direct reservoir parameter estimation using joint inversion of marine seismic ava and csem data a new joint inversion algorithm to directly estimate reservoir parameters is described this algorithm combines seismic amplitude versus angle ava and marine controlled source electromagnetic csem data the rock properties model needed to link the geophysical parameters to the reservoir parameters is described errors in the rock properties model parameters measured in percent introduce errors of comparable size in the joint inversion reservoir parameter estimates tests of the concept on synthetic one dimensional models demonstrate improved fluid saturation and porosity estimates for joint ava csem data inversion compared to ava or csem inversion alone comparing inversions of ava csem and joint ava csem data over the north sea troll field at a location with well control shows that the joint inversion produces estimated gas saturation oil saturation and porosity that is closest as measured by the rms difference l1 norm of the difference and net over the interval to the logged values whereas csem inversion provides the closest estimates of water saturation

estuary enhanced upwelling of marine nutrients fuels coastal productivity in the u s pacific northwest 2014 american geophysical union all rights reserved the pacific northwest pnw shelf is the most biologically productive region in the california current system a coupled physical biogeochemical model is used to investigate the influence of freshwater inputs on the productivity of pnw shelf waters using realistic hindcasts and model experiments that omit outflow from the columbia river and strait of juan de fuca outlet for the salish sea estuary outflow from the strait represents a critical source of nitrogen to the pnw shelf accounting for almost half of the primary productivity on the vancouver island shelf a third of productivity on the washington shelf and a fifth of productivity on the oregon shelf during the upwelling season the columbia river has regional effects on the redistribution of phytoplankton but does not affect pnw productivity as strongly as does the salish sea a regional nutrient budget shows that nitrogen exiting the strait is almost entirely 98 of ocean origin upwelled into the strait at depth mixed into surface waters by tidal mixing and returned to the coastal ocean from the standpoint of nitrogen availability in the coastal euphotic zone the estuarine circulation driven by freshwater inputs to the salish sea is more important than the supply of terrigenous nitrogen by rivers nitrogen rich surface waters exiting the strait follow two primary pathways to the northwest in the vancouver island coastal current and southward toward the washington and oregon shelves nitrogen flux from the juan de fuca strait and eddy region to these shelves is comparable to flux from local wind driven upwelling

mapping of elastic properties of gas hydrates in the carolina trough by waveform inversion gas hydrates are frozen methane gas that forms at appropriate pressure and temperature conditions they are found in the marine sediments along continental margins worldwide they have the economic potential of being tapped as a fuel source and also have the potential as a greenhouse agent after being freed into the atmosphere in seismic sections the occurrence of the base of gas hydrates in some areas is often marked by a bright amplitude reflection such reflections follow the sea floor topography and are called bottom simulating reflectors bsr the bsrs have negative polarity with respect to the sea floor reflection and in a common shot or a cdp gather the amplitude increases with offset the negative impedance contrast causing bsrs may be due to negative velocity contrast between hydrated sediments and normal sediment below or due to the presence of free gas at the base of the hydrates in this paper we carry out a prestack seismic waveform inversion of multichannel seismic data collected in

dissolved and particulate aluminum in the columbia river and coastal waters of oregon and washington behavior in near field and far field plumes the distribution of dissolved soluble and total and particulate leachable and total aluminum was examined in the columbia river and estuary in near field and far field river plumes and in adjacent coastal waters of washington and oregon during the river influence on shelf ecosystems rise cruise of may june 2006 dissolved and particulate aluminum al concentrations were significantly greater in the river than in the coastal waters that mixed to form the plume dissolved al concentrations in the columbia river w80 nm were low relative to other major rivers leachable and total particulate al concentrations within the river reached concentrations greater than 1000 nm and 18 000 nm respectively dissolved al within the columbia river estuary showed a significant removal w60 at salinities between 0 and 10 with salt induced flocculation of colloidal al complexes and enhanced particle scavenging being probable explanations for aluminum removal dissolved and particulate al concentrations were significantly greater in near field plumes relative to surrounding coastal waters as the plume advected from near field to far field away from the river mouth dilution of the plume with lower dissolved al surface waters as well as particle scavenging along the flow path appeared to be controlling dissolved al distributions particle settling as well as dilution with lower particle load waters led to observed decreases in particulate al as the plume moved from near field to far field however the percent leachable particulate aluminum in both near field and far field plumes was remarkably constant at w7 dissolved and particulate al in a far field plume over 100 km southwest of the columbia river mouth were over an order of magnitude greater than surrounding waters illustrating the importance of the columbia river plume as a mechanism for transporting al offshore aluminum could be used to trace the input of biologically required elements such as iron into waters off the shelf

