physical dynamics and biological implications of a mesoscale eddy in the lee of hawai i cyclone opal observations during e flux iii abstract e flux iii march 10 28 2005 was the third and last field experiment of the e flux project the main goal of the project was to investigate the physical biological and chemical characteristics of mesoscale eddies that form in the lee of maui and the island of hawai i focusing on the physical biogeochemical interactions the primary focus of e flux iii was the cyclonic cold core eddy opal which first appeared in the noaa goes sea surface temperature sst imagery during the second half of february 2005 during the experiment cyclone opal moved over 160 km generally southward thus the sampling design had to be constantly adjusted in order to obtain quasi synoptic observations of the eddy analyses of ship transect depth profiles of ctd optical and acoustic doppler current profiler adcp data revealed a well developed feature characterized by a fairly symmetric circular shape with a radius of about 80 km depth profiles of temperature salinity and density were characterized by an intense doming of isothermal isohaline and isopycnal surfaces isopleths of nutrient concentrations were roughly parallel to isopycnals indicating the upwelling of deep nutrient rich water the deep chlorophyll maximum layer dcml shoaled from a depth of about 130 m in the outer regions of the eddy to about 60 m in the center chlorophyll concentrations reached their maximum values in opal s core region about 40 km in diameter where nutrients were upwelled into the euphotic layer adcp velocity data clearly showed the cyclonic circulation associated with opal vertical sections of tangential velocities were characterized by values that increased linearly with radial distance from near zero close to the center to a maximum of about 60 cm s 1 at roughly 25 km from the center and then slowly decayed the vertical extent of the cyclonic circulation was primarily limited to the upper mixed layer as tangential velocities decayed quite rapidly within a depth range of 90 130 m potential vorticity analysis suggests that only a relatively small about 50 km in diameter and shallow to a depth of approximately 70 m portion of the eddy is isolated from the surrounding waters radial movements of water can occur between the center of the eddy and the outer regions along density surfaces within an isopycnal range of t 23 6 t 23 6 kg m 3 and t 24 4 t 24 4 kg m 3 thus the biogeochemistry of the system might have been greatly influenced by these lateral exchanges of water at depth especially during opal s southward migration while the eddy was translating deep water in front of the eddy might have been upwelled into the core region leading to an additional injection of nutrients into the euphotic zone at the same time part of the chlorophyll rich waters in the core region might have remained behind the translating eddy and thus contributed to the formation of an eddy wake characterized by relatively high chlorophyll concentrations

low frequency surface currents and generation of an island lee eddy in panay island philippines abstracthigh frequency doppler radar hfdr and acoustic doppler current profiler adcp time series observations during the philippine straits dynamics experiment philex were analyzed to describ

island wakes in deep water abstract density stratification and planetary rotation distinguish three dimensional island wakes significantly from a classical fluid dynamical flow around an obstacle a numerical model is used to study the formation and evolution of flow around an idealized island in deep water i e with vertical island sides and surface intensified stratification and upstream flow focusing on wake instability coherent vortex formation and mesoscale and submesoscale eddy activity in a baseline experiment with strong vorticity generation at the island three types of instability are evident centrifugal barotropic and baroclinic sensitivities are shown to three nondimensional parameters the reynolds number re rossby number ro and burger number bu the dependence on re is similar to the classical wake in its transition to turbulence but in contrast the island wake contains coherent eddies no matter how large the re value when re is large enough the shear layer at the island is so narrow that the ver

long lived mesoscale eddies in the eastern mediterranean sea analysis of 20 years of aviso geostrophic velocities we analyzed 20 years of aviso data set to detect and characterize long lived eddies which stay coherent more than 6 months in the eastern mediterranean sea in order to process the coarse gridded 1 8 aviso geostrophic velocity fields we optimized a geometrical eddy detection algorithm our main contribution was to implement a new procedure based on the computation of the local and normalized angular momentum lnam to identify the positions of the eddy centers and to follow their lagrangian tra jectories we verify on two mesoscale anticyclones sampled during the egypt campaign in 2006 that our methodology provides a correct estimation of the eddy centers and their characteristic radius corresponding to the maximal tangential velocity our analysis reveals the dominance of anticyclones among the long lived eddies this cyclone anticyclone asymmetry appears to be much more pronounced in eastern mediter ranean sea than in the global ocean then we focus our study on the formation areas of long lived eddies we confirm that the generations of the ierapetra and the pelops anticyclones are recurrent and correlated to the etesian wind forcing we also provide some evidence that the smaller cyclonic eddies formed at the southwest of crete may also be induced by the same wind forcing on the other hand the generation of long lived eddies along the libyo egyptian coast are not correlated to the local wind stress curl but surprisingly their initial formation points follow the herodotus trough bathymetry moreover we identify a new formation area not discussed before along the curved shelf off benghazi

influence of aquifer heterogeneity and return flow on pumping test data interpretation abstract analytical solutions of drawdown in unconfined aquifers are widely applied for determining the specific yield s y and the horizontal and the vertical hydraulic conductivity k r and k z respectively in many previous studies estimates of s y and k z were observed to be highly variable and physically unrealistic this has been attributed to the conceptualization of flow above the declining water table and aquifer heterogeneity in the applied models we present the analysis of time drawdown data from a pumping test instrumented with depth differentiated observation piezometers arranged in clusters applying homogeneous anisotropic aquifer models in combination with nonlinear least squares parameter identification techniques the data were analyzed in different groups analysis of data from individual piezometer clusters and simultaneous analysis of the entire data set from all piezometer clusters global analysis from the cluster analyses estimates of s y and k z exhibit large variances and depart from a priori estimates inferred from the hydrostratigraphy parameter estimates from the global analysis do not fall within the parameter bounds minimum and maximum values defined by the cluster analyses while heterogeneity appears to be the important reason for large parameter variances we discuss the influence of rarely considered aquifer return flow on drawdown and the inconsistent results from the cluster and global analyses we corroborate our findings with data on hydraulic gradients slug test data and results from the application of a more realistic numerical flow model

