxies and benthic 13c variation at site u1308 throughout the pleistocene supporting a link between iceberg discharge and weakening of thermohaline circulation in the north atlantic

a climatological study of the sea and land breezes in the arabian gulf region 1 this study focuses on observations of the sea and land breeze circulations in the southern arabian gulf during the summer months the indian monsoon creates light northwesterly winds over the arabian gulf allowing for the formation of thermally driven circulations observations from a network of stations are used to develop a wind climatology for the arabian gulf region characteristics of the sea and land breeze circulations such as onset time duration and horizontal and vertical extent are described the dense network of surface stations in the united arab emirates uae allows for a fine scale observational study in this region it is found that the sea breeze occurs during all seasons of the year in this region it occurs in the late afternoon and continues through the evening a land breeze sets in during the night surface offshore winds in the land breeze are strong probably due to drainage flow down the inland hills

pre and post sea breeze frontal lines a meso γ scale analysis over south israel a meso g scale observational analysis of the fine surface structure of the sea breeze fronts sbf over the coast of southern israel is presented objective criteria for the sbf passage are derived based on wind speed and direction temperature and humidity a realization of an automized detection system for sbf is described preliminary results indicate that in addition to the primary sbf there are significant and consistent pre and post sbf lines the surface structures of these lines are shown and related to earlier theoretical studies of the sbf forerunners and kelvin helmholz waves although the pre and post sbf lines seem to be important for pollutant transport human comfort and better theoretical understanding of the sbf they have previously attracted little attention in the sbf literature

micro dynamics and macro patterns exploring new archaeological data for the late holocene human water relationship in the murghab alluvial fan turkmenistan in this article we re visit hypotheses about the changing social and environmental landscapes in southern central asia during the late holocene specifically giving attention to the transitional period between the archaeologically defined late bronze early iron age second half of the 2nd millennium bc and the numerous documented changes in the archaeological and physio geographical record during this time we focus on the northeastern murghab alluvial fan turkmenistan as a window into this complex period and examine one aspect of human environmental dynamics there namely the relationship between the location of archaeological sites and mapped ancient watercourses palaeochannels through time our analysis incorporates nearly 400 new archaeological sites documented in the northeastern murghab since 2006 which have not previously been included in published models of settlement and or hydrological dynamics our findings suggest the periods of the late bronze age and early iron age yaz i demonstrate two distinct access to water practices which may correlate to different processes of socio territorial control being implemented while no single line of evidence can adequately disentangle the complex interconnected processes of environmental and social change our results lend themselves to integration with the current working knowledge of the local processes of socio environmental development in the murghab the results also fit more broadly within emerging discourse that recognizes the importance of micro scale processes and adaptation in eurasian prehistory

observations of the sea breeze front during cape part i single doppler satellite and cloud photogrammetry analysis abstract an analysis of two sea breeze events on 6 august an onshore flow event and 12 august an offshore flow event 1991 is presented using single doppler observations satellite images and cloud pictures collected during the convection and precipitation electrification cape experiment documentation of the alongfrontal variability at the leading edge of the sea breeze circulation is presented for the first time the horizontal structure of the front was strongly modulated by the near perpendicular intersections of horizontal convective rolls developing in the ambient air out ahead of the sea breeze on 12 august these intersection points also appeared to be preferred locations for cloud development along the front horizontal convective rolls were also documented on 6 august however their orientation was nearly parallel to the sea breeze front as a result extended sections of these rolls appeared to have merged with the front as it propagated inland rather than having distinct intersection po

numerical simulation of the interaction between the sea breeze front and horizontal convective rolls part i offshore ambient flow abstract a three dimensional cloud resolving model is used to investigate the interaction between the sea breeze circulation and boundary layer roll convection horizontal convective rolls hcrs develop over land in response to strong daytime surface heating and tend to become aligned parallel to the vertical wind shear vector whereas the land sea heating contrast causes the formation of the sea breeze front sbf along the coastline the ability of hcrs to modulate the along frontal structure of the sbf is examined complementing and extending previous observational and numerical studies three simulations are discussed the first two demonstrating that the model can produce both phenomena independently the third is initialized with offshore mean flow and vertical shear perpendicular to the coastline and results in a sharply defined inland propagating sbf that encounters hcrs aligned perpendicular to it before the interaction takes place the sbf is nearly two dimensional and devoid of along front

