upwelling off the west coast of hainan island in summer its detection and mechanisms the summertime upwelling off the west coast of hainan island is newly detected by satellite remote sensing sea surface temperature and confirmed by both historical field observations and numerical modeling furthermore numerical experiments are conducted to gain understanding of the upwelling mechanisms a tidal mixing front tmf is identified as the vital factor triggering the formation of the upwelling the baroclinic pressure gradient force which stems from the intense density difference across the tmf causes a frontal scale circulation at the tmf as a result upwelling appears as a branch of this circulation the southwest monsoon induces downwelling which competes with the front induced upwelling climatologically the upwelling dominates and can reach about 5 m below the sea surface above the slope bottom in calm weather with no or weak winds it is expected that the upwelling can reach all the way to the sea surface

parameterizing tidal dissipation over rough topography the traditional model of tidal dissipation is based on a frictional bottom boundary layer in which the work done by bottom drag is proportional to a drag coefficient and the velocity cubed however away from shallow coastal regions the tidal velocities are small and the work done by the bottom boundary layer can account for only weak levels of dissipation in the deep ocean the energy flux carried by internal waves generated over rough topography dominates the energy transfer away from barotropic flow a parameterization for the internal wave drag over rough topography is included as a dissipative mechanism in a model for the barotropic tides model results suggest that the inclusion of this dissipation mechanism improves hydro dynamical models of the ocean tide it also substantially increases the amount of modeled tidal dissipation in the deep ocean bringing dissipation levels there into agreement with recent estimates from topex poseidon altimetry data

sea surface salinity variability during the indian ocean dipole and enso events in the tropical indian ocean an ocean reanalysis that covers the period from 1871 2008 is used to analyze interannual variability of sea surface salinity sss in the tropical indian ocean the reanalysis sss and the sss anomaly patterns during indian ocean dipole iod and el nino southern oscillation enso events are compared with patterns from argo sss data the mean seasonal sss variation is large in the northern bay of bengal compared to variations in the arabian sea and equatorial indian ocean during a positive iod event positive sss anomalies are found along the sumatra coast due to the combination of wind driven upwelling of subsurface high salinity waters enhanced evaporation and anomalous surface circulation the opposite is true to a lesser extent during negative iod events a dipole mode index for salinity dmis based on sss data and a new index based on the average of salinity in a region off the coast of sumatra is introduced to monitor sss variability during iod and enso events the impact of concomitant el nino events on a positive iod event is large with freshening a negative sss anomaly in the equatorial indian ocean and salting positive sss anomaly off the southern sumatra coast the impact of intense freshening reaches into the southwestern tropical indian ocean the impact of concomitant la nina with negative iod is also large with an intense freshening in the southeastern arabian sea and salting off the northern sumatra coast

on the use of apparent hydraulic diffusivity as an indicator of connectivity summary connectivity of high permeability paths is recognized as important but has not been properly quantified in the groundwater literature in fact it has been shown that the concept is process dependent and difficult to define so that it applies both to water flow and solute transport phenomena field and numerical evidence from hydraulic tests suggest that the apparent hydraulic diffusivity d a could potentially inform about the phenomena in order to test this conjecture we present a monte carlo analysis based on series of fields that display varying degrees of connectivity our results confirm that d a does indeed indicate the presence of connectivity d a is found to correlate well with early tracer arrival time and also with the product of a flow connectivity indicator cf and a transport connectivity indicator ct this indicates that d a accounts both for connectivity effects controlling the average plume movement through cf and for connectivity effects not linked to the effective medium properties that control the progression of the solute front through ct analysis of seven binary fields suggests that flow connectivity hinges more on the continuity of fast paths whereas transport connectivity seems to be more dependent on the width of connected features forming possibly discontinuous fast paths in conjunction with previous studies our results suggest that hydraulic response arrival times and early arrival times of tracer can be expected to correlate well in most types of hydrogeologic systems