monsoon surges trigger oceanic eddy formation and propagation in the lee of the philippine islands 1 two winter monsoon surge events northerly and easterly of january 2005 are captured in a one way coupled atmosphere 8 km resolution and ocean 3 km resolution simulation of the philippines region intensified wind jets and wakes in the lee of mindoro and luzon islands induce the generation and migration of a pair of counter rotating oceanic eddies in the model with propagation direction related to the orientation of the winds during each of the surges features shared by the eddies include size 100 200 km depth 300 m and propagation speed 0 1 0 15 m s 1 for cyclones mean wintertime model wind stress positive negative curl coincides with the climatological cyclone anticyclone distribution from a prior 8 year altimetry based census of eddies in the southeast quadrant of the south china sea during the winter monsoon moreover the simulation results agree with contemporaneous satellite and historical in situ data characterizing regional oceanic eddy and atmospheric surface jet properties

evolution of an oceanic anticyclone in the lee of madeira island in situ and remote sensing survey island wakes are areas of a strong eddy activity influencing the availability and transport of organic matter in the ocean which in turn impact biological productivity despite this eddy formation in the lee of north atlantic tropical islands is scarcely documented except for the canary islands moreover the occurrence of anticyclones leeward of madeira has seldom been detected during the summer of 2011 a multiplatform approach combining satellite data with in situ measurements was used to study an anticyclonic eddy generated in the lee of the madeira island the main objective was to confirm recent numerical evidence suggesting that orographically perturbed winds can induce anticyclonic eddies leeward of madeira particularly during summer months the high resolution sampling of the eddy s interior shows a strong downwelling of 100 m of the isopycnal layer below the mixed layer typical of intrathermocline eddies the 25 km radius of this anticyclonic structure exceeds the local deformation radius by a factor of 2 the vortex rossby number remained moderate ro 0 26 even if the relative core vorticity reached a finite value f 0 7 the occurrence of strong trade winds 10 15 m s 1 prior to the detection of the first surface eddy signatures july 2011 concurrent with opposite flowing geostrophic currents shows that the orographic wind forcing is the main mechanism for generating this mesoscale long lived eddy after leaving the shelter of the island the eddy traveled northwesterly following a perpendicular net ekman transport pathway at a speed of 5 km d for at least 2 months an interaction with a cyclonic partner generated in the area helped precipitate the northward trajectory this study presents the first clear evidence of a wind induced mesoscale anticyclone in the lee of madeira

the worth of data in predicting aquitard continuity in hydrogeological design a bayesian decision framework is developed for addressing questions of hydrogeological data worth associated with engineering design at sites in heterogeneous geological environments the specific case investigated is one of remedial contaminant containment in an aquifer underlain by an aquitard of uncertain continuity the framework is used to evaluate the worth of hard and soft data in investigating the aquitard s continuity the analysis consists of four modules 1 an aquitard realization generator based on indicator kriging 2 a procedure for the bayesian updating of the uncertainty with respect to aquitard windows 3 a monte carlo simulation model for advective contaminant transport and 4 an economic decision model a sensitivity analysis for a generic design example involving a design decision between a no action alternative and a containment alternative indicates that the data worth of a single borehole providing a hard point datum was more sensitive to economic parameters than to hydrogeological or geostatistical parameters for this case data worth is very sensitive to the projected cost of containment the discount rate and the estimated cost of failure when it comes to hydrogeological parameters such as the representative hydraulic conductivity of the aquitard or underlying aquifer the sensitivity analysis indicates that it is more important to know whether the field value is above or below some threshold value than it is to know its actual numerical value a good conceptual understanding of the site geology is important in estimating prior uncertainties the framework was applied in a retrospective fashion to the design of a remediation program for soil contaminated by radioactive waste disposal at the savannah river site in south carolina the cost effectiveness of different patterns of boreholes was studied a contour map is presented for the net expected value of sample information evsi for a single borehole the net evsi of patterns of precise point measurements is also compared to that of an imprecise seismic survey

variation of sea surface height at periods of 65 220 days in the subtropical gyre of the north pacific variations of sea surface height ssh in the north pacific subtropical countercurrent stcc region have been investigated using altimeter derived ssh anomaly data during 1992 1999 it is shown by spectral analyses that the dominant temporal scale of ssh variations in the stcc region is 65 220 days the energy of the ssh variations in this period band is mostly confined to the subtropical gyre and enhanced in the stcc the kuroshio and the kuroshio extension east of the shatsky rise the broad energetic band in the stcc region can be divided into two regions one is located in the latitudinal range of 21 26 n and extending zonally from the philippine sea to 190 along 22 n and the other extends from around 145 to the west of the hawaiian islands along 19 5 n slightly tilting northward toward the east the axes of these two high variability tongues are in agreement with those of the stcc multiple bands estimated from climatological hydrographic data the 65 220 day variations in the stcc region are characterized by westward propagating mesoscale disturbances with wavelengths of 400 1800 km in terms of ratio of the advective speed to the phase speed the mesoscale variations can be classified into two types i e nonlinear eddies with wavelengths of 500 700 km and quasi linear wave motions with longer wavelengths of 1200 km

interactions between a submesoscale anticyclonic vortex and a front abstract the evolution of a submesoscale anticyclonic vortex was observed by high frequency doppler radio current meters and satellite radiometers the vortex formed between two large cyclones to the southwest of oahu hawaii the radius of the core was 15 km the azimuthal velocity reached 35 cm s 1 and the surface vorticity remained below f for 9 days reaching an extremum of 1 7f the flow was ageostrophic near the center and around the periphery of the vortex the initial growth may have been driven by negative wind stress curl in the lee of oahu the vortex was prone to inertial symmetric and anticyclonic ageostrophic instabilities but the temporal evolution of radial profiles of vorticity was inconsistent with angular momentum redistribution by inertial instability a tongue of surface water 0 7 c warmer became entrained northward between the vortex and the colder cyclone to the west as the vortex strengthened a 0 14 c km 1 front formed along the eastern flank of the tongue the sea surface

