assessing the roles of three eddy types in restratifying the labrador sea after deep convection abstractrestratification after deep convection is one of the key factors in determining the temporal variability of dense water formation in the labrador sea in the subsurface it is primarily governed by lateral buoyancy fluxes during early spring the roles of three different eddy types in this process are assessed using an idealized model of the labrador sea that simulates the restratification season the first eddy type warm core irminger rings is shed from the boundary current along the west coast of greenland all along the coastline the boundary current forms boundary current eddies the third type convective eddies arises directly around the convection area in the model the latter two eddy types are together responsible for replenishing 30 of the winter heat loss within 6 months irminger rings add another 45 to this number the authors results thus confirm that the presence of irminger rings is essential for a realistic amount of restratification in this area the model results are com

observations and experiments on the origin and formation of inertinite group macerals the inertinite group macerals include fusinite semifusinite inertodetrinite macrinite micrinite and funginite and secretinite which together replace sclerotinite the macrolithotype fusain comprises fusinite and semifusinite and is now widely accepted as charcoal formed by wildfire activity however alternative origins for fusinite and semifusinite are still claimed this paper considers the use of the terms pyrofusinite degradofusinite rank fusinite and primary fusinite misleading while the definitions of the terms funginite and secretinite are also considered problematic observations made on modern wildfire derived and volcanogenic charcoal assemblages using reflectance and scanning electron microscopy together with experimental charcoalification studies demonstrate that most if not all inertinite macerals have acquired their optical and physical characteristics through the action of elevated temperatures the criteria for the identification of charcoals produced by wildfire and volcanic activity are outlined and the role of the petrographic nomenclature system is discussed

surface mass redistribution inversion from global gps deformation and gravity recovery and climate experiment grace gravity data monitoring hydrological redistributions through their integrated gravitational effect is the primary aim of the gravity recovery and climate experiment grace mission time variable gravity data from grace can be uniquely inverted to hydrology since mass transfers located at or near the earth s surface are much larger on shorter timescales than those taking place within the deeper earth and because one can remove the contribution of atmospheric masses from air pressure data yet it has been proposed that at larger scales this may be achieved independently by measuring and inverting the elastic loading associated with redistributing masses e g with the global network of the international gps service igs this is particularly interesting as long as grace monthly gravity solutions do not yet match the targeted baseline accuracies at the lower spherical harmonic degrees in this contribution 1 we describe and investigate an inversion technique which can deal jointly with gps data and monthly grace solutions 2 previous studies with gps data have used least squares estimators and impose solution constraints through low degree spherical harmonic series truncation here we introduce a physically motivated regularization method that guarantees a stable inversion up to higher degrees while seeking to avoid spatial aliasing 3 we apply this technique to gps data provided by the igs service covering recent years we can show that after removing the contribution ascribed to atmospheric pressure loading estimated annual variations of continental scale mass redistribution exhibit pattern similar to those observed with grace and predicted by a global hydrology model although systematic differences appear to be present 4 we compute what the relative contribution of grace and gps would be in a joint inversion using current error estimates gps could contribute with up to 60 to degree 2 till 4 spherical harmonic coefficients and up to 30 for higher degree coefficients

grace measurements of mass variability in the earth system monthly gravity field estimates made by the twin gravity recovery and climate experiment grace satellites have a geoid height accuracy of 2 to 3 millimeters at a spatial resolution as small as 400 kilometers the annual cycle in the geoid variations up to 10 millimeters in some regions peaked predominantly in the spring and fall seasons geoid variations observed over south america that can be largely attributed to surface water and groundwater changes show a clear separation between the large amazon watershed and the smaller watersheds to the north such observations will help hydrologists to connect processes at traditional length scales tens of kilometers or less to those at regional and global scales

organic matter in australian cambrian oil shales and other iower palaeozoic shales abstract reflected light microscopy transmission electron microscopy tem elemental analysis carbon isotopic compositions and gas chromatography mass spectrometry gc ms have been combined in the study of the organic matter from cambrian oil shales in the georgina basin these have shown two main kinds of organic matter to be present the first kind consists of autochthonous well preserved filamentous structures of inferred cyanobacterial origin with occasional remains of possible methanogenic bacteria the latter point to limited microbial degradation of the substrate namely the inferred cyanobacterial mats represented by the filamentous structures the second kind is a significant humic fraction and a rare third kind of organic matter possibly represents the remains of planktonic algae a close resemblance to organic matter from the thorntonia limestone sequence of middle cambrian age is apparent from tem observations the oil shales may have been deposited in a shallow marine environment where oxygenated waters were separated from reducing sediments by a cyanobacterial mat the humic acids probably represent organic matter which was partially oxidised before it settled on the mat and was ultimately incorporated into the sediment