misocyclone characteristics along florida gust fronts during cape multiple doppler radar and rawinsonde data are used to examine misocyclone characteristics along gust fronts observed during the convection and precipitation electrification cape project in florida the objective of this study is to investigate the observational representativeness of previous numerical simulations of misocyclones by employing a consistent analysis strategy to 11 gust fronts observed in the same region the investigation focuses on the intensity range of misocyclones and their organization along gust fronts the relationship between misocyclone intensity and horizontal wind shear vertical wind shear and static stability and the relationship between misocyclones and convection initiation the intensity of misocyclones as indicated by the maximum values of vertical vorticity varied from 2 8 10 3 to 13 9 10 3 s 1 although all but one case exhibited values less than 6 4 10 3 s 1 organized misocyclone patterns were only found along small segments of gust fronts within those segments misocyclones were spaced between 3 and 7 km results show that the intensity of misocyclones was most closely related to the strength of horizontal wind shear across the gust front the relationship between misocyclone intensity and vertical wind shear and static stability was not as clear although convection was initiated along the gust front in 7 of the 11 cases those regions were not collocated with or in close proximity to misocyclones

late pleistocene and holocene sea level change and coastal paleoenvironment evolution along the iranian caspian shore the authors published by elsevier b v this is an open access article under the cc by nc nd license http creativecommons org licenses by nc nd 4 0

alluvial sediment or playas what is the dominant source of sand and silt in desert soil vesicular a horizons southwest usa 1 vesicular a av soil horizons form beneath desert pavements from the accretion of aeolian sediment dust commonly thought to be derived primarily from desiccating pluvial lakes and playas with contributions from ephemeral washes and alluvial fans particle size distributions of av horizons are typically bimodal with primary modes of very fine silt and fine sand suggesting that the horizon matrix is derived from multiple sources here we conduct detailed chemical and physical analysis of both av horizon soil samples and potential sources of aeolian sediment to better constrain the relative contributions of dust associated with the development of av horizons geochemical data from both sand 125 250 m and silt 2 32 m fractions in av horizons and potential dust sources in the eastern mojave desert and western sonora desert usa point to large contributions from nearby sources including distal alluvial fans and washes and comparably lower contributions from regional sources such as playas the silt mode is derived from suspension transport of dust and the fine sand mode is derived from saltating sand the desiccation of pluvial lakes in the mojave desert is commonly believed to have driven episodes of aeolian activity contributing to sand dunes and av horizon formation we propose that alluvial fans and washes are underappreciated as desert dust sources and that pulses of dust from late pleistocene and holocene alluvial fans dwarfed pulses of dust from desiccating pluvial lakes in the eastern mojave desert

convective initiation ahead of the sea breeze front abstract in earlier work a three dimensional cloud model was used to simulate the interaction between the sea breeze front sbf and front parallel horizontal convective rolls hcrs resulting in the sbf systematically encountering roll updrafts and downdrafts as it progressed inland interestingly deep convection was spawned above an hcr updraft ahead of the sbf as the front approached well before the inevitable front roll merger ostensibly both the sea breeze and roll circulations were required for deep convection to be present in this case at all because convection was entirely absent when either phenomenon was removed further analysis reveals why both circulations were necessary yet not sufficient for the excitation of deep convection in this case the sea breeze circulation sbc made its upstream inland environment more favorable for convection by bringing about persistent if gentle lifting over an extended region stretching well ahead of the sbf this persistent ascent established a moist

interaction between turbulent flow and sea breeze front over urban like coast in large eddy simulation turbulent flow and its interaction with a sea breeze front sbf over an urban like coast with a regular block array were investigated using a building resolving computational fluid dynamics model it was found that during daytime with an offshore ambient flow streaky turbulent structures tended to grow within the convective boundary layer cbl over a warm urban surface ahead of the sbf the structures were organized as streamwise streaks at an interval of a few hundred meters which initiated at the rooftop level with strong wind shear and strengthens in the cbl with moderate buoyancy the streaks then interacted with the onshore propagating sbf as it made landfall the sbf which was initially characterized as a shallow and quasi linear feature over the sea developed three dimensional structures with intensified updrafts at an elevated frontal head after landfall frontal updrafts were locally enhanced at intersections where the streaks merged with the sbf which greatly increased turbulent fluxes at the front the frontal line was irregular because of merging tilting and transformation effects of vorticity associated with streaky structures inland penetration of the sbf was slowed by the frictional effect of urban like surfaces and turbulent flow on land the overall sbf intensity weakened after the interaction with turbulent flow these findings aid understanding of local weather over coastal cities during typical sea breeze conditions

