role of porolithon algal ridge growth in the development of the windward coast of tongatapu island tonga south pacific a description of the algal ridge fringing the windward coasts of the island of tongatapu is given three coastal types can be distinguished according to the height of the algal ridge type a coasts have a low algal ridge and low wave energy surge channels are few and uncovered blowholes are poorly developed the reef flat is wide and has numerous living corals many beaches occur except around promontories where a cliff foot notch is actively forming type b coasts have a medium height algal ridge and experience moderate wave energy surge channels are longer more frequently covered and blowholes consequently better developed the reef flat shore platform has less coral living on its surface large beaches along type b coasts are the outcome of sediment becoming trapped on the shoreward side of the algal ridge following storms type c coasts have a high algal ridge and are characterized by a high energy regime surge channels are almost all covered giving rise to spectacular blowholes except where collapse has caused the algal ridge to assume a buttressed rather than linear form the shore platform surface is devoid of living coral and lies above high tide level the cliff foot notch is shielded by the algal ridge from direct wave attack a notch is forming on the upper part of the outer slope of the shore platform such notches were observed only along type c coasts a model for holocene coastline development is outlined the reef established on the mid holocene shore platform emerged abruptly by 2 m as the result of coseismic uplift around 4000 years ago sea level fell around 3000 years ago erosion concentrated on reducing emerged shore platform level sea level stabilized around 1000 years ago the emerged shore platform continued to be lowered around 600 years ago algal ridge growth commenced thereon rates of vertical growth ranged from 0 5 to 2 1 mm a 1 the process regime along type c coasts changed around 362 years ago when the algal ridge reached a sufficient height to shield the shoreline from the processes which had fashioned it and a lower level notch began to be cut on the reef slope

holocene tectonic histories for five islands in the south central lau group south pacific low level 30 m evidence for emergence is reported for five islands along the south central lau ridge which has a well documented history of late cenozoic uplift most of the evidence is erosional some of the lowest is emerged reef and beachrock all can be linked to higher relative sea levels correlations are established between islands and most of the series of emerged shorelines found to exhibit characteristics of coseismically uplifted series elsewhere dates for various shorelines allow ages and recurrence intervals of coseismic uplift events to be tentatively established for all islands by reconciling this with contemporary sealevel changes magnitudes of coseismic uplift are obtained for the middle and late holocene the islands of moce and oneata have experienced fewest coseismic uplift events with small uplift magnitudes four coseismic uplift events are identified for lakeba with an average magnitude of 2 63 m and an assumed recurrence interval of 1045 years no uplift has apparently occur

distribution of helicity cape and shear in tropical cyclones abstract the previous study of helicity cape and shear in hurricane bonnie 1998 was extended to all eight tropical cyclones sampled by nasa during the convection and moisture experiments camex storms were categorized as having large or small ambient vertical wind shear with 10 m s 1 as the dividing line in strongly sheared storms the downshear mean helicity exceeded the upshear mean by a factor of 4 as in the previous study the helicity differences resulted directly from the tropical cyclone response to ambient shear with enhanced in up out flow and veering of the wind with height present downshear cape in strongly sheared storms was 60 larger downshear mean inflow near the surface and the depth of the inflow layer each were 4 times larger downshear at more than 30 of observation points outside the 100 km radius in the downshear right quadrant midlatitude empirical parameters indicated a strong likelihood of supercells no such points existed upshear in highly sheared storms much small

geochemistry of groundwater in the saint edouard area quebec canada and its influence on the distribution of methane in shallow aquifers abstract shale gas and tight oil production has undergone a tremendous increase in the last decade in north america which was accompanied by animated scientific debate and local public uproar concerning environmental issues especially the risks of contamination for shallow groundwater resources in quebec eastern canada public concerns led to a de facto moratorium on hydraulic fracturing in 2010 for the st lawrence lowlands where the underlying utica shale is known to contain significant gas resources as only a few exploration gas wells have been drilled this vast area may still be considered virgin in 2012 a 4 year project was initiated by the geological survey of canada which aimed at characterizing aquifer vulnerability to deep industrial activities in the saint edouard region located close to quebec city in the st lawrence lowlands as part of this project a baseline study of hydrocarbons and other geochemical parameters was conducted in shallow aquifers this paper presents groundwater geochemical characteristics in the region and assesses the geological hydrogeological and geochemical controls on methane distribution results show that methane is present in 96 of the 48 sampling points over the 500 km2 study area and that concentrations are highly variable from undetected

revisiting azimuthally asymmetric moist instability in the outer core of sheared tropical cyclones abstractthis study revisits the characteristics and physical processes of the azimuthally asymmetric distribution of moist instability in the outer core of vertically sheared tropical cyclones tcs

rapidly intensifying hurricane guillermo 1997 part i low wavenumber structure and evolution abstract the structure and evolution of rapidly intensifying hurricane guillermo 1997 is examined using airborne doppler radar observations in this first part the low azimuthal wavenumber component of the vortex is presented guillermo s intensification occurred in an environmental flow with 7 8 m s 1 of deep layer vertical shear as a consequence of the persistent vertical shear forcing of the vortex convection was observed primarily in the downshear left quadrant of the storm the greatest intensification during the 6 h doppler observation period coincided with the formation and cyclonic rotation of several particularly strong convective bursts through the left of shear semicircle of the eyewall some of the strongest convective bursts were triggered by azimuthally propagating low wavenumber vorticity asymmetries mesoscale budget analyses of axisymmetric angular momentum and relative vorticity within the eyewall are presented to elucidate the mechanisms contributing to guillermo s structural evol

hydraulic fracturing not responsible for methane migration although osborn et al 1 provided important geochemical measurements of dissolved methane in a portion of the appalachian basin their report does not fully appreciate the geologic history of this region and misrepresents potential risks of modern drilling and completion techniques used to develop shale gas resources the fear that hydraulic fracturing is responsible for methane migration from the marcellus shale into shallow groundwater is contrasted by direct observations in microseismic studies that even the longest fractures induced by the hydraulic fracturing process remain thousands of feet below groundwater resources 2