impact of sulphur and trace element geochemistry on the utilization of a marine influenced coal case study from the south wales variscan foreland basin abstract incremental channel samples through two high volatile a bituminous coal seams the amman rider and bute seams below and above the vanderbeckei marine band at the westphalian a b boundary have been analysed using proximate petrographic inductively coupled plasma mass spectrometry icp ms x ray fluorescence xrf and scanning electron microscopy with energy dispersive x ray sem edx techniques the results show that both coals are vitrinite rich and indicate a similar history of palaeomire development with a period of falling water tables towards the middle plies of each seam mean sulphur contents in the coal with the marine roof the amman rider seam 4 19 wt are almost 4 times higher than in the coal with a non marine roof the bute seam 1 09 wt implying that high sulphur contents are derived from sea water sulphate in both coals sulphur is predominantly in the form of pyritic sulphur both syngenetic framboidal and euhedral crystals and epigenetic vein and cleat fill pyrite are present relatively constant levels of organic sulphur at around 2 have been recorded in the amman rider seam sulphur levels in the basal and top plies of each seam are at least twice that of the ply with the lowest sulphur content in the seam reflecting the stages in palaeomire development most strongly influenced by sulphate containing waters thorium uranium ratios are below 2 9 in the coal with a marine roof the amman rider seam indicating an enrichment of u from sea water most marked at the top and bottom of the seam the seam without a marine roof shows th u ratios between 2 5 and 4 9 indicating mild marine enrichment of u the concentrations of environmentally significant trace elements eses are correlated with either the ash or sulphur contents or both the correlation between s and pb as cu ni in the coal with a marine roof implies an origin of these eses from sea water and their mode of occurrence in sulphide minerals most eses in this coal are present at levels at least twice that of the global average in coals the exceptions being pb and zn which have concentrations less than half the global average by contrast the coal without a marine roof and with lower sulphur contents has most eses present at concentrations less than a third of the global average the exceptions being ni and cu diagenetic hydrothermal activity is documented in the middle ply of the coal with a marine roof this hydrothermal system redistributed the sulphur pb and as in this ply the principal utilization of bituminous coals in the south wales coalfield is as feed coals in power station boilers the resultant concentration of most eses in the solid residues from power plant coal combustion theoretically can be alleviated by careful blending of feed coals with low and high ese contents

ice ocean processes over the continental shelf of the southern weddell sea antarctica a review 1 interactions between the southern ocean and the weddell sea ice shelves are important both to the antarctic ice sheet and to the production of globally significant water masses here we review the interaction between the filchner ronne ice shelf and the shelf sea in which it floats the continental shelf processes leading to the production of weddell sea deep and bottom waters from the original off shelf source waters are discussed and a new view is offered of the initial production of high salinity shelf water data from ship based measurements at the ice front from glaciological methods and from measurements made within the sub ice shelf cavity itself are used to describe the pattern of flows beneath the ice shelf we also consider the variability observed within the cavity from tidal to interannual time scales and finish with a discussion of future research priorities in the region

basal mass budget of ross and filchner ronne ice shelves antarctica derived from lagrangian analysis of icesat altimetry traditional methods of deriving temporal variability of antarctic ice shelf elevation from satellite altimetry use a fixed eulerian reference frame where the measured changes include advection of ice thickness gradients between measurement epochs we present a new method which removes advection effects by using an independent velocity field to compare elevations in a moving lagrangian reference frame applying the technique to icesat laser altimetry for the period 2003 2009 over the two largest antarctic ice shelves ross and filchner ronne we show that the lagrangian approach reduces the variability of derived elevation changes by about 50 compared to the eulerian approach and reveals clearer spatial patterns of elevation change the method simplifies the process of estimating basal mass budget from the residual of all other processes that contribute to ice shelf elevation changes we use field data and icesat measurements over ice rises and the grounded ice sheet to account for surface accumulation and changes in firn air content and remove the effect of ice flow divergence using surface velocity and ice thickness data the results show highest basal melt rates 5 m a 1 near the deep grounding lines of major ice streams but smaller melt rates 5 m a 1 near the ice shelf fronts are equally important to total meltwater production since they occur over larger areas integrating over the entire ice shelf areas we obtain basal mass budgets of 50 64 gt a 1 for ross and 124 66 gt a 1 for filchner ronne with changes in firn air content as the largest error source

detection of a locked zone at depth on the parkfield california segment of the san andreas fault the parkfield california segment of the san andreas fault is transitional in character between the creeping segment of the fault to the northwest and the locked carrizo plain segment to the southeast the rate of shallow fault slip decreases from 25 30 mm yr northwest of the epicenter of the 1966 parkfield earthquake to zero at the southeastern end of the 1966 rupture zone data from a network of trilateration lines spanning the san andreas fault near parkfield and extending to the pacific coast near san luis obispo shed light on the rate of fault slip at depth since the 1966 earthquake in this study average rates of line length change and shallow fault slip were inverted to determine the slip rate at depth on the parkfield fault segment the fault is taken to be a vertical surface with unknown distribution of strike slip displacement in an elastic half space a striking result of the inversions is that all solutions providing acceptable fits to the data exhibit a locked zone essentially coincident with the rupture surface of the 1966 parkfield earthquake the data require that the locked zone extend nearly as far north as the 1966 epicenter however the vertical extent of the locked zone is not well resolved over much of the parkfield segment the fault is slipping faster at the earth s surface than it is at seismogenic depths in order to fit the trilateration measurements it is necessary to include a component of contraction normal to the trend of the san andreas the inversion results suggest a spatially uniform normal strain of 0 06 strain yr the orientation of the contraction is compatible with geologic and seismic evidence of active folding and reverse faulting in the region the magnitude of the contraction is consistent with convergence rates inferred from global plate motion models

climate driven deformation of the solid earth from grace and gps 1 grace data indicate large seasonal variations in gravity that are assumed to be related to climate driven fluxes of surface water seasonal redistribution of surface mass should deform the earth and our calculations using grace data suggest vertical deformations of 13 mm in the region of greatest flux the amazon river basin to test the grace gravity hydrology connection we analyzed gps data acquired from sites in this region after accounting for degree 1 variations not observable with grace we find that annual deformation measured with gps correlates highly with predictions calculated from grace measurements these results confirm the variations in surface water sensed by grace which are significantly larger than those predicted by some hydrology models the results also demonstrate that grace can be an important tool for monitoring deformation of the earth and suggest that combined analysis of grace and gps may be a useful approach for estimation of geocenter variations