an investigation of convection behind the cape canaveral sea breeze front abstract a three dimensional numerical simulation of land water circulations near cape canaveral florida is performed using the advanced regional prediction system the role of kelvin helmholtz instability khi in determining the time and location of convection behind the sea breeze front is examined the model configuration attempts to improve upon limitations of previous work e g resolution surface characteristics initial state it provides a detailed and realistic simulation of the desired features the simulation exhibits a single precipitating storm that forms behind the sea breeze front this postfrontal storm develops when an outflow boundary intersects a deep layer of upward motion above the marine air the region of ascent initially is the remnant of a cell that formed along the sea breeze front but before the cell decays a portion of its upward motion is intensified and displaced the modification of the ascent is a product of khi that is occurring on top of the sea breeze interface i

sea breeze circulation over jakarta indonesia a climatology based on boundary layer radar observations abstract characteristics of sea breeze circulation over the tropical site of jakarta indonesia have been documented based on analyses of satellite images and data from long term l band boundary layer radar measurements carried out at serpong 6 4 s 106 7 e inspection of satellite imagery reveals that a sea breeze front develops well along the northern coastal plain of west java and propagates inland until its structure is deformed over complex topography it is found that the sea breeze signal detected by the boundary layer radar is most well defined during the dry season months of july october in all of these months radar observations indicate a late afternoon intensification of sea breeze flow in the 0 5 0 8 km height range between 1700 and 1800 lt which is not elucidated upon by surface measurements the effect of weather conditions on the sea breeze pattern is investigated by using a cloudiness index derived from data of incoming solar radiation the results show that sea breeze intrusion over

observations of the finescale structure of a dryline during vortex 95 abstract the three dimensional finescale structure of a dryline observed over the texas panhandle during the verification of the origins in tornadoes experiment vortex on 6 may 1995 is presented high resolution observations documenting dryline evolution were collected from midafternoon while it moved slowly eastward until late afternoon as it retrogressed back to the west dryline variability in the horizontal along line direction was revealed by airborne doppler radar observations from the national center for atmospheric research electra doppler radar and ground based measurements from the nearby wsr 88d at amarillo texas this variability was created as the dryline interacted with horizontal convective rolls forming west of the dryline the rolls intersected the dryline at periodic locations creating radar reflectivity and vertical velocity maxima more importantly clouds initiated at these intersection points additional dryline variability was generated through the interaction of the low level fl

a high resolution record of holocene environmental and climatic changes from lake balikun xinjiang china implications for central asia a high resolution record of holocene environmental and climatic change in the balikun area was reconstructed from a sediment core from the lake balikun multiproxy data show that the climate was extremely arid during the early holocene before 8 6 cal ka bp moisture began to increase after 8 6 cal ka bp and the climate was humid between 7 9 and 4 3 cal ka bp a significant dry event occurred around 4 3 3 8 cal ka bp the climate became generally wet during the late holocene after 3 8 cal ka bp the holocene pollen and geophysical records do not indicate a wet early holocene making it evident that there was no early holocene humid period associated with peak asian monsoon strength regional comparisons indicate that this region has a different pattern of holocene environmental and climatic change from the asian monsoonal area and south siberia

quantitative paleoenvironmental and paleoclimatic reconstruction using paleosols abstract paleosols fossil soils are preserved throughout the geologic record in depositional settings ranging from alluvial systems to between basalt flows until recently paleosols were studied using primarily qualitative methods in recent years paleopedology has shifted from a largely qualitative field based on comparisons with modern analogues to an increasingly quantitative endeavor some of this change has been a result of applying existing techniques to new materials but many of the innovations have been the result of applying new techniques to new materials including thermodynamic modeling of soil formation isotope geochemistry and applications of empirical relationships derived from modern soils a variety of semi quantitative and quantitative tools has been developed to examine past weathering and pedogenesis and to reconstruct both paleoenvironmental and paleoclimatic conditions at the time that the paleosols formed though it is often not possible to achieve the same temporal resolution as with marine records for paleoclimatic reconstructions proxies based on paleosols are potentially a much more direct means of making paleoclimatic reconstructions because soils form at the earth s surface in direct contact with the atmospheric and climatic conditions at the time of their formation paleoclimatic and environmental properties that may be reconstructed using the new proxies include provenance weathering intensity mean annual precipitation and temperature during pedogenesis nutrient fluxes into and out of the paleosols the atmospheric composition of important gases including co2 and o2 the moisture balance during pedogenesis the soil gas composition reconstructed vegetative covering and paleo altitude

