time scales of pattern evolution from cross spectrum analysis of advanced very high resolution radiometer and coastal zone color scanner imagery we have selected square subareas 110 km on a side from coastal zone color scanner czcs and advanced very high resolution radiometer avhrr images for 1981 in the california current region off northern california for which we could identify sequences of cloud free data over periods of days to weeks we applied a two dimensional fast fourier transform to images after median filtering x y plane removal and cosine tapering we formed autospectra and coherence spectra as functions of a scalar wavenumber coherence estimates between pairs of images were plotted against time separation between images for several wide wavenumber bands to provide a temporal lagged coherence function the temporal rate of loss of correlation decorrelation time scale in surface patterns provides a measure of the rate of pattern change or evolution as a function of spatial dimension we found that patterns evolved or lost correlation approximately twice as rapidly in upwelling jets as in the quieter regions between jets the rapid evolution of pigment patterns lifetime of about 1 week or less for scales of 50 100 km ought to hinder biomass transfer to zooplankton predators compared with phytoplankton patches that persist for longer times we found no significant differences between the statistics of czcs and avhrr images spectral shape or rate of decorrelation in addition in two of the three areas studied the peak correlation between avhrr and czcs images from the same area occurred at zero lag indicating that the patterns evolved simultaneously in the third area maximum coherence between thermal and pigment patterns occurred when pigment images lagged thermal images by 1 2 days mirroring the expected lag of high pigment behind low temperatures and high nutrients in recently upwelled water we conclude that in dynamic areas such as coastal upwelling systems the phytoplankton cells identified by pigment color patterns behave largely as passive scalars at the mesoscale and that growth death and sinking of phytoplankton collectively play at most a marginal role in determining the spectral statistics of the pigment patterns

origin and palaeo environmental significance of the berrazales carbonate spring deposit north of gran canaria island spain the berrazales carbonate spring deposit is a small outcrop constituted mainly by cascade like geometries four main facies have been identified fibrous dense macrocrystalline formed by rapid degassing under high flow conditions framestones of coated plant moulds formed in moderate energy flow favoured by the presence of biogenic support micrite microsparite are primary precipitates in which crystalline aggregates nucleated on organic filaments and or eps banded micrite coarse crystalline were the result of alternating physically chemically and biologically induced precipitation in areas of varying flow velocities most facies underwent different degrees of micritization processes micrite is distributed as thin lines penetrating the crystals as irregular patches or as micrite layers in the first case organic filaments penetrate crystals suggesting that micritization is mainly biogenically driven in the latter cases micritization is caused mostly by partial dissolution microbe participation in micrite formation increased micrite mgco3 content in comparison with coarse crystalline facies isotopic analyses show positive 13c values 2 63 and 4 29 vpdb and negative 18o 5 65 and 4 48 vpdb values positive 13c values clearly indicate deep sourced fluids the berrazales spring deposit studied here very probably is a small part of a larger carbonate building that was largely eroded by fluvial incision calculations of spring water temperature give a range from 20 c to 35 c characteristic of a cold to warm spring favouring precipitation of calcite and important biogenic activity framestones although the study deposit has textural characteristics of tufas proving that the co2 sourced from deep fluids it should be considered as thermogene travertine being one more example of the difficulty of using those terms for ancient sedimentary deposits carbonate spring deposits very rare in the canary islands are good archives of recent volcanic activity fluvial processes and vegetation regimes prevailing in the islands in recent times

sedimentology and geochemistry of a human induced tufa deposit implications for palaeoclimatic research geochemical variations across laminated tufas and travertines may reflect the growth style of the carbonate build up and not just climate related changes this work presents the study of a carbonate deposit formed on a ravine wall in gran canaria island spain from a broken pipe system used for irrigation of banana plantations the deposit is a few tens of metres long and has a stepped morphology formed by successive cascade barriers and pools the main facies are framestones of coated stems laminated bindstones phytoclastic wackestones and silty mudstones all of which display micritic or coarse crystalline textures lamination from a framestone with coarse crystalline texture was studied from a petrological sedimentological and geochemical perspective and water palaeotemperatures were calculated lamination displaying five orders of magnitude from daily to annual or higher was controlled by the discontinuous supply of water lamination consists of crystalline laminae discontinuity couplets at all observed scales estimated mean precipitation rates are 0 7 mm year 1 but discontinuity of sedimentation at all lamination orders may have involved greater precipitation rates whereas elemental geochemistry suggests variable conditions not far from chemical equilibrium stable isotopes suggest that calcite precipitated under disequilibrium conditions however the small dimensions of the deposit and the relatively high flow velocities allowed lack of 13c and 18o isotope fractionation in co2 nor in calcite leading to independent temperature calculations both with mean values of 25 c isotopic trends found throughout lamination cannot be explained by strong changes in water temperature nor in 13cdic or 18ow the correction made to eliminate these isotopic trends yielded narrower temperature ranges this paper discusses the accuracy of temperature estimations despite the difficulties coming from disequilibrium and how isotopic trends through time could be explained by the growth of the deposit and not by climate related changes

characterization of surface water and groundwater in the damascus ghotta basin hydrochemical and environmental isotopes approaches the hydrochemistry of major ions and environmental isotope compositions 18o 2h and tritium of water samples have been used to investigate the characteristics of rainfalls surface water and groundwater in the damascus ghotta basin the groundwater salinity in the damascus ghotta basin gradually increases as the groundwater moves from western to south eastern and north eastern parts of the basin a strong relationship exists between the barada river and the surrounded groundwaters mainly in terms of recharge by infiltration of surface waters the groundwater quality in the adra region has clearly become less saline as a result of establishment of the sewage water treatment station in this area since 1997 the uncommon depleted stable isotope concentrations in the vicinity of al ateibeh lake and adra valley could be interpreted as a result of sub flow recharge from the cenomanian turonian aquifer mostly prolonged along the damascus fault which forms direct contact between this complex and the quaternary alluvium aquifers the extensive exploitation of water from the cenomanian turonian aquifer for drinking water supply would shortly be reflected by a gradual decline of the groundwater table in the damascus ghotta basin amelioration of water quality in the damascus basin still requires further management strategies and efforts to be taken within the forthcoming years

a nested grid model of the oregon coastal transition zone simulations and comparisons with observations during the 2001 upwelling season 1 the oregon coastal transition zone octz extends several hundred kilometers offshore where shelf flows interact with the northern california current a primitive equation numerical ocean model is used to study the upwelling circulation in this region from 1 may to 1 november 2001 this octz model obtains initial and boundary conditions from a larger scale model of the california current system and forcing from a regional atmospheric model product the model results are compared with extensive in situ and remotely sensed data and the model is found to provide a realistic representation of flows both over the shelf and in the broader octz simulation of coastal sea level and shelf currents over the complex topography of the central oregon coast is improved quantitatively relative to previous regional models a particularly significant qualitative improvement is realistic representation of coastal jet separation and eddy formation offshore of cape blanco three dimensional lagrangian analysis of water parcel displacement shows that the surface waters inshore of the separated jet are upwelled from near the bottom along the shelf as far north as 45 5 n a large eddy which incorporates some of this upwelled water and carries it farther westward forms offshore in the late summer ensemble simulations show a distinction between the strongly deterministic response to wind forcing over the shelf and the more unstable less predictable jet separation and offshore eddy formation processes in the region near cape blanco

the pacific decadal oscillation air sea interaction and central north pacific winter atmospheric regimes prominent and persistent anomalies in the atmospheric flow troughs and ridges occur sporadically over the central north pacific and can have profound consequences for the weather of north america we have examined how these events are associated with large scale central north pacific sea surface temperature sst anomalies using an index for the pacific decadal oscillation pdo the anomalies in turbulent air sea heat fluxes and low level baroclinity associated with the pdo are manifested differently during troughs than during ridges in their effects on the transient eddies storms these effects may help explain why prominent troughs ridges occur about 3 2 5 times more frequently during periods when the pdo is significantly positive negative than of opposite sign our results suggest that the state of the mid latitude pacific ocean more fundamentally affects the atmosphere than has been thought