islands as eddy transformation and generation hotspots cabo verde case study abstract deep ocean islands have long been associated with the generation of oceanic eddies in their wakes however their interaction with incoming eddies has seldom been considered this study focuses on the characterization of background and locally generated mesoscale eddies in the cabo verde archipelago between 2003 and 2014 special attention is given to the interaction of incoming eddies with the bathymetry of the islands along with their impacts on the local generation of eddies island induced wind shear effects are also considered in addition some examples of the biological response to background and locally generated eddies are discussed this is achieved by combining remote sensing satellite observations for wind sea surface height and chlorophyll a chla surface concentrations the results show that the interaction between incoming background eddies and the archipelago is a recurrent phenomenon which results in eddy deflection splitting merging intensification and termination sorted by highest to lowest number of occurrences local island induced disturbances are also significant mainly due to atmospheric effects such processes result in the generation of island induced eddies and in wind mediated eddy intensification and confinement more often observed in the leeward group nonetheless it is strongly suggested that many of the locally generated eddies are a direct product or by product of the interaction of background eddies with the islands with respect to the biological realm a locally generated cyclonic eddy is observed to originate a pronounced phytoplankton bloom in the vicinity of the tallest island nonetheless background eddies generated off the african coast are often associated with enhanced chla concentrations when they intersect the archipelago such observations challenge the idea that local biological productivity in deep oceanic islands is exclusively driven by island induced mechanisms

hydrofacies distribution and correlation in the miami valley aquifer system this study combines geostatistical analyses with geologic interpretations to further the quantitative understanding of physical heterogeneity within glaciofluvial aquifers the stochastic simulation of aquifers requires quantitative measures of heterogeneity including both cumulative distribution and spatial correlation functions the heterogeneity in glaciofluvial aquifers is typified by low permeability facies e g till or lacustrine clay juxtaposed with high permeability facies e g sand and gravel outwash the miami valley aquifer system was examined at multiple sites for the spatial distribution and correlation of these two hydrofacies binary indicator geostatistics were used to quantitatively determine at each site the relative volume of each hydrofacies their spatial distribution the major principal direction of their spatial correlation the minor principal direction and the correlation range in these directions the percent by volume of the system that is aquitard material decreases down the valley from 31 to 12 each site has an elevation zone with more aquitard material relative to other elevations at that site the percent aquitard material in these zones decreases down the valley from 45 to 22 the maximum principal direction of spatial correlation in the aquitard zones generally is ne sw subparallel to the trend of the bedrock valley with a range of the order of 0 75 km and minimum maximum anisotropy ratio of 0 4 the locations exceeding 0 5 probability of aquitard occurrence generally occur on the valley margins thus among the sites investigated there is a trend down the valley in the ratio of aquitard volume to aquifer volume and the spatial correlation and distribution of aquitard material are similar within the aquitard zones furthermore these findings are consistent with aspects of the subglacial and proglacial depositional environments responsible for the facies assemblage and thus are likely to be applicable to other parts of the aquifer system and other aquifer systems where similar geologic processes are inferred to have existed

macrodispersion in sand shale sequences macrodispersion in sand shale sequences is investigated by a series of numerical tracer tests hydraulic conductivity is modeled as a binary spatially correlated random function realizations of the random conductivity field are simulated on a nodal grid discretizing the heterogeneous formation corresponding realizations of the random velocity field are obtained by solving the equation for saturated steady state flow particle tracking with flux weighted tracer injection and detection is used to generate experimental residence time distributions rtds moments of the rtd are used to characterize longitudinal tracer spreading results show that macrodispersive transport in sand shale sequences cannot be represented by a fickian model rtds display a bimodal structure caused by the fast arrival of particles traveling along preferential sandstone channels and by the much slower arrival of particles following tortuous routes through sandstone and shale the relative importance of channeling and tortuous flow transport mechanisms is determined by sand shale conductivity contrast shale volume fraction and conductivity spatial correlation structure channeling is promoted by high conductivity contrasts low shale fractions and flow parallel to bedding in anisotropic media low contrasts high shale fractions and flow perpendicular to bedding act to break up channels and to enhance tracer spreading

using high resolution electrical resistivity to estimate hydraulic conductivity and improve characterization of alluvial aquifers abstract shallow alluvial aquifers are important local and regional water resources but obtaining sufficient hydrogeologic data to properly characterize their spatial extent and hydraulic conditions can often be difficult time consuming and expensive in this study we used over 40 000 measurements of electrical resistivity tomography ert data and hydraulic conductivity k data from 33 pump tests across eight shallow alluvial and glacial outwash aquifer field sites in iowa to 1 assess the relation between hydraulic k tests and electrical resistivity er in alluvial and glacial outwash systems and 2 evaluate the application of the er k relationship as input data for local scale groundwater flow modeling average field measured k across the eight sites was 95 m day and ranged from 29 to 246 m day whereas aquifer resistivity ranged from 27 to 896 ohm m both k and er were greater at the glacial outwash aquifer sites compared to the alluvial aquifer sites and a linear relationship r2 0 90 was observed between field measured k and er when incorporating all field sites we evaluated how k derived from the er k relationship compared to k estimated from pump tests and calibrated k in a local scale groundwater flow model the k estimated by the er k relationship was comparable to the k estimated from the pump tests in terms of providing reasonable values for model development utilizing the er k relationship to estimate k would save significant time compared to conducting pump tests hence estimating k from electrical resistivity can provide a non intrusive cost and time efficient way to evaluate and model alluvial aquifers

an oceanic cyclonic eddy on the lee side of lanai island hawai i 1 a young cold core cyclonic eddy displaying a significant increase in surface chlorophyll was observed offshore lanai island hawai i where the marine optical buoy moby is located during one of its deployments moby broke free from its mooring in the course of its 3 day free drifting period moby followed a cyclonic eddy which is manifested by satellite remote sensing data chlorophyll data from moderate resolution imaging spectroradiometer and sea surface temperature sst from a geostationary operational environmental satellite the time series of the sst show that the cold core eddy was in a formative stage it existed as a stand alone eddy for about 9 days before it merged with cold water south of oahu island a high resolution numerical model simulation reproduces similar eddies in terms of location size and intensity an eddy detection algorithm is described and applied to locate and track the modeled eddies the results demonstrate that mesoscale and submesoscale eddies are frequently generated on and pass through the lee side of lanai island and the statistical analysis quantifies the general features of eddies in the area

far reaching effects of the hawaiian islands on the pacific ocean atmosphere system using satellite data we detected a wind wake trailing westward behind the hawaiian islands for 3000 kilometers a length many times greater than observed anywhere else on earth this wind wake drives an eastward ocean current that draws warm water from the asian coast 8000 kilometers away leaving marked changes in surface and subsurface ocean temperature standing in the path of the steady trade winds hawaii triggers an air sea interaction that provides the feedback to sustain the influence of these small islands over a long stretch of the pacific ocean

