residual mean solutions for the antarctic circumpolar current and its associated overturning circulation abstract residual mean theory is applied to the streamwise averaged antarctic circumpolar current to arrive at a concise description of the processes that set up its stratification and meridional overturning circulation on an f plane simple solutions are found in which transfer by geostrophic eddies colludes with applied winds and buoyancy fluxes to determine the depth and stratification of the thermocline and the pattern of associated residual meridional overturning circulation

electromagnetic radiation characteristics and mechanical properties of deformed and fractured sandstone after high temperature treatment abstract in this paper the electromagnetic radiation emr characteristics and mechanical properties observed during sandstone deformation and fracture after high temperature treatment were studied the sandstone mechanical strength was found to decrease after high temperature treatment emr signals and acoustic emission ae signals were produced during the process of sandstone deformation and fracture the emr signals increased with the increase in stress the emr signals change trend was varied after different temperature treatments overall the change trend of emr and ae signals was consistent but not strictly synchronized in addition the mechanisms of generation of the emr and ae signals were different the emr signals were consistent with the hurst statistical law with the hurst index being greater than 0 5 the main frequency of the emr signals increased with the increase in stress at the initial loading stage the main frequency of emr signals was low and its intensity was small with the increase in temperature the intensity of the emr signals increased at the same stress level as the loading increases the main frequency and the emr intensity fluctuated significantly under conditions of instability and failure the emr frequency changed notably and the emr intensity reached the maximum application of emr count as a damage variable reflected the sandstone deformation and fracture process this study provides guidance for application of emr to detect and evaluate the thermal stability of rocks after high temperature treatment

soil water flux in the southern great basin united states temporal and spatial variations over the last 120 000 years the disposal of hazardous and radioactive waste in arid regions requires a thorough understanding of the occurrence of soil water flux and recharge soil water chemistry and isotopic data are presented from three deep vadose zone boreholes 230 m at the nevada test site located in the great basin geographic province of the southwestern united states to quantify soil water flux and its relation to climate the low water contents found in the soils significantly reduce the mixing of tracers in the subsurface and provide a unique opportunity to examine the role of climate variation on recharge in arid climates tracing techniques and core data are examined in this work to reconstruct the paleohydrologic conditions existing in the vadose zone well beyond the timescales typically investigated stable chloride and chlorine 36 profiles indicate that the soil waters deep in the vadose zone range in age from approximately 20 000 to 120 000 years secondary chloride bulges that are present in two of the three profiles support the concept of recharge occurring at or near the last two glacial maxima when the climate of the area was considerably wetter and cooler the stable isotopic composition of the soil water in the profiles is significantly more depleted in heavy isotopes than is modern precipitation suggesting that recharge under the current climate is not occurring at this arid site past and present recharge appears to have been strongly controlled by surface topography with increased incidence of recharge where runoff from the surrounding mountains may have been concentrated the data obtained from this detailed drilling and sampling program shed new light on the behavior of water in thick vadose zones and in particular show the sensitivity of arid regions to the extreme variations in climate experienced by the region over the last two glacial maxima

circulation and stirring in the southeast pacific ocean and the scotia sea sectors of the antarctic circumpolar currenta abstractthe large scale middepth circulation and eddy diffusivities in the southeast pacific ocean and scotia sea sectors between 110 and 45 w of the antarctic circumpolar current acc are described based on a subsurface quasi isobaric rafos float based lagrangian dataset these rafos float data were collected during the diapycnal and isopycnal mixing experiment in the southern ocean dimes the mean flow adjusted to a common 1400 m depth shows the presence of jets in the time averaged sense with speeds of 6 cm s 1 in the southeast pacific ocean and upward of 13 cm s 1 in the scotia sea these jets appear to be locked to topography in the scotia sea but aside from negotiating a seamount chain are mostly free of local topographic constraints in the southeast pacific ocean the eddy kinetic energy eke is higher than the mean kinetic energy everywhere in the sampled domain by about 50 the magnitude of the eke increases drastically by a factor of 2 or more as the current crosses over the hero and

direct observations of the antarctic circumpolar current transport on the northern flank of the kerguelen plateau 1 the standing meander in the antarctic circumpolar current acc found on the northern flank of the kerguelen plateau was investigated during the southern ocean finestructure cruise in november december 2008 an 18 year time series of surface geostrophic currents from satellite altimetry shows that the meander as observed during this survey is typical of the region hydrographic stations were occupied between 65 75 e and 43 48 s on the shelf 200 m depth and slope into the deep ocean to the north of kerguelen 4700 m providing the most detailed survey of this region to date geostrophic shears are referenced to lowered acoustic doppler current profiler velocities to give the first estimate of the total volume transport in this region and the transport budget is closed around the survey box the subtropical front subantarctic front and a northern branch of the polar front together have an associated transport of 174 22 sv eastward while 174 sv is large compared with typical drake passage transports it is reconciled with other estimates of the total transport with the additional 15 sv of the indonesian throughflow baroclinic transport referenced to the deepest common level between station pairs is 119 sv consistent with other estimates of the baroclinic transport in this area at this longitude the fronts of the acc are exceptionally close together we discuss the exchange of properties across the fronts

thermal alterations in the poro mechanical characteristic of an indian sandstone a comparative study abstract knowledge of the variations caused by high temperature to the mechanical properties is a vital asset in processes such as underground coal gasification ucg in situ disposal of nuclear waste and during the recovery of geothermal the study can also provide valuable insights during the restoration of fire damaged buildings due to the presence of heat changes in rock morphology and mineralogy lead to a substantial change in the geomechanical properties of rock effect of high temperatures 1000 c on the tensile and compressive strength of a fine grained indian sandstone have been analysed in this study induced ductility observed at temperatures above 500 c causes the rock to exhibit properties similar to that of a plastic material the geomechanical properties decrease sharply beyond 500 c which has been referred to as the critical temperature of the rock beyond the critical temperature internal structure of the rock undergoes considerable damage in the form of microcracks and fissures created due to phase transition of quartz at 573 c and generation of thermal stress change in internal structure and mineralogy have been analysed by performing xrd x ray powder diffraction and fdxm four dimensional x ray microscopy studies with the help of fdxm change in porosity of rock has been analysed by studying the variation in connected and non connected pores

southern ocean fronts controlled by wind or topography 1 the location of fronts has a direct influence on both the physical and biological processes in the southern ocean here we explore the relative importance of bottom topography and winds for the location of southern ocean fronts using 100 years of a control and climate change simulation from the high resolution coupled climate model higem topography has primary control on the number and intensity of fronts at each longitude however there is no strong relationship between the position or spacing of jets and underlying topographic gradients because of the effects of upstream and downstream topography the southern hemisphere westerlies intensify and shift south by 1 3 in the climate change simulation but there is no comparable meridional displacement of the antarctic circumpolar current s acc path or the fronts within its boundaries even over flat topography instead the current contracts meridionally and weakens north of the acc the subtropical front stf shifts south gradually even over steep topographic ridges we suggest the stf reacts more strongly to the wind shift because it is strongly surface intensified in contrast fronts within the acc are more barotropic and are therefore more sensitive to the underlying topography an assessment of different methods for identifying jets reveals that maxima of gradients in the sea surface height field are the most reliable approximating the position of fronts using sea surface temperature gradients is ineffective at high latitudes while using sea surface height contours can give misleading results when studying the temporal variability of front locations

characteristics of high resolution hydraulic head profiles and vertical gradients in fractured sedimentary rocks summary accurately identifying the position of vertical hydraulic conductivity k v contrasts is critical to the delineation of hydrogeologic units that serve as the basis for conceptual and numerical models of groundwater flow high resolution head profiles have identified the position and thickness of k v contrasts in clayey aquitards but this potential has not yet been thoroughly evaluated in sedimentary rocks this paper describes an experiment in which head profiles with the highest technically feasible resolution were obtained using westbay multilevel systems mls installed in 15 cored holes at three sedimentary rock research sites with contrasting geologic and flow system conditions mlss were installed to maximum depths between 90 and 260 m with 2 5 monitoring zones per 10 m head profiles were measured over multiyear periods the vertical component of hydraulic gradient i e vertical gradient was calculated for each pair of adjacent monitoring intervals in every mls and then categorized based on its repeatability to facilitate interpretation of k v contrasts and comparisons within boreholes between boreholes at the same site and between sites the head and vertical gradient profiles from all three sites display systematic i e simple geometric shapes defined by repeatable intervals of no to minimal vertical gradient indicating relatively high k v units bounded by shorter depth intervals with large up to 50 m m vertical gradients indicating relatively low k v units the systematic nature of the profiles suggests flow in regular and interconnected fracture networks rather than dominated by a few key fractures with irregular orientations the low k v units were typically thin with their positions and thicknesses not predicted by lithostratigraphy or detailed lithologic geophysical and horizontal hydraulic conductivity data hence the position and thickness of units with contrasting k v would not be evident if mlss with the conventional number of monitoring zones had been used furthermore the detailed profiles can be strongly diagnostic of hydrogeologic unit boundaries or layers and can be used to improve the quantitative assessment of flow system conditions that is foundational to understanding contaminant plume migration

understanding the regional variability of eddy diffusivity in the pacific sector of the southern ocean a diagnostic framework is presented based on the nakamura effective diffusivity to investigate the regional variation in eddy diffusivity comparison of three different diffusivity calculations enables the effects of locally enhanced tracer diffusion to be distinguished from the streamwise average it also enables the distinction to be made between locally generated complexity in the tracer structure and that advected into a particular domain the technique is applied to the pacific sector of the southern ocean the results highlight the important role that the mean flow plays in determining eddy diffusivity the effective diffusivity is not simply related to the eddy kinetic energy in regions of a strong mean flow the eddy diffusivity can be suppressed even in the presence of moderately strong eddy activity conversely in a region of weak mean flow the eddy diffusivity can be enhanced even in the presence of only weak eddy activity this casts doubt on the ability of parameterizations based solely on the eddy kinetic energy to adequately characterize the eddy diffusivity in regions of strongly varying mean flow such as the southern ocean the results are however consistent with the eddy transport and mixing variability predicted by potential vorticity based arguments