improved methods for observing earth s time variable mass distribution with grace using spherical cap mascons we discuss several classes of improvements to gravity solutions from the gravity recovery and climate experiment grace mission these include both improvements in background geophysical models and orbital parameterization leading to the unconstrained spherical harmonic solution jpl rl05 and an alternate jpl rl05m mass concentration mascon solution benefitting from those same improvements but derived in surface spherical cap mascons the mascon basis functions allow for convenient application of a priori information derived from near global geophysical models to prevent striping in the solutions the resulting mass flux solutions are shown to suffer less from leakage errors than harmonic solutions and do not necessitate empirical filters to remove north south stripes lowering the dependence on using scale factors the global mean scale factor decreases by 0 17 to gain accurate mass estimates ocean bottom pressure obp time series derived from the mascon solutions are shown to have greater correlation with in situ data than do spherical harmonic solutions increase in correlation coefficient of 0 08 globally particularly in low latitude regions with small signal power increase in correlation coefficient of 0 35 regionally in addition to reducing the error rms with respect to the in situ data reduction of 0 37 cm globally and as much as 1 cm regionally greenland and antarctica mass balance estimates derived from the mascon solutions agree within formal uncertainties with previously published results computing basin averages for hydrology applications shows general agreement between harmonic and mascon solutions for large basins however mascon solutions typically have greater resolution for smaller spatial regions in particular when studying secular signals

time variability of the earth s gravity field hydrological and oceanic effects and their possible detection using grace the grace satellite mission scheduled for launch in 2001 is designed to map out the earth s gravity field to high accuracy every 2 4 weeks over a nominal lifetime of 5 years changes in the gravity field are caused by the redistribution of mass within the earth and on or above its surface grace will thus be able to constrain processes that involve mass redistribution in this paper we use output from hydrological oceanographic and atmospheric models to estimate the variability in the gravity field i e in the geoid due to those sources we develop a method for constructing surface mass estimates from the grace gravity coefficients we show the results of simulations where we use synthetic grace gravity data constructed by combining estimated geophysical signals and simulated grace measurement errors to attempt to recover hydrological and oceanographic signals we show that grace may be able to recover changes in continental water storage and in seafloor pressure at scales of a few hundred kilometers and larger and at timescales of a few weeks and longer with accuracies approaching 2 mm in water thickness over land and 0 1 mbar or better in seafloor pressure

time variable gravity from grace first results eleven monthly grace gravity field solutions are now available for analyses we show those fields can be used to recover monthly changes in water storage both on land and in the ocean to accuracies of 1 5 cm of water thickness when smoothed over 1000 km the amplitude of the annually varying signal can be determined to 1 0 cm results are 30 better for a 1500 km smoothing radius and 40 worse for a 750 km radius we estimate the annually varying component of water storage for three large drainage basins the mississippi the amazon and a region draining into the bay of bengal to accuracies of 1 0 1 5 cm

assessing seasonal and interannual water storage variations in taiwan using geodetic and hydrological data abstract we systematically investigate the spatiotemporal water storage changes in taiwan using geodetic gnss and grace and hydrological precipitation gldas and lsdm assimilation models and in situ groundwater level datasets we use gnss observed vertical deformation to estimate water storage changes based on elastic loading theory and weighted least squares inversion correcting for contributions from global loads using grace the mean annual water thickness change inferred from gnss across taiwan is 0 53 0 17 m and the largest seasonal change of up to 0 91 m is estimated in southwest taiwan comparison of the geodetic and hydrological data shows that the spatial pattern of annual water storage change estimated from gnss gldas and precipitation data are generally consistent indicating significant seasonal water load fluctuations in taiwan however the grace solution significantly underestimates the amplitude of water mass change in taiwan due to leakage effect but temporally correlates well with gnss estimates hydrological assimilation model gldas dominated by shallow soil moisture variations predicts that the average seasonal variation of water thickness is only about 17 of gnss estimates this value is about half of the mean annual lsdm water storage change of 0 18 m including an estimate of both soil moisture and surface water the discrepancy suggests that the contribution of groundwater is substantial and the total water storage change in the hydrological assimilation model is underestimated in taiwan the spatiotemporal distributions derived using independent component analysis ica are generally consistent between the geodetic and hydrological data however comparisons of seasonal amplitudes and phases between all data pairs reveal different response times to precipitation reflecting the complex nature of transient water storage due to variable rainfall patterns infiltration rate soil saturation and runoff the peak rainfall occurs in june july which is one to two months before the peak gnss subsidence water storage of the gldas model also reaches its maximum in august suggesting the water storage is controlled by the infiltration rate and capacity and the total water recharge from rainfall is generally larger than discharge in the summer the highest groundwater levels lag one and two months behind the peak gnss subsidence in western and eastern taiwan respectively indicating a higher infiltration rate in western taiwan

micrinite in southern hemisphere sub bituminous and bituminous coals redefined as fine grained kaolinite a range of complementary analytical techniques including sem eds tem eds and conventional optical microscopy has been rigorously applied to precisely defined areas of micrinite in polished coal samples from australia and new zealand elemental analyses of micrinite regions showed a high abundance of al si and o and high resolution images of micrinite revealed a grain size 1 m electron diffraction and elemental analyses from individual grains within the optically and electron optically correlated micrinite regions are consistent with the occurence of fine grained kaolinite the optical properties of dark clay and micrinite i e fine grained kaolinite can be understood in terms of the diffuse scattering of visible light from the surfaces of materials with different grain sizes in single phase or multi phase mixtures