combined interpretation of pumping and tracer tests theoretical considerations and illustration with a field test pumping and tracer tests are two well established ground water reservoir tests hydraulic conductivity can be derived from both conductivities are studied in a mainly layered heterogeneous coastal aquifer in belgium with a pumping and tracer test and results of both are compared characteristics and important points in performance and interpretation of the tests are discussed the interpretation method of pumping tests must be chosen very carefully application of interpretation methods based on models underestimating or even neglecting the leakage towards the pumped permeable layer results in an overestimation of the horizontal conductivity of this layer the larger the distance of the used observation well s the larger this overestimation becomes this is illustrated here with the interpretation of the drawdown data obtained during the pumping test using different analytical models and a numerical model with an inverse axi symmetric numerical model incorporating layered heterogeneity results of the pumping test are in good agreement with results from the tracer test many discrepancies between pumping and tracer test data performed in layered heterogeneous media can be explained when realistic pumping test interpretation methods are applied and when leakage is not underestimated

enhanced arctic sea ice drift estimation merging radiometer and scatterometer data satellites enable daily and global coverage of the polar oceans and provide a unique monitoring capability of sea ice dynamics sea ice drift maps can be estimated in arctic from several satellite sensors particularly from scatterometers and radiometers this study presents the benefits of combining single drift fields at the same resolution into a merged field built at three and six day lags during winters with a 62 5 km resolution it is shown that combining these drift fields not only increases the reliability of the displacement estimation and the number of estimated vectors to almost a full ice covered area but also expands the time period over which these estimations are reliable from freeze until the melt onset the autumn winter spring sea ice drift fields presented here are systematically produced at institut francais de recherche pour l exploitation de la mer centre d exploitation et de recherche satellitaire the sea ice drift 1992 2011 time series is available and the processing is ongoing these data are available for operational use and for the scientific community

variability of the oceanic mixed layer 1960 2004 abstract a new monthly uniformly gridded analysis of mixed layer properties based on the world ocean atlas 2005 global ocean dataset is used to examine interannual and longer changes in mixed layer properties during the 45 yr period 1960 2004 the analysis reveals substantial variability in the winter spring depth of the mixed layer in the subtropics and midlatitudes in the north pacific an empirical orthogonal function analysis shows a pattern of mixed layer depth variability peaking in the central subtropics this pattern occurs coincident with intensification of local surface winds and may be responsible for the sst changes associated with the pacific decadal oscillation years with deep winter spring mixed layers coincide with years in which winter spring sst is low in the north atlantic a pattern of winter spring mixed layer depth variability occurs that is not so obviously connected to local changes in winds or sst suggesting that other processes such as advection are more important interestingl

first time landslides in vashon advance glaciolacustrine deposits puget lowland u s a abstract advance glaciolacustrine qglv deposits from the last continental glaciation are widespread in the densely populated puget lowland and are prone to shallow landsliding much less frequently in historic time new landslides propagate deeply within intact qglv deposits the exceptional volume and highly mobile nature of the 22 march 2014 state route 530 oso landslide generated considerable uncertainty and public concern about the likelihood for similar deep seated failures initiating from most any slope where these deposits crop out the primary study objectives are to utilize geotechnical data from the small data set of available published and public domain investigations to characterize in general terms hydrogeologic geotechnical and geomorphic factors and their relative contribution to initiating deep seated landslides within intact qglv deposits and to inform future hazard and risk assessments for first time landslides within these deposits qglv deposits are overconsolidated very stiff to hard laminated to massive silt and clay shear strength is anisotropic with cohesion being a significant component of bedding parallel strength and friction dominating strength perpendicular to bedding hydraulic conductivity is likely also anisotropic multi year records of pore pressures within qglv deposits show no to minor seasonal flux only minor pore pressure responses to multi day to multi week episodes of heavy precipitation have been detected back analyses using limit equilibrium methods and peak anisotropic strength under drained conditions demonstrate initial stability of the slopes instability occurs near the fully softened strength we conclude that over the long term loss of cohesive strength rather than hydroclimatic pore pressure response is the more important contributor to diminishing stability and in some cases initiation of first time landslides in qglv deposits the shape and location of the slide surface is strongly influenced by strength anisotropy and stress state sliding surfaces developed near the basal contact of the qglv deposits in all of the five studied landslides higher stress states associated with increasing sequence thickness of the landslide masses decrease stability the length of the basal slide surface and thus the aspect ratio of the landslide mass appears to increase proportionally with sequence thickness of the landslide mass