on the variability of antarctic circumpolar current fronts inferred from 1992 2011 altimetry abstractantarctic circumpolar current acc fronts defined as water mass boundaries have been known to respond to large scale atmospheric variabilities especially the southern hemisphere annular mode sam and el nino southern oscillation enso distinct patterns of localized variability in meridional front displacements during 1992 2011 are derived from the analysis of satellite sea surface height data major basin scale differences are found between the southeast pacific 150 90 w and the southeast indian 75 150 e sectors of the acc frontal positions in the southeast pacific show large year to year meridional fluctuations attributed mostly to enso and in part sam and no apparent seasonal cycles or long term trends in contrast summer winter frontal locations in the southeast indian extend farther to the south north of their long term mean distribution a southward drift of acc fronts is indicated over the indian sector during the past two decades this long term shift is not directly re

enhancement of mesoscale eddy stirring at steering levels in the southern ocean abstract meridional cross sections of effective diffusivity in the southern ocean are presented and discussed the effective diffusivity keff characterizes the rate at which mesoscale eddies stir properties on interior isopycnal surfaces and laterally at the sea surface the distributions are obtained by monitoring the rate at which eddies stir an idealized tracer whose initial distribution varies monotonically across the antarctic circumpolar current acc in the absence of observed maps of eddying currents in the interior ocean the advecting velocity field is taken from an eddy permitting state estimate of the southern ocean sose a three dimensional advection diffusion equation is solved and the diffusivity diagnosed by applying the nakamura technique on both horizontal and isopycnal surfaces the resulting meridional sections of keff reveal intensified isopycnal eddy stirring reaching values of 2000 m2 s 1 in a layer deep beneath the acc but rising toward the surface on the equatorward flank

flow bearing structures of fractured rocks insights from hydraulic property scalings revealed by a pumping test abstract a long duration pumping test conducted over 151 days in a fractured sandstone and shale formation displays a nonstandard drawdown response and anomalous pressure diffusion which cannot be properly interpreted using existing frameworks e g homogeneous double porosity boundary conditions and fractal models an alternative framework with simple geometry and more complex hydraulic properties is thus proposed to interpret such kind of drawdown responses the analytical development allows first to demonstrate all scaling relations in this interpretation framework then and most importantly the multi scale hydraulic test provides consistent scalings of transmissivity t to storativity s over distances ranging from 83 to 383 m in a faulted area drawdown analysis in several monitoring wells shows persistent decrease of transmissivity in highly channelized fracture flow structures in one structure the cubic dependency of transmissivity to storativity identifies a well defined fault and also demonstrates the validity of poiseuille flow at a scale rarely investigated in the other structure the linear dependency of transmissivity to storativity indicates that the flow bearing structure is the surrounding fracture network well designed pumping tests combined with scaling analysis driven by geological evidence thus provide essential information on flow bearing structures for site characterization and modeling tasks at least for moderate to low permeable fractured rocks the scaling of transmissivity to storativity appears to be more informative than any separate interpretation of hydraulic property scaling exponents

observations of pigment and particle distributions in the western north atlantic from an autonomous float and ocean color satellite profiling floats with optical sensors can provide important complementary data to satellite ocean color determinations by providing information about the vertical structure of ocean waters as well as surface waters obscured by clouds here we demonstrate this ability by pairing satellite ocean color data with records from a profiling float that obtained continuous high quality optical data for 3 yr in the north atlantic ocean good agreement was found between satellite and float data and the relationship between satellite chlorophyll and floatderived particulate backscattering was consistent with previously published data upper ocean biogeochemical dynamics were evidenced in float measurements which displayed strong seasonal patterns associated with phytoplankton blooms and depth and seasonal patterns associated with an increase in pigmentation per particle at low light surface optical variables had shorter decorrelation timescales than did physical variables unlike at low latitudes suggesting that biogeochemical rather than physical processes controlled much of the observed variability after 2 25 yr in the subpolar north atlantic between newfoundland and greenland the float crossed the north atlantic current to warmer waters where it sampled an unusual eddy for 3 months this anticyclonic feature contained elevated particulate material from surface to 1000 m depth and was the only such event in the float s record this eddy was associated with weakly elevated surface pigment and backscattering but depthintegrated backscattering was similar to that previously observed during spring blooms such seldom observed eddies if frequent are likely to make an important contribution to the delivery of particles to depth

antarctic circumpolar current transport and barotropic transition at macquarie ridge theory and numerical simulations suggest that topographic interactions are central to the dynamics of the antarctic circumpolar current acc but few observations are available to test these ideas we use direct velocity measurements satellite altimetry and an ocean state estimate to investigate the interaction of the acc with the macquarie ridge satellite altimeter data show that the subantarctic front crosses the ridge through a gap immediately north of macquarie island yearlong current meter records reveal strong deep mean flow 0 2 m s 1 at 3000 m and substantial transport 52 8 106 m3 s 1 in the 50 km wide gap the acc becomes much more barotropic at the ridge acceleration of the deep jet is balanced by the ageostrophic along gap pressure gradient convergence of zonal momentum by the mean vertical velocity and dissipation the study helps explain how the acc negotiates large topographic obstacles and highlights the role of local nonlinear processes in the dynamical balance of the acc

digital imaging technology and experimental archeology a methodological framework for the identification and interpretation of fire modified rock fmr abstract this paper presents the results of a series of experiments for the identification and analysis of fire modified rock fmr fmr is a common but frequently overlooked artifact type experiments were conducted simulating the effects of different hypothetical burning scenarios on rocks similar to those found in a south african middle stone age site a digital imaging method was then used to quantify fmr color values designed to limit intra analyst bias statistical tests and a blind test suggest that unburned rocks and experimental fmr can be separated statistically based on physical appearance two burning scenario models based on measured experimental data were applied to archaeological fmr from a south african middle stone age site named pinnacle point 5 6 pp5 6 and show that the archaeological samples are not statistically different from a simulated campfire and possibly a lithic raw material heat treatment fire

jets and topography jet transitions and the impact on transport in the antarctic circumpolar current the southern ocean s antarctic circumpolar current acc naturally lends itself to interpretations using a zonally averaged framework yet navigation around steep and complicated bathymetric obstacles suggests that local dynamics may be far removed from those described by zonally symmetric models in this study both observational and numerical results indicate that zonal asymmetries in the form of topography impact global flow structure and transport properties the conclusions are based on a suite of more than 1 5 million virtual drifter trajectories advected using a satellite altimetry derived surface velocity field spanning 17 years the focus is on sites of cross front transport as defined by movement across selected sea surface height contours that correspond to jets along most of the acc cross front exchange is localized in the lee of bathymetric features with more than 75 of crossing events occurring in regions corresponding to only 20 of the acc s zonal extent these observations motivate a series of numerical experiments using a two layer quasigeostrophic model with simple zonally asymmetric topography which often produces transitions in the front structure along the channel significantly regimes occur where the equilibrated number of coherent jets is a function of longitude and transport barriers are not periodic jet reorganization is carried out by eddy flux divergences acting to both accelerate and decelerate the mean flow of the jets eddy kinetic energy is amplified downstream of topography due to increased baroclinicity related to topographic steering the combination of high eddy kinetic energy and recirculation features enhances particle exchange these results stress the complications in developing consistent circumpolar definitions of the acc fronts

glacial interglacial co2 change the iron hypothesis several explanations for the 200 to 280 ppm glacial interglacial change in atmospheric co2 concentrations deal with variations in southern ocean phytoplankton productivity and the related use or nonuse of major plant nutrients an hypothesis is presented herein in which arguments are made that new productivity in today s southern ocean 7 4 1013g yr 1 is limited by iron deficiency and hence the phytoplankton are unable to take advantage of the excess surface nitrate phosphate that if used could result in total southern ocean new production of 2 3 1015 g c yr 1 as a consequence of fe limited new productivity holocene interglacial co2 levels preindustrial are as high as they were during the last interglacial 280 ppm in contrast atmospheric dust fe supplies were 50 times higher during the last glacial maximum lgm because of this fe enrichment phytoplankton growth may have been greatly enhanced larger amounts of upwelled nutrients may have been used and the resulting stimulation of new productivity may have contributed to the lgm drawdown of atmospheric co2 to levels of less than 200 ppm background information and arguments in support of this hypothesis are presented

potential vorticity constraints on the dynamics and hydrography of the southern ocean abstract constraints on the hydrography and geostrophic velocity shear of the southern ocean implicit in its potential vorticity field are discussed and illustrated by diagnostic study of observed and modeled potential vorticity fields a stress driven thermodynamically inactive eddy resolving quasigeostrophic model of the southern ocean suggests that through the systematic erosion of potential vorticity gradients by geostrophic eddies the large scale flow equilibrates toward a state in which interior potential vorticity gradients are small observations of the large scale isopycnal distribution of potential vorticity ipv deduced from climatological hydrographic data reveal a much richer structure the most striking feature of the ipv field is the presence of large near surface gradients of ipv a vortocline coinciding with the axis of the antarctic circumpolar current acc to the south of this front potential vorticity pv is large to its north pv has low values and relative to those foun

southern ocean eddy phenomenology mesoscale eddies are ubiquitous features in the southern ocean yet their phenomenology is not well quantified to tackle this task we use satellite observations of sea level anomalies and sea surface temperature sst as well as in situ temperature and salinity measurements from profiling floats over the period 1997 2010 we identified over a million mesoscale eddy instances and were able to track about 105 of them over 1 month or more the antarctic circumpolar current acc the boundary current systems and the regions where they interact are hot spots of eddy presence representing also the birth places and graveyards of most eddies these hot spots contrast strongly to areas shallower than about 2000 m where mesoscale eddies are essentially absent likely due to topographical steering anticyclones tend to dominate the southern subtropical gyres and cyclones the northern flank of the acc major causes of regional polarity dominance are larger formation numbers and lifespans with a contribution of differential propagation pathways of long lived eddies areas of dominance of one polarity are generally congruent with the same polarity being longer lived bigger of larger amplitude and more intense eddies extend down to at least 2000 m in the acc eddies show near surface temperature and salinity maxima whereas eddies in the subtropical areas generally have deeper anomaly maxima presumably inherited from their origin in the boundary currents the temperature and salinity signatures of the average eddy suggest that their tracer anomalies are a result of both trapping in the eddy core and stirring