a major fire event recorded in the mesofossils and petrology of the late permian lower whybrow coal seam sydney basin australia abstract petrographic and mesofossil analyses of plies from the late permian lower whybrow coal new south wales australia have revealed a significant fire event in both the swamp setting and the hinterland the fire event is characterised by a change in the maceral composition the seam during this interval being dominated by inertinite especially semifusinite following the fire event the mineral matter content of the coal increases this may be the result of increased run off and erosion in the hinterland due to destruction of vegetation this major fire event is also reflected in a change in the vegetation as represented by the mesofossil content of the seam prior to the fire event the seam contains abundant bisaccate taeniate pollen sporangia and seed like bodies of possible glossopterid affinity these are lost at the ply in which the fire event is recorded though seed like bodies become important again later the fire event also corresponds to a change in the megaspore content of the coal a new species appearing perhaps as a result of hydrological change following this major fire event a mineral rich ply was deposited which contains miospore masses of spores from fern like plants possibly representing a re colonisation event by rhizomorphs after vegetation death this evidence for a major fire and its implications for the origin of inertinites leads to the conclusion that throughout this and other permian gondwana coals fire was an integral part of the temperate mid high latitude southern hemisphere swamp ecosystem

oceanic isopycnal mixing by coordinate rotation abstract current numerical models of oceanic circulation differentiate between the eddy diffusion and viscosity transport along the geopotential horizontal and vertical directions only in order to model the effect of anisotropic turbulence as diffusive transport along and across density surfaces the isopycnal mixing tensor has been transformed from a diagonal second rank tensor in the isopycnal coordinate system to a tensor containing off diagonal elements in the geopotential coordinate system

numerical simulations of global scale high resolution hydrological crustal deformations 1 high resolution load induced crustal deformations calculated from numerical models are tested for their ability to predict hydrologically induced station height variability as they are known to be large enough to affect epoch wise parameters obtained from the analysis of global geodetic networks loading contributions due to terrestrial water storage as given by global hydrological models are calculated on a 0 5 global regular grid with daily temporal resolution apart from the dominant seasonal variations the hydrological loading signal discloses also rapid changes exceeding 1 mm in several regions that can be associated with major precipitation events and river floods locally strong loading signals with exceptionally high amplitudes in many cases even with nonseasonal nature occur along the major river channels only high resolution loading calculations considering also the water mass anomalies stored in the model river flow can resolve the correct amplitudes in the surrounded area up to 100 km distance the comparison of the modeled hydrological surface deformation with gps station time series shows that high resolution hydrological loading estimates based on global scale models are able to explain a considerable fraction up to 54 of the observed vertical station movements caused by continental water storage variations

velocity field of gps stations in the taiwan area abstract the 131 stations of the taiwan gps network were surveyed 4 6 times from 1990 to 1995 with dual frequency geodetic receivers the standard deviation of an observed baseline length with its linear trend removed is in the range of 6 10 mm for a 3 120 km long baseline the average rates of length change for all baselines of the network and those from nine continuously monitoring permanent stations are used in a least squares adjustment to estimate the velocities of the gps stations relative to paisha penghu situated at the chinese continental margin to the south of fengping in the northern coastal range the velocity vectors of stations in lanhsu lutao and the coastal range trend in the directions of 306 322 with rates of 56 82 mm yr in contrast there is a dramatic decrease in the rates to the north of fengping this may be caused by the motion along the ne sw trending thrusts which obliquely cut the northern coastal range a discontinuity of about 30 mm yr in the rates along with a remarkable change in the directions of station velocity is observed across the longitudinal valley then the moving directions gradually shift to the west for the stations in the western foothills in the kaohsiung pingtung coastal area the station velocities are even directed toward the southwest to the north of the peikang high the velocity vectors of the stations change direction from the west gradually to the north and finally to the east and southeast significant nw se extensional deformation is found in the ilan plain and northern taiwan in general the pattern of the velocity field for gps stations in the taiwan area is quite consistent with the directions of present day tectonic stress

multi centennial variability controlled by southern ocean convection in the kiel climate model a quasi oscillatory multi centennial mode of open ocean deep convection in the atlantic sector of the southern ocean in the kiel climate model is described the quasi periodic occurrence of the deep convection causes variations in regional and global surface air temperature southern hemisphere sea ice coverage southern ocean and north atlantic sea surface height the antarctic circumpolar current and the atlantic meridional overturning circulation amoc the deep convection is stimulated by a strong built up of heat at mid depth when the heat reservoir is virtually depleted a coincidental strong freshening event at the sea surface shuts down the convection the heat originates from relatively warm deep water formed in the north atlantic the several decades lasting recharge process of the heat reservoir depends on the amoc and the weddell gyre and sets a minimum delay for the deep convection to recur while the strength of the amoc increases the weddell gyre weakens during the non convective regime convection onset and shutdown also depend on the stochastic occurrence of favorable sea surface conditions which contributes to the multi centennial period of the phenomenon the shutdown triggers a century long deviation in amoc strength caused by significant reductions in bottom water formation and surface salinity in the southern ocean s atlantic sector additional numerical experimentation reveals that sea ice has an important effect on the frequency of occurrence and intensity of the deep convection further we find intriguing similarities to the weddell polynya observed during the 1970s

long term and seasonal caspian sea level change from satellite gravity and altimeter measurements we examine recent caspian sea level change by using both satellite radar altimetry and satellite gravity data the altimetry record for 2002 2015 shows a declining level at a rate that is approximately 20 times greater than the rate of global sea level rise seasonal fluctuations are also much larger than in the world oceans with a clearly defined geographic region and dominant signal magnitude variations in the sea level and associated mass changes provide an excellent way to compare various approaches for processing satellite gravity data an altimeter time series derived from several successive satellite missions is compared with mass measurements inferred from gravity recovery and climate experiment grace data in the form of both spherical harmonic sh and mass concentration mascon solutions after correcting for spatial leakage in grace sh estimates by constrained forward modeling and accounting for steric and terrestrial water processes grace and altimeter observations are in complete agreement at seasonal and longer time scales including linear trends this demonstrates that removal of spatial leakage error in grace sh estimates is both possible and critical to improving their accuracy and spatial resolution excellent agreement between grace and altimeter estimates also provides confirmation of steric caspian sea level change estimates grace mascon estimates both the jet propulsion laboratory jpl coastline resolution improvement version 2 solution and the center for space research csr regularized are also affected by leakage error after leakage corrections both jpl and csr mascon solutions also agree well with altimeter observations however accurate quantification of leakage bias in grace mascon solutions is a more challenging problem