ignimbrites of amazonis planitia region of mars a series of postulated ignimbrite units is mapped in the amazonis memnonia and aeolis quadrangles of mars the units cover about 2 2 106 km2 within a broad but discontinuous and irregular belt trending east west along the highland lowland boundary the ignimbrites overlie parts of the western and southern aureole materials of olympus mons but are embayed in places by the lava plains of the lowlands stratigraphic relations between the basalt flows from the tharsis montes region and the ignimbrites are not clearly defined crater counts suggest that the younger ignimbrites postdate the lava flows crater counts per square kilometer for the ignimbrites range from 7 29 1 95 10 4 to 6 36 2 01 10 5 for craters larger than 1 km in diameter the ignimbrite materials form thick 100 m extensive relatively flat sheets that are smooth to grooved or gently undulating grooved surfaces appear to be yardangs and in most places are not alined with prevailing wind directions the seven mapped ignimbrite units are characterized by morphologic expression stratigraphic position and crater counts similarities to ignimbrites in the pancake range of central nevada include 1 rounded patches of smooth high albedo nonwelded material superposed on jointed low albedo welded material 2 local complementary joint sets in welded materials and 3 thick flow sheets of great areal extent that follow but subdue underlying topography four major eruptive centers occur in areas where units are thickest and where a dominant nnw sse structural trend is expressed locally by unit margins elongate collapse features and normal faulting a minimum volume of 3 85 106 km3 for the deposits has been calculated from thickness estimates based on shadow measurements and crater rim height relations

a comparison of volcanic eruption processes on earth moon mars io and venus the silicate planets and satellites display a wide range of physical chemical and atmospheric characteristics which may influence the nature of volcanism a major geological process common to the evolution of the surfaces of these bodies consideration of the process of magma ascent and eruption from first principles allows predictions to be made concerning volcanic eruption styles and expected landforms and deposits on each planetary body examination of actual land forms and deposits in light of these predictions leads to a better understanding of the nature of volcanic eruption processes and outlines outstanding problems

the relation of catastrophic flooding of mangala valles mars to faulting of memnonia fossae and tharsis volcanism detailed stratigraphic relations indicate two coeval periods of catastrophic flooding and tharsis centered faulting producing memnonia fossae in the mangala valles region of mars major sequences of lava flows of the tharsis montes formation and local lobate plains flows were erupted during and between these channeling and faulting episodes first late hesperian channel development overlapped in time the tharsis centered faulting that trends north 75 to 90 e next late hesperian early amazonian flooding was coeval with faulting that trends north 55 to 70 e in some reaches resistant lava flows filled the early channels resulting in inverted channel topography after the later flooding swept through both floods likely originated from the same graben which probably was activated during each episode of faulting faulting broke through groundwater barriers and tapped confined aquifers in higher regions west and east of the point of discharge the minimum volume of water required to erode mangala valles about 5 1012 m3 may have been released through two floods that drained a few percent pore volume from a relatively permeable aquifer the peak discharges of the floods may have lasted from days to weeks the perched water discharged from the aquifer may have been produced by hydrothermal groundwater circulation induced by tharsis magmatism tectonic uplift centered at tharsis montes and compaction of saturated crater ejecta due to loading by lava flows

coupling global and regional circulation models in the coastal gulf of alaska abstract as part of the us globec ne pacific program we are simulating currents in the coastal gulf of alaska cgoa to explore sources of interannual and interdecadal variability to do so we have developed a coupled modeling system composed of linked regional and global circulation models the regional model configured with 13 22 km resolution in the cgoa is forced at the surface by observed heat fluxes and wind stresses at the continental boundaries by observed runoff and at the open ocean boundaries by a combination of tracer climatologies and sub tidal velocity and tidal elevation provided by a global finite element model in this communication we describe the coupled system including its present method of intermodel coupling describe a series of multi year model hindcasts compare hindcast results with eulerian and lagrangian field data obtained in the cgoa in fall 1996 and assess the impact of global information barotropic sub tidal velocities and tidal elevations on the regional model under the present coupling strategy we find that the regional model produces appropriate current systems alaskan stream alaska coastal current and scalar fields but with mesoscale variability of ssh and velocities at somewhat reduced strength relative to data and with temperature gradients somewhat larger than those observed barotropic sub tidal information from the global model penetrates the regional model interior supplying additional mesoscale variability and modifying regional velocity and scalar fields in both shallow and deep areas tidal information exerts a significant influence on sub tidal scalar and velocity structure only in specific shallow areas where the tides and tidal mixing are strongest pending the exploration of alternate coupling schemes we infer from these results that on a time scale of months purely barotropic information from outside the cgoa will have a modest impact on its mean regional circulation but a potentially stronger impact on the statistics and details of mesoscale eddies

mars mapping with delay doppler radar mars radar imaging results from arecibo 12 6 cm observations are presented the images were derived from delay doppler mapping using a coded long pulse technique to mitigate the effects of echo overspreading images of the depolarized echo are used to identify regions of high decimeter scale roughness some of the strongest echo features are located on the major shield volcanoes or on relatively young off shield flows such as the olympus and pavonis lava aprons the shields themselves have highly irregular radar signatures suggesting complex volcanic histories some mars radar features have twice the depolarized brightness of the roughest terrestrial lava flows apparently due to higher levels of multiple scattering from surfaces of spectacular roughness or from volume scattering low brightness smooth areas are associated with older surfaces such as fractured and highland terra as well as with terrain interpreted to be debris lobes ash flows and aureoles in particular a close connection was found between the 12 6 cm counterpart of the stealth feature and the medusae fossae formation postulated to be deep ignimbrite deposits marte valus is anomalous in being the only outflow channel showing strongly enhanced echoes which supports the idea that this channel and the elysium basin that it drained are filled with lava flows a weak radar feature was found for the south polar residual ice cap comparisons with goldstone 3 5 cm data show that the south polar enhancement is much weaker at 12 6 cm than at 3 5 cm indicating that the southern ice cap becomes optically thin at the longer wavelength a north polar enhancement has also been found which is comparable in strength to the 12 6 cm south polar feature

modeling studies of the coastal circulation off northern california statistics and patterns of wintertime flow we conduct modeling studies of the coastal circulation off northern california in the vicinity of the eel river 40 6 n the site of the 1995 2000 strata formation on margins strataform marine geology observational program using a series of nested hydrostatic primitive equation models to aid in the understanding of the shelf flow field that receives and transports sediments during the winter floods the basic objectives of our numerical studies are to model the continental shelf and slope flow and to understand the dominant dynamical processes we simulate the shelf and slope flow surrounding cape mendocino during 100 days in winter 1996 1997 using a 3 km resolution model embedded in a 9 km resolution regional model of the north pacific ocean the naval research laboratory s pacific west coast pwc model the validity of the model simulations is assessed by comparison with current measurements from a strataform shelf tripod outfitted with an acoustic doppler current profiler and with satellite altimetry good agreement is found between the amplitude and time variability of the 3 km resolution modeled and observed alongshore currents on the shelf the 3 km resolution model outperforms the 9 km resolution pwc model using statistical maps of flow variables strong alongshore variability in wintertime flow is documented the role of the forcing supplied by wind and river runoff in establishing this flow asymmetry between regions north and south of cape mendocino is examined using empirical orthogonal functions the evolution of a robust anticyclonic eddy over the shelf and slope adjacent to cape mendocino is described the eddy forms when strong poleward winds weaken and reverse direction during winter storms the important role of alongshore pressure gradients in the shelf circulation is documented