architecture of the sierra ladrones formation central new mexico depositional controls on the permeability correlation structure statistical models of hydrogeological heterogeneity are often used in aquifer and reservoir characterization the number of data required to estimate objectively the spatial correlation structure of permeability however is often prohibitive the objective of this study was to develop a better understanding of how information about depositional processes can be used to characterize hydrogeological heterogeneity an outcrop of the fluvial interfluvial sierra ladrones formation of new mexico was studied for this purpose on the basis of previous studies of paleogeography and our own field observations deposits of the sierra ladrones formation are interpreted as marginal ancestral rio grande flood plain and tributary deposits architectural elements were mapped over a 0 16 km sup 2 peninsular outcrop of pliocene pleistocene deposits of the central albuquerque basin geostatistical analysis of the architectural element map data indicates non orthogonal anisotropy in the horizontal direction the orientations of the strongest n30 degree w and weakest n90 degree e correlation correspond to the orientation of the tributary system and the ancestral rio grande flood plain respectively in the vertical direction the correlation structure exhibits exponential behavior corresponding to the average element thicknesses the results demonstrate that information about depositional environment can be used to help to quantify statistically subsurface heterogeneity 28 refs 9 figs 1 tab

spatiotemporal variations of mesoscale eddies in the sulu sea mesoscale eddies have been observed in the sulu sea but their characteristics have not been well described this study investigates the eddy population in the sulu sea using 22 years of satellite altimeter data with high spatiotemporal resolution on average there are approximately 1 6 eddies observed in the sulu sea each day and 1 8 eddy tracks generated each month two of the main eddy genesis regions are west of negros island and the zamboanga peninsula the mean radius lifespan and propagation speed of the eddies are 76 6 km 32 days and 4 5 cm s respectively the eddy radius and amplitude are generally large in the central sulu sea but small on its margin the mean eddy kinetic energy and vorticity generally monotonically decrease from south to north consistent with the distributions of background current kinetic energy over the seasonal cycle there are more cyclonic eddies during boreal winter and they tend to have a larger amplitude and radius than the other 3 seasons while there are more anti cyclonic eddies during boreal summer and they tend to have a larger amplitude and radius than the other 3 seasons the instability of the mean current and the island gap wind jets are the two key eddy genesis mechanisms in the sulu sea

spatial variability in river sediments and its link with river channel geometry 1 this study explores the link between spatial variability within fluvial sedimentary strata and river channel geometry this link is then used to determine the macrodispersion coefficients for solute transport in groundwater flow in river deposits in doing that we combine concepts from sedimentology geostatistics and the stochastic lagrangian theory of subsurface transport it is proposed to analyze the spatial variability of river sediments in terms of transition probabilities the transition probabilities can be determined from the averages and variances of the lengths of stratasets and their volumetric fractions using concepts developed by carle and fogg 1996 and ritzi 2000 strataset length scales are shown to correlate well with the geometry of the river channel and its bed forms and can be determined indirectly from aerial photogrammetry and more directly through surface ground penetrating radar surveys stratal dimensions can also be related using lagrangian transport analysis to macrodispersivity of subsurface transport this allows relationships between the geometry of river channels and subsurface transport parameters of associated fluvial deposits for demonstration the longitudinal macrodispersivity in a compound bar deposit in the gravelly braided sagavanirktok river was investigated

modeling heterogeneity of gravel sand braided stream alluvial aquifers at the facies scale abstract the coarse grained alluvial aquifers are recurrently considered as almost homogeneous and isotropic media nevertheless water flow through these sediments is controlled by internal architecture therefore a better knowledge is necessary to understand the effects of facies heterogeneity on the conductivity magnitude and anisotropy within these aquifers in this work we search interactions at the facies scale within a glacio fluvial aquifer among sedimentary heterogeneity distribution of permeability and anisotropy the case study concerns pleistocene sequences of the ticino basin northern italy where three model blocks dug into real sediments at a quarry site have been investigated at the meter scale these model blocks represent the most diffuse facies associations 1 sand gravel dunes 2 gravel bedforms and 3 poorly sorted mass gravity deposits facies maps with 2 cm resolution were obtained for each block and used to condition 3d geostatistical simulation of the sediment volumes with a hierarchical modification of sisim conductivities of samples were either measured with laboratory tests or estimated with empirical formulas conductivity values were finally introduced as input data into the numerical flow model to compute the upscaled tensor of equivalent conductivity at the model block scale the results of field infiltration tests were used to verify the outcomes of upscaling experiments which identified the primary influence on the most permeable facies open framework gravel on both conductivity magnitude and anisotropy ratio the latter property is unrelated to the abundance of this facies but is controlled by its spatial distribution within the blocks as the connectivity of open framework gravel increases model blocks become more anisotropic on the other hand the low permeable sand facies of dunes do not produce significant anisotropy at the block scale these results show the importance of introducing the hierarchical assemblage of different rank depositional units in conceptual aquifer models in addition we identified the most significant depositional units to forecast the spatial distribution of aquifer heterogeneity at different scales

spatial moments analysis of kinetically sorbing solutes in aquifer with bimodal permeability distribution 1 we analyze the influence of the formation structure upon transport of nonreactive and kinetically sorbing solutes in heterogeneous porous formations formation structure is represented through a bimodal distribution of hydraulic conductivity with two scales of spatial variability which is a simplified yet realistic model of spatial variability kinetic sorption is modeled using a linear reversible rate expression we derive new closed form solutions of the second ergodic spatial moments of a kinetically sorbing solute although these solutions are obtained through a perturbation expansion in term of logconductivity variance they are not limited to any particular model of spatial variability we show that the formation structure as described by the bimodal model has a significant impact on plume moments of a non reactive tracer at moderate contrast between mean hydraulic conductivity of the two hydrofacies when the two scales of variability have comparable weight on the contrary the impact diminishes when bimodality weakens at both low and high contrast as expected the large time asymptotic longitudinal macrodispersion coefficient is influenced by the structure only through the variance and integral scale of log conductivity and thus the result for the bimodal model is identical to that of a unimodal gaussian field sharing the same second order statistics the impact of kinetic sorption depends upon the plume travel time since injection at early times sorption kinetics tends to accentuate the difference between the longitudinal macrodispersivity in bimodal and unimodal fields while at later times the difference is minimal because overall macrodispersivity is dominated by the spreading caused by nonequilibrium sorption in a bimodal formation transverse macrodispersivity peaks later and declines to zero slower than in a gaussian unimodal field with the same second order statistics these results demonstrate that even a very simplified facies model such as the bimodal model relying on a statistical distribution of high and low conductivity zones has important impacts upon global parameters describing the migration of nonreactive and reactive tracers consequently larger effects are expected for quantities such as early arrival times and btc tailing which are more directly influenced by the spatial patterns of high hydraulic conductivity than global parameters such as macrodispersivity furthermore these solutions contribute to bridge the gap between stochastic modeling and applications since bimodal fields can be obtained to honor soft data typically available in applications for example through conditional simulations using stratigraphic information from well logs