finding concealed active faults extending the southern whidbey island fault across the puget lowland washington 1 the southern whidbey island fault zone swif as previously mapped using borehole data potential field anomalies and marine seismic reflection surveys consists of three subparallel northwest trending strands extending 100 km from near vancouver island to the northern puget lowland east of puget sound the swif makes landfall between the cities of seattle and everett but is concealed beneath a thick mantle of young glacial deposits and vegetation a 20 km wide northwest trending swath of subparallel low amplitude aeromagnetic anomalies crosses this region of the puget lowland and is on strike with the swif the most prominent aeromagnetic anomaly the cottage lake lineament extends at least 18 km and lies approximately on strike with the swif on whidbey island subtle scarps and topographic lineaments on pleistocene surfaces visible on high resolution lidar topography at a number of locations along the swif lie on or near these magnetic anomalies in the field scarps exhibit northeast side up and vertical relief of 1 to 5 m excavations across several lidar scarps lying on or near magnetic anomalies show evidence for multiple folding and faulting events since deglaciation most likely above buried reverse oblique faults excavations in areas away from magnetic anomalies do not show evidence of tectonic deformation in total paleoseismological evidence suggests that the swif produced at least four earthquakes since deglaciation about 16 400 years ago the most recent less than 2700 years ago

characterization of hydrogeologic properties for a multi layered alluvial aquifer using hydraulic and tracer tests and electrical resistivity survey a multi layered aquifer typical of riverbank alluvial deposits in korea was studied to determine the hydrologic properties the geologic logging showed that the subsurface of the study site was comprised of four distinctive hydrogeologic units silt sand highly weathered and fresh bedrock layers the electrical resistivity survey supplied information on lateral extension of hydrogeologic strata only partially identified by a limited number of the geologic loggings the laboratory column tracer test for the recovered core of the sand layer resulted in a hydraulic conductivity of 5 00 10 2 cm s the slug tests performed in the weathered rock layer yielded hydraulic conductivities of 4 32 7 72 10 4 cm s hydraulic conductivities for the sand layer calculated from the breakthrough curves of bromide ranged between 2 08 10 3 and 2 44 10 2 cm s with a geometric mean of 6 89 10 3 cm s which is 7 times smaller than that from the laboratory column experiment the trend of increasing hydraulic conductivity with an increase in tracer travel length is likely a result of the increased likelihood of encountering a high conductivity zone as more of the aquifer is tested the combined hydrogeologic site characterization using hydraulic tests tracer tests and column test with geologic loggings and geophysical survey greatly enhanced the understanding of the hydrologic properties of the multi layered alluvial aquifer

glaciofluvial infilling and scour of the puget lowland washington during ice sheet glaciation the puget lobe the southwesternmost extension of the cordilleran ice sheet last advanced into the puget lowland of western washington at about 15 ka the advancing ice sheet deposited voluminous sediment on a prograding proglacial outwash plain that extended from the olympic mountains to the cascade range herein recognized as the great lowland fill subsequent overrunning by the ice sheet excavated deep linear troughs now occupied by the large lakes and marine waters of puget sound excavation of these troughs and valleys of the puget lowland required the net transport of about 1000 km3 of sediment almost entirely during ice occupation and primarily by subglacial water these landforms of glaciofluvial deposition and erosion define the modern landscape here emphasizing the importance of these processes in the region s geomorphology