submesoscale streamers exchange water on the north wall of the gulf stream the gulf stream is a major conduit of warm surface water from the tropics to the subpolar north atlantic here we observe and simulate a submesoscale 20 km mechanism by which the gulf stream exchanges water with subpolar water to the north along isopycnals the front has a sharp compensated temperature salinity contrast with distinct mixed water between the two water masses 2 and 4 km wide this mixed water does not increase downstream despite substantial energy available for mixing a series of streamers detrain this water at the crest of meanders subpolar water replaces the mixed water and resharpens the front the water mass exchange accounts for a northward flux of salt of 0 5 2 5 psu m2 s 1 large scale diffusivity o 100 m2 s 1 this is similar to bulk scale flux estimates of 1 2 psu m2 s 1 and supplies fresher water to the gulf stream required for the production of 18 subtropical mode water

the effects of fire on rock weathering some further considerations of laboratory experimental simulation fire in the natural environment is a widespread agent of geomorphological and biological change temperatures can exceed 1000 c there is often a rapid rise from ambient conditions through a steep thermal gradient promoting rock disintegration laboratory simulation studies have established that temperature changes which are representative of natural fires affect rock material properties which can then be related to weathering susceptibility this study extends previous work by more closely replicating the natural environment a through the simulation of rainfall and b by encasing samples to reflect the exposure of a single rock face to a passing fire event rock samples collected on cyprus were prepared and tested following previously reported procedures change in modulus of elasticity was monitored using a non destructive ultrasonic method the data corroborate previous work but with somewhat different degrees of change the new results are more likely to be representative of natural conditions and real world change the rate of rock disintegration and effects such as case hardening appear to be a function of rock thermal characteristics material properties and environmental constraints such as diurnal temperature range copyright 1999 john wiley sons ltd

when mixed layers are not mixed storm driven mixing and bio optical vertical gradients in mixed layers of the southern ocean author s carranza mm gille st franks pjs johnson ks pinkel r girton jb abstract 2018 american geophysical union all rights reserved mixed layers are defined to have homogeneous density temperature and salinity however bio optical profiles may not always be fully homogenized within the mixed layer the relative timescales of mixing and biological processes determine whether bio optical gradients can form within a uniform density mixed layer vertical profiles of bio optical measurements from biogeochemical argo floats and elephant seal tags in the southern ocean are used to assess biological structure in the upper ocean within the hydrographically defined mixed layer the profiles show significant vertical variance in chlorophyll a chl a fluorescence and particle optical backscatter biological structure is assessed by fitting chl a fluorescence and particle backscatter profiles to functional forms i e gaussian sigmoid exponential and their combinations in the southern ocean which characteristically has deep mixed layers only 40 of nighttime bio optical profiles were characterized by a sigmoid indicating a well mixed surface layer of the remaining 60 that showed structure 40 had a deep fluorescence maximum below 20 m depth that correlated with particle backscatter furthermore a significant fraction of these deep fluorescence maxima were found within the mixed layer 20 80 depending on mixed layer depth definition and season results suggest that the timescale between mixing events that homogenize the surface layer is often longer than biological timescales of restratification we hypothesize that periods of quiescence between synoptic storms which we estimate to be 3 5 days depending on season allow bio optical gradients to develop within mixed layers that remain homogeneous in density

semiarid unsaturated zone chloride profiles archives of past land use change impacts on water resources in the southern high plains united states 1 unsaturated zone chloride profiles in semiarid regions provide a decadal to century scale record of past environmental changes similar to climate change records provided by tree rings and ice cores impacts of conversions from natural ecosystems to rain fed agriculture on water resources are recorded in chloride profiles in semiarid regions as typified by the southern high plains shp texas southwestern united states large chloride accumulations beneath natural grassland and shrubland ecosystems 3 profiles reflect evapotranspirative enrichment of atmospherically derived chloride during the holocene indicating no recharge in interdrainage areas conversion to rain fed agriculture is recorded by downward displacement 9 profiles or complete flushing 10 profiles of chloride bulges indicating increased recharge increased recharge associated with cultivation median 24 mm yr 5 of precipitation 19 profiles was quantified using chloride mass balance calculations the timing of land use change was estimated using chloride data and results 43 89 years are consistent with aerial photo records and landowner surveys new equilibrium volumetric recharge rates beneath rain fed agriculture in the shp 0 63 km3 yr will require decades to establish and represent one to eight times recharge rates for baseline precultivated conditions that are focused beneath ephemeral lake or playa drainages 0 08 0 83 km3 yr these chloride profiles generally represent decadal scale monitoring of subsurface response to land use change

distribution of upper circumpolar deep water on the warming continental shelf of the west antarctic peninsula we use autonomous underwater vehicles to characterize the spatial distribution of upper circumpolar deep water ucdw on the continental shelf of the west antarctic peninsula wap and present the first near synoptic measurements of mesoscale features eddies containing ucdw on the wap thirty three subsurface eddies with widths on the order of 10 km were detected during four glider deployments each eddy contributed an average of 5 8 x 1016 j to the sub pycnocline waters where a cross shelf heat flux of 1 37 x 1019 j yr 1 is required to balance the diffusive loss of heat to overlying winter water and to the near coastal waters approximately two thirds of the heat coming onto the shelf diffuses across the pycnocline and one third diffuses to the coastal waters long term warming of the sub pycnocline waters is a small residual of this balance sixty percent of the profiles that contained ucdw were part of a coherent eddy between 20 and 53 of the lateral onshore heat flux to the wap can be attributed to eddies entering marguerite trough a feature in the southern part of the shelf which is known to be an important conduit for ucdw a northern trough is identified as additional important location for eddy intrusion

boulder weathering and erosion associated with a wildfire sierra ancha mountains arizona an april may 2000 coon creek fire burned 37 5 km 2 of the sierra ancha mountains 32 3 km miles north of globe az including 25 sandstone and 19 diorite boulders surveyed in 1989 and resurveyed after the burn after the summer 2000 monsoon season and after the winter 2001 season when viewed from the perspective of cumulative eroded area both sandstone and diorite displayed bimodal patterns with 79 of sandstone boulder area and 93 of diorite boulder area undergoing either no fire induced erosion or fire induced erosion 76 mm when stretched over cumulative boulder areas erosion due to the fire averaged 26 mm for sandstone and 42 mm for diorite post fire erosion from thunderstorm summer rains averaged i mm for 5 diorite and i mm for 10 sandstone boulders while only a single diorite boulder eroded an average of 1 2 mm after the winter winter erosion removed an average of 5 5 mm from 14 sandstone boulders thus fire appears to increase a rock s susceptibility to post fire weathering and erosion processes as predicted by goudie et al earth surf process landf 17 1992 605 in contrast to experimental research indicating the importance of size in fire weathering no statistically significant relationship exists between erosion and boulder height or boulder surface area a result similar to zimmerman et al quat res 42 1994 255 these data exclude 12 original sites and 85 boulders at sites impacted by the fire that could not be relocated with a reasonable cause for the lack of relocation being boulder obliteration by the fire given evidence from 1 0 be and 2 6 al cosmogenic nuclides earth planet sci lett 186 2001 269 supporting the importance of boulders in controlling evolution of nonglaciated bouldered landscapes geol soc amer bull 76 1965 1165 fire obliteration of boulders could be an important process driving drainage evolution in nonglaciated mountains

low frequency variability of southern ocean jets both observations and high resolution numerical models show that the southern ocean circumpolar flow is concentrated in a large number approximately 8 to 12 of narrow filamentary jets it is shown here that coherent jets exhibit a range of low frequency variability on timescales of months to years that can lead to displacement and to intermittent formation and dissipation of jets using output from an eddy resolving ocean general circulation model in local regions near topographic features the impact of energy exchange between eddy and mean flow components on jet persistence and variability is examined a novel approach that uses a time dependent definition of the mean flow provides a clearer picture of eddy mean flow interactions in regions with spatially and temporally varying flow structure the dynamics are largely consistent with those in idealized quasi geostrophic models including topographically organized and surface enhanced reynolds stress forcing of the mean flow jets form during periods of enhanced eddy activity but may persist long after the eddy activity has decayed similarly jets may evolve in a downstream sense with jet formation localized near topography and undergoing modification in response to changing bathymetry the evolution of both temperature and potential vorticity is used to show that the low frequency variability of the jets impacts water mass structure and tracer transport this study highlights various examples of southern ocean dynamics that will prove difficult to capture through parameterizations in coarser climate models

geochemical estimates of paleorecharge in the pasco basin evaluation of the chloride mass balance technique the pasco basin in southeastern washington state provides a unique hydrogeologic setting for evaluating the chloride mass balance technique for estimating recharge this basin was affected by late pleistocene catastrophic floods when glacial dams in western montana and northern idaho were breached it is estimated that multiple missoula floods occurred between 13 000 and 15 000 years b p and reached a high water elevation of 350 m these floods removed accumulated chloride from the sediment profile effectively resetting the chloride mass balance clock at the beginning of the holocene the rate of chloride accumulation qcl in the sediments was determined by two methods and compared the first method measured qcl by dividing the calculated natural fallout of 36cl by a measured ratio of 36cl cl in the pore water while the second method used the total mass of chloride in the profile divided by the length of time that atmospheric chloride had accumulated since the last flood although the two methods are based on different approaches they showed close agreement in laboratory studies the sediment to water ratio for chloride extraction was sensitive to the grain size of the sediments low extraction ratios in silt loam sediments led to significant underestimation of pore water chloride concentration br cl ratios were useful for distinguishing nonatmospheric e g rock sources of chloride field studies showed little spatial variability in estimated recharge at a given site within the basin but showed significant topographic control on recharge rates in this semiarid environment an extension of the conventional chloride mass balance model was used to evaluate chloride profiles under transient time varying annual precipitation conditions this model was inverted to determine the paleorecharge history for a given soil chloride profile and the parameters of the root extraction model required to estimate paleoprecipitation