discrimination between pressure and fluid saturation changes from time lapse seismic data explicit expressions for computing saturation and pressure related changes from time lapse seismic data have been derived and tested on a real time lapse seismic data set necessary input is near and far offset stacks for the baseline seismic survey and the repeat survey the method has been tested successfully in a segment where pressure measurements in two wells verify a pore pressure increase of 5 to 6 mpa between the baseline survey and the monitor survey estimated pressure changes using the proposed relationships fit very well with observations between the baseline and monitor seismic surveys 27 of the estimated recoverable hydrocarbon reserves were produced from this segment the estimated saturation changes also agree well with observed changes apart from some areas in the water zone that are mapped as being exposed to saturation changes which is unlikely saturation changes in other segments close to the original oil water contact and the top reservoir interface are also estimated and conf

ebb tide dynamics and spreading of a large river plume abstract momentum balances in the near field region of a large tidally pulsed river plume are examined the authors concentrate on a single ebb tide of the columbia river plume using the regional ocean modeling system roms configured to hindcast flow conditions on the washington and oregon shelves and in the columbia river estuary during ebb plume interior streamwise balances are largely between advection pressure gradient and frictional forces stream normal balances in this region reduce to centrifugal cross stream pressure gradient and coriolis terms i e the gradient wind balance commonly assumed in river plume bulge investigations temporal derivatives are most important at the plume front and as the ebb progresses winds were light and contributed little to the force balance midebb stress and vertical salt flux were largest at a midplume depth where stratification and vertical shear were also high consistent with shear induced mixing internal stress slows the spreading plume consi

calculation of river seawater endmembers and differential trace metal scavenging in the columbia river plume abstract a simple model is presented for calculating river and seawater mixing zone endmembers this model allows construction of a conservative mixing line with respect to trace metals scavenged from surface waters in the absence of direct endmember sampling results of the model suggest a transition from non conservative to conservative behavior of the trace metals gallium ga and zirconium zr along a transect extending offshore of the columbia river indicating environmental controls on differential scavenging mechanistic explanation of observed differential scavenging is supported by wind data indicating northward transport of columbia river plume waters followed by southwest offshore transport columbia river plume waters transported to the southwest at the time of sample collection were therefore flanked offshore by aged plume waters returning from the north while upwelling conditions provide nutrients during southerly transport of plume waters northward plume transport is associated with downwelling low nutrient conditions low phytoplankton abundance during periods of northward plume transport reduces trace metal scavenging therefore dilution of river waters with ocean surface waters of comparatively low ga and zr concentrations results in near conservative mixing of ga and zr in offshore aged plume waters results of this work suggest dynamic modification of trace metal residence time within close geographic proximity established by physical and biologic controls dictated by local winds lower trace metal scavenging rates resulting in a longer residence time are suggested during northward transport of columbia river plume waters compared to higher scavenging rates and thus shorter residence times during southerly transport of plume waters gallium demonstrating high analytical precision reduced contamination risk and decreased complications of upwelled sources relative to zr is proposed to provide identification of aged columbia river plume waters

avo inversion of troll field data a stratigraphic elastic inversion scheme has been applied to a data set from the troll east field offshore norway the objective of the present work is to obtain estimates of the p and s wave velocities and densities of the subsurface the inversion is carried out on tau minus p transformed common depth point cmp gathers the forward modeling is performed by convolving a wavelet with the reflectivity that includes water bottom multiples transmission effects and absorption and array effects a damped gauss newton algorithm is used to minimize a least squares misfit function inversion results show good correlation between the estimated v sub p v sub s ratios and the lithologies in the wells the v sub p v sub s ratio is estimated to 2 1 3 0 for shale and 1 6 2 0 for sandstones in the reservoir the v sub p v sub s ratio is estimated to 1 55 in the gas sand and to 1 62 below the fluid contact

a model study of the salish sea estuarine circulation arealistichindcastsimulationofthesalishsea whichencompasses theestuarinesystemsofpugetsound the strait ofjuan de fuca and the strait of georgia is described for the year 2006 the model shows moderate skill when compared against hydrographic velocity and sea surface height observations over tidal and subtidal time scales analysis of the velocity and salinity fields allows the structure and variability of the exchange flow to be estimated for the first time from the shelf into the farthest reaches of puget sound this study utilizes the total exchange flow formalism that calculates volume transports and salt fluxes in an isohaline framework which is then compared to previous estimates of exchange flow in the region from this analysis residence time distributions are estimated for puget sound and its major basins and are found to be markedly shorter than previous estimates the difference arises from the ability of the model and the isohaline method for flux calculations to more accurately estimate the exchange flow in addition evidence is found to support the previously observed spring neap modulation of stratification at the admiralty inlet sill however the exchange flow calculated increases at spring tides exactly opposite to the conclusion reached from an eulerian average of observations