physical dynamics and biological implications of cyclone noah in the lee of hawai i during e flux i abstract quasi synoptic observations of the horizontal and vertical structure of a cold core cyclonic mesoscale eddy feature cyclone noah were conducted in the lee of hawai i from november 4 22 2004 as part of the e flux interdisciplinary collaborative research program cyclone noah appears to have spun up to the southwest of the alenuihaha channel between maui and hawai i as a result of strong and persistent northeasterly trade winds through the channel shipboard hydrographic surveys 2 5 months later suggest that noah weakened and was in a hypothesized spin down phase of its life cycle although the initial surface expression of noah was limited in scale to 40 km in diameter and as evidenced by surface temperatures 2 3 c cooler than the surrounding waters depth profiles revealed a fully developed semi elliptical shallow feature 200 m 144 km long and 90 km wide based on sigma t 23 kg m 3 with tangential speeds of 40 80 cm s 1 and substantial isopycnal doming potential vorticity distribution of noah suggests that radial horizontal flow of the core water was inhibited from the surface to depths of 75 m with high vorticity confined above the sigma t 23 5 kg m 3 isopycnal surface upward displacements of isopycnal surfaces in the eddy s center 50 m were congruent with enhanced pigment concentrations 0 50 mg m 3 comparisons of the results obtained for e flux i noah and e flux iii opal suggest that translation characteristics of cyclonic hawaiian lee eddies may be important in establishing the biogeochemical and biological responses of the oligotrophic ocean to cyclonic eddies

generation of mesoscale eddies in the lee of the hawaiian islands 1 the ocean west of the main hawaiian islands is characterized by enhanced eddy kinetic energy arising from the abundance of locally generated mesoscale eddies most frequently in the area west of the island of hawaii two mechanisms of eddy generation in the wake of an island are examined with numerical model experiments the first eddy generation and shedding by an oceanic flow around an oceanic barrier requires the existence of strong westward flows to the north and south of the island of hawaii model solutions show such westward flows and generation of eddies by these flows although the intensity of the eddies and the generation frequency are much lower than that derived from altimetry as a result these eddies contribute an insignificant amount of eddy kinetic energy in the region the second eddy generation and shedding by an atmospheric flow around an atmospheric barrier is based on oceanic upwelling and downwelling induced by surface wind shear effectively introducing sinks and sources to the ocean interior previous idealized modeling studies have shown that oceanic eddies can be generated by sufficiently strong forcing source or sink providing an explanation why eddy occurrences in the lee of the island of hawaii coincide with periods of strong trade winds eddy generation characteristics in the model experiments are consistent with this mechanism in terms of time of occurrence strength and the resulting eddy kinetic energy major discrepancies are in eddy propagation and therefore eddy distribution in the regional domain due to the complex nature of eddy eddy interactions

simulating the heterogeneity in braided channel belt deposits 1 a geometric based methodology and code 1 a geometric based simulation methodology was developed and incorporated into a computer code to model the hierarchical stratal architecture and the corresponding spatial distribution of permeability in braided channel belt deposits the code creates digital models of these deposits as a three dimensional cubic lattice which can be used directly in numerical aquifer or reservoir models for fluid flow the digital models have stratal units defined from the kilometer scale to the centimeter scale these synthetic deposits are intended to be used as high resolution base cases in various areas of computational research on multiscale flow and transport processes including the testing of upscaling theories the input parameters are primarily univariate statistics these include the mean and variance for characteristic lengths of sedimentary unit types at each hierarchical level and the mean and variance of log permeability for unit types defined at only the lowest level smallest scale of the hierarchy the code has been written for both serial and parallel execution the methodology is described in part 1 of this paper in part 2 guin et al 2010 models generated by the code are presented and evaluated

on the influence of a lower layer on the propagation of nonlinear oceanic eddies abstract the one layer reduced gravity also called equivalent barotropic model has been widely used in countless applications although its validity is based on the assumption that a second lower layer is sufficiently deep to be dynamically inactive the question of how deep that second layer ought to be has not yet received thorough examination when one considers the importance of the two processes excluded from the reduced gravity model namely barotropic motion and baroclinic instability the conventional choice of a second layer much deeper than the first might be too simplistic a scaling analysis aimed at covering all two layer regimes geostrophic as well as ageostrophic leads to a double criterion requiring that the total depth of fluid be much larger than either of two values these values resulting from f plane and plane dynamics apply to the shorter and longer scales respectively a number of numerical experiments on the propagation of eddies on the plane with various eddy radii a

physical and bio optical observations of oceanic cyclones west of the island of hawai i abstract interdisciplinary observations of mesoscale eddies were made to the west of the island of hawai i a central goal of the studies is to improve our understanding of the coupling of physical biological and biogeochemical processes that occur within these eddies a specific objective was to test the hypothesis that the physical mechanisms of mesoscale eddies result in increases in nutrient availability to the euphotic layer increases in primary production changes in biological community compositions and size distributions and increases in carbon flux to the deep sea data were obtained from ships surface drifters and satellite sensors during three separate field experiments variability was associated with two well developed cyclonic cold core mesoscale eddies cyclone noah and cyclone opal which were observed during the e flux i survey november 6 20 2004 and e flux iii survey march 10 27 2005 field campaigns respectively no mesoscale eddies were found during e flux ii survey january 10 19 when winds were erratic in magnitude and direction supporting the hypothesis that persistent trade winds drive the production of cold core mesoscale eddies in the lee of the hawaiian islands cold core eddies were present in the e flux study area for about 2 3 of a year beginning may 1 2004 and trade winds prevailed for about 3 4 of the same year both cyclone noah and cyclone opal were generated during strong persistent northeasterly trade wind conditions and appeared downwind of the alenuihaha channel separating the islands of maui and hawai i the likely production mechanism for both mesoscale cold core eddies involves localized wind stress curl induced upwelling produced by trade wind forcing cyclone noah was likely spun up by strong trade winds just to the southwest of the alenuihaha channel 20 10 n 156 40 w between august 13 and 21 2004 based on modis satellite sea surface temperature sst imagery and quikscat satellite wind data and apparently began to dissipate by mid december 2004 cyclone opal was likely spun up by strong trade winds between february 2 and 18 2005 southwest of the alenuihaha channel 20 30 n 156 30 w but was no longer evident in april 2005 both cyclone noah and cyclone opal had strong physical chemical and biological expressions and displayed similar maximum tangential current speeds of 60 cm s 1 however cyclone opal was more symmetric and larger in scale roughly 180 200 km in diameter compared to 160 km in horizontal scale for cyclone noah both mesoscale eddies displayed significant doming in their centers and in some cases outcroppings of isothermal isopycnal nutrient and chlorophyll a isopleths after formation and a slow drift southward cyclone noah remained in nearly the same location roughly 19 60 n 156 50 w during the 3 week in situ sampling period whereas cyclone opal drifted southward by 165 km over a similar time span of sampling interestingly the physical manifestations of both features were relatively unchanged during the ship based surveys however the biology appears to have evolved within cyclone opal the present report sets the context for several other e flux studies