structural and statistical characterization of joints and multi scale faults in an alternating sandstone and shale turbidite sequence at the santa susana field laboratory implications for their effects on groundwater flow and contaminant transport abstract this paper describes the properties of faults and fractures in the upper cretaceous chatsworth formation exposed at santa susana field laboratory and its surroundings simi hills california where groundwater flow and contamination have been studied for over three decades the complex depositional architecture of this turbidite consisting of alternating sandstones and shales interacting with formative stress conditions are responsible for multi scale fault hierarchies and permeable fractures in which nearly all groundwater flow occurs intensity and distribution of background fractures and their relation to bedding thickness are established for sandstones the dominant lithology the architecture of faults with increasing displacement is described and relationships among fault dimensional parameters captured data from 400 boreholes and piezometers reveal the effect of faults and fractures on groundwater flow large hydraulic head differences observed across fault zones with shale rich cores indicate these structures as cross flow barriers moreover hydraulic head profiles under ambient conditions and pumping tests suggest strong hydraulic connectivity in all directions to depth of hundreds of meters this outcrop based structural characterization relates the horizontal hydraulic conductivity to the observed well connected fracture network and explains the strong vertical connectivity across low hydraulic conductivity shales as faults and sheared fractures provide flow pathways

fronts and habitat zones in the scotia sea abstract the fronts in the antarctic circumpolar current acc comprise the southern acc front saccf the polar front pf and sub antarctic front saf which together with the southern boundary sb separate zones with distinct water mass properties in the southern ocean they are important for describing habitat ranges of oceanic species over the range of trophic levels and are also key habitat zones in their own right for a variety of species frontal positions were studied along a transect running s to n across the scotia sea during three hydrographic cruises in spring 2006 summer 2008 and autumn 2009 subsurface data from these cruises and argo data are here combined with aviso satellite absolute dynamic topography data to locate these fronts facilitating study of their ecological significance within the scotia sea northern and southern dynamic height limits are found for each front as opposed to the more usual one dimensional line thus the sb was found between 132 to 116 dyn cm the saccf between 115 to 99 dyn cm and the pf between 71 to 45 dyn cm argo data allow the sensitivity of the dynamic heights found to be tested against seasonal interannual and longitudinal effects and each is found to be small although the saf lay beyond the northern extent of the transect we sampled along argo profiles allowed us to determine its limits as lying between 5 and 29 dyn cm the dynamic height limits found are thus suitable for assessing the location in relation to fronts of any sample or tracked animal within this area the chlorophyll distribution across the scotia sea is assessed relative to frontal positions and known iron sources the physical conditions sea surface temperature sea ice and mixed layer depth along the sampling transect are also presented allowing the oceanographic conditions of the stations occupied across the scotia sea to be assessed

abrupt transitions in submesoscale structure in southern drake passage glider observations and model results abstractenhanced vertical velocities associated with submesoscale motions may rapidly modify mixed layer depths and increase exchange between the mixed layer and the ocean interior these dynamics are of particular importance in the southern ocean where the ventilation of many density classes occurs here we present results from an observational field program in southern drake passage a region preconditioned for submesoscale instability due to its strong mesoscale eddy field persistent fronts strong down front winds and weak vertical stratification two gliders sampled from december 2014 through march 2015 upstream and downstream of shackleton fracture zone sfz the acquired time series of mixed layer depths and buoyancy gradients enabled calculations of potential vorticity and classifications of submesoscale instabilities the regions flanking the sfz displayed remarkably different characteristics despite similar surface forcing mixed layer depths were nearly twice as deep and horizontal buoyancy

configuration of a southern ocean storm track abstractdiagnostics of ocean variability that reflect and influence local transport properties of heat and chemical species vary by an order of magnitude along the southern ocean s antarctic circumpolar current acc topographic hotspots are important regions of localized transport anomalies this study uses a primitive equation channel model to investigate the structure of eddy kinetic energy eke one measure of variability in an oceanic regime a storm track approach emphasizes the importance of stationary eddies which result from flow interactions with topography on setting eke distributions the influence of these interactions extends far downstream of the topography and impacts eke patterns through localized convergence and divergence of heat unlike for zonal averages local contributions to the stationary fluxes from terms that integrate to zero in a zonal average are important the simulations show a strong sensitivity of the zonal structure as well as the distribution and amplitude of sta

temperature influence on the physical and mechanical properties of a porous rock san julian s calcarenite this work has been funded by the universidad de alicante under the projects uausti11 11 vigrob 212 and gre09 40 and by the generalitat valenciana under the project gv 2011 044

exploitation of inherited weakness in fire damaged building sandstone the fatiguing of shocked stone abstract the problem of the long term impact of historical fire on masonry is not clearly understood much research focuses on the damage that is caused by fire in isolation and omits to investigate the subsequent exploitation of weaknesses inherited from fire events fire can for example cause significant physical chemical and mineralogical change to sandstone which may then be exploited by background environmental factors such as salt and freeze thaw weathering to explore this experimentally blocks of peakmoor sandstone were subjected to a real fire as well as lime rendering removal and frost cycle pre treatments and their subsequent response to salt weathering cycles was monitored by weight loss and visual assessment of the pattern of surface damage results illustrate that the post fire deterioration of sandstone is strongly conditioned by fracture networks and soot cover inherited from the fire the exploitation of fractures can lead to spalling during salt weathering cycles this takes place as granular dissagregation steadily widens cracks and salts concentrate and crystallise in areas of inherited weakness soot cover can have a profound effect on subsequent performance it reduces surface permeability and can be hydrophobic in character limiting salt ingress and suppressing decay in the short term however as salt crystals concentrate under the soot crust detachment of this layer can occur exposing fire damaged stone beneath understanding the subsequent exploitation of stone exposed to fire damage by background environmental factors for example salt weathering temperature cycling is key to the post fire management of stone decay

parameterization of mixed layer eddies part i theory and diagnosis ageostrophic baroclinic instabilities develop within the surface mixed layer of the ocean at horizontal fronts and efficiently restratify the upper ocean in this paper a parameterization for the restratification driven by finite amplitude baroclinic instabilities of the mixed layer is proposed in terms of an overturning streamfunction that tilts isopycnals from the vertical to the horizontal the streamfunction is proportional to the product of the horizontal density gradient the mixed layer depth squared and the inertial period hence restratification proceeds faster at strong fronts in deep mixed layers with a weak latitude dependence in this paper the parameterization is theoretically motivated confirmed to perform well for a wide range of mixed layer depths rotation rates and vertical and horizontal stratifications it is shown to be superior to alternative extant parameterizations of baroclinic instability for the problem of mixed layer restratification two companion papers discuss the numerical implementation and the climate impacts of this parameterization

spatial average aquifer recharge through atmospheric chloride mass balance and its uncertainty in continental spain the atmospheric chloride mass balance cmb method allows spatial evaluations of the average diffuse aquifer recharge by rainfall in large and varied territories when long term steady conditions can be assumed often the distributed average cmb variables necessary to calculate have to be estimated from the available variable length data series which may be of suboptimal quality and spatial coverage this paper explains the use of these data and the reliability of the results in continental spain chosen as a large and varied territory the cmb variables have been regionalized by ordinary kriging at the same 4976 nodes of a 10 km 10 km grid nodal values vary from 14 to 810 mm year 1 90 ranging from 30 to 300 mm year 1 the recharge to precipitation ratios vary from 0 03 in low permeability formations and semiarid areas to 0 65 in some carbonate massifs integrated average results for the whole of continental spain yield a potential aquifer recharge of 64 km3 year 1 the net recharge over permeable formations 40 of the territory being 32 km3 year 1 two main sources of uncertainty affecting given by the coefficient of variation cv induced by the inherent natural variability of the variables cvr and from mapping have been segregated the average cvr is 0 13 and could be improved with longer data series the average is 0 07 and may be decreased with better data coverage the estimates were compared with other regional and local recharge estimates being 4 and 1 higher respectively copyright 2012 john wiley sons ltd

using the cl br ratio as a tracer to identify the origin of salinity in aquifers in spain and portugal summary a study on the applicability of the cl br molar ratio for identifying the origin of groundwater salinity is presented according to the experience gained in spain and portugal cl br ratios in atmospheric bulk deposition have helped to distinguish groundwater in which cl derives only from atmospheric sources from groundwater in which cl is contributed by endogenous lithological or anthropogenic sources considering the seawater cl br ratio of 655 4 cl br ratios may be increased up to 1500 in groundwater by the addition of wastewater loaded with nacl or leaching of solid waste and decreased to 300 by the use of br based pesticides or leaching farm animal or septic waste leaching and dissolution of natural and industrial nacl and of gypsum rich formations containing some nacl may yield cl br ratios between one thousand and several thousand although leaching of potassium halides near salt mines produces cl br ratios below the seawater ratio when cl content in groundwater is not affected by extreme evaporation up to halite saturation at 6 2 mol l 1 of nacl and if there are no other cl sources recharge by rainfall can be estimated by relating cl in atmospheric bulk deposition to derived groundwater the cl br ratio appears to be a good tracer for discriminating non atmospheric cl contributions to groundwater provided chemical analyses are accurate since its variability is not wide data have been collected from different areas of spain and portugal and are explained and illustrated by two cases described in detail the donana aquifer in southwest spain and the canary islands both showing the mixing paths