reservoir characterization using crosswell electromagnetic inversion a feasibility study for the snorre field north sea the spatial resolution of a commercially available crosswell electromagnetic em system is demonstrated using models derived from three time steps from a reservoir simulation of the snorre field in the north sea the numerical simulation of the snorre field waterflood shows that crosswell em field measurements provide high sensitivity to changes in the reservoir over time this sensitivity is achieved by combining the reservoir geometry derived from surface 3 d seismic interpretation reservoir conductivities at well locations and constrained em inversion of the reservoir s electrical conductivity inversions of 2 d and 3 d numerical models show that the changes in electrical conductivity attributable to changes in water saturation can be quantitatively mapped as a function of time the inversions provide smooth estimates of the spatial variation of reservoir electrical conductivity that can discriminate between the level of water saturation at different stages of the waterflood inversions performed on

modeling upwelling circulation off the oregon coast 1 time dependent three dimensional upwelling circulation on the continental shelf off the oregon coast is studied using a primitive equation numerical model a limited area domain with a high resolution curvilinear grid is utilized the response of the coastal ocean to forcing by observed wind stress and heat flux during the summer 2001 time period of the coastal ocean advances in shelf transport coast field experiment is investigated model results are compared to coast current and hydrographic measurements the shelf velocity and density fields are generally characterized by the presence of a southward alongshore coastal jet with an upwelling density front on the shoreward side of the jet the large variability in shelf topography associated with heceta bank exerts a major influence on the shelf velocity and density fields over the bank the alongshore coastal jet is displaced offshore and colder upwelled water extends farther from the coast northward mean flow and upward motion are found inshore of the jet three dimensional flow structures in response to variable shelf bottom topography are presented and an analysis of time and space dependent alongshore momentum balances is applied to clarify the associated dynamics in general northward pressure gradients set up over the bank during southward upwelling winds accelerate currents on the inshore side of the jet northward when the winds relax analysis of term balances in the depth averaged equation for potential temperature shows that during upwelling across shore advection makes the major contribution to cooling over most of the region except inshore over heceta bank where alongshore advection also plays a significant role

determining azimuthal variations in frontal froude number from sar imagery 1 river plume fronts are the locus of strong mixing between plume and ambient coastal waters contribute to coastal productivity and exert a major impact on coastal ecosystems the frontal froude number fr is an important parameter characterizing the frontal status with respect to both propagation and vertical mixing in this study we examine azimuthal variations in fr using a new remote sensing method we derive fr from sar image data on the basis of the sar imaging theory and the mechanism of internal wave fission at front this method is applied to a sar image showing a front off the columbia river cr mouth taken on 31 may 2003 at 14 33 19 utc under weak wind conditions fr increases from south to north along the front this variation is consistent with potential vorticity conservation and the influence of tidal currents on the plume this calculation confirms arguments based on vessel observations by jay et al 2009

estuarine versus transient flow regimes in juan de fuca strait 1 residual currents in juan de fuca strait are observed to switch between two fundamental states estuarine and transient the estuarine regime which prevails roughly 90 of the time in summer and 55 of the time in winter has a fortnightly modulated three layer structure characterized by strong 50 cm s 1 outflow above 60 15 m depth moderate 25 cm s 1 inflow between 60 and 125 m depth and weak 10 cm s 1 inflow below 125 10 m depth rotation increases the upper layer depth by 40 m on the northern side of the channel and upwelling favorable coastal winds augment inflow in the bottom layer by as much as 5 cm s 1 rotation combined with modulation of the estuarine currents by tidal mixing in the eastern strait leads to fortnightly variability in the along channel velocity and cross channel positioning of the core flow regions transient flows which occur roughly 10 of the time in summer and 45 of the time in winter are rapidly evolving horizontally and vertically sheared reversals in the estuarine circulation generated during poleward wind events along the outer coast major events can persist for several weeks force a net inward transport and give rise to an o 10 km wide surface intensified o 100 cm s 1 inflow along the southern olympic peninsula boundary of the strait this olympic peninsula countercurrent is typically accompanied by an abrupt decrease in salinity indicating that it is a buoyancy flow originating with low density water on the northern washington shelf