propagation of big island eddies using satellite altimetry data we have observed a series of anticyclonic eddies as they form at the big island of hawaii and have tracked them as they move away from the island while similar eddies have been observed near the hawaiian islands in previous studies the fate of the anticyclonic eddies has previously been unclear the eddies that we observed initially propagated to the southwest but consistently changed propagation direction to the northwest later in their lifetimes this was intriguing to us as theoretically the decay of isolated anticyclonic eddies on a plane should cause them to continually move toward the southwest such isolated eddy dynamics are unable to account for the observed change to northwestward eddy propagation and the presence of the westward flowing north equatorial current turns out to be important to the big island eddy dynamics the eddies are not passively advected by the north equatorial current rather the mean flow changes the propagation characteristics of the eddies an existing theory that includes meridionally varying purely zonal mean flow is shown to account for the observed propagation of the big island eddies if the zonal variation of the mean flow is considered

an observational study of oceanic eddy generation mechanisms by tall deep water islands gran canaria 1 oceanic eddy generation by tall deep water islands is common phenomenon it is recognized that these eddies may have a significant impact on the marine system and related biogeochemical fluxes hence it is important to establish favourable conditions for their generation with this objective we present an observational study on eddy generation mechanisms by tall deep water islands using as a case study the island of gran canaria observations show that the main generation mechanism is topographic forcing which leads to eddy generation when the incident oceanic flow is sufficiently intense wind shear at the island wake may acts only as an additional eddy generation trigger mechanism when the impinging oceanic flow is not sufficiently intense for the case of the island of gran canaria we have observed a mean of ten generated cyclonic eddies per year eddies are more frequently generated in summer coinciding with intense trade winds and canary current

vorticity balance off the south shore of oahu hawaii derived by high frequency radio doppler current observations abstracthigh frequency radio doppler surface current observations off the south shore of oahu hawaii are used to calculate the vorticity equation at a 2 km spatial resolution in terms of a time

hydrostratigraphic interpretation using indicator geostatistics in this paper we describe an approach that uses indicator geostatistics to interpret qualitative borehole logs and compute experimental variograms for complex alluvial sediments borehole descriptions are first transformed into binary indicator values based on inferred relative permeability from the borehole descriptions the resulting indicator data can then be used to compute variograms and construct three dimensional variogram models the ranges of computed indicator variograms for a groundwater contamination site in santa clara valley california are very sensitive to the orientation of the search plane these variograms are consistent with known stratigraphie features and describe the spatial structure of deposits from different depositional environments indicator kriging weighs all the available data on the basis of a three dimensional anisotropic variogram model and provides an estimate of uncertainty in the hydrostratigraphic correlation kriged indicator values represent probabilities that sediments at a specific location fall into one of two indicator categories the location of the 0 5 indicator contour is approximately the boundary between high and low permeability sediments that might be constructed in a geologic cross section

currents observed north of oahu during the first five years of hot abstract shipboard adcp sections from 30 hawaii ocean time series cruises over a 5 year period show a mean flow 15 degrees north of west reaching a maximum of 17 cm s 1 about 50 km north of oahu this north hawaiian ridge current is highly variable from cruise to cruise and from year to year it was generally strong in the sections 1988 1991 and weak or absent in 1992 and 1993 there is no prominent annual cycle unresolved short period oscillations are so energetic as to obscure the mean current in individual sections the 5 year mean is highly significant however at five times the estimated standard error currents also were measured with a shipboard adcp during the nominally 3 day occupations of the hot station aloha the mean over 32 cruises was near 6 cm s 1 in magnitude at all depths from 20 to 200 m but the median was near zero hence the northern boundary of the north hawaiian ridge current was usually south of aloha the inter cruise standard deviation of velocity varied from 22 cm s 1 at 20 m to 11 cm s 1 at 200 m for the zonal component and 13 cm s 1 to 8 cm s 1 for the meridional component intra cruise variability during the 17 cruises with the best sampling in depth and time was dominated by a linear trend near inertial oscillations and diurnal and semidiurnal tides each of these four elements had an rms value near 6 cm s 1 at 20 m decreasing to 2 4 cm s 1 at 250 m the vertical shear field was dominated by the diurnal tide and near inertial oscillations the semidiurnal tide and the trend had larger vertical scales of variability and consequently made smaller contributions to the shear

dynamically balanced absolute sea level of the global ocean derived from near surface velocity observations 1 the 1992 2002 time mean absolute sea level distribution of the global ocean is computed for the first time from observations of near surface velocity for this computation we use the near surface horizontal momentum balance the velocity observed by drifters is used to compute the coriolis force and the force due to acceleration of water parcels the anomaly of horizontal pressure gradient is derived from satellite altimetry and corrects the temporal bias in drifter data distribution ncep reanalysis winds are used to compute the force due to ekman currents the mean sea level gradient force which closes the momentum balance is integrated for mean sea level we find that our computation agrees within uncertainties with the sea level computed from the geostrophic hydrostatic momentum balance using historical mean density except in the antarctic circumpolar current a consistent horizontally and vertically dynamically balanced near surface global pressure field has now been derived from observations