computing ocean surface currents over the coastal california current system using 30 min lag sequential sar images as compared with conventional methods for measuring ocean surface currents spaceborne synthetic aperture radar sar offers cloud penetrating ocean current observation capability at high spatial resolution while some studies have shown the potential of sar for studying ocean surface currents through feature tracking they have only analyzed a few images to demonstrate the basic measurement technique and no concise general technique has been developed this paper shows the application of the maximum cross correlation mcc method to generate ocean surface currents from nearly two years of available sequential spaceborne c band sar imagery from the envisat asar and ers 2 advanced microwave instrument sar sensors over the coastal california current system the data processing strategies are discussed in detail and results are compared with hf radar measured currents one dimensional wavenumber spectra of the sar derived surface currents agree with the k 2 power law as predicted by submesoscale resolution models comparisons with hf radar currents show encouraging results with mcc sar vectors oriented slightly counterclockwise relative to hf radar vectors mcc sar surface currents are found to have larger magnitudes than hf radar currents approx 11 cm s which may be due to the fact that sar penetrates only a few centimeters into the ocean surface whereas hf radar currents are averaged over the top 1 m of the ocean surface the larger part of this magnitude difference is contained in the along shore component which can be attributed to higher hf radar accuracy in the direct radial cross shore measurements as compared with along shore components derived from multiple cross shore radial measurements

ancient and modern slopes in the tharsis region of mars the directions of lava flows in the tharsis region of mars are used to identify regional palaeo slopes vent areas and local topography a comparison is made between these flow directions and the present day radar measured topography good agreement between these data sets indicates that little infra regional tectonic deformation has occurred following the emplacement of the preserved lavas

the azuaje travertine an example of aragonite deposition in a recent volcanic setting n gran canaria island spain the azuaje travertines in the north of gran canary island crop out in the azuaje gorge which is incised into miocene volcanic breccias of the roque nublo formation this travertine is interesting because of the scarcity of travertines in the canary islands and its close relationship with recent volcanic events part of the travertine overlies a lava flow dated at 2420 40 years bp the travertine is composed mainly of aragonite in both perched systems on the gorge walls and in gorge bottom deposits parallel to the present stream perched systems include deposits from the feeder conduits within the roque nublo formation that spilled out through waterfalls and over barriers the gorge valley bottom system includes barrier and pool deposits the main laminated facies are composed mostly of large fibrous aragonite crystals while there are also common micritic and porous microfabrics shrubs coated grains coated bubbles and rafts are present in many of the deposits detailed study of the microfacies shows the presence of sparsely distributed biogenic features the 13c values are between 4 0 and 11 0 and the 18o values range between 11 0 and 2 0 vpdb these 13c values lie within the range of those of thermogene travertines fed by thermal waters that cooled downstream as indicated by the increase of the carbon and oxygen isotope values in that direction the common occurrence of fibrous radial fabrics is interpreted to be due to disequilibrium conditions during aragonite precipitation disequilibrium was likely caused by rapid co2 degassing of the thermalwaters that led to a rapid increase in the degree of aragonite saturation thus themorphology of the aragonite crystals and the isotopic composition indicate that the formation of the azuaje travertine was mostly due to abiogenic processes induced by rapid degassing of thermalwaters linked to the presence of a recent lava flow within the gorge in short the azuaje travertine shows the important role of volcanic activity in travertine deposition in the facies distribution as well as in the geochemical signatures of the deposits and so can be used as a recent analogue for ancient travertine deposits in volcanic settings

isotopic study of water resources in a semi arid region western iraq hydrochemistry and stable isotopic technique were used in studying the water resources interaction in a semi arid area western iraq throughout iraq 28 groundwater samples 7 surface water samples from the study area and 18 rainwater samples were analyzed for 2h and 18o stable isotopes and hydrochemical analysis in this study the temperature altitude and continental effects on the isotopic composition of rain water in iraq were studied the results show that isotopes content in rainwater in the current study increases with increasing temperature and a good correlation exists between increasing latitude with decreasing 18o values rainwater isotopes show evidence of temperature effect and continental effect associated with altitude effect generally due to variation in temperature and altitude throughout iraq the values of isotopic composition of rainwater range from 7 25 to 2 79 and from 45 to 9 7 for 18o and d respectively the similarity of isotopic composition of water of the euphrates river and haditha reservoir with that of groundwater taken from neighbor wells gives indication that intermixing between them is exist while the groundwater of the wells far from the surface water resources is mostly affected by rainwater

time evolution of surface chlorophyll patterns from cross spectrum analysis of satellite color images sequences of coastal zone color scanner czcs images from the offshore region adjacent to vancouver island canada have been analyzed to estimate the time rate of decorrelation of surface phytoplankton chlorophyll pigment patterns in these high latitude high pigment areas czcs derived pigment estimates were lower than those obtained from ship samples by about a factor of 3 their frequency distributions were skewed in opposite directions and subareas of the images often showed a discontinuity in the frequency distribution at a concentration of 1 5 mg m 3 where the algorithm changes czcs bands we selected cloud free subareas that were common to several images separated in time by 1 17 days image pairs were subjected to two dimensional auto spectrum and cross spectrum analysis in an array processor and spectra of squared coherence were formed the squared coherence estimates for several wave bands were plotted against time separation in analogy with a time lagged cross correlation function threshold levels for significant coherence were estimated from many realizations of squared coherence calculated for pairs of synthetic random uncorrelated fields with specified power law behavior 1 5 near the observed range 1 5 2 for wavelengths of 50 150 km significant coherence is lost after 7 10 days and for wavelengths of 25 50 km significant coherence is lost after 5 7 days in both cases offshore regions maintain coherence longer than coastal regions for wavelengths of 12 5 25 km only the offshore regions maintained coherence after 1 day but that was clearly lost after the next time separation of 6 days the implication for the formation of monthly average large scale surface maps to estimate open ocean productivity e g esaias et al 1986 is that all mesoscale patterns 150 km length scale will not be resolved

the ascraeus mons fan shaped deposit volcano ice interactions and the climatic implications of cold based tropical mountain glaciation abstract amazonian aged fan shaped deposits extending to the northwest of each of the tharsis montes in the tharsis region on mars have been interpreted to have originated from mass wasting volcanic tectonic and or glacial processes we use new data from mro mgs and odyssey to characterize these deposits building on recent evidence for cold based glacial activity at pavonis mons and arsia mons we interpret the smaller ascraeus fan shaped deposit to be of glacial origin our geomorphological assessment reveals a number of characteristics indicative of glacial growth and retreat including 1 a ridged facies interpreted to be composed of drop moraines emplaced during episodic glacial advance and retreat 2 a knobby facies interpreted to represent vertical downwasting of the ice sheet and 3 complex ridges showing a cusp like structure we also see evidence of volcano ice interactions in the form of 1 an arcuate inward facing scarp interpreted to have formed by the chilling of lava flows against the glacial margin 2 a plateau feature interpreted to represent a subglacial eruption and 3 knobby facies superimposed on flat topped flows with leveed channels interpreted to be subglacial inflated lava flows that subsequently drained and are covered by glacial till we discuss the formation mechanisms of these morphologies during cold based glacial activity and concurrent volcanism on the basis of a mid to late amazonian age 250 380 ma established from crater size frequency distribution data we explore the climatic implications of recent glaciation at low latitudes on mars gcm results show that increased insolation to the poles at high obliquities 45 forces sublimation of polar ice which is transported to lower latitudes and deposited on the flanks of the tharsis montes we assess how local orographic effects the mass balance of the glacier and the position of equilibrium line altitudes all played a role in producing the observed geomorphologies in doing so we outline a glacial history for the evolution of the ascraeus mons fan shaped deposit and compare its initiation growth and demise with those of arsia mons and pavonis mons