wave induced mixing in the upper ocean distribution and application to a global ocean circulation model 1 from the reynolds stress expression the wave induced vertical viscosity or diffusivity bv is defined which can be used as a parameter to estimate the strength of wave induced mixing in addition a parameter d5 is introduced to represent a wave induced mixing penetration depth the global distribution of bv averaged over the upper 20 m is calculated and its latitudinal transects in boreal summer and winter is discussed the results show that in summer the wave induced mixing is strong in the southern oceans south of 30 s and in winter it is strong in the north pacific and the north atlantic north of 30 n as well as in the southern oceans south of 40 s adding bv to the vertical diffusivity in a global ocean circulation model yields a temperature structure in the upper 100 m that is closer to the observed climatology than a model without the wave induced mixing

a shallow geothermal experiment in a sandy aquifer monitored using electric resistivity tomography groundwater resources are increasingly used around the world for geothermal exploitation systems to monitor such systems and to estimate their governing parameters we rely mainly on borehole observations of the temperature field at a few locations bulk electric resistivity variations can bring important information on temperature changes in aquifers we have used surface electric resistivity tomography to monitor spatially temperature variations in a sandy aquifer during a thermal injection test heated water 48 c was injected for 70 hours at the rate of 87 l h in a 10 5 c aquifer temperature changes derived from time lapse electric images were in agreement with laboratory water electric conductivity temperature measurements in parallel a coupled hydrogeologic saturated flow and heat transport model was calibrated on geophysical data for the conceptual model and on hydrogeologic and temperature data for the parameters the resistivity images showed an upper flow of heated water along the well above the injection screens and led to a new conceptualization of the hydrogeologic source term the comparison between the temperature models derived from resistivity images and from the simulations was satisfactory quantitatively resistivity changes allowed estimating temperature changes within the aquifer and qualitatively the heated plume evolution was successfully monitored this work demonstrates the ability of electric resistivity tomography to study heat and storage experiments in shallow aquifers these results could potentially lead to a number of practical applications such as the monitoring or the design of shallow geothermal systems

heat transport and temperature distribution during managed artificial recharge with surface ponds summary managed aquifer recharge mar is a well established practice for managing groundwater reserves in a sustainable way in this paper we look at the influence of temperature variations of the infiltration water in the recharged aquifer the paper focuses on mar systems consisting of an infiltration pond surrounded by extraction wells a number of different 2d configurations and an operational system in the belgian dune area are investigated using field observations and numerical modelling with seawat seasonally varying temperature in the infiltration water results in a zonation of subsequent lower and higher temperatures in the aquifer the impact of infiltration water temperature in the aquifer is significant but restricted to the area between the pond and extraction wells quickly decreasing farther from the infiltration area colder water during winter results in a decrease of infiltration capacity which can be as high as 1 5 2 times with respect to summer infiltration infiltration water temperature variations equally influence residence times of the infiltrated water in general residence times become smaller for water infiltrated during summer and larger for water infiltrated during winter infiltration and extraction rate their ratios and seasonal variability and location of extraction wells are all contributing factors to the impact of varying temperature of the infiltration water finally it is shown that temperature provides only a rough proxy for residence times of solutes because of the important conduction of heat

role of mixed layer dynamics in tropical north atlantic interannual sea surface temperature variability abstractthis study examines the causes of observed sea surface temperature sst anomalies in the tropical north atlantic between 1982 and 2015 the emphasis is on the boreal winter and spring seasons when tropical atlantic ssts project strongly onto the atlantic meridional mode amm results from a composite analysis of satellite and reanalysis data show important forcing of sst anomalies by wind driven changes in mixed layer depth and shortwave radiation between 5 and 10 n in addition to the well known positive wind evaporation sst and shortwave radiation sst feedbacks between 5 and 20 n anomalous surface winds also drive pronounced thermocline depth anomalies of opposite signs in the eastern equatorial atlantic and intertropical convergence zone itcz 2 8 n a major new finding is that there is strong event to event variability in the impact of thermocline depth on sst in the itcz region in contrast to the more consistent relationship in the eastern equatorial atlantic much stronger anomalie