effects of the cold tongue in the south china sea on the monsoon diurnal cycle and rainfall in the maritime continent we investigate the effects of the cold tongue in the south china sea scs on the winter monsoon rainfall and diurnal cycle in the maritime continent using a numerical model verified with satellite rainfall and reanalysis data composite analysis of the observation and reanalysis data based on cold tongue index indicates that the penetration of the monsoon to java sea is enhanced when the cold tongue is strong a sensitivity experiment without the cold tongue shows that the winter monsoon is diminished over scs and around coastal regions because of anomalous low level cyclonic circulation associated with enhanced convection over scs due to the warmer sea surface temperature sst the diurnal cycle in particular the night morning rainfall over the sea in coastal regions is modified the effect on daytime rainfall over the land is relatively weaker along the northern coast of java far from the scs the night morning rainfall is much reduced over the java sea when the cold tongue is suppressed because of the weakened land breeze front as a result of the weakened northerly monsoon in contrast the afternoon evening rainfall on java island is slightly enhanced showing that the local impacts are not simply the result of large scale subsidence from the convective anomaly in the scs along the northwestern coast of borneo adjacent to the scs the weakened winter monsoon tends to reduce the rainfall at the land breeze front near the coastline on the other hand the warmer sst forces a stronger land breeze and the weakened monsoon encourages further and faster offshore propagation of the land breeze front consequently the rainfall peak shifts further offshore in the sensitivity experiment we conclude that the cold tongue has two effects the sustenance of a strong monsoon indirect effect and the cooling of local sst direct effect which have opposite influences on the diurnal cycle in the maritime continent

tropical island convection in the absence of significant topography part ii nowcasting storm evolution abstract this paper examines influences on the short range prediction of organized convection under conditions of strong diurnal forcing the analyses are based on data provided by the maritime continent thunderstorm experiment which was conducted in 1995 over the tiwi islands 11 s 50 100 km north of the australian continent organized convection over the tiwi islands is often dubbed hector by residents and researchers alike the authors purpose is to utilize results from these analyses to improve convective storm nowcast systems and their associated forecast and warning products the environmental near surface wind direction is shown to be singularly influential in statistically predicting the location of convection and its time of occurrence over the tiwi islands this finding is robust despite the fact that mean wind speeds were merely 1 4 m s 1 the island boundary layer water vapor mixing ratio derived from a morning sounding and inland surface stations is shown to be correlated with measu

sea breeze simulation over the malay peninsula in an intermonsoon period 1 this study presents a characteristic intermonsoon weather situation over the malay peninsula the coupled ocean atmosphere mesoscale prediction system coamps is used to investigate the mesoscale details of the simulated sea breeze circulations over the malay peninsula on 23 april 2002 the occurrence of sea breeze collisions occurring in the inland region of the southern malay peninsula is noted on the peninsula scale convection was first initiated along the low level convergence line that became established along the west coastal region of the malay peninsula in the early afternoon deep clouds that led to thunderstorms developed in the northwestern part of the malay peninsula after the sea breeze encountered the mountain wave induced under the ambient easterlies above the mountain ridge line the convective activity was further enhanced over the central malay peninsula because of the interaction between sea breeze front and gap winds from the mountains this case study suggests that the malay peninsula is a potentially fertile ground for many dynamically interesting case studies of land sea breeze circulations

introduction to holocene climate change new perspectives we live in the holocene its variability is our variability to fully understand modern climate change we need to accurately record how climate has been changing over the holocene s 11700 years as that is the backdrop to what is happening now on 4 5 april 2013 the geological society examined a range of evidence for changes in the holocene climate in a meeting entitled holocene climate change and organized by colin summerhayes nick mccave paul valdes graeme barker eric wolff and dan charman we hoped to find out more about what governed the occurrence of past cool events such as those that occurred at 8200 years ago and in the little ice age between roughly ad 1300 and 1850 and warm periods such as the holocene climate optimum the roman warm period and the medieval climate anomaly to what extent were these events global rather than regional what drove them what produced roughly periodic changes at intervals of about 1500 years seen in marine sediment records and speleothems was it ever warmer in the past 10000 years than it has been in the past 20 years if so when and by how much recent improvements in physical stratigraphy chemical stratigraphy and numerical modelling now allow us to examine in much more detail than before the effects of a wide variety of natural causes natural cycles and greenhouse gases and to integrate results from different land ice and ocean areas in ways not formerly possible to improve our understanding of holocene climate change the meeting was deliberately made broad in scope covering changes in ocean circulation and sea level terrestrial change change in the polar regions the modelling of any or all of those and the interaction between climate and humans as is often the case many of the 33 papers and