martian tharsis bulge insight to mantle related processes abstract when examining the tectonics of the one plate planet mars it is possible to test and even to develop further some ideas with respect to earth s plate tectonic paradigm the definition of terrestrial plate movements does not unambiguously identify the actual mantle processes involved one way to leam more about the endogenous development of planets is to undertake comparative studies the main tectonic structures of mars are interpreted here to give information concerning mantle processes which may relate to those processes driving earth s plate tectonics but which in the case of mars have been insufficient to break martian lithosphere into plates but which have been sufficient to cause rift block tectonics and to build the tharsis bulge

planetary radar astronomy planetary radar research reported during 1979 1982 was highlighted by radar observations of venus by the pioneer venus spacecraft earth based high resolution imaging of venus and the moon construction of accurate topographic profiles for martian tropical regions observational and theoretical advances in relating the radar signatures of mars and the moon to surface characteristics and the initial radar detections of echoes from a comet and a mainbelt asteroid this review begins with a brief synopsis of radar definitions and technical terminology and then summarizes recent results for individual targets readers interested in radar astronomy prior to the current quadrennium are directed to excellent reviews by jurgens 1982a pettengill 1978 evans 1969 muhleman 1966 and pettengill and shapiro 1965 detailed descriptions of planetary radar techniques include pettengill 1970 and evans and hagfors 1968

multi scale modeling of the north pacific ocean assessment and analysis of simulated basin scale variability 1996 2003 1 a primitive equation ocean general circulation model is used to investigate climate impacts in the north pacific ocean in the 1996 to 2003 period the objective is to assess the model ability to reproduce observed modes of variability and study their impact in the northeast pacific this work is done within the framework of the u s global ecosystem globec northeast pacific program studying the links between climate variability and ecosystem dynamics three large scale events are considered the 1997 1998 el nino the 1999 regime shift and the 2002 cold fresh subsurface anomalous water mass that was observed in the gulf of alaska and off the coast of oregon the circulation model is shown to generate the correct seasonal to interannual large scale variability and is able to represent the climatic signals of interest in the eastern pacific we show that the influence of the 1997 1998 el nino reached the coastal gulf of alaska and induced an increase in the upper ocean heat content along the coast of north america an analysis of the sea surface temperature for the model years shows agreement between model and data in the representation of the 1999 shift to a cold phase in the eastern and northern north pacific finally using the model results we speculate that the origin of the 2002 cold fresh anomaly in the northeast pacific was due to enhanced mixing during the preceding winter in the center of the alaska gyre owing to anomalous changes in the density structure of the upper ocean this water was able to move geostrophically toward the coast and it persisted in the northeast pacific below the mixed layer the following year

assimilation of surface velocity data into a primitive equation coastal ocean model summer of 1998 are 0 42 and 0 78 respectively demonstrating the effectiveness of the das our estimates of the error covariances are shown to be appropriate through a series of objective statistical tests analysis of the term balances of the model equations show that the dominant modeled dynamical balances are preserved by the das and that uncertainties in the spatial variability of the wind forcing are likely to be one source of model error by varying the relative magnitudes of the estimated forecast and observation error covariances the das is shown to be most effective when approximately 80 of the analysis is made up of the model solution index terms 4263 oceanography general ocean prediction 4219 oceanography general continental shelf processes 4255 oceanography general numerical modeling 3337 meteorology and atmospheric dynamics numerical modeling and data assimilation 4516 oceanography physical eastern boundary currents 4594 oceanography physical instruments and techniques keywords practical data assimilation numerical modeling upwelling highfrequency radar data

the combined effect of transient wind driven upwelling and eddies on vertical nutrient fluxes and phytoplankton dynamics along ningaloo reef western australia we investigate the influence of wind stresses stratification and coastal mesoscale eddies on upwelling intensity vertical nutrient fluxes and phytoplankton biomass on the continental shelf off ningaloo reef in northwestern australia during an austral spring summer period a three dimensional 3 d hydrodynamic model roms regional ocean modeling system was coupled with a four component nitrogen based biogeochemical npzd model nitrogen phytoplankton zooplankton detritus to resolve the shelf circulation as well as the coupled nutrient and phytoplankton dynamics within a broad shelf region surrounding ningaloo reef the simulated currents temperatures and chlorophyll a concentrations generally agreed well with both the remotely sensed satellite images and observational data collected during a field experiment from september to november 2010 scenario tests for an individual wind driven upwelling event under a variety of hypothetical physical forcing conditions showed that shelf currents and biogeochemical variables were largely a function of wind stress and stratification however the functional relationships derived from this single wind event could not be extrapolated to other periods of the upwelling season due to the additional influence of 3 d mesoscale processes on the shelf the presence intensification and propagation of a coastal anticyclonic eddy during the study period strongly influenced the spatial and temporal variations in nutrient profiles which in turn caused fluctuations in vertical nutrient fluxes that were largely independent of wind stress these results emphasize that it is necessary to fully capture the 3 d details of the mesoscale and submesoscale coastal dynamics to properly predict upwelling induced coastal phytoplankton dynamics in eddy intensive shelf regions such as ningaloo reef

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

horizontal transport and the distribution of nutrients in the coastal transition zone off northern california effects on primary production phytoplankton biomass and species composition conductivity temperature depth surveys during 1988 encountered strong baroclinic jets that were evident in acoustic doppler current profiler and hydrographic data during june and july 1988 a filament with high surface nitrate high chlorophyll abundant populations of neritic centric diatoms and higher rates of primary production was evident perpendicular to the coast between point arena and point reyes however the high nutrient and phytoplankton regions were not in the baroclinic jets but were south and inshore of them surface water transported offshore by the strong baroclinic jets was found to have relatively low nutrient content suggesting that the jets themselves do not carry significant levels of coastally upwelled high nutrient water to the ocean interior the low nutrient and salinity content of the jet suggests that the water originated several hundred kilometers upstream although the jets themselves do not appear to transport significant levels of nutrients directly from the coastal regime to the oceanic regime dynamic processes associated with a meandering jet are likely responsible for high surface nutrients found several hundred kilometers offshore processes such as upwelling along the southern edge of the seaward jet result in significant enrichment of the coastal transition zone and in large blooms of neritic diatoms during 1988 the high nutrient high phytoplankton filament was present when the survey sequence began but then decayed after a month the surface and subsurface nitrate fields were coherent with the dynamic topography field throughout the survey sequence however the surface and integrated chlorophyll fields were coherent only through the first two surveys a decrease in phytoplankton biomass began during the third survey coincident with physical changes which occurred in that time frame 1 an intensification of the undercurrent and 2 changes in the surface circulation from predominantly offshore to predominantly longshore understanding the processes responsible for the uncoupling between biology and physics is paramount for realistic biological models of this region

arecibo radar imagery of mars the major volcanic provinces abstract we present earth based radar images of mars obtained with the upgraded arecibo s band 12 6 cm radar during the 2005 2012 oppositions the imaging was done using the same long code delay doppler technique as for the earlier pre upgrade imaging but at a much higher resolution 3 km and for some regions a more favorable sub earth latitude this has enabled us to make a more detailed and complete mapping of depolarized radar reflectivity a proxy for small scale surface roughness over the major volcanic provinces of tharsis elysium and amazonis we find that vast portions of these regions are covered by radar bright lava flows exhibiting circular polarization ratios close to unity a characteristic that is uncommon for terrestrial lavas and that is a likely indicator of multiple scattering from extremely blocky or otherwise highly disrupted flow surfaces all of the major volcanoes have radar bright features on their shields although the brightness distribution on olympus mons is very patchy and the summit plateau of pavonis mons is entirely radar dark the older minor shields paterae and tholi are largely or entirely radar dark which is consistent with mantling by dust or pyroclastic material other prominent radar dark features include the fan shaped deposits possibly glacial associated with the three major tharsis montes shields various units of the medusae fossae formation a region south and west of biblis patera where stealth deposits appear to obscure tharsis flows and a number of dark halo craters with radar absorbing ejecta blankets deposited atop surrounding bright flows several major bright features in tharsis are associated with off shield lava flows these include the olympus mons basal plains volcanic fields east and south of pavonis mons the daedalia planum flows south of arsia mons and a broad expanse of flows extending east from the tharsis montes to echus chasma the radar bright lava plains in elysium are concentrated mainly in cerberus and include the fluvio volcanic channels of athabasca valles grjota valles and marte valles as well as an enigmatic region at the southern tip of the cerberus basin some of the cerberus bright features correspond to the distinctive platy ridged flows identified in orbiter images the radar bright terrain in amazonis planitia comprises two distinct but contiguous sections a northern section formed of lavas and sediments debouched from marte valles and a southern section whose volcanics may derive in part from local sources this south amazonis region shows perhaps the most complex radar bright structure on mars and includes features that correspond to platy ridged flows similar to those in cerberus