the columbia river plume study subtidal variability in the velocity and salinity fields a comprehensive study of the strongly wind driven midlatitude buoyant plume from the columbia river located on the u s west coast demonstrates that the plume has two basic structures during the fall winter season namely a thin 5 15 m strongly stratified plume tending west to northwestward during periods of southward or light northward wind stress and a thicker 10 40 m weakly stratified plume tending northward and hugging the coast during periods of stronger northward stress the plume and its velocity field respond nearly instantaneously to changes in wind speed or direction and the wind fluctuations have timescales of 2 10 days frictional wind driven currents cause the primarily unidirectional flow down the plume axis to veer to the right or left of the axis for northward or southward winds respectively farther downstream currents turn to parallel rather than cross salinity contours consistent with a geostrophic balance in particular during periods when the plume is separated from the coast currents tend to flow around the mound of fresher water at distances exceeding about 20 km from the river mouth the along shelf depth averaged flow over the inner to midshelf is linear and depth averaged acceleration is governed to lowest order by the difference between surface and bottom stress alone in this region along shelf geostrophic buoyancy driven currents at 5 m calculated from surface density and along shelf geostrophic wind driven currents computed from a depth averaged linear model are comparable in magnitude 10 25 cm s 1

analytical studies on transient groundwater flow induced by land reclamation using different fill materials land reclamation may have a significant influence on groundwater regimes analytical solutions have been developed in the past to study the impact of land reclamation on a steady state groundwater flow and transient flow in fill materials assuming that the reclamation site consists of a single zone of uniform hydraulic parameters in this paper we derive analytical solutions to describe the transient water table change in response to multi stage land reclamation where the fill material is uniform in each stage but the hydraulic conductivity of the fill material varies from stage to stage by introducing the method of separation of variables we develop a transient analytical solution to study the impact of land reclamation consisting of fill material with different hydraulic properties on groundwater dynamics the results show that the water table first increases significantly into the reclaimed zone following the fill material deposition and then the increase gradually propagates into the original aquifer the change of water table in the original aquifer mainly depends on the value of hydraulic conductivity of the fill materials examples in this paper illustrate how the aquifer system experiences a long time unsteady state flow as a result of the reclamation and it takes at least tens of years for the system to approach a new equilibrium it is suggested that for a large scale reclamation project the response of the groundwater regime to reclamation should be carefully studied copyright 2013 john wiley sons ltd

influences of the juan de fuca eddy on circulation nutrients and phytoplankton production in the northern california current system 1 a diagnostic circulation model and water mass analyses are used to examine variability in the structure and circulation of the juan de fuca eddy a highly productive region at the northern end of the california current results from three years of field studies demonstrate that the eddy increases in spatial extent from early to late summer as the vertically averaged contribution of california undercurrent source water grows from 60 in june to 80 in september typical near surface eddy radii range from 15 km in the early summer to 30 km in september and increase with depth below 100 m eddy radii are 40 km fresher water associated with the estuarine outflow from the juan de fuca strait is advected around the eddy margin during southward wind conditions the combination of cyclonic geostrophic flow and wind driven currents in the surface ekman layer cause the eddy to be leaky on its southern perimeter eddy surface circulation becomes more retentive up to 32 d observed during periods of weak winds or frequent northward reversals the presence of the eddy facilitates large inputs of dissolved inorganic nutrients into the region through two mechanisms doming of california undercurrent water within the eddy and enhanced cross shelf advection of juan de fuca strait outflow the combination of these sources results in a persistent broad 100 km offshore region of elevated macronutrients the retentive circulation patterns combined with persistent nutrient supply may favor the development of toxigenic diatom blooms of pseudo nitzschia species in this region

three interacting freshwater plumes in the northern california current system 1 the northern california current system is impacted by two primary freshwater sources the strait of juan de fuca and the columbia river the columbia is frequently bidirectional in summer with branches both north and south of the river mouth simultaneously we describe the interaction of these two warm columbia plumes with each other and with the colder plume originating from the strait the interactions occurred when a period of strong downwelling favorable winds and high columbia river discharge was followed by persistent and strong upwelling favorable winds the northward plume that developed under the downwelling winds extended over 200 km along the coast to the strait of juan de fuca and into the strait the plume subsequently wrapped around juan de fuca strait water in the counterclockwise seasonal eddy just offshore of the strait inspection for similar wind and outflow conditions 0 15 n m 2 and 104 m3 s 1 respectively suggest that these events might have occurred in roughly half the years since 1994 surface drifters deployed in the columbia plume near its origin tracked this plume water northward along the coast then reversed direction at the onset of upwelling favorable winds tracking plume water southward past the river mouth once again recent 1 2 day old and aged 14 day old plume water folded around the newly emerging southwest tending columbia plume forming a distinctive sock shaped plume this plume was a mixture of 10 new 1 day old water and 90 recent and aged water from prior north tending plumes