groundwater recharge assessment in an upland sandstone aquifer of southern california abstract the chloride mass balance cmb method was used to obtain long term recharge values for the santa susana field laboratory ssfl site which features a groundwater flow system beneath an upland ridge formed of sandstone and shale beds in the simi hills ventura county southern california this application relied on the availability of on site measurements of bulk atmospheric chloride deposition comprised of dry fallout and wet concentration a large number of groundwater samples 1490 collected over three decades from 206 wells spanning a depth range from 10 to 360 m and measurements of chloride in surface runoff during rain events the use of the cmb method is suited to the assessment of recharge for the study area because the mean chloride values in groundwater show minimal spatial trends indicating no sources other than atmospheric in addition the cl br ratio was used to exclude wells with possible anthropogenic chloride the site wide average recharge ranges between 1 8 and 9 5 of the mean annual precipitation 455 mm with a mean value of 4 2 the measured surface runoff varies from 2 3 to 10 2 with mean value of 6 1 28 mm and therefore the volume of water lost to evapotranspiration is between 95 9 and 80 3 with a mean value of 89 6 408 mm the long term recharge calculated using the cmb method is consistent with tritium distribution based on a subset of groundwater monitoring wells and with an analysis of steady flow in the groundwater mound beneath the ssfl furthermore the recharge value matches those in the literature for sandstone aquifers in arid and semi arid climates this recharge estimate has important relevance for site characterization in terms of constraining the volumetric groundwater flow rates and water balance and understanding the mechanisms of transport towards the water table moreover this is the first application of the cmb in an upland area of california hence the method is demonstrated to be robust and applicable to many upland bedrock areas in southern california and similar regions around the world and can be used to quantify groundwater flow rates and supplies relevant to water resource management

combined use of straddle packer testing and flute profiling for hydraulic testing in fractured rock boreholes summary a combination of high resolution hydraulic tests using straddle packers and transmissivity t profiling using the flute flexible liner method liner profiling in densely fractured rock boreholes is shown to be efficient for the determination of the vertical distribution of t along the entire hole the liner t profiling method takes a few hours or less to scan the entire borehole length resulting in a t profile under favorable conditions this method has good reliability for identifying the highest t zones identified by distinct decreases in liner velocity when these zones are covered by the descending liner in contrast for one short test interval e g 1 2 m the multiple test straddle packer method takes a few hours to measure t with good precision and accuracy using a combination of steady state and transient tests e g constant head step tests slug tests and constant rate pumping tests because of the time consuming aspect of this multiple test method it is most efficient in each borehole to conduct straddle packer testing only in priority zones selected after assessment of other borehole data collected prior to packer testing the t profile from the liner method is instrumental in selecting high permeable zones for application of the multiple test method using straddle packers which in turn refines the t estimation from the liner profile results from three boreholes in densely fractured sandstone demonstrate this approach showing the synergistic use of the methods with emphasis on information important for determining hydraulic apertures

the formation of nonzonal jets over sloped topography coherentjetsareubiquitousfeaturesoftheocean scirculation andtheircharacteristics suchasorientation and energetics may be influenced by topography in this study the authors introduce a large scale topographic slope with an arbitrary orientation into quasigeostrophic doubly periodic barotropic and baroclinic systems in both systems the flow organizes itself into coherent tilted nonzonal jets that are aligned perpendicular to the barotropic potential vorticity pv gradient in the two layer system the upper layer the lower layer and the barotropic pv gradients all have different orientations and therefore the jets cross the layer wise pv gradients the fact that the jets cross layer wise pv gradients and the requirement of conservation of pv for fluid parcels together results in the drift of the tilted jets across the domain like their zonalcounterparts thetiltedjetsexhibitstrongtransportanisotropy thedynamicalresponsetojetdeflection is very strong in the two layer baroclinic case with eddy energy production increasing by orders of magnitude as the topographic slope becomes more zonal this increase in eddy energy is also reflected in an increase in jet spacing and a reduction in strength of the across jet transport barriers shown using an effective diffusivity diagnostic the dynamics identified here while formally valid within the constraints of quasigeostrophic scalings provide important insight into the sensitive relationship between flow orientation and flow stability in regions with broad topographic slopes

analysis of horizontal and vertical processes contributing to natural iron supply in the mixed layer in southern drake passage abstract horizontal advection vertical mixing and mixed layer entrainment all affect iron concentrations and biological productivity in the ona basin near the shackleton transverse ridge str in southern drake passage trace metal sampling in the region indicates that dissolved iron concentrations are significantly higher on the continental shelf near the antarctic peninsula and the south shetland islands than they are in the deep waters away from the shelf comparisons between satellite derived sea surface height ssh and chlorophyll a chl a levels in the ona basin show 95 correlation between chl a concentrations and horizontal advection of these iron rich shelf waters during the months of november and december for the years 1997 2010 however no significant correlations are found for january april while high chl a concentrations in the ona basin persist through march enhanced vertical diapycnal mixing and mixed layer entrainment are considered as alternative mechanisms for delivering iron into the ona basin mixed layer and sustaining the high chl a concentrations estimates of iron flux based on in situ measurements of dissolved iron concentrations suggest that diapycnal mixing alone can supply iron to the base of the mixed layer at a rate of 64 2 nmol m 2 day 1 during the summer in addition the summer mixed layer in the ona basin deepens from january to april allowing for iron rich water to be steadily entrained from below estimates based on monthly mixed layer climatologies produce average daily entrainment rates ranging from 5 to 25 nmol m 2 day 1 while neither diapycnal mixing nor entrainment alone is always sufficient to meet the estimated iron demand for the ona basin bloom numerical simulation suggests that the combined effect of the two processes can consistently supply sufficient iron to sustain the bloom

multiple jets of the antarctic circumpolar current south of australia abstract maps of the gradient of sea surface height ssh and sea surface temperature sst reveal that the antarctic circumpolar current acc consists of multiple jets or frontal filaments the braided and patchy nature of the gradient fields seems at odds with the traditional view derived from hydrographic sections that the acc is made up of three continuous circumpolar fronts by applying a nonlinear fitting procedure to 638 weekly maps of ssh gradient ssh it is shown that the distribution of maxima in ssh i e fronts is strongly peaked at particular values of absolute ssh i e streamlines the association between the jets and particular streamlines persists despite strong topographic and eddy mean flow interactions which cause the jets to merge diverge and fluctuate in intensity along their path the ssh values corresponding to each frontal branch are nearly constant over the sector of the southern ocean between 100 e and 180 the front positions inferred from ssh agree closely with

open ocean submesoscale motions a full seasonal cycle of mixed layer instabilities from gliders abstractthe importance of submesoscale instabilities particularly mixed layer baroclinic instability and symmetric instability on upper ocean mixing and energetics is well documented in regions of strong persistent fronts such as the kuroshio and the gulf stream less attention has been devoted to studying submesoscale flows in the open ocean far from long term mean geostrophic fronts characteristic of a large proportion of the global ocean this study presents a year long submesoscale resolving time series of near surface buoyancy gradients potential vorticity and instability characteristics collected by ocean gliders that provides insight into open ocean submesoscale dynamics over a full annual cycle the gliders continuously sampled a 225 km2 region in the subtropical northeast atlantic measuring temperature salinity and pressure along 292 short 20 km hydrographic sections glider observations show a seasonal cycle in near surface stratification throughout the fall september november

an advective mechanism for deep chlorophyll maxima formation in southern drake passage we observe surface and subsurface fluorescence derived chlorophyll maxima in southern drake passage during austral summer backscatter measurements indicate that the deep chlorophyll maxima dcms are also deep biomass maxima and euphotic depth estimates show that they lie below the euphotic layer subsurface offshore and near surface onshore features lie along the same isopycnal suggesting advective generation of dcms temperature measurements indicate a warming of surface waters throughout austral summer capping the winter water ww layer and increasing off shelf stratification in this isopycnal layer the outcrop position of the ww isopycnal layer shifts onshore into a surface phytoplankton bloom a lateral potential vorticity pv gradient develops such that a down gradient pv flux is consistent with offshore along isopycnal tracer transport model results are consistent with this mechanism subduction of chlorophyll and biomass along isopycnals represents a biological term not observed by surface satellite measurements which may contribute significantly to the strength of the biological pump in this region

preliminary observations on the impact of complex stress histories on sandstone response to salt weathering laboratory simulations of process combinations historic sandstone structures carry an inheritance or a memory of past stresses that the stone has undergone since its placement in a facade this inheritance which conditions present day performance may be made up of long term exposure to a combination of low magnitude background environmental factors for example salt weathering temperature and moisture cycling and superimposed upon these less frequent but potentially high magnitude events or exceptional factors for example lime rendering severe frost events fire the impact of complex histories on the decay pathways of historic sandstone is not clearly understood but this paper seeks to improve that understanding through the use of a laboratory process combination study blocks of quartz sandstone peakmoor from nw england were divided into subsets that experienced different histories lime rendering and removal fire and freeze thaw cycles in isolation and combination that reflected the event timeline of a real medieval sandstone monument in ne ireland bonamargy friary mccabe et al 2006b these subsets were then subject to salt weathering cycles using a 10 salt solution of nacl and mgso4 that represents the every day stress environment of for example sandstone structures in coastal or polluted urban location block response to salt weathering was monitored by collecting drying and weighing the debris that was released as blocks were immersed in the salt solution at the beginning of each cycle the results illustrate the complexity of the stone decay system showing that seemingly small variations in stress history can produce divergent response to salt weathering cycles applied to real world historic sandstone structures this concept may help to explain the spatial and temporal variability of sandstone response to background environmental factors on a single facade and encourage conservators to include the role of stress inheritance when selecting and implementing conservation strategies

constraining modern and historical recharge from bore hydrographs 3h 14c and chloride concentrations applications to dual porosity aquifers in dryland salinity areas murray basin australia summary water table fluctuations and renewal rates based on 3h and 14c concentrations in bores screened within 5 m of the water table were used to estimate recharge rates in five dryland salinity areas in northern victoria australia given the resolution of each technique both methods yield broadly similar results of 4 90 mm yr up to 14 of modern rainfall that reflect the recharge rates following land clearing over the last 200 years deeper bores show mixing of modern recharge with older water flowing laterally through the aquifers recharge estimates based on cl concentrations are up to two orders of magnitude lower