the california current system in relation to the northeast pacific ocean circulation abstract the california current system is described in its regional setting using two modern datasets argo provides a broadscale view of the entire eastern north pacific ocean for the period 2004 2010 and the high resolution xbt network includes transects from honolulu to san francisco 1991 2010 and to los angeles 2008 2010 together these datasets describe a california current of 500 800 km width extending along the coast from 43 n to 23 n the mean southward transport of the california current is about 5 sv off central and southern california with about 2 5 sv of northward flow on its inshore side interannual variations are 50 or more of the mean transports the salinity minimum in the core of the california current is supplied by the north pacific current and by freshwater from the northern continental shelf and modified by alongshore geostrophic and across shore ekman advection as well as eddy fluxes and air sea exchange the heat and freshwater content of the california current vary in response to the fluctuating strength of the alongshore geostrophic flow on its offshore side the california current is influenced by north pacific intermediate waters at its deepest levels and by eastern subtropical mode waters on shallower density surfaces in total the sources of the california current its alongshore advection and its strong interactions with the inshore upwelling region and the offshore gyre interior combine to make this a rich and diverse ecosystem the present work reviews previous contributions to the regional oceanography and uses the new datasets to paint a spatially and temporally more comprehensive description than was possible previously

valles marineris mars wet debris flows and ground ice abstract detailed study of the valles marineris equatorial troughs suggests that the landslides in that area contained water and probably were gigantic wet debris flows one landslide complex generated a channel that has several bends and extends for 250 km further support for water or ice in debris masses includes rounded flow lobes and transport of some slide masses in the direction of the local topographic slope differences in speed and emplacement efficiency between martian and terrestrial landslides can be attributed to the entrainment of volatiles on mars but they can also be explained by other mechanisms support that the wall rock contained water comes from the following observations 1 the water within the landslide debris must have been derived from wall rock 2 debris appears to have been transported through tributary canyons 3 locally channels emerged from the canyons 4 the wall rock apprarently disintegrated and flowed easily and 5 fault zones within the troughs are unusually resistant to erosion the study further suggests that in the equatorial region of mars material below depths of 400 800 m was not desiccated during the time of landslide activity within the last billion years of martian history therefore the martian ground water or groundice reservoir if not a relic from ancient times must have been replenished

preface to special section on enhanced subarctic influence in the california current 2002 1 this special section discusses a rare phenomenon strong enhancement of subarctic influence in the california current system in the summer of 2002 this cold fresh anomaly in the upper halocline was more extreme than any prior observation though historical records extend back for several decades the subarctic anomaly extended more than 1500 km along the u s west coast from 49 n to 33 n it brought high nutrient waters into the coastal upwelling zone off oregon and northern california and produced exceptionally high chlorophyll concentrations inner shelf oxygen concentrations were very high near the surface and very low near the bottom the presence of this subarctic water mass was associated with anomalous southward currents detected by three different methods by satellite tracked drifters a mid shelf mooring and by satellite altimetry large scale wind forcing over the northeastern pacific during the previous winter and spring seems to be responsible for these anomalies

diagnostic and prognostic numerical circulation studies of the south atlantic bight some of the results from a series of diagnostic and prognostic numerical simulations of the circulation in the south atlantic bight sab are described the numerical model developed for the study is a three dimensional primitive equation time dependent coordinate model with an imbedded turbulent closure submodel which should yield realistic ekman surface and bottom layers an implicit numerical scheme in the vertical direction and a mode splitting technique in time are adopted for computational efficiency a significant portion of the paper is concerned with realistic specification of initial conditions for temperature and salinity surface forcing and lateral open boundary conditions the latter are determined by a simple diagnostic geostrophic and ekman dynamics model which provides dynamically consistent temperature salinity and velocity boundary conditions it appears from an exaination of the numerical simulations that the full model yields results that share many features in common with our general understanding of the circulation of the south atlantic bight the region includes shallow shelf waters as well as deeper water dominated by the gulf stream data for synoptic skill assessment however are not available

equilibrium structure and dynamics of the california current system this paper addresses the structure and dynamical mechanisms of regional and mesoscale physical variability in the subtropical northeast pacific ocean using the regional oceanic modeling system roms the model is configured with a u s west coast domain that spans the california current system ccs with a mesoscale horizontal resolution up to as fine as 3 5 km its mean seasonal forcing is by momentum heat and water fluxes at the surface and adaptive nudging to gyre scale fields at the open water boundaries its equilibrium solutions show realistic mean and seasonal states and vigorous mesoscale eddies fronts and filaments the level of eddy kinetic energy eke in the model is comparable to drifter and altimeter estimates in the solutions with sufficiently fine resolution because the model lacks nonseasonal transient forcing the authors conclude that the dominant mesoscale variability in the ccs is intrinsic rather than transiently forced the primary eddy generation mechanism is the baroclinic instability of upwelling alongshore currents there is progressive movement of meanseasonal currents and eddy energy offshore and downward into the oceanic interior in an annually recurrent cycle the associated offshore eddy heat fluxes provide the principal balance against nearshore cooling by mean ekman transport and upwelling the currents are highly nonuniform along the coast with important influences by capes and ridges in both maintaining mean standing eddies and launching transient filaments and fronts

mars paleostratigraphic restoration of buried surfaces in tharsis montes volcanism in the tharsis province of mars occurred in several different areas and was generally continuous without large time intervals between eruptive episodes major lava flow units are numerous and extensive but relatively thin in many places impact craters on buried surfaces project above younger flows that overlie them a new application of crater dating methods has been developed to aid in the identification of these buried surfaces and to determine their lateral extent the technique is especially adaptable to the tharsis region where the stratigraphic succession of major flow units has been established by detailed geologic mapping knowledge of the overall stratigraphy allows correlations to be made between known and unknown surfaces by comparing their crater frequencies at diameters large enough to insure their recognition on the buried unit the method has been applied to aid in the restoration of buried rock units and to construct a series of paleostratigraphic maps showing the sequence of major eruptive events in the tharsis region

a modeling study of shelf circulation off northern california in the region of the coastal ocean dynamics experiment 2 simulations and comparisons with observations 1 this is the second part of a modeling study of wind forced flow on the continental shelf off northern california in the region 37 40 n of the coastal ocean dynamics experiment code gan and allen 2002 analyzed the shelf flow response to idealized wind stress forcing in a process oriented study the study here applies forcing from observed winds and heat flux for april may 1982 and compares the model results with moored current and temperature measurements the princeton ocean model pom is used in a three dimensional limited area domain with a high resolution curvilinear grid approximately 1 km horizontal spacing 60 vertical levels and realistic coastline and bottom topography the objectives of the study are to simulate the response of the shelf circulation field to time varying observed wind stress and heat flux to compare model results with oceanographic observations to establish confidence in the model and to subsequently analyze the model fields and the model dynamical balances to help understand the behavior of the observed flow the model variables show overall good agreement with corresponding observations similar to the conclusions by gan and allen 2002 it is found that the alongshore variability of upwelling is mainly controlled by the interaction of the wind forced shelf flow with the coastline and bottom topography different dynamical regimes in the regions north and south of the coastal capes formed by pt reyes and pt arena and in the more uniform region between these capes are identified and investigated the results demonstrate that the coastal capes play a dominant role in causing alongshore variability of the upwelling flow including the setup of an alongshore pressure gradient that forces northward currents during relaxation of southward upwelling favorable winds an analysis of the balance of terms in the equation for potential temperature indicates that across shore temperature advection is the major contributor to the cooling of coastal water during upwelling with a larger magnitude to the south of the capes to the north of the capes however alongshore temperature advection is the dominant contributor to the colder water near the coast