observations of the sea breeze front during cape part ii dual doppler and aircraft analysis abstract the three dimensional kinematic structures of offshore and onshore flow sea breeze fronts observed during the cape experiment are shown using high resolution dual doppler and aircraft data the fronts interact with horizontal convective rolls hcrs that develop within the convective boundary layer nearly perpendicular intersections between the hcrs and sea breeze front were observed during the offshore flow case close to the front the hcr axes were tilted upward and lifted by the frontal updrafts consequently a deeper updraft was created at the intersection points providing additional impetus for cloud development furthermore clouds forming at periodic intervals along the ncrs intensified as they propagated over the front during the onshore flow case the hcr orientation was nearly parallel to the front extended sections of the front merged with the hcrs this process strengthened the front and is explained as the merger of like sign vortices associated with both the front and hcrs

methane and carbon dioxide adsorption diffusion experiments on coal upscaling and modeling numerical modelling of the processes of co2 storage in coal and enhanced coalbed methane ecbm production requires information on the kinetics of adsorption and desorption processes in order to address this issue the sorption kinetics of co2 and ch4 were studied on a high volatile bituminous pennsylvanian upper carboniferous coal vrr 0 68 from the upper silesian basin of poland in the dry and moisture equilibrated states the experiments were conducted on six different grain size fractions ranging from 0 063 to f3 mm at temperatures of 45 and 32 jc using a volumetric experimental setup co2 sorption was consistently faster than ch4 sorption under all experimental conditions for moist coals sorption rates of both gases were reduced by a factor of more than 2 with respect to dry coals and the sorption rate was found to be positively correlated with temperature generally adsorption rates decreased with increasing grain size for all experimental conditions based on the experimental results simple bidisperse modelling approaches are proposed for the sorption kinetics of co2 and ch4 that may be readily implemented into reservoir simulators these approaches consider the combination of two first order reactions and provide in contrast to the unipore model a perfect fit of the experimental pressure decay curves the results of this modeling approach show that the experimental data can be interpreted in terms of a fast and a slow sorption process half life sorption times as well as the percentage of sorption capacity attributed to each of the two individual steps have been calculated further it was shown that an upscaling of the experimental and modelling results for co2 and ch4 can be achieved by performing experiments on different grain size fractions under the same experimental conditions in addition to the sorption kinetics sorption isotherms of the samples with different grain size fractions have been related to the variations in ash and maceral composition of the different grain size fractions d 2004 elsevier b v all rights reserved

the effect of latitude on the sea breeze abstract long term five day integrations of a nonlinear numerical model of the sea breeze at the equator 20 n 30 n and 45 n indicate the importance of latitude on the sea breeze circulation during the hours of strong heating when friction is largest and the static stability is smallest a local sea breeze frontal circulation develops in a similar way at all four latitudes evaluation of the terms in the circulation theorem indicates the dominance of the solenoid term horizontal pressure gradient force associated with the strong temperature contrast during this period during the rest of the period however the pressure gradient and frictional forces weaken the static stability increases and the coriolis force is dominant except at the equator therefore quite different circulations evolve at the different latitudes at the equator the absence of the coriolis force results in a sea breeze at all times at the other latitudes the coriolis force is responsible for producing the large scale lan

thunderstorm initiation organization and lifetime associated with florida boundary layer convergence lines abstract the initiation organization and longevity of thunderstorms associated with boundary layer convergence lines in the cape canaveral florida vicinity are examined using data from the convection and precipitation electrification cape experiment the project was conducted during july and august 1991 under low vertical wind shear situations this observational study is based on doppler radar mesonet balloon sounding and satellite data the primary convergence lines studied were the east coast sea breeze front ecsbf and a frequently occurring gust front from the west termed the west coast front wcf that originates with storms initiated by the west coast sea breeze front significantly fewer storms were associated with the ecsbf in comparison to the wcf this was because the convergence with the ecsbf was shallower and weaker and the updrafts were shallow and tilted the environmental winds were generally westerly near the top of the ecsbf and at storm steering level as a result the low le

barrier effect of the indo pacific maritime continent on the mjo perspectives from tracking mjo precipitation abstractexplanations for the barrier effect of the indo pacific maritime continent mc on the mjo should satisfy two criteria first they should include specific features of the mc namely its intricate land sea distributions and elevated terrains second they should include mechanisms for both the barrier effect and its overcoming by some mjo events guided by these two criteria a precipitation tracking method is applied to identify mjo events that propagate across the mc mjo c and those that are blocked by the mc mjo b about a half of mjo events that form over the indian ocean propagate through the mc most of them 75 become weakened over the mc the barrier effect cannot be explained in terms of the strength horizontal scale or spatial distribution of mjo convection when it approaches the mc from the west a distinction between mjo b and mjo c is their precipitation over the sea versus land in the mc region mjo c events rain much more over the sea than over land whereas rainfall over