heat induced alteration of glauconitic minerals in the middle stone age levels of blombos cave south africa implications for evaluating site structure and burning events abstract in this paper we conduct geochemical and colourimetric measurements of glauconite grains in micromorphological thin sections from the middle stone age site of blombos cave south africa to investigate the formation internal structure and reworking of heat exposed cave deposits that are related to prehistoric burning events controlled heating experiments were first carried out on glauconite rich loose sediments and block samples both of which were collected from the blombos cave bedrock the control samples were then subjected to fourier transform infrared spectrometry ftir microscopic fourier transform infrared spectrometry micro ftir and petrographic colourimetric analyses the control experiment shows that glauconitic minerals undergo a gradual and systematic colour change when temperatures reach higher than c 300 400 c primarily due to dehydration and iron oxidation they also undergo clear structural changes when temperatures reach higher than c 550 c due to dehydroxylation and mineral transformation by assessing the nature and degree of heat induced optical and molecular alteration in glauconitic minerals we demonstrate how glauconite grains in thin sections can be classified by the temperature to which they were exposed 20 400 c 400 c 600 c and 800 c to assess the archaeological relevance of our controlled heating experiment we applied this glauconite classification scheme to 200 grains found in three micromorphological thin sections of a middle stone age msa combustion feature these grains were individually geo referenced within the local coordinate system of blombos cave through a thin section based gis mapping procedure with improved spatial control we were able to study both the general distribution of non altered and heat altered glauconite grains in their original sedimentary context as well as to calculate heat distribution models that cover the entire sampled section this combined geo chemical optical and spatio contextual approach provides insights into more elusive aspects of msa site structure and burning events such as heat intensity burning frequency temperature distribution internal hearth structure and post depositional reworking the workflow we propose may easily be implemented and adapted to other archaeological contexts and to analogous sedimentary materials that show comparable heat induced alteration patterns

differences in the quality of polishing between sound and weathered granites aesthetic characteristics are important when rocks are used as construction materials among all the surface finishes available the polished finish is the one which best enhances the rock attractiveness colour c roughness r and gloss g are surface properties usually used to assess the rock polishing in this research the crg properties were assessed in polished samples of three ornamental granites with different textures and physical mechanical properties one weathered and two sound c was evaluated in cie l a b and cie l c abhab systems r with ra and rz parameters and g using the 20 60 and 85 geometries the weathered granite presents a noticeable colour variation especially in the b parameter while the sound ones have a more homogeneous colour sound and more textural homogeneous granites have a low surface roughness and high gloss which are uniformly distributed the weathered granite shows a higher surface roughness and lower gloss with scattered distribution the mineral contacts are the main cause of the surface irregularities the results show the interdependence between the crg properties and stress the importance of the polishing process for enhancing the aesthetic characteristics of the granites crg properties could be used for quality control in granite processing plants thus avoiding noticeable differences in the facades of buildings particularly when weathered granites are used

enhanced detection of hydraulically active fractures by temperature profiling in lined heated bedrock boreholes summary the effectiveness of borehole profiling using a temperature probe for identifying hydraulically active fractures in rock has improved due to the combination of two advances improved temperature sensors with resolution on the order of 0 001 c and temperature profiling within water inflated flexible impermeable liners used to temporarily seal boreholes from hydraulic cross connection the open hole cross connection effects dissipate after inflation so that both the groundwater flow regime and the temperature distribution return to the ambient background condition this paper introduces a third advancement the use of an electrical heating cable that quickly increases the temperature of the entire static water column within the lined hole and thus places the entire borehole and its immediate vicinity into thermal disequilibrium with the broader rock mass after heating for 4 6 h profiling is conducted several times over a 24 h period as the temperature returns to background conditions this procedure referred to as the active line source als method offers two key improvements over prior methods first there is no depth limit for detection of fractures with flow second both identification and qualitative comparison of evidence for ambient groundwater flow in fractures is improved throughout the entire test interval the benefits of the als method are demonstrated by comparing results from two boreholes tested to depths of 90 and 120 m in a dolostone aquifer used for municipal water supply and in which most groundwater flow occurs in fractures temperature logging in the lined holes shows many fractures in the heterothermic zone both with and without heating but only the als method shows many hydraulically active fractures in the deeper homothermic portion of the hole the identification of discrete groundwater flow at many depths is supported by additional evidence concerning fracture occurrence including continuous core visual inspection acoustic televiewer logs and tests for hydraulic conductivity using straddle packers as well as rock core voc data where available that show deep penetration and many migration pathways confidence in the use of temperature profiles and the conceptual model is provided by numerical simulation and the demonstrated reproducibility of the evolution of the temperature signal measured in the lined holes with and without heating this approach for using temperature profiling in lined holes with heating is a practical advance in fractured rock hydrogeology because the liners are readily available the equipment needed for heating is low cost and rugged and the time needed to obtain the profiles is not excessive for most projects

eulerian and lagrangian isopycnal eddy diffusivities in the southern ocean of an eddying model abstractlagrangian isopycnal diffusivities quantify the along isopycnal mixing of any tracer with mean gradients along isopycnal surfaces they are studied in the southern ocean of the 1 10 parallel ocean program pop model using more than 50 000 float trajectories concurrent eulerian isopycnal diffusivities are estimated directly from the eddy fluxes and mean tracer gradients consistency spatial variation and relation to mean jets are evaluated the diffusivities are calculated in bins large enough to reduce contributions from the rotational components that do not lead to net tracer mixing because the mean jets are nonzonal and nonparallel meridional dispersion includes standing eddies and is significantly different from cross stream dispersion with the subtraction of the local eulerian mean the full lagrangian diffusivity tensor can be estimated along stream diffusivities are about 6 times larger than cross stream diffusivities along streamline averages of eulerian and lagrangian isopycnal d

mineralogical and colour changes of quartz sandstones by heat seven german and three hungarian monumental sandstones have been tested in laboratory conditions to analyse the effect of heat the studied quartz sandstones have a wide range of cements and grain sizes including silica carbonate clay and ferrous mineral cemented varieties of fine medium to coarse grained types cylindrical specimens were heated up to 150 300 450 600 750 and 900 c in an oven the mineralogical and textural changes were recorded and compared by using microscopy xrd dta dtg and sem colours and colour differences a b l values were also measured and evaluated colour changes are related to mineral transformations the most intense colour change is caused by the oxidation of iron bearing minerals to hematite that takes place up to 900 c when temperature increases the green glauconite becomes brownish while the chlorite changes to yellowish at first the colour of burnt sandstone is not a direct indicator of burning temperature since there are sandstones in which the burnt specimens are lighter and less reddish than the natural ones porosity increase is related to micro cracking at grain boundaries above 600 c and within the grains at and above 750 c and mineral transformations the clay mineral structure collapses at different temperatures kaolinite up to 600 c chlorite above 600 c and leads to a slight increase in porosity the most drastic change is observed in calcite cemented sandstones where the carbonate structure collapses at 750 c and cao appears at 900 c subsequently it is transformed to portlandite due to absorption of water vapour from the air this leads to the disintegration of sandstone at room temperature a few days after the heat shock

shelf derived iron inputs drive biological productivity in the southern drake passage water entrainment while fe 228 ra ratios were used to calculate the fe flux in the summer of 2006 we found rapid mixing and significant lateral iron export namely a dissolved iron flux of 1 1 10 5 mol d 1 and total acid leachable iron flux of 1 1 10 6 mol d 1 all of which is transported in the mixed layer from the shelf region offshore this dissolved iron flux is significant especially considering that the bloom observed in the offshore region 0 5 2 mg chl a m 3 had an iron demand of 1 1 to 4 10 5 mol fe net vertical export fluxes of particulate fe derived from 234 th 238 u disequilibrium and fe 234 th ratios accounted for only about 25 of the dissolved iron flux on the other hand vertical upward mixing of iron rich deeper waters provided only 7 of the lateral dissolved iron flux we found that similarly to other studies in iron fertilized regions of the southern ocean lateral fluxes overwhelm vertical inputs and vertical export from the water column and support significant phytoplankton blooms in the offshore regions of the drake passage

the dynamical subtropical front 1 the southern ocean subtropical front stf is thought to play a key role in the global climate system theory suggests that the latitude of the stf regulates the volume of saline agulhas leakage into the atlantic ocean from the indian here we use satellite sea surface temperature sst and sea surface height ssh data to study the physical characteristics of the stf water mass boundary we find that the strong currents in this region do not align with the surface water mass boundary therefore we provide a new climatology for these currents which we define as the dynamical stf dstf the dstf is the eastward extension of the western boundary current in each basin and is characterized by strong sst and ssh gradients and no seasonal cycle at the center of each basin it merges with the sub antarctic front on the eastern side of basins the stf surface water mass boundary coincides with a separate region of multiple sst fronts we call this the subtropical frontal zone stfz the fronts in the stfz have a large seasonal cycle and no ssh signature despite lying close to the same water mass boundary the dstf and stfz are completely unrelated we therefore suggest the term stf only be used when referring to the surface water mass boundary when studying the strong currents on the western side of basins the term dstf is more relevant and similarly the term stfz better describes the region of enhanced sst gradients towards the east

jet jumping low frequency variability in the southern ocean abstractthe authors study intrinsic variability in the position of jets in a plane channel ocean with simple topography using a quasigeostrophic numerical model this study links the variability in jet position with abyssal anticyclones that form as a result of interaction of mesoscale eddies and subsurface topography reminiscent of such flows as the zapiola anticyclone a simple dynamical framework explaining this behavior is developed in this framework this study shows that the topographic anticyclones form closed regions of homogenized yet time varying potential vorticity neighboring topographic anticyclones are coupled by eddy fluxes interaction of a baroclinic jet with these two or more anticyclones can drive variability in local jet strength predictions of the dynamical framework are then compared with the results of the numerical model and it is demonstrated that this model has merit in explaining the observed model variability this study argues that this simple mode of variability has