the propagation of tsunami generated acoustic gravity waves in the atmosphere abstracttsunami generated acoustic gravity waves have been observed to propagate in the atmosphere up to the ionosphere where they have an impact on the total electron content the authors simulate numerically the propagation of two dimensional linear acoustic gravity waves in an atmosphere with vertically varying stratification and horizontal background winds the authors goal is to compare the difference in how much energy reaches the lower ionosphere up to an altitude of 180 km where the atmosphere is assumed to be anelastic or fully compressible the authors consider three specific atmospheric cases a uniformly stratified atmosphere without winds an idealized case with a wind jet and a realistic case with an atmospheric profile corresponding to the 2004 sumatra tsunami results show that for the last two cases the number and height of turning points are different for the anelastic and compressible assumptions and the net result is that compressibility enhances the total transmission of energy

application of remote wind forced coastal trapped wave theory to the oregon and washington coasts abstract the theory of coastal trapped waves generated by remote wind forcing clarke is used to calculate coastal subsurface pressure ssp and longshore velocity along the oregon and washington coasts for three two month periods summer of 1972 summer of 1978 and winter of 1977 the response in ssp and longshore velocity is assumed to be dominated by the mode one wave in every case coherence squared between observed and modeled ssp is significant at the 95 level over the entire low frequency band 0 2 cpd with an average phase difference less than 30 greater than 80 of the variance in coastal ssp is accounted for by the mode one coastal trapped wave ctw the ssp response off washington and oregon during summer is primarily 35 of the variance a result of wind forcing between san francisco and cape mendocino california wind stress in this region during summer is significantly larger than that off oregon and washington at low frequencies so that the ctw generated off california propagate

numerical simulations of a buoyancy driven coastal countercurrent off vancouver island abstract a three dimensional prognostic numerical model has been developed to study the ocean circulation around vancouver island british columbia in a series of simulations the model is applied to examine the role of buoyancy forcing in the dynamics of the summer coastal countercurrent found off the west coast of vancouver island the forcing is provided by the fraser river discharge into the strait of georgia an estuarine circulation establishes itself in juan de fuca strait from which a distinctive right bounded current is formed and advances along the coast sensitivity studies are conducted to determine the robustness of this current to initial conditions opposing wind enhanced vertical mixing and grid resolution finally various characteristics of the numerically modeled coastal flow are compared with observations

a numerical modeling study of the upwelling source waters along the oregon coast during 2005 abstract regional ocean circulation along the oregon coast is studied numerically for forcing fields derived from year 2005 and climatological mean conditions the primary object is to study directly the lagrangian pathways by which fluid arrives in the oregon upwelling zone roughly half of the upwelling fluid is found to arrive in the regional domain from alongshelf source points primarily north but also south of the oregon upwelling zone while the other half ultimately arrives from points offshore and west of the zone for both the year 2005 and the climatological simulations different regimes of dominant alongshelf source waters are found with cape blanco being a dividing point for northern versus southern sources and with the water parcels coming primarily from depths below 100 m for the offshore sources most upwelling fluid originates from depths between 150 and 250 m during 2005 but from within the upper 150 m for the climatological simulations in both cases there are specific regions alon

modeling the generation of the juan de fuca eddy 1 numerical simulations with the regional ocean modeling system are used to study the generation of the cyclonic juan de fuca eddy located off the entrance of juan de fuca strait in summer an initial simulation forced with average summer upwelling favorable winds tides and buoyancy boundary conditions that maintain an estuarine flow in juan de fuca strait produces an eddy and currents that are in reasonable agreement with observations sensitivity studies are then carried out to explore the importance of these three forcing mechanisms the relative proximity of dense water in the bottom estuarine flow entering the strait is shown to lead to enhanced upwelling off cape flattery when either wind or tidal forcing is applied this upwelled water then mixes with the estuarine outflow and is advected offshore the tidal upwelling arises through three mechanisms m2 vertical excursions of nearly 20 m at 50 m depth west of the cape on the flood tide strong tidally rectified vertical velocities west of the cape and the spilling of denser bottom water over the western wall of juan de fuca canyon on the ebb tide the cyclonic eddy is a consequence of geostrophic adjustment to the doming isopycnals that arise from the upwelling these model simulations refute an earlier hypothesis that the eddy is generated when california undercurrent water is drawn up tully canyon and onto the vancouver island shelf suggesting instead that these canyon dynamics play only a secondary role in maintaining the eddy once it is formed