lee region of gran canaria the mountainous canary islancls present obstacles to the trade wincls ancl to the canary current flowing equatorwarc past them in situ observations of hydrographic properties ancl surface wincls south of gran canaria together with advancecl very high resolution racliometer ancl synthetic aperture racial images e uring 2 weeks in summer 1995 are analyzecl a cyclonic edcly shecl l rom the west of the islancl c1riftecl southwestwarcl at 5 s j while the southeast coast was approachecl by an upwelling filament originating off nw africa a wincllee region bounclecl by intense horizontal shear lines hacl a weak return islandwarcl wincl in its center the lee formee a triangulai c1iurnally varying war111 water 001 with two sea surface temperature maxima separatecl by lower temperatures below the return wincl shallow temperature stratification occurrecl behincl the islancl in contrast to the l1niform surface mixecllayer in exposecl regions upwelling ancl clownwelling of 10 20 111 were indicatecl on the cyclonic ancl anticyclonic sicles of the lee region in the sar la u lines of strong current shear along a temperature front between the cyclonic eclcly the upwelling filament were iclentifiable i iowever the racial images were clominatecl atmospheric phenomena including mountain lee wave paclcets winclrows and wincl lines estimation of the wincl field l rom the sar backscatter intensity revealed ex structure and intensification on the eclges of the warm lee

westward motion of mesoscale eddies abstract since the pioneering work of nof the determination of the westward drift of mesoscale eddies under the planetary beta effect has been a recurrent theme in mesoscale oceanography and several different formulae have been proposed in the literature here recpatiulation is sought and within the confines of a single layer model a generalized formula is derived although it is similar to nof s the present formula is established from a modified definition and with fewer assumptions it also recaptiulates all other formulae for the one layer model and applies to a wide variety of situations including cases when the vortex develops a wake of rossby waves or undergoes axismmetrization following the derivation of the formula a physical interpretation clarifies the migration mechanism which can be divided between a self induced propulsion and a reaction from the displaced ambient fluid numerical simulations with primitive and geostrophic equations validate the formula for a variety of length sc

aerial observations of hawaii s wake abstract under the influence of the east northeasterly trade winds the island of hawaii generates a wake that extends about 200 km to the west southwest during the harp project in july and august 1990 five wake surveys were carried out by the ncar electra the patterns of wind and aerosol concentration revealed by these flights suggest that hawaii s wake consists of two large quasi steady counterrotating eddies the southern clockwise rotating eddy carries a heavy aerosol load due to input from the k volcano at the eastern end of the wake the eddies are potentially warmer and more humid than the surrounding trade wind air several other features are discussed sharp shear lines near the northern and southern tips of the island dry and warm air bands along the shear lines a small embedded wake behind the kohala peninsula wake centerline clouds hydraulic jumps to the north and south of the island a descending inversion connected with accelerating trade winds and evidence for side to side wake mo

large lenses of highly saline mediterranean water isolated compact anticyclonic eddies or salt lenses were found in the canary basin hydrographic surveys of three such lenses show large anomalies of salinity and temperature 0 8 2 5 c they are centered at 1100 m have a vertical extent of up to 900 m and radii of 50 km current meter records indicate anticyclonic velocities up to 29 cm s 1 fine structure with vertical scales of 20 m and less possibly due to intrusive decay appears at the outer edges of the lenses whereas the centers are free of such structure the probability of finding a salt lens at any station in the canary basin is fairly high 0 08

major hydrogeochemical processes in the two reservoirs of the yangbajing geothermal field tibet china abstract the yangbajing geothermal field with the highest reservoir temperature in china is located about 90 km northwest to lhasa city capital of tibet where high temperature geothermal fluids occur both in shallow and deep reservoirs the geophysical survey by the indepth international deep profiling of tibet and the himalayas project group proved the existence of magmatic heat source at yangbajing in the study area the hydrochemistry of cold surface waters and groundwaters and that of thermal groundwaters from both reservoirs are distinctively different however analysis of the relationship between enthalpy values and cl concentrations of cold groundwaters and geothermal fluids indicates that the geothermal fluids from the shallow reservoir were formed as a result of mixing of cold groundwaters with geothermal fluids from the deep reservoir in other words the geothermal fluids from the deep reservoir flowed upwards into the shallow reservoir where it was diluted by the shallow cold groundwaters to form the shallow geothermal fluids with much lower temperature a binary mixing model with two endmembers the cold groundwaters and the deep geothermal fluids was proposed and the mixing ratios for the geothermal fluid from each shallow well were estimated using the mixing ratios the concentrations of some constituents in shallow geothermal fluids such as as b sio 2 so 4 2 and f were calculated and their differences with the actual concentrations were estimated the results show that the differences between estimated and actual concentrations of as and b are small the average absolute values being only 1 9 and 7 9 respectively whereas those of sio 2 so 4 2 and f are much bigger indicating that other hydrogeochemical processes are responsible for the concentrations of these constituents it is postulated that sio 2 precipitation due to water temperature decrease h 2 s oxidation and ion exchange between oh in geothermal waters and exchangeable f in fluoride bearing silicate minerals during the geothermal fluid upflow might be the causes for the observed concentration differences

characterization of alluvial hydrostratigraphy with indicator semivariograms current trends in hydrogeology seek to enlist sedimentary concepts in the interpretation of permeability structures however depositional models tend to account insufficiently for heterogeneities caused by complex controls on sediment preservation conversely geostatistical methods empirically describe both random and structured attributes this paper presents comparative indicator semivariograms for proximal medial and distal alluvial fan settings in santa clara valley california hydrostratigraphic structures revealed by a binary textural indicator are consistent within each setting yet differ from one setting to another in the bedrock bounded proximal setting buried channel deposits exhibit a small nugget effect and a zonal anisotropy with correlation ranges up to 900 m in the distal setting deposits display relatively weak hydrostratigraphic correlation with a relative nugget effect of 50 and a correlation range of 80 m in the medial setting the correlation range is similar to the proximal area but with a large nugget effect similar to the distal area