the influence of shelf processes in delivering dissolved iron to the hnlc waters of the drake passage antarctica abstract dissolved trace element distributions near elephant island in the drake passage show extremely high levels of dissolved fe and mn in waters above the shelf the entrainment of this enriched shelf water by the fe poor antarctic circumpolar current acc as it passes through the shackleton gap delivers an estimated 2 8 106 mol yr 1 dissolved fe to the offshore waters of the drake passage the magnitude and spatial distribution of dissolved fe mn and al over the shelf are consistent with a diagenetically produced sedimentary source but are inconsistent with eolian or upwelling sources the systematics of the mn and fe concentrations suggest that there are two distinct sources of dissolved fe to the surface waters of this region the highest fe concentrations are associated with bransfield strait water which can be identified by its characteristic temperature and salinity t s properties both inside the bransfield strait and in the bransfield current outflow between elephant and clarence islands most of the shelf area is dominated by a second water type with t s properties that are typical of modified antarctic surface water which while also enriched has a lower fe mn ratio the predominantly linear relationships between the fe and mn concentrations at the stations in each of these water mass types suggest that the distribution of these elements is largely controlled by physical mixing processes and that biological removal of fe on the shelf while certainly occurring is limited perhaps as a result of rapid physical flushing processes and relatively slow biological growth rates the consequent export of large quantities of this shelf derived fe into the acc is likely responsible for the extensive regions of enhanced primary production seen in satellite imagery downstream of the drake passage

vertical structure and transport of the antarctic circumpolar current in drake passage from direct velocity observations 1 the structure of the antarctic circumpolar current acc in drake passage is examined using 4 5 years of shipboard acoustic doppler current profiler adcp velocity data the extended 1000 m depth range available from the 38 khz adcp allows us to investigate the vertical structure of the current the mean observed current varies slowly with depth while eddy kinetic energy and shear variance exhibit strong depth dependence objectively mapped streamlines are self similar with depth consistent with an equivalent barotropic structure vertical wavenumber spectra of observed currents and current shear reveal intermediate wavenumber anisotropy and rotation indicative of downward energy propagation above 500 m and upward propagation below 500 m the mean observed transport of the acc in the upper 1000 m is estimated at 95 2 sv or 71 of the canonical total transport of 134 sv mean current speeds in the acc jets remain quite strong at 1000 m 10 20 cm s 1 vertical structure functions to describe the current and extrapolate below 1000 m are explored with the aid of full depth profiles from lowered adcp and a 3 year mean from the southern ocean state estimate sose a number of functions including an exponential are nearly equally good fits to the observations explaining 75 of the variance fits to an exponentially decaying function can be extrapolated to give an estimate of 154 38 sv for the full depth transport

the effect of stylolites on the deterioration of limestone possible mechanisms of damage evolution this study presents five different lithotypes of limestone containing stylolites and commonly used as dimension stones in egypt hungary and israel all the studied limestones are generally hard dense with high degree of cementation and have high strength and low porosity stylolites are small tooth like irregular surfaces most often developed on the carbonate rich stones insoluble particles i e organic matter oxides and clays are usually incorporated within the stylolitic planes the presence of stylolites and their filling materials generally has a large effect on the physical and mechanical properties of the host stones the main aim of this study is to evaluate the damage mechanism of different stylolitic limestones and to understand the role of the clay in the deterioration of these stones hundred cube samples 2 cm of all the studied limestones were subjected to 500 thermal cycles 10 70 c and 20 cube samples 3 cm of a grey israeli limestone with high open porosity were subjected to multiple wet dry cycles the changes in mass strength and ultrasound vp velocity were measured to follow any damage that happened due to cycling the thermal cycling was proved to be an effective deterioration mechanism of both egyptian and hungarian lithotypes the response of israel grey lithotype to the wet dry cycling was clearly shown by the splitting of the tested samples through the stylolite planes and the sharp decrease of their strength

the relations between modulus of elasticity and temperature in the context of the experimental simulation of rock weathering by fire fires occur frequently in many biomes and generate high temperatures on the ground surface there are many field examples of fire causing rock disintegration the simulation of fire in the laboratory using a furnace and the monitoring of changes in rock modulus of elasticity with a grindosonic apparatus reveal that different rocks respond differently to heating significant decreases in elasticity occur at temperatures as low as 200 c and granites display particularly marked reductions extended periods of heating are not required for significant reductions to occur it is postulated that the degree of change in elasticity as a result of simulated fire is such that rock outcrops subjected to real fires are likely to be sufficiently modified as to increase their susceptibility to erosion and weathering processes

a sealed flint knapping site from the younger dryas in the scheldt valley belgium bridging the gap in human occupation at the pleistocene holocene transition in w europe based on the evidence of a recently excavated sealed site situated at ruien rosalinde in the belgian scheldt valley the response of hunter gatherers to changing climate at the transition from the temperate allerod to the cold younger dryas is discussed radiocarbon dated to the end of the allerod or the very beginning of the younger dryas the site of ruien provides the earliest evidence of a refined lithic technology characterized by the use of a soft stone hammer and the production of straight and regular blade let s from intensively prepared cores with two opposite platforms and sharp striking angles in the course of the younger dryas and early pre boreal this knapping method will become standard all over europe from the tanged point technocomplex in the north to the epi laborian in the south it contrasts sharply with the knapping style of previous lithic traditions such as the late federmesser azilian and bromme technocomplexes which was much less elaborated and mainly oriented towards the knapping of short irregular blades with a hard stone hammer this apparently abrupt technological change was also accompanied by increased raw material procurement networks extending over up to 250 km and a marked microlithisation of the hunting equipment finally the site of ruien is also important as it demonstrates the limited archaeological visibility of younger dryas sites explaining the scarcity of such sites within western europe

a new tritium interface method for determining the recharge rate of deep groundwater in the bavarian molasse basin abstract a new inexpensive method for estimating recharge rates of deep groundwater is described using the aquifer in the bavarian molasse basin as an example the depth of the interface between tritium bearing and tritium free groundwater together with the hydraulic conductivity of the leaky layer overlying the aquifer and the duration of anthropogenic tritium input were used to calculate recharge rates of 1 61s km 2 for the study area the results agree with the recharge rates determined by other methods

circumpolar structure and distribution of the antarctic circumpolar current fronts 1 mean circumpolar paths 1 high resolution hydrographic sections and maps of the gradient of sea surface height ssh reveal that the antarctic circumpolar current acc consists of multiple jets or frontal filaments here we use a 15 year time series of ssh observations to determine the circumpolar structure and distribution of the acc fronts the jets are consistently aligned with particular streamlines along the entire circumpolar path confirming and extending the results of an earlier study restricted to the region south of australia the intensity of the fronts as measured by the cross front gradient of ssh varies along the fronts and the individual branches merge and diverge often in response to interactions with bathymetry maps of absolute velocity at 1000 m depth derived from argo trajectories confirm the existence of multiple current cores throughout the southern ocean high resolution hydrographic sections and profiles of temperature and salinity from argo floats are used to show that the front locations derived from fitting ssh contours to maps of ssh gradient are consistent with locations inferred from the traditional criteria based on water mass properties suitably modified to account for multiple frontal branches three regions are examined in detail the crozet plateau the kerguelen plateau and the scotia sea these examples show how recognition of the multiple jets of the acc can help resolve discrepancies between previous studies of acc fronts

new perspectives on frontal variability in the southern ocean abstractthe frontal structure of the southern ocean is investigated using the wavelet higher order statistics enhancement whose frontal detection method introduced in chapman s work this methodology is applied to 21 yr of daily gridded absolute dynamic topography adt data to obtain daily maps of the locations of the fronts by forming frontal occurrence frequency maps and then approximating these occurrence maps by a superposition of simple functions the time mean locations of the fronts as well as a measure of their capacity to meander are obtained and related to the frontal locations found by previous studies the spatial and temporal variability of the frontal structure is then considered the number of fronts is found to be highly variable throughout the southern ocean increasing splitting downstream of large bathymetric features and decreasing merging in regions where the fronts are tightly controlled by the underlying topography these splitting merging events are related to changes in

estimating southern ocean storm positions with seismic observations author s hell momme c gille sarah t cornuelle bruce d miller arthur j bromirski peter d crawford alex d

oceanic restratification forced by surface frontogenesis potential vorticity pv conservation implies a strong constraint on the time evolution of the mean density at a given depth the authors show that on an f plane and in the absence of sources and sinks of pv it only depends on two terms namely the time evolution of the product between density anomaly and relative vorticity and the vertical pv flux this primitive equation result which applies at any depth suggests that the ageostrophic dynamics induced by baroclinic eddies strongly affect the mean oceanic stratification profile this result is illustrated for two simple initial value simulations of a baroclinic balanced jet for initial situations propitious to surface frontogenesis the simulations show a restratification over the whole water column characterized by the amplification in time of the brunt vaisala frequency in the upper oceanic layers in the absence of surface frontogenesis such as when the jet is initialized at the middepth of the water column the restratification is much weaker and slower because both simulations have similar kinetic energy and growth rate of baroclinic instability the results clearly reveal that the restratification is driven by surface frontogenesis in the first case and by vertical pv flux in the interior in the second case the authors also point out that the dynamics of the interior pv is tightly related to the surface dynamics because of total mass conservation