multiscale structure and evolution of hurricane earl 2010 during rapid intensification abstractthe structure and evolution of hurricane earl 2010 during its rapid intensification as sampled by aircraft is studied here rapid intensification occurs in two stages during the early stage covering 24 h earl was a tropical storm experiencing moderate northeasterly shear with an asymmetric distribution of convection and the symmetric structure was shallow broad and diffuse the upper level circulation center was significantly displaced from the lower level circulation at the beginning of this stage deep vigorous convection termed convective bursts was located on the east side of the storm and appeared to play a role in positioning the upper level cyclonic circulation center above the low level center by the end of this stage the vortex was aligned and extended over a deep layer and rapid intensification began during the late stage rapid intensification continued as earl intensified 20 m s 1 during the next 24 h the vortex remained aligned in the presence of weaker vertical shear

eastern pacific hurricanes jimena of 1991 and olivia of 1994 the effect of vertical shear on structure and intensity abstract shear is a key inhibitor of tropical cyclone intensification although its signature is readily recognized in satellite imagery and theoretical or modeling studies provide some insight detailed observations have been limited airborne radar and in situ observations in hurricanes jimena of 1991 and olivia of 1994 are a step toward better understanding each storm was observed on two consecutive days initially both had small eyes 16 18 km radius and maximum winds of 57 m s 1 over sea surface temperatures sst 28 c in easterly environmental shear jimena maintained constant intensity or weakened gradually for 2 days in 13 20 m s 1 easterly shear olivia intensified in 8 m s 1 shear on the first day overnight the shear diminished to reverse and became westerly on the second day olivia weakened as the shear increased to 15 m s 1 from the west the storm moved over cooler sst and became surrounded by dryer air as convection weakened and the outer rainbands ceased to be effective barriers

distributions of shallow to very deep precipitation convection in rapidly intensifying tropical cyclones abstractshear relative distributions of four types of precipitation convection in tropical cyclones tcs are statistically analyzed using 14 years of tropical rainfall measuring mission trmm precipitation radar pr data the dataset of 1139 trmm pr overpasses of tropical storms through category 2 hurricanes over global tc prone basins is divided by future 24 h intensity change it is found that increased and widespread shallow precipitation defined as where the 20 dbz radar echo height 6 km around the storm center is a first sign of rapid intensification ri and could be used as a predictor of the onset of ri the contribution to total volumetric rain and latent heating from shallow and moderate precipitation 20 dbz echo height between 6 and 10 km in the inner core is greater in ri storms than in non ri storms while the opposite is true for moderately deep 20 dbz echo height between 10 and 14 km and very deep precipitation 20 dbz echo height 14 km the authors argue that ri is more likely

inner core structure of hurricane alicia from airborne doppler radar observations abstract airborne doppler radar measurements are used to determine the horizontal winds vertical air motions radar reflectivity and hydrometer fallspeeds over much of the inner core region within 40 km of the eye of hurricane alicia 1983 the reconstructed flow field is more complete and detailed than any obtained previously the data show both the primary azimuthal and secondary radial height circulations the primary circulation was characterized by an outward sloping maximum of tangential wind the secondary circulation was characterized by a deep layer of radial inflow in the lower troposphere and a layer of intense outflow above 10 km altitude the rising branch of the secondary circulation was located in the eyewall and sloped radially outward discrete convective scale bubbles of more intense upward motion were superimposed on this mean rising current and convective scale downdrafts were located throughout and below the core of maximum precipitation in the eyewall precipitation particle

azimuthal distribution of deep convection environmental factors and tropical cyclone rapid intensification a perspective from hwrf ensemble forecasts of hurricane edouard 2014 abstractforecasts from the operational hurricane weather research and forecasting hwrf based ensemble prediction system for hurricane edouard 2014 are analyzed to study the differences in both the tropical cyclone inner core structure and large scale environment between rapidly intensifying ri and non intensifying ni ensemble members an analysis of the innercore structure reveals that as deep convection wraps around from the downshear side of the storm to the upshear left quadrant for ri members vortex tilt and asymmetry reduce rapidly and ri occurs for ni members deep convection stays trapped in the downshear downshear right quandrant and storms do not intensify the budget calculation of tangential wind tendency reveals that the positive radial eddy vorticity flux for ri members contributes significantly to spinning up the tangential wind in the middle and upper levels and reduces vortex tilt the negative eddy vorticity flux for ni members spins down the tangential wind in the middle and u

downdrafts and the evolution of boundary layer thermodynamics in hurricane earl 2010 before and during rapid intensification abstractusing a combination of noaa p 3 aircraft tail doppler radar noaa and nasa dropsondes and buoy and drifter based sea surface temperature data different types of downdrafts and their infl

the geochemistry of naturally occurring methane and saline groundwater in an area of unconventional shale gas development abstract since naturally occurring methane and saline groundwater are nearly ubiquitous in many sedimentary basins delineating the effects of anthropogenic contamination sources is a major challenge for evaluating the impact of unconventional shale gas development on water quality this study investigates the geochemical variations of groundwater and surface water before during and after hydraulic fracturing and in relation to various geospatial parameters in an area of shale gas development in northwestern west virginia united states to our knowledge we are the first to report a broadly integrated study of various geochemical techniques designed to distinguish natural from anthropogenic sources of natural gas and salt contaminants both before and after drilling these measurements include inorganic geochemistry major cations and anions stable isotopes of select inorganic constituents including strontium 87sr 86sr boron 11b lithium 7li and carbon 13c dic select hydrocarbon molecular methane ethane propane butane and pentane and isotopic tracers 13c ch4 13c c2h6 tritium 3h and noble gas elemental and isotopic composition helium neon argon in 105 drinking water wells with repeat testing in 33 of the wells total samples 145 in a subset of wells n 20 we investigated the variations in water quality before and after the installation of nearby 50 mg l the integrated geochemical data indicate that the saline groundwater originated via naturally occurring processes presumably from the migration of deeper methane rich brines that have interacted extensively with coal lithologies these observations were consistent with the lack of changes in water quality observed in drinking water wells following the installation of nearby shale gas wells in contrast to groundwater samples that showed no evidence of anthropogenic contamination the chemistry and isotope ratios of surface waters n 8 near known spills or leaks occurring at disposal sites mimicked the composition of marcellus flowback fluids and show direct evidence for impact on surface water by fluids accidentally released from nearby shale gas well pads and oil and gas wastewater disposal sites overall this study presents a comprehensive geochemical framework that can be used as a template for assessing the sources of elevated hydrocarbons and salts to water resources in areas potentially impacted by oil and gas development