coupling of swelling internal stress evolution and diffusion in coal matrix material during exposure to methane we construct theoretical models for time dependent swelling of coal matrix material upon adsorption of a single gas taking into account a coupling between stress strain chemical potential and diffusion two models are developed the first model a corresponds to diffusion and hence swelling rates being controlled by the jump frequency of adsorbed molecules between closely spaced adsorption sites and the second model b to transport controlled by diffusion of unadsorbed molecules through diffusion paths linking distant adsorption sites to test these models we performed axial swelling experiments on a single 4 mm sized cylindrical sample of medium volatile bituminous coal exposed to ch4 at pressures up to 40 mpa at 40 c using 1 d high pressure dilatometry the models were calibrated to the experimental data by adjustment of a single valued diffusion coefficient independent of gas pressure and adsorbed concentration the results show that the data can be accurately explained only by model b the implication is that the gas transport the associated adsorption and hence time dependent swelling are controlled by the diffusion of unadsorbed molecules and not by molecules jumping between the adjacent adsorption sites our model describes a full coupling between stress strain sorption and diffusion in coal matrix material in terms of parameters that have clear physical meaning and are easily obtained from sorption and swelling experiments on coal of any rank exposed to any gas it therefore offers an important tool for modeling permeability evolution with time during enhanced coalbed methane operations 2017 american geophysical union all rights reserved

the numerical simulation of nonsupercell tornadogenesis part ii evolution of a family of tornadoes along a weak outflow boundary abstract nonsupercell tornadogenesis along a weak outflow boundary has been simulated using a three dimensional moist convective cloud model thermodynamic conditions similar to those observed for nonsupercell tornado nst events of the high plains were utilized in the model initialization as the ensemble system of storm outflow boundary and leading edge vortices evolve six distinct life cycle stages for the development and decay of nsts are documented that span a period of about 35 min consistent with the results of part i of this numerical study vortex sheet dynamics exert considerable control over the outflow leading edge the progression of pretornadic life cycle stages serves to concentrate vertical vorticity effectively along the outflow boundary in discrete misocyclone circulations aligned in a 3 km wavelength pattern the organization of larger scale misocyclones and ultimate intensification to initial tornadic intensity occurs coincident with the rapid development of deep convection overhe

late pleistocene and holocene palaeoenvironments in and around the middle caspian basin as reconstructed from a deep sea core this article has been made available through open access by the brunel open access publishing fund

multi proxy survey of open air surface scatters in drylands archaeological and physico chemical characterisation of fossilised dunes in north gujarat india this research aims at improving our understanding of open air archaeological surface scatters in drylands their extension and the intensity of human activities during their occupation to do so the study of physico chemical proxies is integrated to that of archaeological artefacts by means of systematic field survey combined with laboratory sedimentary analyses and a robust statistical approach in most dry regions archaeological survey has traditionally aimed at the collection of artefacts when present the study of physical and geochemical samples has been limited to excavated archaeological levels in this work we evaluate the archaeological significance of physico chemical proxies from surface samples collected within and around four mid and late holocene surface scatters in north gujarat a semi arid region located at the south west margin of the thar desert in india the four archaeological scatters are found on top of fossilised sand dunes archaeologically they represent subsistence strategies based on hunting and gathering agro pastoralism or a succession mixture of the two the four locations were systematically sampled across a linear transect for each sampling unit the archaeological materials were quantified and classified by means of a linear discriminant analyses physio chemical variables were ordinated in a pca space and clustered through a hierarchical clustering results were displayed along the dune transect and integrated into a correspondence analysis significant differences are attested in the spatial distribution and content of ca p and grain size allowing us to suggest a set of distinct cultural soilscapes that characterise the dunes of the study area vertisols agric horizons in interdunal lower slopes aridisols relict dune surfaces in the mid slope and anthrosols top dune the last show a strong correspondence with the presence of archaeological artefacts and the different intensity of human footprint are discussed accordingly to potential past subsistence strategies and the intensity of human occupation

tropical island convection in the absence of significant topography part i life cycle of diurnally forced convection abstract diurnally forced convection was observed over the tiwi islands north of the australian continent as part of the maritime continent thunderstorm experiment immature peninsula scale 5 15 km sea breezes were observed to initiate moist convection early each day principally through convergence that results from the confluence or collision of peninsula breeze fronts convection initiated by peninsula scale breezes usually fails to organize beyond a small cluster of cells and dissipates as a local event mature island scale 100 km breezes develop by late morning and subsequently play a pivotal role in the forcing and evolution of organized convection the initiation of mesoscale convective systems mcss is observed to be a direct consequence of breeze front collisions for only 20 of the days on which organized convection develops this is referred to as type a forcing and it occurs when normal convective development is delayed or otherwise suppressed type a forcing is nature s backup mech