hydrography and circulation in the filchner depression weddell sea antarctica cold and dense ice shelf water isw emerging from the filchner ronne ice shelf cavity in the southwestern weddell sea flows northward through the filchner depression to eventually descend the continental slope and contribute to the formation of bottom water new ship born observations of hydrography and currents from filchner depression in january 2013 suggest that the northward flow of isw takes place in a middepth jet along the eastern flank of the depression thus questioning the traditional view with outflow along the western flank this interpretation of the data is supported by results from a regional numerical model which shows that isw flowing northward along the eastern coast of berkner island turns eastward and crosses the depression to its eastern side upon reaching the filchner ice front the ice front represents a sudden change in the thickness of the water column and thus a potential vorticity barrier transport estimates of northward isw flux based on observations ranges from 0 2 to 1 0 sv

seasonal water storage stress modulation and california seismicity establishing what controls the timing of earthquakes is fundamental to understanding the nature of the earthquake cycle and critical to determining time dependent earthquake hazard seasonal loading provides a natural laboratory to explore the crustal response to a quantifiable transient force in california water storage deforms the crust as snow and water accumulates during the wet winter months we used 9 years of global positioning system gps vertical deformation time series to constrain models of monthly hydrospheric loading and the resulting stress changes on fault planes of small earthquakes the seasonal loading analysis reveals earthquakes occurring more frequently during stress conditions that favor earthquake rupture we infer that california seismicity rates are modestly modulated by natural hydrological loading cycles

optimizing estimates of annual variations and trends in geocenter motion and j2 from a combination of grace data and geophysical models the focus of the study is optimizing the technique for estimating geocenter motion and variations in j2 by combining data from the gravity recovery and climate experiment grace satellite mission with output from an ocean bottom pressure obp model and a glacial isostatic adjustment gia model swenson et al 2008 sun et al 2016 first we conduct an end to end numerical simulation study we generate input time variable gravity field observations by perturbing a synthetic earth model with realistically simulated errors we show that it is important to avoid large errors at short wavelengths and signal leakage from land to ocean as well as to account for self attraction and loading sal effects second the optimal implementation strategy is applied to real grace data we show that the estimates of annual amplitude in geocenter motion are in line with estimates from other techniques such as slr and global gps inversion at the same time annual amplitudes of c10 and c11 are increased by about 50 and 20 respectively compared to estimates based on swenson et al 2008 estimates of j2 variations are by about 15 larger than slr results in terms of annual amplitude linear trend estimates are dependent on the adopted gia model but still comparable to some slr results

seasonal fluctuations in the mass of the amazon river system and earth s elastic response 1 a gps station in manaus near the center of the amazon basin manifests an annual cycle of vertical displacement with a peak to peak amplitude of 50 75 mm this is by far the largest crustal oscillation observed to date and nearly 2 3 times larger than the amplitude predicted for this region vertical ground displacement is strongly anti correlated with the local stage height of the amazon river with no detectable time lag between the two time series this suggests that we are observing for the first time a purely elastic response to changes in the weight of a flowing river system we use a simple hydrological model to relate stage height to the regional pattern of flooding and argue that the elastic oscillations observed in manaus are dominated by changes in water loading developed within 200 km of the gps station

current measurements near ronne ice shelf implications for circulation and melting we present the first year long current meter records ever obtained near the floating filchner ronne ice shelf in the weddell sea the currents are steered along the ice front but in the lower layer where the bottom topography is descending toward the west the current has a component toward the ice front of about 3 cm s 1 during winter the temperature stayed near the surface freezing point while the salinity increased indicating that ice was formed and brine released the seasonal variation in salinity was 0 15 0 05 psu corresponding to the formation of 1 2 m of ice on a shelf depth of 400 m the transport of high salinity shelf water hssw into the ice shelf cavity was found to be of the order 0 5 106 m3 s 1 the production of this water due to oscillating tides and off shelf winds was found to be of the same order of magnitude in contact with glacial ice at great depths and because of the depression of the freezing point the hssw is transformed to ice shelf water isw by cooling and melting processes the melting rate was estimated to 1 1011 ton yr 1 this corresponds to the melting of 0 2 m ice per year if the melting is evenly distributed over the filchner ronne ice shelf if the melting is concentrated along a path from the berkner shelf around the berkner island to the filchner depression then melting rates up to 7 m yr 1 must be expected a comparison of hssw characteristics in the ronne depression our winter observations on the berkner shelf and the isw flowing out of the filchner depression indicates that very little water passes through the cavity from the ronne to the filchner depression it appears that most of the isw originating from processes on the berkner shelf escapes the cavity in the filchner depression this leaves the berkner shelf as the important source of isw and subsequently of the weddell sea bottom water formed from isw