the role of vortical hot towers in the formation of tropical cyclone diana 1984 abstract a high resolution 3 km horizontal grid spacing near cloud resolving numerical simulation of the formation of hurricane diana 1984 is used to examine the contribution of deep convective processes to tropical cyclone formation this study is focused on the 3 km horizontal grid spacing simulation because this simulation was previously found to furnish an accurate forecast of the later stages of the observed storm life cycle the numerical simulation reveals the presence of vortical hot towers or cores of deep cumulonimbus convection possessing strong vertical vorticity that arise from buoyancy induced stretching of local absolute vertical vorticity in a vorticity rich prehurricane environment at near cloud resolving scales these vortical hot towers are the preferred mode of convection they are demonstrated to be the most important influence to the formation of the tropical storm via a two stage evolutionary process i preconditioning of the local environment via diabatic production of mul

precipitation processes and vortex alignment during the intensification of a weak tropical cyclone in moderate vertical shear abstractthe mechanisms underlying the development of a deep aligned vortex and the role of convection and vertical shear in this process are explored by examining airborne doppler radar and deep

dual aircraft investigation of the inner core of hurricane norbert part i kinematic structure abstract on 24 25 september 1984 air motions and physical processes in the eyewall region of hurricane norbert were investigated with two national oceanic and atmospheric administration noaa aircraft operations center aoc wp 3d research aircraft one aircraft equipped with the airborne doppler radar flew repeated radial penetrations of the eyewall mapping the three dimensional wind field throughout a 40 km radius of the storm center these data provide the first complete documentation of the three dimensional wind field of the inner core of a hurricane on spatial scales of 10 25 km in the horizontal and 1 km in the vertical and temporal scales of 1 2 h the wind field was asymmetric and the asymmetry varied with altitude as altitude increased the location of the maximum tangential wind sloped upwind from left of the storm track at 1 km altitude to right of the storm track above 3 km the radial wind at 1 km altitude was inward in front of the storm and outward behind this pattern in the radial

asymmetric hurricane boundary layer structure from dropsonde composites in relation to the environmental vertical wind shear this study investigates the asymmetric structure of the hurricane boundary layer in relation to the environmentalverticalwind shearin theinner core region data from1878 gps dropsondesdeployed by research aircraft in 19 hurricanes are analyzed in a composite framework kinematic structure analyses based on doppler radar data from 75 flights are compared with the dropsonde composites shear relative quadrantmeancomposite analysesshow that boththekinematicandthermodynamic boundarylayerheight scalestend to decrease with decreasing radius consistent with previous axisymmetric analyses there is still a clear separation between the kinematic and thermodynamic boundary layer heights both the thermodynamic mixed layer and height of maximum tangential wind speed are within the inflow layer the inflow layer depth is found to be deeper in quadrants downshear with the downshear right dr quadrant being the deepest the mixed layer depth and height of maximum tangential wind speed are alike at the eyewall but are deeper outside in quadrants left of the shear the results also suggest that air parcels acquire equivalent potential temperature ue from surface fluxes as they rotate through the upshear right ur quadrant from the upshear left ul quadrant convection is triggered in the dr quadrant in the presence of asymmetric mesoscale lifting coincident with a maximum in ue energy is then released by latent heating in the downshear left dl quadrant convective downdrafts bring down cool and dry air to the surface and lower ue again in the dl and ul quadrants this cycling process may be directly tied to shear induced asymmetry of convection in hurricanes

pollen analysis of mangrove sediments as a sea level indicator assessment from tongatapu tonga increasing necessity for precision in holocene sea level records calls for definitive sea level indicators to be assessed these are reviewed by use of examples from the s w pacific and the technique of pollen analysis of mangrove sediments evaluated as a high resolution sea level indicator example is given how a fully calibrated sea level reconstruction can be gained from holocene mangrove peat units from tongatapu tonga by application of features established from a modern analogue of surface samples to interpret fossil pollen patterns

how does hurricane edouard 2014 evolve toward symmetry before rapid intensification a high resolution ensemble study abstracta 14 member high resolution ensemble of edouard 2014 a moderately sheared tropical storm that underwent rapid intensification ri is used to determine causes of vortex alignment and pr

rapid development of the tropical cyclone warm core this paper presents a simple theoretical argument to isolate the conditions under which a tropical cyclone can rapidly develop a warm core thermal structure and subsequently approach a steady state the theoretical argument is based on the balanced vortex model and in particular on the associated transverse circulation equation and the geopotential tendency equation these second order partial differential equations contain the diabatic forcing and three spatially varying coefficients the static stability a the baroclinity b and the inertial stability c thus the transverse circulation and the temperature tendency in a tropical vortex depend not only on the diabatic forcing but also on the spatial distributions of a b and c experience shows that the large radial variations of c are typically the most important effect under certain simplifying assumptions as to the vertical structure of the diabatic forcing and the spatial variability of a b and c the transverse circulation equation and the geopotential tendency equation can be solved via separation of variables the resultingradialstructureequationsretainthedynamicallyimportantradialvariationofcandcanbe solvedin terms of green s functions these analytical solutions show that the vortex response to a delta function in the diabatic heating depends critically on whether the heating occurs in the low inertial stability region outside the radius of maximum wind or in the high inertial stability region inside the radius of maximum wind this resultsuggeststhatrapidintensification isfavoredforstormsthathaveat leastsome oftheeyewallconvection inside the radius of maximum wind the development of an eye partially removes diabatic heating from the high inertial stability region of the storm center however rapid intensification may continue if the eyewall heating continues to become more efficient as the warm core matures and static stability increases over the inner core conditions there become less favorable for deep upright convection and the storm tends to approach a steady state