morphometric properties of martian volcanoes 1 mars orbiter laser altimeter mola data have been used to construct digital elevation models dem of the martian volcanoes in order to determine height flank slope caldera depth and volumes summit elevations range from 21 1 km to 0 5 km and relief varies from 1 0 km to almost 22 km average flank slopes are in the range of 1 to 10 consistent with basaltic shield volcanism the very low slopes of highland patera are also consistent with pyroclastic volcanism minimum volumes range from 1012 to 1015 m3 estimates of the time required to build these volcanoes on the basis of long term terrestrial eruption rates range from hundreds of thousands to tens of millions of years

a modeling study of shelf circulation off northern california in the region of the coastal ocean dynamics experiment response to relaxation of upwelling winds 1 a two part modeling study of the wind forced flow on the continental shelf off northern california in the region 37 40 n of the coastal ocean dynamics experiment code is pursued this paper involves a process oriented study with idealized wind stress forcing gan and allen 2002 involves forcing with observed winds and heat flux for april may 1982 and comparison of model results with code observations a characteristic but previously unexplained response observed during code following the weakening or relaxation of southward upwelling favorable winds is the time dependent development of northward currents over the inner shelf next to the coast the presence of northward winds is not necessary for this occurrence the objective in this paper is to investigate the dynamics of the shelf flow response to upwelling wind relaxation events under idealized conditions in the basic case experiment a spatially uniform upwelling favorable southward wind stress of 0 1 pa is applied to the ocean initially at rest the stress is held constant for 10 days and then decreased linearly to zero over 3 days in response to the southward wind stress southward alongshore currents develop on the shelf accompanied by upwelling of cold dense water near the coast considerable spatial variability in the shelf flow clearly related to the alongshore variations in coastline and bottom topography is found the alongshore currents tend to separate from the coast south of capes and the coldest surface water is found at those locations as the winds decrease northward currents similar to those observed develop on the inner shelf next to the coast at many alongshore locations examination of the alongshore momentum balances shows that the northward currents are forced by a northward pressure gradient force associated with negative alongshore pressure gradients these pressure gradients are set up by the interaction of the wind forced flow with the alongshore variations in shelf topography in general negative alongshore pressure gradients intensified off pt reyes and pt arena by the gradient wind balance are found south of capes the negative pressure gradients geostrophically balance onshore flow at depth and upwelling is strengthened in these locations north of capes positive pressure gradients that are primarily in balance with nonlinear advective effects are found after the winds cease the forced across shelf circulation weakens and the resulting unbalanced negative pressure gradients south of the capes accelerate the alongshore currents northward processes with similar dynamics are found embedded in the more complex coastal ocean response to observed time varying winds by gan and allen 2002

textural and isotopic evidence for ca mg carbonate pedogenesis abstract models for evaluating the terrestrial carbon cycle must take into account not only soil organic carbon represented by a mixture of plant and animal remains but also soil inorganic carbon contained in minerals mainly in calcite and dolomite thick soil caliches derived from weathering of mafic and ultramafic rocks must be considered as sinks for carbon storage in soils the formation of calcite and dolomite from pedogenic alteration of volcanic tephras under an aridic moisture regime is studied in an unusually thick 3 m soil profile on gran canaria island canary islands spain the biological activity of the pedogenic environment soil respiration releases co2 incorporated as dissolved inorganic carbon dic in waters it drives the formation of low magnesian calcite and calcian dolomite over basaltic substrates with a 13c negative signature 8 to 6 vs v pdb precipitation of authigenic carbonates in the soil is accompanied by the formation of mg rich clay minerals and quartz after the weathering of basalts mineralogical textural compositional and isotopic variations throughout the soil profile studied indicate that dolomite formed at greater depths and earlier than the calcite the isotopic signatures of the surficial calcite and deeper dolomite crusts are primary and resulted from the dissolution precipitation cycles that led to the formation of both types of caliches under different physicochemical conditions dolomite formed within a clay rich matrix through diffusive transport of reactants it is precipitated from water with more negative 18o values 1 5 to 3 5 vs v smow in the subsoil compared to those of water in equilibrium with surficial calcite thus calcite precipitated after dolomite and directly from percolating solutions in equilibrium with vadose water enriched in 18o 0 5 to 1 5 due to the evaporation processes the accumulation of inorganic carbon reaches 586 1 kg m 2 in the soil studied which means that the carbon sequestration capacity of mafic rocks must be taken into account for certain terrestrial settings dolomite together with calcite should be assessed when quantifying carbon stored in arid semiarid soils as a result of the natural weathering processes

the role of climate and aeolian dust input in calcrete formation in volcanic islands lanzarote and fuerteventura spain calcretes are widely described in non marine settings with carbonates in their catchment or vicinity areas but in volcanic islands without carbonates in their substrate calcretes are not very common in lanzarote and fuerteventura canary islands characterized by impressive volcanic landscapes the sedimentary carbonate rocks are rare except for some recent marine and aeolian deposits in these settings very well developed calcretes cover large areas of the present landscape the source of calcium required for the formation of these calcretes has not been discussed in much detail till now although its role is critical to an understanding of the climatic conditions in which calcium was transported and fixed and of the calcrete formation processes the petrological and geochemical studies 87sr 86sr ratios 13c 18o major trace and ree carried out in this paper do confirm the important role of aeolian dust input in the formation of these calcretes canarian calcretes were mainly generated by pedogenic processes and are composed of various irregular carbonate lamina interbedded with fine clastic deposits our study indicates that these interbeddings were the result of several stages in which during dry periods aeolian dust deposition alternated with leaching and calcite precipitation during wetter periods when plants insects and bacteria played an important role in carbonate precipitation the 18o 2 70 to 2 22 vpdb and 13c 8 21 to 0 24 vpdb values indicate that calcretes were formed by pedogenic processes comparison of calculated 18o values for the canary calcretes with continental mid latitude calcrete values reflects the more homogeneous temperature regimes of calcrete formation in island oceanic settings calcrete87sr 86sr ratios 0 706357 to 0 709208 show strong affinity with those obtained in aeolian carbonate dust and marine deposits and are relatively different from those obtained in basalts ree major and trace element concentrations show that ca bearing minerals from volcanic host rock contributed little to calcrete formation and most of the calcium was supplied by aeolian deposits such as the aeolian dust coming from the sahara and sahel or sand dunes

role of membrane stresses in the support of planetary topography the principal purpose of this paper is to examine whether membrane stresses can support topographic loads on planetary elastic lithospheres it is found that the ability of a spherical shell to support loads through membrane stresses is determined by the nondimensional parameter ed gr2 where d is the thickness of the elastic lithosphere is the density difference between the mantle and crust and r is the radius of the planetary body when this parameter is large membrane stresses can fully support topographic loads without flexure and when it is small the influence of membrane stresses can be neglected solutions of the equation governing the behavior of a spherical shell are obtained for a topographic load expressed in terms of spherical harmonics spherical harmonic expansions of the measured gravity and topography for mars and the moon are compared with the theory it is found that for mars the support of topography is primarily due to membrane stresses for n 8 and for the moon for n 17 for mars the data for 4 n 7 give 0 5 for the moon the data have considerable scatter that is attributed to the mascons but generally correlate with 0 5 if bending stresses are neglected the governing equation for the deflection of the spherical shell is legendre s equation a general solution is obtained for an axisymmetric load this solution is applied to the tharsis region on mars the 60 65 compensation of this region requires that 0 6 the well defined fracture pattern surrounding the tharsis region is attributed to tensional membrane stresses