radar observations of the diurnally forced offshore convective lines along the southeastern coast of taiwan this study documents offshore convective lines along the southeastern coast of taiwan a frequent but poorly understood mesoscale phenomenon that influences coastal weather during the taiwan mei yu season doppler radar and surface observations were gathered from a specially chosen period 11 15 may 1998 when the offshore convective lines were active off the southeastern coast of taiwan these observations were used to show the basic character structure and possible formative processes of offshore convective lines the synoptic environment accompanying these events was found to be relatively undisturbed and featured uniformly prevailing southerly south southeasterly winds in the boundary layer with southwesterlies westerlies aloft examination of radar data during the study period indicates that the lines generally occurred 10 30 km offshore and were characterized by an elongated narrow zone 5 10 km wide of heavy precipitation the lines were oriented roughly parallel to the coastline and generally did not move significantly the intensity of the radar reflectivity associated with the lines exhibited a marked diurnal variation and was closely related to the coastal offshore flow developing at night detailed analyses of an event on 14 15 may 1998 further show the important physical link between the offshore flow and the development of the line the offshore line was found to be located near and immediately ahead of the seaward extent of the offshore flow particularly a very narrow zone 2 km of low level heavy precipitation 40 45 dbz coincided with regions of strong updrafts and convergence where the prevailing southerly onshore flow encountered the cool offshore flow nearshore this offshore flow induced convergence given a stable thermodynamic condition in the lowest 1 km in the inflow region was a crucial low level forcing that provided lifting to trigger moist deep convection in this case the line s precipitation tilt eastward was confined primarily to the warmer inflow side rather than feeding the offshore flow to the west of the line no consistent upshear tilt of updrafts throughout the storm layer was observed which is consistent with the presence of a strong westerly shear in the line s environment both of these observations explain a relatively strong weak modification of low level onshore offshore flow by precipitation additionally a combination of surface and doppler radar observations indicates that the leading edge of the offshore flow moved seaward very slowly at 0 7 m s 1 and possessed a frontal character with notable discontinuities in near surface wind and temperature instead of pressure and dewpoint temperature

a numerical study on sea land breezes as a gravity current kelvin helmholtz billows and inland penetration of the sea breeze front abstract a two dimensional nonhydrostatic compressible and dry numerical model was developed by using high spatial resolution and an appropriate turbulence model fine structure and dynamics of the sea breeze head were investigated kelvin helmholtz kh instability was found to occur in the foremost part of the head consequently kh billows were generated there and grew in amplitude while travelling backward relative to the advancing front along the zero velocity boundary the kh billows entrained the upper air into the sea breeze the resultant turbulent mixing and wave perturbations induced a top friction force acting on the sea breeze head structure of the kh billow and the wavelike motion induced by it near the ground were also investigated and compared with the results obtained in laboratory density currents linear theories and observations the kh instability khi did not occur at all stages of the sea breeze and this resulted in a diurnal variation of the fine structure and dynamics of

numerical simulation of the interaction between the dryline and horizontal convective rolls abstract the results of high resolution simulations of an idealized dryline environment are discussed the use of a single high resolution domain combined with accurate advection numerics and minimized numerical filtering allows the explicit resolution of large horizontal convective roll hcr circulations and their daytime evolution the horizontal convective rolls are oriented in the direction of the lower planetary boundary layer pbl wind shear by midafternoon a north south oriented dryline develops near the center of the simulation domain with the pbl circulations from both sides intersecting the dryline at multiple locations west of the dryline the hcr bands evolve into open convective cell occ structures having stronger and deeper vertical circulations compared to the occs and hcrs to the east the occs and hcrs east of the dryline impact the dryline and convective cloud location by modulating the low level moisture and upslope easterly flow the interaction between occ and hcr circulations

a nonclassical cold front observed during cops 91 frontal structure and the process of severe storm initiation abstract this case study addresses the issue of gravity current and bore development at surface cold fronts and the role of these phenomena in the generation of severe frontal convection the event investigated occurred on 27 april 1991 during the cooperative oklahoma profiler studies 1991 field project the development of a bore from a gravity current like structure along a cold front the subsequent propagation of the bore ahead of the front on a low level inversion and the process of severe thunderstorm development along the front are revealed by a dense network of remote sensing and other special observations evidence for the gravity current and bore is strengthened by comparisons made between the synthesized observations and theory the bore developed after a nocturnal inversion which acted as a waveguide had become established the bore and gravity current were both evident as fine lines in the radar reflectivity displays a microscale envelope of enhanced water vapor with an embedded roll cl