quadrant distribution of tropical cyclone inner core kinematics in relation to environmental shear abstractairborne doppler radar data collected in tropical cyclones by national oceanic and atmospheric administration wp 3d aircraft over an 8 yr period 2003 10 are used to statistically analyze the vertical structure of tropical cyclone eyewalls with reference to the deep layer shear convective evolution within the inner core conforms to patterns shown by previous studies convection initiates downshear right intensifies downshear left and weakens upshear analysis of the vertical distribution of radar reflectivity and vertical air motion indicates the development of upper level downdrafts in conjunction with strong convection downshear left and a maximum in frequency upshear left intense updrafts and downdrafts both conform to the shear asymmetry pattern while strong updrafts occur in the eyewall intense downdrafts show far more radial variability particularly in the upshear left quadrant though they concentrate along the eyewall edges strong updrafts are collocated with low level inflow and

late holocene slip rate and recurrence of great earthquakes on the san andreas fault in northern california the slip rate of the san andreas fault 45 km north of san francisco at olema california is determined by matching offset segments of a buried late holocene stream channel stream deposits from 1 800 plus minus 78 yr b p are offset 42 5 plus minus 3 5 m across the active 1906 fault trace for a minimum late holocene slip rate of 24 plus minus 3 mm yr when local maximum coseismic displacements of 4 9 to 5 5 m from the 1906 earthquake are considered with this slip rate the recurrence of 1906 type earthquakes on the north coast segment of the san andreas fault falls within the interval of 221 plus minus 40 yr both comparable coseismic slip in 1906 and similar late holocene geologic slip rates at the olema site and a site 145 km northwest at point arena prentice 1989 suggest that the north coast segment behaves as a coherent rupture unit

an expanded dataset of hurricane eyewall sizes and slopes abstractusing airborne doppler radar data from 39 flights into hurricanes from 2004 to 2010 the authors examine the outward slope of the eyewall revisiting the recent studies of stern and nolan the slope of the radius of maximum winds rmw is found to increase nearly linearly with size and is uncorrelated with intensity the slope of the eyewall absolute angular momentum surface m increases with increasing size strong correlation and decreases with increasing intensity weak to moderate correlation two other measures of eyewall slope are also investigated the 20 dbz reflectivity isosurface dbz20 and the radius of maximum azimuthal mean updraft rwmax the slopes of both dbz20 and rwmax increase with their size the slope of dbz20 decreases with intensity though the correlation is weak while the slope of rwmax is uncorrelated with intensity the absolute angular momentum decreases on average along the rmw by 9 from 2 to 8 km heights with this larger dataset the previous results are genera

importance of the upper level warm core in the rapid intensification of a tropical cyclone 1 in this study the rapid intensification ri of tropical cyclone is examined using a 72 h cloud permitting prediction of hurricane wilma 2005 with a record breaking intensity of 882 hpa results show the formation of an upper level warm core from the descending air of stratospheric origin in the eye which coincides with the onset of ri it reaches the peak amplitude of more than 18 c from its initial conditions at the time of peak intensity the descending air is associated with the detrainment of convective bursts in the eyewall and it appears as perturbation cyclonic radial inflows above the upper outflow layer and causes the subsidence warming below we hypothesize that the upper divergent outflow layer favors the generation of a warm core by protecting it from ventilation by environmental flows use of the hydrostatic equation shows that the warm core of stratospheric origin contributes more than twice as much as the lower level warm column to the pressure change at the peak intensity of wilma results suggest that more attention be paid to the magnitude of storm relative flows and vertical wind shear in the upper troposphere rather than just vertical shear in the typical 850 200 hpa layer in order to reasonably predict the ri of tropical cyclones

shear relative asymmetries in tropical cyclone eyewall slope abstractrecent studies have analyzed the azimuthal mean slope of the tropical cyclone tc eyewall this study looks at the shear relative azimuthal variability of different metrics of eyewall slope the 20 dbz surface the radius of maximum wind rmw and an angular momentum m surface passing through the rmw the data used are doppler radar composites from the noaa hurricane research division hrd this study examines 34 tcs with intensities ranging from 3 to 75 m s 1 and shear magnitudes ranging from 0 to 10 m s 1 calculation of the mean slope in each quadrant for all cases shows that rmw slope has the strongest asymmetry with downshear slope larger than upshear in 62 of cases slopes of momentum surfaces and dbz surfaces are also greater downshear in some cases 65 for m and 47 for dbz but there is more variance than in the rmw slope the azimuthal phase of maximum slope occurs most often downshear particularly downshear left consistent with the depiction of a mean vortex tilt approximate

thermodynamic and kinematic influences on precipitation symmetry in sheared tropical cyclones bertha and cristobal 2014 abstractprior studies have shown an association between symmetrically distributed precipitation and tropical cyclone tc intensification although environmental vertical wind shear typically forces an asymmetric precipitation distribution in tcs the magnitude of this asymmetry can exhibit considerable variability even among tcs that experience similar shear magnitudes this observational study examines the thermodynamic and kinematic influences on precipitation symmetry in two such cases bertha and cristobal 2014 consistent with the impact of the shear both tcs exhibited a tilted vortex as well as a pronounced azimuthal asymmetry with the maximum precipitation occurring in the downshear left quadrant however bertha was characterized by more symmetrically distributed precipitation and relatively modest vertical motions while cristobal was characterized by more azimuthally confined precipitation and much more vigorous vertical motions observations showed three potential hindrances to precipitat

analytical investigation of hydraulic fracture induced seismicity and fault activation more recent public discourse has taken place regarding the potential correlation between seismic activity and hydraulic fracturing in shale gas reservoirs public fears about the risk of seismicity stem mainly from past earthquakes induced by conventional deep injections because the two types of projects share similar mechanisms of rock failure and fault activation although previous earthquake risks associated with fluid injection were not serious the situation would be far more problematic if hydraulic fracturing in a shale gas reservoir triggered a similar sized earthquake due to potential environmental issues in fact almost all documented injection induced earthquakes have been associated with long duration and high volume injection rather than short term hours pressurization e g hydraulic fracturing in general hydraulic fracturing operations mostly induce microseismic events through rock failure and activation of small fractures although shale reservoirs in tectonically active zones pose a high risk of inducing large magnitude seismic activities the internal geological conditions and external stimulation conditions are impossible to be satisfied simultaneously to trigger activation of an entire fault and to result in a destructive earthquake during hydraulic fracturing operations