results from a three dimensional nested biological physical model of the california current system and comparisons with statistics from satellite imagery 1 a three dimensional model of the california current system ccs from 35 n to 48 n extending offshore to 134 w is coupled with a four component trophic model the model reproduces many conspicuous characteristics in the ccs including complex filamentary mesoscale surface features seen in the pigment and temperature from satellite imagery wind driven coastal upwelling at appropriate spatial and temporal scales and the close correlation between prominent features seen in pigment and those in temperature observed by satellites abbott and zion 1985 statistical estimates of the characteristic spatial scales of variability as calculated from the coupled nested model agree with those previously estimated from satellite images for both surface temperature and pigment denman and abbott 1988 1994 model estimates of the characteristic temporal scales of variability from decorrelation times agree with those previously estimated from satellite images typical model decorrelation times lie between 2 and 4 days in agreement with calculations from earlier sequences of coastal zone color scanner czcs and advanced very high resolution radiometer avhrr satellite images denman and abbott 1988 1994

effects of the 2013 2016 northeast pacific warm anomaly on physical and biogeochemical variables off northwestern baja california derived from a numerical npzd ocean model abstract interannual climatic anomalies have important physical and biological consequences for the southern part of the california current system ccs two examples of these anomalies are the blob and el nino phenomena the blob was an anomalously warm water mass that formed in the gulf of alaska during fall 2013 and then affected most of the eastern north pacific including the waters off baja california mexico in this work we use a biogeochemical nutrient phytoplankton zooplankton detritus npzd model coupled to a three dimensional hydrodynamic model which allowed the simulation of some of the physical and biological consequences of the anomalous warm 2013 2016 period the blob was observed in 2014 and el nino by mid 2015 a model observation comparison showed that in some cases the model solution deviates substantially from the observed vertical thermal structure but the temporal evolution of the spatially averaged variables diagnosed by the model shows good agreement with the observations except for the period from late 2015 to mid 2016 when the sea surface temperature sst is underestimated and the model failed to reproduce the correct sign of the surface chlorophyll a schl anomalies an eof analysis of the 15 year 2003 2017 record of monthly mean modeled variables allowed the identification of two main contributions to the model variability one mode mostly correlated with the multivariate el nino southern oscillation enso index mei explaining 50 of the variance of temperature t and dissolved nitrogen n and 10 of the variance of chlorophyll a chl and another mode mostly correlated with the coastal upwelling index cui anomaly explaining 50 70 of variance of chl and only 10 20 of variance of t and n in the 2013 2016 period an el nino signal diagnosed by the mei induced a remarkable warming off northwestern baja california as a consequence the thermocline and the nutricline deepened during this period and caused a deepening and weakening of the subsurface chl maximum scm around the southern region of the study area near punta baja these effects were more intense at the surface over the shelf but in the northern region south of southern california bight the effects were more intense subsurface seaward of the shelf break this enso modulated subsurface warming tends to weaken the southern california eddy during el nino events and intensify it during la nina episodes during the 2013 2015 period there was also a weakening of the upwelling favorable winds which caused a prolonged negative anomaly of the wind forcing reducing the nutrient flux and causing negative chl anomalies finally in addition to the partial relation between the enso and the warming observed along the baja california coast the anomalies were observed in this area 4 6 months before the onset of the el nino conditions mei 0 5 period when the blob was affecting the southern part of the ccs

exemple d etude geochimique et isotopique de circulations aquiferes en terrain volcanique sous climat semi aride amurga gran canaria iles canaries abstract a hydrochemical and isotopic study of a groundwater flow system in volcanic media has been carried out in the southern part of gran canaria canary islands monthly samples of precipitation were collected over a two year period at stations distributed all over the island sampling of groundwaters took place mainly from drillholes in the amurga phonolitic massif but also from wells and springs discharging from the volcanic and related detrital formations the 2 h vs 18 o relationship of the precipitation is close to the global meteoric water line two distinct altitudinal isotopic gradients are observed on the warm and dry southern slope the combination of a contribution of saharan dusts and seasprays and of partial evaporation explains the high content of dissolved salts cl so 2 4 in precipitation additional processes may be invoked as sources of groundwater mineralization leaching of silicate minerals during infiltration and or from hydrolysis during the long residence time of the waters in the volcanic rocks salt content is increased through a concentration of the percolating solutions by evaporation as shown by their stable isotope contents 18 o 2 h the groundwaters in the phonolitic aquifer are well differentiated from the deeper groundwaters which are recharged at an altitude of about 1000m above sea level or even less if exceptional episodes of rain have a lower heavy isotope content the interpretation of the 13 c contents of soil co 2 sampled throughout the area and of the 13 c and 14 c contents of total dissolved inorganic carbon tdic leads to the concept of an incorporation of pure biogenic carbon under open system conditions in the amurga waters for these groundwaters high estimates of residence time ca 11000 years can be calculated from the low 14 c activities in the neighbouring valleys the input of deep dead volcanic carbon and the occurrence of mixing do not allow an exact quantification of residence time values however they seem to be shorter than those measured for the amurga waters

fluid rock interaction in the miocene post caldera tejeda intrusive complex gran canaria canary islands insights from mineralogy and o and h isotope geochemistry the intra caldera volcaniclastic deposits of the miocene tejeda caldera on gran canaria host an similar to 12 km diameter intrusive complex comprising a peralkaline trachytic to phonolitic cone sheet swarm surrounding a central core of hypabyssal syenite stocks both intrusive rock types display textural and mineralogical features indicative of secondary fluid rock interaction including 1 deuteric mineral phases e g aegirine alkali amphibole analcime 2 turbid alkali feldspars and 3 hydrothermal mineral phases phyllosilicates fe ti oxides mn oxides and quartz altered cone sheets have whole rock delta o 18 values ranging from 0 center dot 1 to 10 center dot 0 parts per thousand n 22 and whole rock delta d values between 62 and 149 parts per thousand n 28 three altered syenite samples have whole rock delta o 18 values of 2 center dot 5 1 center dot 5 and 0 center dot 9 parts per thousand and corresponding delta d values of 91 99 and 121 parts per thousand the h2o concentrations of the altered cone sheets range from 0 center dot 4 to 0 center dot 8 wt n 28 and the altered syenites have h2o concentrations of 0 center dot 5 0 center dot 5 and 0 center dot 6 wt respectively the majority of altered samples are depleted in o 18 relative to the typical delta o 18 range for unaltered trachytes and syenites delta o 18 6 8 parts per thousand indicative of interaction with local meteoric water delta o 18 c 8 parts per thousand at temperatures epsilon 150 degrees c only one cone sheet sample appears petrographically unaltered and has a typical igneous isotopic composition delta o 18 7 center dot 1 parts per thousand delta d 48 parts per thousand and a relatively high h2o concentration 2 center dot 2 wt a weak correlation r 0 center dot 55 between delta d and h2o is observed in the cone sheets reflecting the combined effects of magmatic h2o exsolution and subsequent deuteric and hydrothermal alteration no systematic variation in delta o 18 or delta d was detected across the cone sheet swarm most likely reflecting overprinting of isotopic compositions during successive intrusive events however the highest delta o 18 values 8 center dot 2 10 center dot 0 parts per thousand occur in clay bearing cone sheets from the central part of the intrusive complex suggesting enhanced infiltration of relatively cool meteoric water in this area overall at least three phases of fluid rock interaction can be distinguished 1 deuteric alteration c 300 500 degrees c by late magmatic fluids expelled from a solidifying crystal mush 2 hydrothermal alteration epsilon 150 300 degrees c by meteoric water during the final stages of crystallization and or immediately following solidification of the intrusive complex 3 retrograde alteration related to the influx of relatively cool 150 degrees c meteoric waters