southern ocean mixed layer depth from argo float profiles 1 argo float profiles of temperature salinity and pressure are used to derive the mixed layer depth mld in the southern ocean mld is determined from individual profiles using both potential density and potential temperature criteria and a monthly climatology is derived from individual mlds using an objective mapping method quantitative data are available in the auxiliary material the spatial structures of mlds are similar in each month with deep mixed layers within and just north of the antarctic circumpolar current acc in the pacific and indian oceans the deepest mixed layers are found from june to october and are located just north of the acc where antarctic intermediate water aaiw and subantarctic mode water samw are formed examination of individual mlds indicates that deep mixed layers mld 400 m from both the density and temperature criteria are concentrated in a narrow surface density band which is within the density range of samw the surface salinity for these deep mixed layers associated with the samw formation are slightly fresher compared to historical estimates differences in air sea heat exchanges wind stress and wind stress curl in the pacific and indian oceans suggest that the mode water formation in each ocean basin may be preconditioned by different processes wind mixing and ekman transport of cold water from the south may assist the samw formation in the indian ocean in the eastern pacific the formation of mode water is potentially preconditioned by the relative strong cooling and weak stratification from upwelling

evidence for enhanced eddy mixing at middepth in the southern ocean abstract satellite altimetric observations of the ocean reveal surface pressure patterns in the core of the antarctic circumpolar current acc that propagate downstream eastward but slower than the mean surface current by about 25 the authors argue that these observations are suggestive of baroclinically unstable waves that have a steering level at a depth of about 1 km detailed linear stability calculations using a hydrographic atlas indeed reveal a steering level in the acc near the depth implied by the altimetric observations calculations using a nonlinear model forced by the mean shear and stratification observed close to the core of the acc coinciding with a position where mooring data and direct eddy flux measurements are available reveal a similar picture albeit with added details when eddy fluxes are allowed to adjust the mean state computed eddy kinetic energy and eddy stress are close to observed magnitudes with steering levels between 1 and 1 5 km broadly consistent with observatio

how much deep water is formed in the southern ocean three tracers are used to place constraints on the production rate of ventilated deep water in the southern ocean the distribution of the water mass tracer po4 phosphate star in the deep sea suggests that the amount of ventilated deep water produced in the southern ocean is equal to or greater than the outflow of north atlantic deep water from the atlantic radiocarbon distributions yield an export flux of water from the north atlantic which has averaged about 15 sv over the last several hundred years cfc inventories are used as a direct indicator of the current production rate of ventilated deep water in the southern ocean although coverage is as yet sparse it appears that the cfc inventory is not inconsistent with the deep water production rate required by the distributions of po4 and radiocarbon it has been widely accepted that the major part of the deep water production in the southern ocean takes place in the weddell sea however our estimate of the southern ocean ventilated deep water flux is in conflict with previous estimates of the flux of ventilated deep water from the weddell sea which lie in the range 1 5 sv possible reasons for this difference are discussed

a comparison of recharge estimates to a fractured sedimentary aquifer in south africa from a chloride mass balance and an integrated surface subsurface model the paper describes the use of an integrated surface subsurface modelling approach to estimate recharge to a semi arid karoo aquifer and a comparison of the results with a chloride mass balance on a sub area scale parameters were not calibrated to test the success with which the model can be applied in regions of scarce data the chloride balance suggests a mean annual recharge of 4 5 mm year 1 based on a mean annual rainfall of 460 mm the model predicts 5 8 mm year 1 from a mean annual rainfall of 483 mm during the simulation period recharge was found to be highly variable in space with a positively skewed distribution in time spatial variability was attributed to differences in the distribution of soil moisture content resulting from variations in slope soil texture and depth both methods suggest that recharge is considerably less than the mean of 9 9 mm year 1 estimated from the currently prescribed rainfall recharge relationship for karoo aquifers

nonlinear characteristics of acoustic emissions during the deformation and fracture of sandstone subjected to thermal treatment ae signals during thermally damaged sandstone deformation conformed to the r s statistical law

using earth tide induced water pressure changes to measure in situ permeability a comparison with long term pumping tests good constraints on hydrogeological properties are an important first step in any quantitative model of groundwater flow field estimation of permeability is difficult as it varies over orders of magnitude in natural systems and is scale dependent here we directly compare permeabilities inferred from tidal responses with conventional large scale long term pumping tests at the same site tidally induced water pressure changes recorded in wells are used to infer permeability at ten locations in a densely fractured sandstone unit each location is either an open hole well or a port in a multilevel monitoring well tidal response is compared at each location to the results of two conventional long term and large scale pumping tests performed at the same site we obtained consistent values between the methods for a range of site specific permeabilities varying from 10 15 m2 to 10 13 m2 for both open wells with large open intervals and multilevel monitoring well we conclude that the tidal analysis is able to capture passive and accurate estimates of permeability

temperature dependent mechanical behaviour of australian strathbogie granite with different cooling treatments abstract understanding the mechanical behaviour of reservoir rock under different temperatures with different cooling conditions is necessary for safe and effective deep geo engineering applications including geothermal energy extraction deep geological disposal of nuclear waste deep mining and coal gasification projects the aim of this study is therefore to investigate the effect of increasing temperature from room temperature to 800 c followed by two cooling methods both rapid and slow on the mechanical behaviour of australian strathbogie granite under uniaxial conditions further a separate experimental program was conducted under continuous heating conditions without cooling the samples to compare the results of cooled samples in order to investigate the strain developments in granite subjected to heating following slow and rapid cooling aramis photogrammetry technology was adopted and the corresponding fracture propagation patterns were investigated using an acoustic emission ae system optical microscopic imaging technology was used to identify the corresponding micro structural alterations and crack formation patterns according to the results once the rock mass is subjected to higher thermal stresses strength and elastic characteristics are significantly reduced mainly due to thermally induced damage in terms of both inter granular and intra granular cracks the stress strain response revealed that the failure mode of granite is changed from brittle to quasi brittle fracturing with increasing temperature the following cooling causes the strength and elastic characteristics of the granite to be further decreased through the enhancement of crack density and the influence of rapid cooling is much greater than that of slow cooling due to sudden thermal shock this is evidenced by the ae results according to which both high pre heated temperatures and high cooling rates cause much quicker crack initiation and propagation in granite with lesser seismicity in the quasi brittle region

topographic influence on submesoscale dynamics in the southern ocean topography influences the circulation in the southern ocean generating stationary meanders in the lee of topographic features triggering hot spots of mesoscale eddy kinetic energy and modifying jets and fronts however the relationship between topography and submesoscale flows with length scales of order 1 10 km has not yet been explored the first submesoscale resolving 1 80 resolution ocean model with realistic topography of the indian sector of the southern ocean is used to investigate this interaction the results show spatial inhomogeneity in submesoscale activity that is correlated with topography topographic influence is primarily indirect topography controls mesoscale flows which in turn generate submesoscale activity mesoscale eddy kinetic energy and strain rate can be used to first order to infer submesoscale vertical velocity implying a possible route to parameterise submesoscale activity in coarser resolution models

rapid southern ocean front transitions in an eddy resolving ocean gcm the formation of persistent multiple fronts is an established feature of the antarctic circumpolar current acc front strength and location are closely linked to eddy properties and therefore have important implications for the eddy driven closure of the southern ocean meridional overturning circulation acc front structure is analyzed here by calculating regional probability density functions pdfs of potential vorticity diagnosed in an eddy resolving ocean general circulation model rapid spatial transitions in the number of fronts and in the density classes over which they occur are found front transitions are associated with the major topographic obstacles kerguelen island campbell plateau and drake passage multiple fronts are preferentially found downstream of these features these findings highlight the significant departure from zonal symmetry of the acc front structure and emphasize the importance of local dynamics on large scale southern ocean properties

mechanisms of recharge in a fractured porous rock aquifer in a semi arid region abstract eleven porewater profiles in rock core from an upland exposed sandstone vadose zone in southern california with thickness varying between 10 and 62 m were analyzed for chloride cl concentration to examine recharge mechanisms estimate travel times in the vadose zone assess spatial and temporal variability of recharge and determine effects of land use changes on recharge as a function of their location and the local terrain the profiles were classified into four groups reflecting the range of site characteristics century to millennium average recharge varied from 4 to 23 mm y 1 corresponding to 1 moreover the temporal variability of recharge was estimated and along each profile past recharge rates calculated based on the sequence of cl concentrations in the vadose zone recharge rates increased at specific times coincident with historical changes in land use the consistency between the timing of land use modifications and changes in cl concentration and the match between observed and simulated cl concentration values in the vadose zone provide confidence in porewater age estimates travel times recharge estimates and reconstruction of recharge histories this study represents an advancement of the application of the chloride mass balance method to simultaneously determine recharge mechanisms and reconstruct location specific recharge histories in fractured porous rock aquifers the proposed approach can be applied worldwide at sites with similar climatic and geologic characteristics

sandstone alterations triggered by fire related temperatures the aim of the study was to identify and describe changes in two different sandstone types when undergoing different environmental and extreme temperature regimes to assess the possibility of finding insolation weathering and how these sandstones would behave during and after a fire the first step was the simulation in the laboratory of temperature regimes up to 60 c which would correspond to extreme events that could be found in insolation cycles even in central europe and the second one was the temperature above 200 c simulating in laboratory conditions the thermal regime of a potential fire situation at temperatures up to 200 400 600 and 800 c heating the samples above 400 c led to gradual changes in mineral composition colour surface roughness and physical properties reaching eventually total rock breakdown through spalling and granular disaggregation the different behaviour of sandstones exposed to high temperatures is mainly caused by their different mineral composition with various ratios of minerals that are more or less chemically stable at high temperatures as well as by the differences in the porosity

an eddy permitting southern ocean state estimate abstract an eddy permitting general circulation model of the southern ocean is fit by constrained least squares to a large observational dataset during 2005 06 data used include argo float profiles ctd synoptic sections southern elephant seals as oceanographic samplers seaos instrument mounted seal profiles xbts altimetric observations envisat geosat jason 1 and ocean topography experiment topex poseidon and infrared and microwave radiometer observed sea surface temperature an adjoint model is used to determine descent directions in minimizing a misfit function each of whose elements has been weighted by an estimate of the observational plus model error the model is brought into near agreement with the data by adjusting its control vector here consisting of initial and meteorological boundary conditions although total consistency has not yet been achieved the existing solution is in good agreement with the great majority of the 2005 and 2006 southern ocean observations and better repr