the relationship between spatial variations in the structure of convective bursts and tropical cyclone intensification as determined by airborne doppler radar abstractthe relationship between radial and azimuthal variations in the composite characteristics of convective bursts cbs that is regions of the most intense upward motion in tropical cyclones

rapid intensification of a sheared fast moving hurricane over the gulf stream abstracthurricane irene 1999 rapidly intensified from 65 to 95 kt 33 4 to 48 9 m s 1 in 18 h during the rapid intensification ri period the northeastward storm motion increased from 10 to 18 m s 1 the ambient southwesterly vertical wind shear increased from 6 7 to 10 13 m s 1 and the downshear tilt of the inner core vortex increased the azimuthal wavenumber 1 asymmetric convection that developed was consistent with a superposition of shear induced and storm motion induced forcing for vertical motion downshear and ahead of the center although the diabatic heating remained strongly asymmetric it was of sufficient intensity to dramatically increase the azimuthally averaged heating this heating occurred almost entirely inside the radius of maximum winds a region known to favor rapid warm core development and spinup of the vortex it is hypothesized that asymmetric forcing from the large vertical wind shear and rapid storm motion were responsible for ri an unanswered question is what determin

water resource impacts during unconventional shale gas development the pennsylvania experience abstract improvements in horizontal drilling and hydrofracturing have revolutionized the energy landscape by allowing the development of so called unconventional gas resources the marcellus play in the northeastern u s a documents how fast this technology developed the number of unconventional marcellus wells in pennsylvania pa increased from 8 in 2005 to 7234 today publicly available databases in pa show only rare evidence of contamination of surface and groundwaters this could document that incidents that impact pa waters have been relatively rare and that contaminants were quickly diluted however firm conclusions are hampered by i the lack of information about location and timing of incidents ii the tendency to not release water quality data related to specific incidents due to liability or confidentiality agreements iii the sparseness of sample and sensor data for the analytes of interest iv the presence of pre existing water impairments that make it difficult to determine potential impacts from shale gas activity and v the fact that sensors can malfunction or drift although the monitoring data available to assess contamination events in pa are limited the state manages an online database of violations overall one fifth of gas wells drilled were given at least one non administrative notice of violation nov from the pa regulator through march 2013 3 4 of gas wells were issued novs for well construction issues and 0 24 of gas wells received novs related to methane migration into groundwater between 2008 and 2012 161 of the 1000 complaints received by the state described contamination that implicated oil or gas activity natural gas was reported for 56 and brine salt components for 14 of the properties six percent of the properties were impacted by sediments turbidity and or drill cuttings most of the sites of groundwater contamination with methane and or salt components were in previously glaciated northern pa where fracture flow sometimes allows long distance fluid transport no cases of subsurface transport of fracking or flowback fluids into water supplies were documented if marcellus related flowback production waters did enter surface or groundwaters the most likely contaminants to be detected would be na ca and cl but those elements are already common in natural waters the most marcellus specific fingerprint elements are sr ba and br for example variable br concentrations measured in southwestern pa streams were attributed to permitted release of wastewaters from unconventional shale gas wells into pa streams through municipal or industrial wastewater treatment plants before 2011 discharge has now been discontinued except for brines from a few plants still permitted to discharge conventional oil gas brines after treatment overall drinking water supply problems determined by the regulator to implicate oil gas activities peaked in frequency in 2010 while spill rates increased through 2012 although many minor violations and temporary problems have been reported the picture that emerges from pa is that the fast shale gas start may have led to relatively few environmental incidents of significant impact compared to wells drilled however the impacts remain difficult to assess due to the lack of transparent and accessible data

analyzing simulated convective bursts in two atlantic hurricanes part i burst formation and development abstractunderstanding the structure and evolution of the tropical cyclone tc inner core remains an elusive challenge in tropical meteorology especially the role of transient asymmetric features such as localized strong updrafts known as convective bursts cbs this study investigates the formation of cbs and their role in tc structure and evolution using high resolution simulations of two atlantic hurricanes dean in 2007 and bill in 2009 with the weather research and forecasting wrf model several different aspects of the dynamics and thermodynamics of the tc inner core region are investigated with respect to their influence on tc convective burst development composites with cbs show stronger radial inflow in the lowest 2 km and stronger radial outflow from the eye to the eyewall around z 2 4 km than composites without cbs asymmetric vorticity associated with eyewall mesovortices appears to be a major factor in some of the radial flow anomalies that lead to cb development the anomalous outfl

the dynamics of intensification in a hurricane weather research and forecasting simulation of hurricane earl 2010 we use a high resolution numerical simulation of atlantic hurricane earl 2010 to increase our understanding of earl s intensification in relatively strong vertical shear in the context of a recent paradigm for tropical cyclone intensification the integrity of the simulation is judged by comparing analyses thereof with those of the unprecedented observational data gathered in earl consistent with the classical view of spin up the amplification of the tangential wind field above the boundary layer is found to occur as the absolute angular momentumsurfaces are drawn inwards by the aggregate heating of the rotating convective clouds in the interior of the vortex in addition to this classical pathway spin up occurs within the inner core boundary layer where the maximum tangential winds occur the latter is another element of the new paradigm despite the detrimental influence of the shear on the vortex alignment and on depressing the pseudo equivalent potential temperature outside the developing eyewall the combined eddy processes associated with the vortical plume structures in and around the developing eyewall region are shown to contribute to an enhanced overturning circulation and an intensifying storm these eddy processes are distinctly agradient effects that are not features of the classical spin up mechanism it remains to be understood how the rotating convective updraughts combine to produce the diagnosed structures of the eddy terms themselves and how vortex rossby waves and other eddies contribute to the alignment of the vortex during intensification