parameters influencing porosity in sandstones a model for sandstone porosity prediction thirteen parameters were reviewed for their influence on porosity in sandstone core material during compaction in basins of average geothermal gradients the first order parameters are age time of burial detrital quartz content maximum depth of burial and sorting overpressure may slow the compaction process depending on onset of overpressure during burial approximately 2 primary porosity may be preserved for every 1 000 psi 6 9 mpa above hydrostatic pressure depth related temperature and median grain size were found to be only second order parameters on the basis of 428 cases function coefficients were calculated for the relationship between porosity and the first order parameters this function permits porosity prediction with a high degree of accuracy th equation is valid for sandstones older than 3 ma with little or no cement no leaching depth of burial in excess of 500 m and little or no shear stresses secondary porosity is excluded and estimations will therefore be conservative where leaching occurred due to interrelationship of compaction and cementation the porosity reduction by cement is usually only a small fraction of the total reduction the function can therefore also be applied to little cemented sandstones

landslide mobility and hazards implications of the 2014 oso disaster abstract landslides reflect landscape instability that evolves over meteorological and geological timescales and they also pose threats to people property and the environment the severity of these threats depends largely on landslide speed and travel distance which are collectively described as landslide mobility to investigate causes and effects of mobility we focus on a disastrous landslide that occurred on 22 march 2014 near oso washington usa following a long period of abnormally wet weather the landslide s impacts were severe because its mobility exceeded that of prior historical landslides at the site and also exceeded that of comparable landslides elsewhere the 8 10 6 m 3 landslide originated on a gently sloping

strong intraseasonal variability of meridional currents near 5 n in the eastern indian ocean characteristics and causes abstractthis paper reports on strong intraseasonal upper ocean meridional currents observed in the indian ocean between the bay of bengal bob and the equator and elucidates the underlying physical processes responsible for them in situ measurements from a subsurface mooring at 5 n 90 5 e reveal strong intraseasonal variability of the meridional current with an amplitude of 0 4 m s 1 and a typical period of 30 50 days in the upper 150 m which by far exceeds the magnitudes of the mean flow and seasonal cycle such prominent intraseasonal variability is however not seen in zonal current at the same location further analysis suggests that the observed intraseasonal flows are closely associated with westward propagating eddylike sea surface height anomalies sshas along 5 n the eddylike sshas are largely manifestations of symmetric rossby waves which result primarily from intraseasonal wind stress forcing in the equatorial waveguide and reflection of the equatorial kelvin waves at the eastern bou

progressive shear surface development in cohesive materials implications for landslide behaviour the aim of this study was to investigate mechanisms of progressive shear surface development using a series of specialised triaxial cell tests intact and remoulded samples of gault clay from the ventnor undercliff on the isle of wight in southern england were subjected to pore pressure reinflation ppr testing in a triaxial cell in which failure is generated by increasing pore pressure under a constant total stress state in addition a novel very long term 500 days creep test was undertaken in which the sample eventually failed at a constant stress state below the failure envelope the experiments showed that undisturbed samples of the gault clay failed in a brittle manner generating a linear trend when plotted using the saito technique on the other hand remoulded samples showed ductile behaviour as indicated by a non linear saito trend a number of otherwise identical ppr tests were conducted in which the rate of increase in pore water pressure was varied these tests showed that strain rate generated at any point in the ppr tests depended on both the effective stress and the rate of change of effective stress the latter is important because a change in stress generates a change in strain thus whilst tests at different rates of change of effective stress are similar when plotted in q p space and in strain p space they are markedly different in strain rate p space the long term creep test failed when the stress state had been constant for over 80 days this mechanism was reminiscent of creep rupture occurring below the failure envelope defined in the conventional experiments we conclude that first time failure in the gault clay is a progressive mechanism dominated by the development of micro cracking which leads to strain localisation and the development of one or more shear surfaces at failure whilst this mechanism may usually occur in response to a change in stress the study indicates that failure can develop progressively in the remoulded gault clay shear strains cannot localise along a singular shear surface the results provide new insight into the mechanisms of landslide movement operating within the ventnor landslide complex and indicate that present movements are likely to be occurring on a pre existing shear surface the lab tests suggest that this material is unlikely to undergo catastrophic failure