a case study of severe storm development along a dryline within a synoptically active environment part ii multiple boundaries and convective initiation abstract a dryline that occurred on 16 may 1991 within a synoptically active environment is examined in detail using research aircraft radar surface satellite and upper air observations the work focuses on multiple boundaries in the dryline environment and initiation of tornadic storms in two along line areas aircraft measurements in the boundary layer reveal that both the east west extent of moisture gradients and the number of regions containing large moisture gradients vary in the along dryline direction aircraft penetrations of thinlines observed in clear air return from radar reveal that all thinlines are associated with convergence and a moisture gradient and that more distinct thinlines are associated with stronger convergence however significant moisture gradients are not always associated with either thinlines or convergent signatures convective clouds on this day formed at the dryline rather than significantly east of the dryline the three thunderstorm cells that occurred in east cen

adsorption kinetics of co2 ch4 and their equimolar mixture on coal from the black warrior basin west central alabama abstract laboratory experiments were conducted to investigate the adsorption kinetic behavior of pure and mixed gases co 2 ch 4 approximately equimolar co 2 ch 4 mixtures and he on a coal sample obtained from the black warrior basin at the littleton mine twin pine coal company jefferson county west central alabama the sample was from the mary lee coal zone of the pottsville formation lower pennsylvanian experiments with three size fractions 45 150 m 1 2 mm and 5 10 mm of crushed coal were performed at 40 c and 35 c over a pressure range of 1 4 6 9 mpa to simulate coalbed methane reservoir conditions in the black warrior basin and provide data relevant for enhanced coalbed methane recovery operations the following key observations were made 1 co 2 adsorption on both dry and water saturated coal is much more rapid than ch 4 adsorption 2 water saturation decreases the rates of co 2 and ch 4 adsorption on coal surfaces but it appears to have minimal effects on the final magnitude of co 2 or ch 4 adsorption if the coal is not previously exposed to co 2 3 retention of adsorbed co 2 on coal surfaces is significant even with extreme pressure cycling and 4 adsorption is significantly faster for the 45 150 m size fraction compared to the two coarser fractions

numerical study of precipitation core gap structure along cold fronts abstract the mechanism responsible for the core gap structure of precipitation along narrow cold frontal rainbands ncfrs is investigated through analyses of idealized cloud resolving simulations of cold fronts the control simulation in which the prefrontal thermal stratification is characterized by a weak convective instability at low levels with convective available potential energy cape of 60 j kg 1 reproduces the typical alongfront variability of observed ncfrs the simulated ncfr is broken up into regularly spaced ellipsoidal cores oriented at a clockwise angle to the cold front while horizontal shear instability hsi has frequently been proposed as a mechanism leading to the alongfront variability of ncfrs no characteristic features of hsi are recognized in the simulated vertical vorticity field at the leading edge of the cold front the alongfront variability in precipitation is attributed to the formation of a wavelike disturbance just above the leading edge of the cold front the wave

holocene vegetation history and sea level changes in the se corner of the caspian sea relevance to sw asia climate the palynological investigation of core tm 27 7 m long taken in a dried out lagoon reveals both holocene vegetation history in the north eastern foothills of the alborz mountains and past water level changes of the caspian sea cs the delay in woodland expansion at the beginning of the holocene which is typical of eastern turkey the iranian plateau and recorded in the cs south basin is only weakly felt as the region is close to glacial refugia of trees the succession of the main trees out of their refugia has been established as deciduous quercus carpinus betulus parrotia persica and fagus orientalis pterocarya fraxinifolia presenting therefore close affinities to south european interglacials of the early pleistocene this suggests a similarity in climate a pterocarya decline is observed after ad 495 the studied region is close to the easternmost tree distribution this could explain why it has been affected earlier than elsewhere in the northern alborz and the caucasus in addition human activities during the sasanian empire and the subsequent drying of the climate contributed to weakening the spread of this tree a maximal sea level occurs in the first part of the holocene from 10 6 to 7 2 cal ka it is suggested that the cs levels were significantly influenced by the monsoon precipitations over the western himalayas via the uzboy inflow this is followed by low levels from 7 2 to 3 5 cal ka with a minimum at 3 9 cal ka the neocaspian period should be considered a biozone rather than a chronozone as the environmental conditions reconstructed from dinocyst assemblages are different in shallow shelf waters and in the deep basins