transport modeling in heterogeneous aquifers 1 statistical description and numerical generation of gravel deposits transport of solutes in groundwater is decisively influenced by the heterogeneity of the aquifer the goal of the present work is the numerical generation of synthetic heterogeneous aquifer models based on a statistical description of heterogeneities in gravel aquifers large unweathered outcrops in several gravel pits in northeastern switzerland were investigated in this context on the basis of sedimentological observations it was possible to specify distinct sedimentary structures appearing as lenses or layers all structures have been identified in each of the investigated outcrops by inspecting and analyzing photographs of the outcrops it was possible to estimate the probability density functions pdf of the geometrical attributes of the sedimentary structures disturbed and undisturbed samples were taken from these structures to estimate the pdf of their hydraulic properties that is the hydraulic conductivity and the porosity the information obtained is used to generate distinct numerical realizations by unconditional stochastic simulation of synthetic aquifers having the same statistical properties with respect to hydraulic conductivity and porosity as the investigated deposits

comparing statistical models of physical heterogeneity in buried valley aquifers the hypothesis that physical heterogeneity has similarities in separate aquifers created by similar depositional environments is tested by comparing statistical characteristics of facies assemblages the comparisons are made for a number of data rich sites in two buried valley aquifers in the north american midcontinent the white river aquifer in indiana and the miami valley aquifer in ohio these were proglacial valleys that directed drainage away from quaternary ice margins and were filled with glaciofluvial sediments predominantly sand and gravel s lithofacies with interbedded mud and diamicton m lithofacies at scales encompassing assemblages of both lithofacies m and s permeability is strongly bimodal we find that it is useful to compare statistics that characterize the proportions geometry and spatial distribution of each facies the results give rise to a general model for heterogeneity in valley fill sediments along the proglacial sluiceway in both aquifers the proportion of facies m is 15 the mean thickness of facies m is 3 5 m and of the order of 10 m for facies s the coefficient of variation in thickness for either facies is of the order of 1 with thickness ranging over orders of magnitude correspondingly the vertical autotransition probabilities are exponential and they are relatively symmetric with effective range of the order of 10 m the lateral facies lengths are indicated to vary over orders of magnitude and to be multimodally distributed with mean lengths of the order of 102 m effective range in correlation structure of the order of 103 m and lateral anisotropy ratio 2 there is some variation in how the facies m are vertically embedded within the facies s the white river aquifer and areas in the miami aquifer have facies proportions relatively stationary with elevation in other areas of the miami there are near horizontal zones having relatively higher or lower proportions however such variations on the general model give rise to similar statistics for mass transport within the context of a relevant remediation problem and thus would lead to a similar conclusion or decision thus one general model is applicable to both aquifers in this context in a broader sense we have illustrated a method by which other examples developed from data rich sites can be compared

generation and intensification of mesoscale anticyclones by orographic wind jets the case of ierapetra eddies forced by the etesians

transient upwelling hot spots in the oligotrophic north pacific 1 vertical exchange between deep nutrient rich and nutrient depleted surface waters controls the physical supply of nutrients into the euphotic zone in the oligotrophic waters of the subtropical north pacific ocean sea surface temperature and ocean color satellite images are used in this study to show that submesoscale chlorophyll patches are locally intensified these patches are associated with surface temperature fronts and regions of strong stretching of the eddying flow the latter are identified by calculating the finite size lyapunov exponents of the geostrophic flow derived from the sea surface height field from altimetry surface frontogenesis and nonlinear ekman pumping nlep arise as natural candidates for the sporadic generation of large vertical velocities that could favor the formation of these features a high resolution regional numerical model simulation confirms that large vertical velocities are indeed associated with strong density fronts and gradients of relative vorticity using the q vector divergence as a proxy for frontogenetically generated vertical velocities yields good agreement with the model vertical velocities particularly in regions where they are large the pattern and magnitude of nlep suggests that it is also contributing to the strong vertical motions although nlep and model vertical velocities are not necessarily in phase surface frontogenesis and nlep provide a possible explanation for the episodic injection of nutrients at the submesoscale which are then horizontally stirred and modulated by the unstable manifolds of the flow field given that these surface intensified processes would be biogeochemically more effective when the pycnocline is shallow they could also serve as one possible explanation for the late summer chlorophyll blooms that are known to occur in the region

is the south pacific helium 3 plume dynamically active it is suggested that the hydrothermal vents of the south pacific rise produce a beta governed circulation at mid depth and that perhaps the associated plume of excess3he lupton and craig 1 points westward because of the dynamics of this circulation rather than as a passive tracer

linear wind forced beta plumes with application to the hawaiian lee countercurrent abstracttwo numerical ocean models are used to study the baroclinic response to forcing by localized wind stress curl i e a wind forced plume which is a circulation cell developing to the west of the source region and composed of a set of zonal jets with implications for the hawaiian lee countercurrent hlcc an idealized primitive equation model regional ocean modeling system roms and a global eddy resolving general circulation model ocean general circulation model for the earth simulator ofes in addition theoretical ideas inferred from a linear continuously stratified model are used to interpret results in roms vertical mixing preferentially damps higher order vertical modes the damping thickens the plume to the west of the forcing region weakening the near surface zonal jets and generating deeper zonal currents the zonal damping scale increases monotonically with the meridional forcing scale indicating a dominant role of vertical viscosity over diffusion a consequence of the

eddy activity in the lee of the hawaiian islands abstract persistent northeasterly trade winds have a substantial impact on the oceanic circulation around the hawaiian islands a regional ocean model is applied to understand the effect of different temporal and spatial resolutions of surface momentum forcing on the formation of strong mesoscale vortices and on the simulation of realistic levels of eddy kinetic energy the higher spatial and temporal resolutions of wind forcing is shown to substantially affect the vorticity and deformation field in the immediate lee of the hawaiian islands and produce patterns of eddy kinetic energy similar to observations this suggests that the surface eddy field in the region is mostly dominated by the local surface momentum forcing mesoscale cyclones and anticyclones formed in the lee of the island of hawaii are shown to have different propagation patterns mesoscale cyclones are more confined to the lee and are hence subject to interactions with the strong wind forcing and deformation field as well as smaller vortices formed in the wake of the other islands mesoscale anticyclones show not only a tendency to propagate further westward but also to persist as coherent features as they propagate even at relatively lower values of relative vorticity the large strain rates that affect the propagation of the cyclones cause them to break down into filaments of positive vorticity rossby numbers of o 1 within vortices and filaments indicate that nonlinear interactions between the wind stress and the vertical component of the relative vorticity field is potentially important in producing large vertical velocities modeled cyclonic eddies show a good resemblance to observations both in terms of vertical structure and propagation patterns