holocene coral reef terraces and coseismic uplift of huon peninsula papua new guinea abstract as many as six levels of emerged holocene coral terraces occur along 40 km of coastline on the huon peninsula papua new guinea recording uplift history since culmination of the postglacial transgression the holocene reef crest ca 6000 yr b p is tilted down to the northwest parallel to the coast and concordant with the deformation of the last interglacial coral reef terrace and descends from 23 to 12 m in the study area the pattern and rate of deformation have been uniform in the late quaternary because average uplift rates have remained the same since the last interglaciation the holocene terraces described here are erosional features with regressive encrusting corals developed upon the holocene transgressive reef the multiple levels represent episodic probably coseismic uplift which has occurred repeatedly in the last ca 6000 yr significant longshore variation in the age of the lowest terrace from 1700 to 2500 yr b p suggests independent coseismic uplift on different sectors of the coast this is supported by age height relationships of the higher holocene terraces nonlinear uplift during the holocene with recurrence intervals increasing toward the present is clearly recorded by the regressive terraces in each subregion some of the holocene regressive terraces grade laterally into fluvial terraces capped with debris flow deposits probably reflecting seismically triggered mass movement

kinematics of the secondary eyewall observed in hurricane rita 2005 abstractairborne doppler radar data collected from the concentric eyewalls of hurricane rita 2005 provide detailed three dimensional kinematic observations of the secondary eyewall feature the secondary eyewall radar echo shows a ring of heavy precipitation containing embedded convective cells which have no consistent orientation or radial location the axisymmetric mean structure has a tangential wind maximum within the reflectivity maximum at 2 km altitude and an elevated distribution of its strongest winds on the radially outer edge the corresponding vertical vorticity field contains a low level maximum on the inside edge which is part of a tube of increased vorticity that rises through the center of the reflectivity tower and into the midlevels the secondary circulation consists of boundary layer inflow that radially overshoots the secondary eyewall a portion of this inflowing air experiences convergence and supergradient forces that cause the air to rise and flow radially outward back into th

multiscale analysis of tropical cyclone kinematic structure from airborne doppler radar composites abstractthe multiscale inner core structure of mature tropical cyclones is presented via the use of composites of airborne doppler radar analyses the structure of the axisymmetric vortex and the convective and turbulent scale properties within this axisymmetric framework are shown to be consistent with many previous studies focusing on individual cases or using different airborne data sources on the vortex scale these structures include the primary and secondary circulations eyewall slope decay of the tangential wind with height low level inflow layer and region of enhanced outflow radial variation of convective and stratiform reflectivity eyewall vorticity and divergence fields and rainband signatures in the radial wind vertical velocity vorticity and divergence composite mean and variance fields statistics of convective scale fields and how they vary as a function of proximity to the radius of maximum wind show that the inner eyewall edge is associated with stronger updrafts and higher refl

paleoshoreline record of relative holocene sea levels on pacific islands abstract understanding the history of relative holocene sea levels on pacific islands is important for constraining fundamental geodynamic theories interpreting the environments of early human occupation sites and forecasting future environmental conditions on the islands an observational paleoshoreline record is provided by emergent paleoshoreline indicators formed at higher relative sea levels hence standing at higher elevations than modern counterparts emergent paleoshoreline notches in limestone seacliffs record paleo high tide levels and emergent paleoreef flats record paleo low tide levels whereas emergent paleobeachrock locally records paleo intertidal levels both paleonotches and paleoreefs occur along the coasts of high standing islands exposing volcanic bedrock and uplifted reef complexes but low lying coralline atolls lack sufficient relief to preserve paleonotches controls on relative holocene sea level include global eustatic and regional hydro isostatic changes in ambient sea level relative to island landmasses and shifts in the elevations of islands relative to sea level caused by thermal subsidence of the oceanic lithosphere or thermally rejuvenated loci of hotspot volcanism by flexure of the lithosphere under the load of growing volcanic edifices hawaii samoa society islands by arching of the lithosphere over trench forebulges loyalty islands niue bellona rennell and by tectonism within forearc belts between active volcanic chains and trenches mariana islands tonga vanuatu the dominant pattern of relative sea level change where not overprinted by local tectonism or lithospheric flexure was a uniform early holocene rise in eustatic sea level followed by a regionally variable late holocene hydro isostatic drawdown in sea level the resultant was a mid holocene highstand in relative sea level that affected the development of shoreline morphology throughout the tropical pacific ocean the earliest human migrations into intra oceanic island groups of both the northwestern and southwestern pacific ocean followed close on the heels of the mid holocene sea level highstand and took advantage of newly attractive coastal environments engendered by sea level drawdown the effects of the mid holocene highstand were modified to varying degrees in different island groups by geodynamic uplift or subsidence

far field test of the ice 4g model of global isostatic response to deglaciation using empirical and theoretical holocene sea level reconstructions for the fiji islands southwestern pacific holocene paleosea level data for fiji represented by 77 dates and emergence magnitudes are presented screened and adjusted most data are from coral microatolls potentially the most precise paleosea level indicators in this region holocene sea level changes are reconstructed for five areas within fiji known to have had different late quaternary tectonic histories resulting analysis suggests that postglacial sea level in fiji reached its present level more than 6900 14c yr b p it also suggests either that a single maximum 5650 3200 14c yr b p perhaps 2 19 m but more likely 1 35 1 50 m occurred or that two maxima occurred 6100 4550 14c yr b p 0 75 1 85 m and 3590 2800 14c yr b p 0 90 2 46 m broad agreement exists between these empirical sea level reconstructions and those derived theoretically using the ice 4g model predicted maximum 4000 14c yr b p 2 1 m this suggests that both methods of reconstructing holocene sea level changes are valid as are the assumptions underpinning the ice 4g model the most important of these that eustatic sea level had effectively stopped rising by late middle holocene time 5000 4000 yr b p is confirmed by observations from fiji