oceanographic conditions south of berkner island beneath filchner ronne ice shelf antarctica we have made oceanographic measurements at two sites beneath the southern filchner ronne ice shelf hot water drilled access holes were made during january 1999 allowing conductivity temperature depth ctd profiling and the deployment of instrument moorings the ctd profiles show that the entire water column is below the surface freezing point we estimate the summer flux of water between the two sites to be 2 106 m3 s 1 the summer potential temperature salinity properties of the water column suggest that this flow is part of a recirculation in the deepest part of the subice shelf cavity and the filchner depression the recirculation is driven by a combination of the melting of deep basal ice and the freezing that results from the depressurization of the cold buoyant water as it ascends the ice shelf base the source of the water was high salinity shelf water hssw produced in the ronne depression this is the water that provides the external heat necessary for the strong melting at the deep grounding lines in the vicinity of foundation ice stream instruments moored at the drill sites show that during the winter hssw formed on the berkner shelf flows beneath the ice shelf and largely displaces the recirculating water from the two sites this provides an externally driven through flow that is warmer nearer the surface freezing point and slower than the internal recirculation and which is low enough in density to escape the filchner depression

ongoing drought induced uplift in the western united states the western united states has been experiencing severe drought since 2013 the solid earth response to the accompanying loss of surface and near surface water mass should be a broad region of uplift we use seasonally adjusted time series from continuously operating gps stations to measure this uplift which we invert to estimate mass loss the median uplift is 4 mm with values up to 15 mm in california s mountains the associated pattern of mass loss which ranges up to 50 cm of water equivalent is consistent with observed decreases in precipitation and streamflow we estimate the total deficit to be about 240 gt equivalent to a 10 cm layer of water over the entire region or the annual mass loss from the greenland ice sheet

organic geochemistry in relation to the depositional environments of middle jurassic coal seams danish central graben and implications for hydrocarbon generative potential middle jurassic strata from the harald gas field in the danish central graben include five coal seams the precursor mires were situated in coastal plain environments and peat formation occurred during water table rise related to relative sea level rise in a sequence stratigraphic framework the seams are situated at the transition zone between the lowstand and transgressive systems tracts or in the transgressive systems tract close to a level that can be correlated with the maximum flooding surface influence from relative sea level rise on peat accumulation is reflected in the petrographic and organic geochemical composition of the seams the coals that represent peat accumulation during rapid relative sea level rise are characterized by a higher average hydrogen inde extractability hydrocarbon yield and thermally extracted and generated bitumen content s1 s2 compared to the coals that represent peat formation during the initial stages of relative sea level rise slow rate of water table rise in the latter coals pr ph ratios are higher and the content of c29 steranes is higher and the content of c27 is lower with regard to thermal maturity the coals are in the oil window and may possess the potential to generate and release liquid hydrocarbons this is supported by the composition of oil samples derived from sandstones in the harald field multivariate data analysis shows a positive correlation between s1 s2 which is taken to indicate the generative potential of the coals nd in particular the macerals telinite telocollinite and cutinite the microlithotypes vitrite and clarite and total organic carbon such a petrographic composition is favored in precursor mires characterized by continuously waterlogged anoxic conditions these conditions are best met in mires situated on the lower coastal plain during rapid relative sea level rise the knowledge obtained from multivariate modeling of the data and sedimentological and sequence stratigraphic interpretations of the coal bearing strata may thus make it possible to locate the coals with the highest generative potential

detecting rock uplift across southern taiwan mountain belt by integrated gps and leveling data abstract rock uplift on the earth surface is a key observation for studies of tectonics and geodynamic processes geodetic measurements from global positioning system gps and leveling are able to track vertical deformation over a wide range of spatial and temporal scale taiwan mountain belt is subject to a rapid uplift rate of 20 mm yr as revealed by gps and leveling measurements in previous studies the extremely high rates motivate us to analyze a set of newly processed gps and leveling data along a nw se transect across southern taiwan by considering the effects of the earthquake related deformation as well as hydrological and surface processes our estimates of rock uplift rates from gps and leveling are from 12 to 14 mm yr across the southern central range of taiwan vertical velocity changes on the small spatial scale are primary related to fault locking in the seismic cycle the large spatial feature showing the mean uplift rate of 6 mm yr between the eastern central range and the frontal thrust faults can be explained by a large scale pop up structure assuming the depth of 15 20 km in the orogenic wedge and the horizontal shortening of 30 mm yr our results draw attention to carefully study geodetic vertical deformation in the mountain belts and seek relevant causes

the late triassic callide coal measures queensland australia coal petrology and depositional environment abstract the late triassic carnian rhaetian callide coal measures are preserved in a partly fault bounded basin remnant in east central queensland australia the sequence comprises up to 150 m of interbedded clastic sedimentary rocks and at least four major coal seams including one coal body up to 23 m thick the sequence was deposited initially in high gradient alluvial fan systems which gave way through time to sandy low sinuosity rivers the restricted intermontane and entirely alluvial nature of sediment accumulation is here considered to have influence the petrographic characteristics of callide coals and their external geometry the main coal seam from the callide measures shows variation in the predominance of some macerals indicating successions of environmental changes the application of transmission electron microscopy tem to the study of the callide coal has enabled a better understanding of the nature and origin of some of the less understood macerals such as micrinite and vitrinite b two forms of vitrinite have been observed each with a distinct reflectance range the wood sourced vitrinite a displays an average reflectance of 0 56 implying a higher rank than the 0 49 ro total vitrinite reflectance recorded in previous publications vitrinite b and a together represent the most commonly occurring macerals in the callide coal samples of the present study the lower reflecting vitrinite b which forms bands often several hundred m in thickness in tem shows sub micron electron transparent laminae of lipid rich material alternating with a more conventional vitrinite material the vitrinite b is interpreted to represent accumulations of leaves the callide coal has entered the oil window and oil has been generated from some exinite cutinite and resinite as evident from change in fluorescence and the presence of exsudatinite in cell cavities and cleats vitrinite b is seen under the microscope to also be generating oil micrinite the origin of which has been much debated occurs in selected horizons only as lenticular bodies suggesting cell filling or filling of spaces between laminations in vitrinite b tem shows micrinite to consist predominantly of sub micron pyrite and possibly other mineral particles adsorbed on humic acids