numerical treatment of cross shelf open boundaries in a barotropic coastal ocean model abstract using a barotropic coastal ocean model with a straight coastline and uniform cross shelf bottom slope seven different cross shelf open boundary conditions four of which are applied in either implicit or explicit form are compared in three numerical experiments 1 a mound of water is allowed to collapse and radiate waves toward the open boundaries 2 a uniform alongshelf wind stress is applied at zero time over the entire shelf and held constant for the duration of the experiment 3 a uniform cross shelf wind stress is applied at zero time over the entire shelf and held constant for the duration of the experiment the boundary condition which is most transparent to waves consists of a sponge at the outer edge of the model domain with an orlanski radiation condition at the outer edge of the sponge several open boundary conditions perform adequately in the wind stress experiments but the orlanski radiation condition alone without a sponge appears to give the best total performance of thes

statistics of mars topography from the mars orbiter laser altimeter slopes correlations and physical models data obtained recently by the mars orbiter laser altimeter mola were used to study the statistical properties of the topography and slopes on mars we find that the hemispheric dichotomy manifested as an elevation difference can be described by long baseline tilts but in places is expressed as steeper slopes the bimodal hypsometry of elevations on mars becomes unimodal when referenced to the center of figure contrary to the earth for which the bimodality is retained however ruling out a model in which the elevation difference is expressed in a narrow equatorial topographic step cannot be done by the hypsometry alone mars slope distribution is longer tailed than those of earth and venus indicating a lower efficiency of planation processes relative to relief building tectonics and volcanics we define and compute global maps of statistical estimators including the interquartile scale rms and median slope and characteristic decorrelation length of the surface a correspondence between these parameters and geologic units on mars is inferred surface smoothness is distinctive in the vast northern hemisphere plains where slopes are typically 0 5 amazonis planitia exhibits a variation in topography of 1 m over 35 km baselines the region of hematite mineralization in sinus meridiani is also smooth with median slopes lower than 0 4 but does not form a closed basin the shallower long wavelength portion of the lowlands topographic power spectrum relative to the highlands can be accounted for by a simple model of sedimentation such as might be expected at an ocean s floor the addition of another process such as cratering is necessary to explain the spectral slope in short wavelengths among their application these mola derived roughness measurements can help characterize sites for landing missions

the mars observer laser altimeter investigation the primary objective of the mars observer laser altimeter mola investigation is to determine globally the topography of mars at a level suitable for addressing problems in geology and geophysics secondary objectives are to characterize the 1064 nm wavelength surface reflectivity of mars to contribute to analyses of global surface mineralogy and seasonal albedo changes to assist in addressing problems in atmospheric circulation and to provide geodetic control and topographic context for the assessment of possible future mars landing sites the principal components of mola are a diode pumped neodymium doped yttrium aluminum garnet laser transmitter that emits 1064 nm wavelength laser pulses a 0 5 m diameter telescope a silicon avalanche photodiode detector and a time interval unit with 10 ns resolution mola will provide measurements of the topography of mars within approximately 160 m footprints and a center to center along track foot print spacing of 300 m along the mars observer subspacecraft ground track the elevation measurements will be quantized with 1 5 m vertical resolution before correction for orbit and pointing induced errors mola profiles will be assembled into a global 0 2 deg x 0 2 deg grid that will be referenced to mars center of mass with an absolute accuracy of approximately 30 m other data products will include a global grid of topographic gradients corrected individual profiles and a global 0 2 deg x 0 2 deg grid of 1064 nm surface reflectivity

new radar derived topography for the northern hemisphere of mars earth based radar altimetry data for the northern equatorial belt of mars 6 s 23 n have recently been reduced to a common basis corresponding to the 6 1 mbar reference surface a first look at these data indicates that the elevations of tharsis elysium and lunae planum are lower by 2 5 km than has been suggested by previous estimates these differences show that the required amount of tectonic uplift or constructional volcanism for each area is less than has been previously envisioned atmospheric or surficial conditions are suggested which may explain the discrepancies between the radar topography and elevations measured by other techniques the topographies of chryse planitia syrtis major and valles marineris are also described

late stage intrusive activity at olympus mons mars summit inflation and giant dike formation by mapping the distribution of 351 lava flows at the summit area of olympus mons volcano on mars and correlating these flows with the current topography from the mars orbiter laser altimeter mola we have identified numerous flows which appear to have moved uphill this disparity is most clearly seen to the south of the caldera rim where the elevation increases by 200 m along the apparent path of the flow additional present day topographic anomalies have been identified including the tilting down towards the north of the floors of apollo and hermes paterae within the caldera and an elevation difference of 400 m between the northern and southern portions of the floor of zeus patera we conclude that inflation of the southern flank after the eruption of the youngest lava flows is the most plausible explanation which implies that intrusive activity at olympus mons continued towards the present beyond the age of the youngest paterae 200 300 myr neukum et al 2004 robbins et al 2011 we propose that intrusion of lateral dikes to radial distances 2 000 km is linked to the formation of the individual paterae at olympus mons two specific dikes to the se of the volcano are inferred to have volumes of 4 400 km3 and 6 100 km3 greater than the volumes of individual calderas and implying triggering of both caldera collapse and lateral dike injection by the arrival of large inputs of magma from the mantle a comparable disparity between lava flow direction and current topography together with a tilted part of the caldera floor has been identified at ascraeus mons

the olympus mons aureole formation by gravitational spreading new observations of the aureole deposits of olympus mons are in agreement with previous suggestions that the aureole lobes could have been formed by movement under gravity away from the observed scarps the characteristic corrugated morphology of the aureole is probably secondary formed by erosion along structural inhomogeneities geometries of the corrugations and translational faults in the aureole deposits favor a mechanism of emplacement that involves material with substantial shear strength rather than viscous flow estimates of the aspect ratios of terrestrial landslides nappes and ash flows suggest that the aureole deposits are more similar in overall shape to slide emplaced bodies than to pyroclastic flows although martian physical conditions permit the formation of ash flows there is no positive evidence for their existence a gravitational spreading mechanism is proposed that involves imbricate thrusting in distal regions analogous with terrestrial thrust sheets corrugations in the aureole developed by erosion along imbricate or listric faults basal shear stresses on the decoupling surface may have been of the order of 106 pa 10 bars the nature of the decoupling surfaces in the proximal regions is uncertain but is likely to have been the topographic surface in distal parts the aureole deposits were probably emplaced as a series of sheets by spreading under gravity from an ancestral olympus mons which extended farther to the northwest than does the present volcano as a result of the accumulation of lavas under the then prevailing stress conditions recent lava eruptions from the volcano have been concentrated in northeast and southwest sectors indicating a changed stress regime since aureole emplacement

a modeling study of the three dimensional continental shelf circulation off oregon part ii dynamical analysis abstract sixty day simulations of the subinertial continental shelf circulation off oregon are performed for a hindcast study of summer 1999 in part i the model results are shown to compare favorably with in situ currents and hydrographic measurements obtained from an array of moored instruments and field surveys and high frequency radar derived surface currents in this paper the modeled three dimensional time varying circulation and dynamical balances are analyzed providing a detailed synoptic description of the continental shelf circulation off oregon for summer 1999 the circulation is clearly wind driven and strongly influenced by alongshore variations in shelf topography in the region of the coast where the alongshore topographic variations are small the upwelling circulation is consistent with standard conceptual models for two dimensional across shore circulation in the regions where the alongshore topographic variations are greater the upwelling circulation is highly three dimensional ov