observations of the structure and evolution of hurricane edouard 2014 during intensity change part ii kinematic structure and the distribution of deep convection abstractthe structural evolution of the inner core and near environment throughout the life cycle of hurricane edouard 2014 is examined using a synthesis of airborne and satellite measurements this study specifically focuses on differences in the distribution of deep convection during two periods when edouard intensified toward hurricane status and when edouard peaked in intensity and began to weaken while both periods saw precipitation maximized in the downshear left and upshear left quadrants deep convection was only seen from the aircraft during the intensifying period deep convection was located farther inside the radius of maximum winds rmw during the intensifying period than the weakening period this convection is traced to strong updrafts inside the rmw in the downshear right quadrant tied to strong low level convergence and high convective available potential energy cape as the storm remained over warm water in a moist environment strong updrafts persisted upshear left and were collo

a numerical study of hurricane erin 2001 part ii shear and the organization of eyewall vertical motion a high resolution numerical simulation of hurricane erin 2001 is used to examine the organization of vertical motion in the eyewall and how that organization responds to a large and rapid increase in the environmental vertical wind shear and subsequent decrease in shear during the early intensification period prior to the onset of significant shear the upward motion in the eyewall was concentrated in small scale convective updrafts that formed in association with regions of concentrated vorticity herein termed mesovortices with no preferred formation region around the eyewall asymmetric flow within the eye was weak as the shear increased an azimuthal wavenumber 1 asymmetry in storm structure developed with updrafts tending to occur on the downshear to downshear left side of the eyewall continued intensification of the shear led to increasing wavenumber 1 asymmetry large vortex tilt and a change in eyewall structure and vertical motion organization during this time the eyewall structure was dominated by a vortex couplet with a cyclonic anticyclonic vortex on the downtilt left downtilt right side of the eyewall and strong asymmetric flow across the eye that led to strong mixing of eyewall vorticity into the eye upward motion was concentrated over an azimuthally broader region on the downtilt side of the eyewall upstream of the cyclonic vortex where low level environmental inflow converged with the asymmetric outflow from the eye as the shear diminished the vortex tilt and wavenumber 1 asymmetry decreased while the organization of updrafts trended back toward that seen during the weak shear period based upon the results for the erin case as well as that for a similar simulation of hurricane bonnie 1998 a conceptual model is developed for the organization of vertical motion in the eyewall as a function of the strength of the vertical wind shear in weak to moderate shear higher wavenumber asymmetries associated with eyewall mesovortices dominate the wavenumber 1 asymmetry associated with the shear so that convective scale updrafts form when the mesovortices move into the downtilt side of the eyewall and dissipate on the uptilt side under strong shear conditions the wavenumber 1 asymmetry characterized by a prominent vortex couplet in the eyewall dominates the vertical motion organization so that mesoscale ascent with embedded convection occurs over an azimuthally broader region on the downtilt side of the eyewall further research is needed to determine if these results apply more generally

vertical motion characteristics of tropical cyclones determined with airborne doppler radial velocities abstract vertical motions in seven atlantic hurricanes are determined from data recorded by doppler radars on research aircraft the database consists of doppler velocities and reflectivities from vertically pointing radar rays collected along radial flight legs through the hurricane centers the vertical motions are estimated throughout the depth of the troposphere from the doppler velocities and bulk estimates of particle fallspeeds portions of the flight tracks are subjectively divided into eyewall rainband stratiform and other regions characteristics of the vertical velocity and radar structure are described as a function of altitude for the entire dataset and each of the four regions in all of the regions more than 70 of the vertical velocities range from 2 to 2 m s 1 the broadest distribution of vertical motion is in the eyewall region where 5 of the vertical motions are 5 m s 1 averaged over the entire dataset the mean vertical velocity is upward at all altitudes mean downward mot

environmental flow impacts on tropical cyclone structure diagnosed from airborne doppler radar composites abstractfollowing a recent demonstration of multicase compositing of axisymmetric tropical cyclone tc structure derived from airborne doppler radar measurements the authors extend the analysis to the asymmetric structure using an unprecedented database from 75 tc flights in particular they examine the precipitation and kinematic asymmetry forced by the tc s motion and interaction with vertical wind shear for the first time they quantify the average magnitude and phase of the three dimensional shear relative kinematic asymmetry of observed tcs through a composite approach the composite analysis confirms principal features of the shear relative tc asymmetry documented in prior numerical and observational studies e g downshear tilt downshear right convective initiation and a downshear left precipitation maximum the statistical significance of the composite shear relative structure is demonstrated through a stratification of cases by shear magnitude the impact of storm motion on eyewall convect

convective bursts downdraft cooling and boundary layer recovery in a sheared tropical storm abstracttropical storm edouard 2002 experienced episodic outbreaks of convection downshear within the storm core in the presence of 11 15 m s 1 of ambient vertical wind shear these outbreaks lasted 2 6 h and were followed by long periods with no deep convection flights from u s air force reconnaissance aircraft within the boundary layer were used to investigate the cause of one such oscillation low equivalent potential temperature e air filled the boundary layer as convection ceased creating a 4 6 k deficit in e within the convective region soundings within 110 km of the center were supportive of convective downdrafts with midlevel relative humidity below 15 and large downdraft cape deep convection ceased within 75 km of the center for more than 8 h tangential velocity reached hurricane force locally during the convective outbreak then became nearly symmetric after convection stopped arguably as a result of axisymmetrization and the storm weakened nevertheless the corresponding lack of

microatolls as sea level indicators on a mid ocean atoll microatolls are discoid corals with flat upper surfaces that develop when upward coral growth is constrained by exposure at low tide they have been widely viewed as important and relatively precise indicators of modern and paleo sea level positions because of their sensitivity to the water air interface though this has rarely been directly established by survey to a precise datum this study involved an accurate survey of 282 microatolls growing in a range of intertidal environments open reef flats interisland passages lagoons across the cocos keeling islands a mid ocean atoll in the indian ocean the upper surface elevation of modern microatolls was found to vary through more than 40 cm across the environments in which these corals occur on cocos representing more than 30 of the spring tide range much of the variation reflects subtle ponding at low water levels across extensive low gradient reef surfaces associated with interisland passages microatolls in open reef flat habitats are typically constrained within the narrowest and most consistent elevation range around the atoll the environment in which individual fossil microatolls occurred when they were alive is significant in reconstructing former sea levels