isopycnal mixing in ocean circulation models abstract a subgrid scale form for mesoscale eddy mixing on isopycnal surfaces is proposed for use in non eddy resolving ocean circulation models the mixing is applied in isopycnal coordinates to isopycnal layer thickness or inverse density gradient as well as to passive scalars temperature and salinity the transformation of these mixing forms to physical coordinates is also presented

modeling ice shelf cavities in a z coordinate ocean general circulation model 1 processes at the ice shelf ocean interface and in particular in ice shelf cavities around antarctica have an observable effect on the solutions of basin scale to global coupled ice ocean models despite this these processes are not routinely represented in global ocean and climate models it is shown that a new ice shelf cavity model for z coordinate models can reproduce results from an intercomparison project of earlier approaches with vertical or isopycnic coordinates as a proof of concept ice shelves are incorporated in a 100 year global integration of a z coordinate model in this simulation glacial meltwater can be traced as far as north as 15 s the observed effects of processes in the ice shelf cavities agree with previous results from a coordinate model notably the increase in sea ice thickness however melt rates are overestimated probably because the parameterization of basal melting does not suit the low resolution of this configuration

estimating geocenter variations from a combination of grace and ocean model output 1 in this study we estimate a time series of geocenter anomalies from a combination of data from the gravityrecoveryandclimateexperiment grace satellitemissionandthe outputfromoceanmodels amatrixequationisderivedrelating totalgeocentervariations to the grace coefficients of degrees two and higher and to the oceanic component of the degree one coefficients we estimate the oceanic component from two state of the art ocean models results are compared to independent estimates of geocenter derived from other satellite data such as satellite laser ranging and gps finally we compute degree one coefficients that are consistent with the processing applied to the grace level 2 gravity field coefficients the estimated degree one coefficients can be used to improve estimates of mass variability from grace which alone cannot provide them directly

active fault creep variations at chihshang taiwan revealed by creep meter monitoring 1998 2001 1 the daily creep meter data recorded at chihshang in 1998 2001 are presented the chihshang creep meter experiment was set up across the chihshang thrust fault the most active segment of the longitudinal valley fault which is the present day plate suture between the eurasian and the philippine sea plates in eastern taiwan near continuous data recording at two sites revealed different surface fault motions yet similar annual shortening rates 16 2 mm at the tapo site comprising two connected creep meters and 15 0 mm at the chinyuan site three creep meters straddling parallel fault branches four of the five creep meters showed a seasonal variation with the fault moving steadily during the rainy season from april to october and remaining quiescent during the rest of the year the only exception was recorded by the creep meter located on a melange composed hillslope where local gravitational landsliding played an additional role other than tectonic faulting through comparison with daily precipitation data we inferred that moderate rainfall suffices to trigger or facilitate slippage on the surface fault during the transition period of the dry wet season during the observation period from 1998 to 2001 the subsurface seismicity exhibited clusters of microearthquakes on the chihshang fault at depths of 10 25 km recurrent earthquakes occurred regardless of whether the season was wet or dry indicating that the stress relaxation associated with seismicity in the seismogenic zone did not transfer immediately up to the surface the accumulated strain on the chihshang fault at shallow surface levels was released through creep during the wet season in addition to these short term seasonal variations an apparent decrease in the annual slipping rate on the chihshang fault during the last few years deserves further investigation in order to mitigate against seismic hazard

bituminite a tem view abstract an illinois coal high volatile bituminous b of carboniferous age containing typical bituminite has been examined by transmission electron microscopy tem to supplement observations with the light microscope with tem the bituminite has a fine fairly regular structure including voids of a characteristic shape this structure is almost certainly inherited from a botanical precursor and is thought to represent much altered remains of former colonies of algae probably green algae the present remains contain abundant lipid rich globules and probably also include matter of algal and bacterial origin which cannot be resolved even at tem resolutions

wintertime ocean conditions over the southern weddell sea continental shelf antarctica 1 during the austral winter of 2007 a weddell seal tagged with a miniaturized conductivity temperature depth ctd instrument travelled over the central southern weddell sea continental shelf the instrument yielded 750 ctd profiles 250 of them to the sea floor the data show a full depth flow of water onto the shelf via a sill at the shelf break 74 s 44 w the warmth from the core of the flow was able to maintain the surface mixed layer above the freezing point resulting in a band of reduced ice production an estimate of the on shelf flux suggests that this flow accounts for most of the estimated 3 sv of water draining from the southern weddell sea continental shelf

seasonal and long term vertical deformation in the nepal himalaya constrained by gps and grace measurements 1 we analyze continuous gps measurements in nepal southern side of the himalaya and compare gps results with grace observations in this area we find both gps and grace show significant seasonal variations further comparison indicates that the observed seasonal gps height variation and grace derived seasonal vertical displacement due to the changing hydrologic load exhibit very consistent results for both amplitude and phase for continuous gps stations whose observation time span are longer than 3 years the average wrms reduction is 45 when we subtract grace derived vertical displacements from gps observed time series the comparison for annual amplitudes between gps observed and grace derived seasonal displacements also shows consistent correlation the good seasonal correlation between gps and grace is due to the improved gps processing strategies and also because of the strong seasonal hydrological variations in nepal besides the seasonal signal grace also indicates a long term mass loss in the himalaya region assuming no gia effect this mass loss therefore will lead to crustal uplift since the earth behaves as an elastic body we model this effect and remove it from gps observed vertical rates with a 2d dislocation model most gps vertical rates especially in the central part of nepal can be interpreted by interseismic strain from the main himalayan thrust and several exceptions may indicate the complexity of vertical motion in this region and some potential local effects

interannual variability and ventilation timescales in the ocean cavity beneath filchner ronne ice shelf antarctica 1 multiyear time series of ocean current and temperatures from beneath filchner ronne ice shelf antarctica demonstrate both seasonal and interannual variability the seasonal signal is visible at all measurement sites although it was swamped for a 2 year period 1999 2001 when extraordinarily light sea ice cover in the southern weddell sea during the 1997 1998 austral summer caused an anomalously large pulse of high salinity shelf water to flush beneath the ice shelf the pulse was observed twice at an instrumented site near the berkner island coast once on its way to the filchner depression and once after the signal had propagated around the depression and returned to the site as an anomalously large pulse of ice shelf water the timings of the signal allow an estimate of 24 30 months for the flushing timescales of the sub ice shelf ocean cavity indicating that the cavity is highly responsive to external forcing a timescale for the full ventilation of the cavity of 4 5 years is obtained from the length of time the sub ice shelf conditions take to return to their original state a timescale significantly shorter than previous estimates

melting and freezing beneath filchner ronne ice shelf antarctica 1 we use remote sensing data sets to evaluate the spatial distribution of melt beneath the filchner ronne ice shelf fris the net melt rate of 83 4 24 8 gtons yr is 2 5 5 times lower than previous glaciological estimates but is similar to existing oceanographic estimates the spatial distribution however differs significantly from standard conceptual and numerical models in which most melt occurs along the grounding lines our results suggest most grounding line melt is refrozen while the dominant ice shelf water isw source is melting near the ice shelf front probably associated with tidal action this suggests that changes in ice shelf extent can impact isw production rates in the weddell sea

stability of the west antarctic ice sheet in a warming world equivalent to 0 28 to 0 56 mm yr 1 sea level rise with the rate growing over at least the past two decades 1 4 these observations intensify concerns about the ice sheet s stability that were first raised more than four decades ago 5

seasonal long term and short term deformation in the central range of taiwan induced by landslides seasonal movement of gps stations is often attributed to hydrological loading and other environmental factors for the first time we observe seasonal motion associated with slow moving landslides eight of 26 continuous gps cgps sites in the central range of taiwan show long term landslide induced motion at rates of 3 15 mm yr 20 60 of their tectonic interseismic velocities the directions of movements after heavy rains and in the wet season are consistent with the slope directions derived from a high resolution elevation model constructed by airborne lidar long term and seasonal interseismic motions are modulated by slow moving landslides seasonal motions of landslides at lushan show peak to peak amplitudes of 3 19 mm estimates of interseismic crustal strain can be biased if surface processes are not taken into account preliminary analyses indicate that rainfall and topography play strong roles in the occurrence of landslides discrimination between surface processes and motion that has a tectonic origin is the key to natural hazard assessments

sustained water loss in california s mountain ranges during severe drought from 2012 to 2015 inferred from gps drought struck california during 7 of the 9 years from 2007 to 2015 reducing the state s available water resources pumping of central valley groundwater has produced spectacular land subsidence uplift of the adjacent sierra nevada mountains has been proposed to be either tectonic uplift or solid earth s elastic response to unloading of central valley groundwater we find that of the 24 mm of uplift of the sierra nevada from october 2011 to october 2015 just 5 mm is produced by central valley groundwater loss less than 2 mm is tectonic uplift and 17 mm is solid earth s elastic response to water loss in the sierra nevada we invert gps vertical displacements recording solid earth s elastic response to infer changes in water storage across the western u s from january 2006 to october 2017 we find water changes to be sustained over periods of drought or heavy precipitation the sierra nevada lost 15 19 km3 of water during drought from october 2006 to october 2009 gained 18 14 km3 of water during heavy precipitation from october 2009 to october 2011 and lost 45 21 km3 of water during severe drought from october 2011 to october 2015 95 confidence limits such large changes are not in hydrology models snow accumulation in october is negligible and long term soil moisture change is small we infer that there must be large loss of either deep soil moisture or groundwater in river alluvium and in crystalline basement in the sierra nevada the results suggest there to be parching of water in the ground during the summer of years of drought and seeping of melting snow into the sierra nevada in the spring of years of heavy precipitation

calving fluxes and basal melt rates of antarctic ice shelves iceberg calving has been assumed to be the dominant cause of mass loss for the antarctic ice sheet with previous estimates of the calving flux exceeding 2 000 gigatonnes per year1 2 more recently the importance of melting by the ocean has been demonstrated close to the grounding line and near the calving front3 4 5 so far however no study has reliably quantified the calving flux and the basal mass balance the balance between accretion and ablation at the ice shelf base for the whole of antarctica the distribution of fresh water in the southern ocean and its partitioning between the liquid and solid phases is therefore poorly constrained here we estimate the mass balance components for all ice shelves in antarctica using satellite measurements of calving flux and grounding line flux modelled ice shelf snow accumulation rates6 and a regional scaling that accounts for unsurveyed areas we obtain a total calving flux of 1 321 144 gigatonnes per year and a total basal mass balance of 1 454 174 gigatonnes per year this means that about half of the ice sheet surface mass gain is lost through oceanic erosion before reaching the ice front and the calving flux is about 34 per cent less than previous estimates derived from iceberg tracking1 2 7 in addition the fraction of mass loss due to basal processes varies from about 10 to 90 per cent between ice shelves we find a significant positive correlation between basal mass loss and surface elevation change for ice shelves experiencing surface lowering8 and enhanced discharge9 we suggest that basal mass loss is a valuable metric for predicting future ice shelf vulnerability to oceanic forcing

modeling the influence of the weddell polynya on the filchner ronne ice shelf cavity abstractopen ocean polynyas in the weddell sea of antarctica are the product of deep convection which transports warm deep water wdw to the surface and melts sea ice or prevents its formation t