significance of emerged holocene corals around ovalau and moturiki islands fiji southwest pacific abstract the volcanic islands ovalau and moturiki in central fiji have been subsiding very slowly for most of the past few thousand years and thus have potential for helping define holocene eustatic changes in this otherwise tectonically active region dates from fossil microatolls porites spp emerged above the modern reef flats around these islands indicate such changes ten dates from around ovalau are presented they indicate a general fall of sea level from a high 1 6 m above its present level within the period 6000 3000 yr bp the dates are readily divisible into discrete vertical groups which may indicate the inability of some reefs to reach lowest astronomical tide level as they commonly do where freshwater plumes enter the ocean alternatively the vertical separation of dates may indicate rapid transgressive regressive oscillations the distribution of dates is also characterized by a temporal hiatus of about 1000 years around 4200 yr bp which can be explained as a result of a either a rapid sea level fall around this time b a series of prolonged low sea level episodes associated with an increased frequency of el nino events or c increased nearshore deposition of terrigenous sediment perhaps associated with an increased tropical cyclone frequency or early human impact

characteristics of deep tropical and subtropical convection from nadir viewing high altitude airborne doppler radar abstract this paper presents observations of deep convection characteristics in the tropics and subtropics that have been classified into four categories tropical cyclone oceanic land and sea breeze vertical velocities in the convection were derived from doppler radar measurements collected during several nasa field experiments from the nadir viewing high altitude er 2 doppler radar edop emphasis is placed on the vertical structure of the convection from the surface to cloud top sometimes reaching 18 km altitude this unique look at convection is not possible from other approaches such as ground based or lower altitude airborne scanning radars the vertical motions from the radar measurements are derived using new relationships between radar reflectivity and hydrometeor fall speed various convective properties such as the peak updraft and downdraft velocities and their corresponding altitude heights of reflectivity levels and widths of reflectivity cores are estimated the most significant

an analysis of the observed low level structure of rapidly intensifying and mature hurricane earl 2010 abstract we examine dynamic and thermodynamic aspects of atlantic hurricane earl 2010 during its intensification and mature phases over four days of intensive measurements during this period earl underwent an episode of rapid intensification maturity secondary eyewall replacement re intensification and the early part of its decline the observations are used to appraise elements of a new model for tropical cyclone intensification the results affirm the conventional vortex interior and boundary layer spin up mechanisms that form dynamical elements of the azimuthally averaged view of the new intensification model the average maximum tangential winds beneath the eyewall are found to exceed the gradient wind by between 20 and 60 the results suggest also that the gradient wind balance approximation in the low level vortex interior above the strong inflow layer may not be as accurate in the inner core region of a tropical cyclone during its intensification as has been widely held an analysis of the low level thermodynamic structure affirms the radial increase of moist equivalent potential temperature e with decreasing radius during the intensification process a necessary ingredient of the new model for maintaining convective instability in the presence of a warming upper troposphere an unanticipated finding is the discovery of an unmixed boundary layer in terms of e within several hundred kilometres of the vortex centre in the inner core region this finding is not consistent with the axisymmetric eruption of the boundary layer into the eyewall unless there are non conservative eddy processes acting to modify the entropy of ascending air

airborne doppler observations of the inner core structural differences between intensifying and steady state tropical cyclones abstractdifferences in the inner core structure of intensifying in intensity increase of at least 20 kt 24 h 1 where 1 kt 0 51 m s 1 and steady state ss intensity remaining between 10 kt 24 h 1 tropical cyclones tcs are examined using composites of airborne doppler observations collected from noaa p 3 aircraft missions the in dataset contains 40 eyewall passes from 14 separate missions while the ss dataset contains 53 eyewall passes from 14 separate missions intensifying tcs have a ringlike vorticity structure inside the radius of maximum wind rmw lower vorticity in the outer core a deeper stronger inflow layer and stronger axisymmetric eyewall upward motion compared with steady state tcs there is little difference in the vortex tilt between 2 and 7 km and both in and ss tcs show an eyewall precipitation and updraft asymmetry whose maxima are located in the downshear and downshear left region the azimuthal coverage of eyewall and outer core precipitation is greater for in tcs

hydraulic fractures how far can they go the maximum reported height of an upward propagating hydraulic fracture from several thousand fracturing operations in the marcellus barnett woodford eagle ford and niobrara shale usa is 588 m of the 1170 natural hydraulic fracture pipes imaged with three dimensional seismic data offshore of west africa and mid norway it is 1106 m based on these empirical data the probability of a stimulated and natural hydraulic fracture extending vertically 350 m is 1 and 33 respectively constraining the probability of stimulating unusually tall hydraulic fractures in sedimentary rocks is extremely important as an evidence base for decisions on the safe vertical separation between the depth of stimulation and rock strata not intended for penetration

convective scale variations in the inner core rainbands of a tropical cyclone airborne doppler radar documented a variety of convective scale structures within the inner core rainbands of hurricane rita 2005 as predicted by past studies wind shear determined azimuthal variations in the convection all convective scale circulations had radial inflow at low levels upward motion and outflow in the midtroposphere convective cells at smaller radii contained a low level tangential jet determined largely by tangential acceleration due to angular momentum conservation uy r term while cells at larger radii contained a low level and or midlevel jet determined jointly by the uy r and vertical advection terms the outflow was at a higher lower altitude for the outer inner cells radial variations in the convective cells are attributable to differencesin buoyancy and vertical shear of the radial wind u z more buoyant updrafts at larger radii enhance vertical advection of y creating local tangential jets at midlevels at smaller radii the stronger low level radial inflow contributes to a greater u z confining convectively generated jets to low levels the low level tangential jet and convectively generated pressure gradients produce outward pointing supergradient acceleration that decelerates the boundary layer inflow consequently this supergradient flow will enhance convergence and convection at the radius of inner rainbandcells increasing the likelihoodof secondary eyewall formation it is hypothesized that a critical zone for secondary eyewall formation exists where sufficiently high u z consistently constrains the altitudes of convectively generated supergradient flow so that convection in this radial zone leads to a newly developed eyewall once an incipient secondary eyewall forms at a certain radius subsidence occurring along its inner edge separates it from the primary eyewall